JP2003188445A - Optical amplifier and optical amplifier components - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly efficient optical amplifier and optical amplifier components for a 1500 nm band which has excellent mechanical strength and weather resistance property. <P>SOLUTION: The optical amplifiers 1-1, 1-2 use, as an optical amplifying medium, Er-added optical fiber where Er is added at least to either one of a core and a clad or an Er-added waveguide where Er is added at least to either one of the core and the clad formed on a substrate. At least one optical amplifier is provided and this optical amplifier is comprised of an optical amplifying medium and an excited light source. At least one optical filter 2 is provided and this optical filter is configured to control the optical amplification of a first wavelength band by reducing the light beam of the first wavelength band which shows the maximum gain among wavelength bands where the gain can be obtained by the optical amplifying medium. With this controlling process, the optical amplification of a second wavelength band located at the hem in the low wavelength side to show a comparatively small gain can be accelerated among the wavelength bands where the gain can be obtained by the optical amplifying medium, and thereby an optical signal of the amplified second wavelength band can be outputted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplifier and an optical amplification component, and more particularly, to an optical amplification medium including an Er-doped optical fiber having Er added to at least one of a core and a clad, or an Er-doped optical waveguide. The present invention relates to an optical amplifier and an optical amplification component used in.

[0002]

2. Description of the Related Art Due to the explosive increase in communication demand typified by the Internet in recent years, the necessity for increasing the capacity of an optical transmission system of a trunk system has increased, and signals of a plurality of wavelengths are transmitted to one fiber. , Wavelength multiplexing (Wavelength-divis
Ion-multiplexing (WDM) systems are being developed. In the trunk type WDM system, since the optical amplifier is used as the repeater, the wavelength band to be used is limited to the amplification wavelength band of the optical amplifier.

As an optical amplifier, an Er-doped fiber amplifier (EDFA) in which Er is added as an active ion to a silica-based fiber is used, and an amplification band is about 1545 to 1560 nm and about 1570 to 16 nm.
00 nm. Here, the dispersion of the EDFA gain between the wavelength-division multiplexed channels (WDM channels) to be transmitted is reduced, the dispersion of the signal-to-noise ratio (SN ratio) between the WDM channels at the time of transmission is eliminated, and the system is extended. May be planned.

In this case, in order to reduce variations in EDFA gain between channels, an optical filter is added to the EDFA to flatten the gain spectrum (gain flattening). The amplification band when the gain is flattened by the optical filter of the EDFA is about 1530 to 1560 n in the 1550 nm band.
m is approximately 1570 to 1605 nm in the 1580 nm band (for example, see Non-Patent Document 1).

On the other hand, the above-mentioned 1550 nm band and 15
Development of a system exceeding the transmission capacity of the 80 nm band is also in progress, and as a wavelength band different from the 1550 nm band and the 1580 nm band, a new wavelength range (1500 nm) near 1500 nm where the transmission loss and dispersion value of the optical fiber for transmission is small.
A system using the (nm band) has been researched and developed (for example, see Non-Patent Document 2).

In the system studied by Miyamoto et al., A Tm-doped fiber amplifier (TDF) is used as an optical amplifier.
A) is used. TDFA amplifies the signal light by stimulated emission of Tm ions that are added in a minute amount to the fiber. However, since phonon energy is high in silica-based glass, even if Tm ions are added to the silica-based fiber, the non-radiative transition probability from the amplification starting position is larger than the stimulated emission transition probability, so that sufficient amplification is achieved. This cannot be done, and the Tm-doped silica fiber amplifier gain is about 10 dB at most (see Non-Patent Document 3, for example).

In an optical transmission system using an optical amplifier as a repeater, the transmission loss between the optical amplifiers is about 1.
Since it is 5 dB or more (about 25 dB at maximum), the gain of the Tm-doped silica fiber amplifier of Segi et al. Is not sufficient. Therefore, in place of the silica fiber, a fluoride glass having a small phonon energy is used as a host of Tm ions.
TDFA has been realized using an m-doped fluoride fiber as an amplification medium (see, for example, Non-Patent Document 4).

[0008]

[Patent Document 1] JP-A-5-129683

[0009]

[Patent Document 2] JP-A-6-318754

[0010]

[Patent Document 3] Japanese Patent Laid-Open No. 10-229238

[0011]

[Patent Document 4] JP-A-5-129683

[0012]

[Patent Document 5] JP-A-6-318754

[0013]

[Patent Document 6] Japanese Patent Laid-Open No. 10-229238

[0014]

[Non-Patent Document 1] T. Ito et al., OFC2000 PD24

[0015]

[Non-Patent Document 2] Y. Miyamoto et al., OAA2001, PD6,
J. Bromage et al., OFC2001; PD4

[0016]

[Non-Patent Document 3] Segi et al., 2001 IEICE General Conference C-2-143

[0017]

[Non-Patent Document 4] S. Aozasa et al., IEE Electronics
Letters, vol. 36, no. 5, pp.418-419, 2000

[0018]

[Non-Patent Document 5] HS Kim et al, IEEE Phonics Tecn
ology Letters, vol. 10, no.8, pp. 790-792, 1998,
H. Masuda et al., IEEE Phonics Tecnology Letters, v
ol. 34, no. 6, pp. 567-568, 1998

[0019]

However, the theoretical mechanical strength of the fluoride fiber is smaller than that of the silica fiber. In addition, the weather resistance is low, such that it easily reacts with water to be crystallized, resulting in increased loss and reduced mechanical strength. Therefore, in order to supplement the mechanical strength, it is necessary to have a special packaging having a structure in which stress is not easily applied to the fiber and having excellent moisture resistance.

Further, a WDM coupler for pumping light multiplexing,
Optical amplifier components such as an isolator for suppressing oscillation and a filter for gain flattening use a silica-based fiber as a pigtail fiber. Therefore, when a Tm-doped fluoride fiber is used as an amplification medium, a fluoride is used. It is necessary to connect different types of fibers such as fibers and silica-based fibers. Here, since the melting point of fluoride glass is different from that of silica glass, the fusion splicing technique widely used for connecting silica fibers cannot be used.

Therefore, a mechanical connection is made by using a V-groove or the like. However, if the connecting portion becomes larger than that of the fusion splicing, or if there is a gap between the fluoride fiber and the silica-based fiber due to vibration, reflection occurs. However, there is a problem that the amplification characteristic of the optical amplifier is deteriorated due to the oscillation.

On the other hand, in the system studied by Bromage et al., A fiber Raman amplifier (FR) is used as an optical amplifier.
A) is used. In FRA, the fiber length of the amplification medium is required to be about several km, and it is difficult to downsize the optical amplifier. Furthermore, the power conversion efficiency from pumping light to signal light is 1
It is extremely small, 0% or less, and when a semiconductor laser (LD) is used as an excitation light source, a plurality of high-power LDs are required, which is an expensive optical amplifier.

The present invention has been made in view of the above problems, and an object thereof is a conventional 1500 n
The optical amplification medium of the m-band optical amplifier solves the problem that the power conversion efficiency is small or the mechanical strength is small and the weather resistance is low, and the mechanical strength and weather resistance are excellent, and the high efficiency 1500
An object of the present invention is to provide an optical amplifier component for realizing a nm band optical amplifier and a highly efficient 1500 nm band optical amplifier.

[0024]

In order to achieve such an object, the present invention provides an Er-doped fiber in which at least one of a core and a clad is doped with Er, or a core and a clad formed on a substrate. An optical amplifier using an Er-doped waveguide, at least one of which is Er-doped, as an optical amplification medium, comprising at least one optical amplification unit comprising the optical amplification medium and a pumping light source. Controlling means for suppressing the light amplification in the first wavelength band by reducing the light in the first wavelength band where the gain is maximum in the wavelength band in which the gain is obtained in the optical amplification medium; Therefore, in the wavelength band where the gain is obtained in the optical amplification medium,
It is characterized in that it is located at the skirt on the low wavelength side, promotes optical amplification of a second wavelength band having a relatively small gain, and outputs the amplified optical signal of the second wavelength band.

The invention described in claim 2 is the same as claim 1
In the invention described in (3) above, an optical filter is provided as a means for suppressing the optical amplification in the first wavelength band.

The invention described in claim 3 is the same as claim 1
Or in the invention described in 2, the number of the pumping light source is one, the optical amplification unit shares the pumping light source, and a branching unit for branching the pumping light generated by the pumping light source, and a branching unit by the branching unit. And an optical means for guiding the generated excitation light to each optical amplification section.

The invention according to claim 4 is the same as the invention according to claim 1, 2 or 3, which comprises N optical amplifying sections and (N-1) optical filters. The optical amplifying section and the optical filter are alternately connected in series so that the optical amplifying section is provided in.

The invention described in claim 5 is the same as claim 1.
In the invention described in any one of (1) to (4), the total loss of the optical filters is 25 dB in the first wavelength band.
The above is characterized.

The invention according to claim 6 is the same as claim 1
In the invention described in any one of (1) to (5), the total loss of the optical filters is 30 dB or more in the first wavelength band.

The invention described in claim 7 is the same as claim 1.
In the invention described in any one of (1) to (6), the first wavelength band is 1
520 to 1560 nm, and the second wavelength band is 1
It is characterized by being 485 to 1520 nm.

The invention described in claim 8 is the invention according to claim 7.
In the invention described in (1), the optical filter is 1490-
It is an optical filter that flattens the optical power of 1520 nm.

The invention described in claim 9 is the same as in claim 8.
In the invention described in paragraph 1, the optical filter has an optical power attenuation amount in the first wavelength band and 1500 to 500 so as to flatten a gain from the first wavelength band to the second wavelength band. It is an optical filter in which the balance of the optical power attenuation amount at 1520 nm is adjusted, and in addition to the second wavelength band, the signal light of the first wavelength band is also amplified and output.

The invention according to claim 10 is the invention according to any one of claims 1 to 6, wherein the first wavelength band is 1490 to 1560 nm and the second wavelength band is 1450 to 1490 nm. It is characterized by

The invention described in claim 11 is the invention described in claims 1 to 6, wherein the first wavelength band is 1520 nm to 1560 nm and the second wavelength band is 1485 to 1520 nm and 1570. ~ 1610
It is characterized by being nm.

According to a twelfth aspect of the present invention, in the invention according to the first to eleventh aspects, the equivalent fiber length or equivalent waveguide length (fiber length or waveguide length, Er It is characterized in that the additive concentration (wt ppm) product is a predetermined value with which a signal gain of 15 dB or more can be obtained in the second wavelength band.

According to a thirteenth aspect of the present invention, in the invention of the twelfth aspect, the equivalent fiber length or the waveguide length of the optical amplification medium is 1.5 × 10 ⁻⁴ m.
-It is characterized by being an Er-doped silica-based fiber or a waveguide having a wtppm or more.

According to a fourteenth aspect of the invention, in the invention of the twelfth aspect, the equivalent fiber length or waveguide length of the optical amplification medium is 0.7 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped tellurite fiber or waveguide having a wtppm or more.

According to a fifteenth aspect of the invention, in the invention of the twelfth aspect, the optical amplification medium has the equivalent fiber length or waveguide length of 1.2 × 10 ⁻⁴ m.
It is characterized by being an Er-doped aluminosilicate fiber or a waveguide of wtppm or more.

According to a sixteenth aspect of the present invention, in the invention according to the twelfth aspect, the equivalent fiber length or the waveguide length of the optical amplification medium is 1.0 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped phosphate salt fiber or waveguide of wtppm or more.

Further, the invention according to claim 17 is the invention according to claim 12, wherein the equivalent fiber length or the waveguide length of the optical amplification medium is 1.3 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped fluorophosphate fiber or waveguide of wtppm or more.

The invention according to claim 18 is the invention according to claim 12, wherein the optical amplification medium has the equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m.
-It is characterized by being an Er-doped fluoride fiber or a waveguide of wtppm or more.

The invention according to claim 19 is the invention according to claim 12, wherein the equivalent fiber length or the waveguide length of the optical amplification medium is 0.6 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped bismuth oxide-based fiber or waveguide of wtppm or more.

According to a twentieth aspect of the invention, in the invention of the twelfth aspect, the equivalent fiber length or waveguide length of the optical amplification medium is 1.5 × 10 ⁻⁴ m.
It is characterized by being an Er-doped chalcogenide fiber or a waveguide of wtppm or more.

The invention described in claim 21 is characterized in that, in the invention described in any one of claims 1 to 20, it is provided with an electric means for controlling the temperature of the Er-doped fiber.

The invention according to claim 22 is the same as the invention according to claims 1 to 21, wherein the E of the optical amplification medium is
The total loss of r at 1480 nm is a predetermined value with which a signal gain of 15 dB or more can be obtained in the second wavelength band.

According to a twenty-third aspect of the invention, in the invention of the twenty-second aspect, the optical amplification medium is an Er-doped quartz fiber or a waveguide having a total Er loss at 1480 nm of 33 dB or more. Characterize.

In the invention described in claim 24, in the invention described in claim 22, the optical amplification medium is an Er-doped tellurite fiber or a waveguide having a total Er loss at 1480 nm of 32 dB or more. Is characterized by.

[0048] According to a twenty-fifth aspect of the invention, in the twenty-third aspect of the invention, the optical amplification medium is an Er-doped aluminosilicate fiber or a waveguide having a total Er loss at 1480 nm of 30 dB or more. It is characterized by

According to a twenty-sixth aspect of the present invention based on the twenty-second aspect, the optical amplifying medium is an Er-doped phosphate fiber or a waveguide having a total Er loss at 1480 nm of 33 dB or more. It is characterized by

According to a twenty-seventh aspect of the present invention based on the twenty-second aspect, the optical amplification medium is an Er-doped fluorophosphate fiber or a waveguide having a total Er loss at 1480 nm of 35 dB or more. Is characterized by.

In the invention described in Item 28, in the invention described in Item 22, the optical amplification medium is an Er-doped fluoride fiber or a waveguide having a total Er loss at 1480 nm of 32 dB or more. Is characterized by.

According to a twenty-ninth aspect of the present invention, in the invention according to the twenty-second aspect, the optical amplification medium is an Er-doped bismuth oxide-based fiber or waveguide having a total Er loss at 1480 nm of 30 dB or more. It is characterized by

According to a thirtieth aspect of the present invention, in the invention according to the twenty-second aspect, the optical amplification medium is an Er-doped chalcogenide fiber or a waveguide having a total Er loss at 1480 nm of 35 dB or more. Characterize.

According to a thirty-first aspect of the invention, in the invention of the first to thirtieth aspects, the excitation light source is 98
It is characterized by being a 0 nm band semiconductor laser.

According to a thirty-second aspect of the present invention, at least one of the core and the clad wired on the wiring board is made of Er.
In an optical amplifying component comprising an Er-doped optical fiber doped with ???, the gain being the maximum in the wavelength band in which the gain is obtained in the Er-doped optical fiber? Of at least one optical filter that reduces light in the wavelength band of 1 to suppress optical amplification of the first wavelength band, and in the wavelength band in which gain is obtained in the optical amplification medium by the suppression, a low wavelength It is characterized in that it is located at the tail of the side and promotes optical amplification of a second wavelength band having a relatively small gain, and the amplified optical signal of the second wavelength band is output.

The invention described in Item 33 is an optical amplification component comprising an Er-doped optical fiber in which at least one of a core and a clad is doped with Er, and the Er-doped optical fiber is used as an optical amplification medium. A grating is formed in the core or the clad, and the grating reduces the light in the first wavelength band having the maximum gain in the wavelength band in which the gain is obtained in the Er-doped optical fiber to reduce the first wavelength. A grating having an optical filter function of suppressing optical amplification of a band, and by the suppression,
In the wavelength band in which the gain is obtained in the optical amplification medium, the optical amplification is performed in the second wavelength band located at the skirt on the low wavelength side and having a relatively small gain, and the amplified second wavelength band An optical signal is output.

According to a thirty-fourth aspect of the invention, in the thirty-third aspect of the invention, the grating is a chirped grating.

The invention described in Item 35 is the invention described in Item 33, wherein the grating is a plurality of gratings having different periods.

The invention described in Item 36 is provided with an optical waveguide which is formed on a substrate and in which at least one of a core and a clad is doped with Er, and a silica-based pigtail fiber connected to the optical waveguide. In an optical amplification component using the Er-doped optical waveguide as an optical amplification medium, the light in the first wavelength band having the maximum gain is reduced in the wavelength band in which the gain is obtained by the Er-doped optical waveguide, and At least one optical filter that suppresses optical amplification in the wavelength band of 1 is provided, and the suppression is located at the skirt on the low wavelength side in the wavelength band in which the gain is obtained in the optical amplification medium, and the gain is relatively high. The amplified second light which promotes optical amplification in the small second wavelength band.
It is characterized in that an optical signal in the wavelength band of is output.

The invention described in Item 37 is the invention described in Items 32 to 36, wherein the total loss of the optical filters is 25 dB or more in the first wavelength band. .

The invention described in Item 38 is the invention described in Items 32 to 36, wherein the total loss of the optical filters is 30 dB or more in the first wavelength band. .

The invention described in Item 39 is the optical amplification component, wherein at least one of the core and the clad is provided with N Er-doped fibers, and the Er-doped fibers are used as an optical amplification medium. At least N optical filters that suppress light amplification in the first wavelength band by reducing the light in the first wavelength band in which the gain is maximum in the wavelength band in which the gain is obtained by the Er-doped fiber or ( N-1)
Provided individually, the Er-doped fiber and the optical filter are alternately connected in series, and by the suppression, in the wavelength band in which the gain is obtained in the optical amplification medium, located at the skirt on the low wavelength side,
It is characterized in that the amplification of the second wavelength band having a relatively small gain is promoted and the amplified optical signal of the second wavelength band is output.

[0063] The invention as set forth in claim 40, further comprising an Er-doped fiber in which at least one of the core and the clad is doped with Er, and in the optical amplification component using the Er-doped fiber as an optical amplification medium, the core or the clad is provided. To at least one of them is doped with at least one kind of rare earth ion selected from Pr, Nd, Sm, Tb, Dy, and Tm, and the rare earth ion is in a wavelength band where a gain is obtained in the Er-doped fiber. Is a rare earth ion having a function of an optical filter that reduces light in the first wavelength band having the maximum gain and suppresses optical amplification in the first wavelength band,
Due to the suppression, in the wavelength band where the gain is obtained in the optical amplification medium, the second wavelength band which is located at the bottom of the low wavelength side and has a relatively small gain is promoted to be amplified. It is characterized in that an optical signal in the wavelength band of is output.

The invention as set forth in claim 41, further comprising an Er-doped fiber in which at least one of the core and the clad is doped with Er, and the Er-doped fiber is used as an optical amplification medium in the optical amplification component. The fiber is bent with a radius of curvature equal to or less than a reference value and has a loss due to the bending, and the loss due to the bending is a first wavelength at which the gain is maximum in a wavelength band where the gain is obtained in the Er-doped fiber. Has a function of reducing light in the band to suppress optical amplification in the first wavelength band, and is positioned at the skirt on the low wavelength side in the wavelength band in which gain is obtained in the optical amplification medium by the suppression. Then
It is characterized in that the amplification of the second wavelength band having a relatively small gain is promoted and the amplified optical signal of the second wavelength band is output.

According to the 42nd aspect of the present invention, at least one of the core and the clad is provided with an Er-doped fiber, and in the optical amplification component using the Er-doped fiber as an optical amplification medium, a plurality of claddings are provided. And having a cutoff wavelength of a fundamental mode of light propagating through the Er-doped fiber, and a loss on a wavelength side longer than the cutoff wavelength has a maximum gain in a wavelength band in which the gain is obtained in the Er-doped fiber. Has a function of reducing light in the first wavelength band to suppress optical amplification in the first wavelength band, and by the suppression,
In the wavelength band in which the gain is obtained in the optical amplification medium, the optical amplification is performed in the second wavelength band located at the skirt on the low wavelength side and having a relatively small gain, and the amplified second wavelength band An optical signal is output.

The invention as set forth in claim 43 is the invention as set forth in claim 41 or 42, wherein the Er-doped fiber is any of a W-type fiber, a triple-clad type fiber and a quadruple-clad type fiber. Is characterized by.

In the invention described in Item 44, in the invention described in Items 41, 42 or 43, the function of suppressing the optical amplification in the first wavelength band gives a loss to the first wavelength band. It is a function, and the total loss is 30 dB or more in the first wavelength band.

The invention described in Item 45 is the invention described in Items 32 to 44, in which the first wavelength band is 1520 to 1560 nm and the second wavelength band is 1485 to 1520 nm. It is characterized by

The invention described in Item 46 is, in the invention described in Items 32 to 40, characterized in that the optical filter is an optical filter which flattens the optical power of 1490 to 1520 nm.

The invention according to claim 47 is the invention according to claims 32 to 40, wherein the optical filter has a flattened gain from the first wavelength band to the second wavelength band. As described above, the optical filter is such that the balance between the optical power attenuation amount in the first wavelength band and the optical power attenuation amount in 1500 to 1520 nm is adjusted, and in addition to the second wavelength band, the first wavelength The band is also amplified and output.

The invention described in Item 48 is the invention described in Items 32 to 44, in which the first wavelength band is 1490 to 1560 nm and the second wavelength band is 1450 to 1490 nm. It is characterized by

The invention described in Item 49 is the invention described in Items 32 to 48, wherein the equivalent fiber length or equivalent waveguide length of the optical amplification medium is 15 dB in the second wavelength band. It is characterized in that it is a predetermined value with which the above signal gain is obtained.

The invention described in claim 50 is the invention described in claim 49, wherein the equivalent fiber length or waveguide length of the optical amplification medium is 1.5 × 10 ⁻⁴ m.
-It is characterized by being an Er-doped silica-based fiber or a waveguide having a wtppm or more.

According to a fifty-first aspect of the present invention based on the fifty-ninth aspect, the optical amplification medium has an equivalent fiber length or waveguide length of 0.7 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped tellurite fiber or waveguide having a wtppm or more.

The invention of claim 52 is the invention of claim 49, wherein the equivalent fiber length or waveguide length of the optical amplifying medium is 1.2 × 10 ⁻⁴ m.
It is characterized by being an Er-doped aluminosilicate fiber or a waveguide of wtppm or more.

The invention described in Item 53 is the invention described in Item 49, wherein the equivalent fiber length or waveguide length of the optical amplification medium is 1.0 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped phosphate salt fiber or waveguide of wtppm or more.

According to the invention described in Item 54, in the invention described in Item 49, the equivalent fiber length or waveguide length of the optical amplification medium is 1.3 × 10 ⁻⁴ m.
It is characterized in that it is an Er-doped fluorophosphate fiber or waveguide of wtppm or more.

According to a 55th aspect of the present invention, in the 49th aspect of the present invention, the equivalent fiber length or waveguide length of the optical amplification medium is 1.5 × 10 ⁻⁴ m.
-It is characterized by being an Er-doped fluoride fiber or a waveguide of wtppm or more.

According to a 56th aspect of the present invention, in the invention according to the 49th aspect, the equivalent fiber length or waveguide length of the optical amplification medium is 0.6 × 10 ⁻⁴ m ·
It is characterized by being an Er-doped bismuth oxide-based fiber or a waveguide of wt ppm or more.

The invention described in Item 57 is the invention described in Item 49, wherein the equivalent fiber length or waveguide length of the optical amplification medium is 1.5 × 10 ⁻⁴ m.
It is characterized by being an Er-doped chalcogenide fiber or a waveguide of wtppm or more.

The invention described in Item 58 is characterized in that, in the invention described in Items 32 to 57, electrical means for controlling the temperature of the Er-doped fiber is provided.

The invention described in Item 59 is the invention described in Items 32 to 58, in which the total loss of Er of the optical amplification medium at 1480 nm is 15 dB or more in the second wavelength band. Is a predetermined value that can be obtained.

According to the invention described in Item 60, in the invention described in Item 59, the optical amplification medium is an Er-doped quartz fiber or a waveguide whose total loss of Er at 1480 nm is 33 dB or more. Characterize.

Further, in the invention described in Item 61, in the invention described in Item 59, the optical amplification medium is an Er-doped tellurite fiber or a waveguide having a total Er loss at 1480 nm of 32 dB or more. Is characterized by.

According to the invention described in Item 62, in the invention described in Item 59, the optical amplification medium is an Er-doped aluminosilicate fiber or waveguide having a total Er loss at 1480 nm of 32 dB or more. It is characterized by

According to a 63rd aspect of the present invention, in the 59th aspect of the present invention, the optical amplification medium is an Er-doped phosphate fiber or a waveguide having a total Er loss at 1480 nm of 33 dB or more. It is characterized by

According to a sixty-fourth aspect of the invention, in the fifty-ninth aspect of the invention, the optical amplifying medium is an Er-doped fluorophosphate fiber or a waveguide having a total Er loss at 1480 nm of 35 dB or more. Is characterized by.

According to the 65th aspect of the present invention, in the 59th aspect of the present invention, the optical amplification medium is an Er-doped fluoride fiber or a waveguide having a total Er loss at 1480 nm of 32 dB or more. Is characterized by.

The invention described in Item 66 is the invention described in Item 59, wherein the optical amplification medium is an Er-doped bismuth oxide fiber or a waveguide having a total Er loss at 1480 nm of 30 dB or more. It is characterized by

According to a 67th aspect of the present invention, in the 59th aspect of the present invention, the optical amplifying medium is an Er-doped chalcogenide fiber or a waveguide having a total Er loss at 1480 nm of 35 dB or more. Characterize.

The invention described in Item 68 is the optical amplification component according to any one of Items 32 to 67, a pumping light source for generating pumping light to the optical amplification component, and pumping light from the pumping light source. Optical means for coupling the signal light of the second wavelength band and guiding it to the optical amplification component is provided.

The invention described in Item 69 is the invention described in Item 68, wherein the excitation light source is 980 nm.
It is a band semiconductor laser.

According to a 70th aspect of the present invention, there is provided an optical amplifying component according to any one of the 32nd to 67th aspects, a pumping light source for generating a pumping light to the optical amplifying component, and a wavelength band of 1450 to 1520nm. And a fiber grating that reflects a part of light at a part of the wavelength in the wavelength band of 1450 to 1520 nm.

According to a seventy-first aspect of the present invention, there is provided an optical amplifying component according to any one of the thirty-second to sixty-seventh aspects, a pumping light source for generating pumping light to the optical amplifying component, and a wavelength band of 1450 to 1520 nm. A mirror that totally reflects a part or the whole wavelength band, a mirror that reflects a part of the light in a part or the whole wavelength band of 1450 to 1520 nm, and 1450 to
The laser device is provided with a bandpass filter that transmits a part of the wavelength of the wavelength band of 1520 nm.

The invention described in Item 72 is the invention described in Item 70 or Item 71, wherein the excitation light source is a 980 nm band semiconductor laser.

The invention described in Item 73 is characterized by including the optical amplification component described in Items 32 to 67 and a pumping light source for generating pumping light to the optical amplification component.

The invention according to claim 74 is the same as the invention according to claim 73, wherein the excitation light source is 980 nm.
It is a band semiconductor laser.

The invention described in Item 75 is provided with the optical amplifier according to any one of Items 1 to 31 or 68 and 69 as an amplifying section, and amplifies the signal light in the wavelength band of 1570 to 1610 nm. Equipped with an amplifier, 1490-1
Signal light in the wavelength band of 520 nm and 1570 to 16
The optical amplifier includes a demultiplexer for demultiplexing the signal light in the wavelength band of 10 nm and a multiplexer for demultiplexing the signal light.
The ASE light of 520 to 1560 nm is transmitted to the above-mentioned 1570 to 1
It is characterized in that an optical means for guiding the signal light in the wavelength band of 610 nm to the amplification section is provided.

In the optical amplifier of the present invention, the equivalent fiber length (the product of the fiber length and the Er-doped concentration (wt ppm)) is the length at which the signal gain is equal to or higher than a predetermined practical reference value, Er. Using doped fiber or Er-doped optical waveguide,
Further, the most main feature is to provide an optical filter for reducing the ASE light power of 1520 nm to 1560 nm generated in the Er-doped fiber or the Er-doped optical waveguide.

FIG. 22 shows an Er-doped silica fiber (ED
FIG. 23 is a diagram showing an example of the gain coefficient with respect to the average population inversion ratio in the longitudinal direction of the fiber in F). As can be seen from FIG.
The gain coefficient of EDF in the m band becomes positive and 1500n
Amplification gain can be expected in the m band. However, the wavelength band having a particularly large gain coefficient is 1520 nm to 1560 nm, and the peak of the gain coefficient is in the vicinity of 1530 nm. The peak value of the gain coefficient is 2 to 6 times the gain coefficient in the 1500 nm band.

Therefore, if the EDF is simply excited by the pumping light, only the amplification of the signal light having a large gain coefficient of 1520 to 1560 nm (particularly in the vicinity of 1530 nm) or the spontaneous emission light strongly occurs, and the signal light or the spontaneous emission in the vicinity of 1530 nm is generated. The amplified light (ASE) saturates the EDFA, and it is impossible to realize a large gain of 15 dB or more in the 1500 nm band.

Therefore, E for amplifying the signal of 1500 nm band
1520nm ~ 1560nm to realize DFA
This suppresses ASE (especially near 1530 nm) and
It is necessary to avoid the occurrence of saturation due to E. Therefore, in the optical amplifier and the optical amplification method of the present invention, it is 1520 nm to 1
It has a large loss at 560 nm (especially in the vicinity of 1530 nm), and in the 1500 nm band, by using an optical filter with a very small loss, it is 1520 nm to 1560 n.
m while effectively suppressing the growth of ASE of 1500 nm
It becomes possible to amplify the band signal.

Although there are EDFAs provided with an optical filter as a conventional technique (see, for example, Non-Patent Document 5), they have the amplification characteristics shown in FIGS. 23 (a) and 23 (b). Kim et al., Gain flattening in 1550 nm band, Masuda et al. In 1550 nm band and 1580
Only the gain flattening is performed in the wavelength band spanning the nm band, and the gain in the 1500 nm band is 10 dB or less in the optical amplifier of Kim et al. (FIG. 23 (a), Kim.
Et al. Do not show a gain in the wavelength band of 1520 nm or less, but it can be easily inferred that the gain is 10 dB or less), M
In the optical amplifier of Asuda et al., no gain is obtained in the 1500 nm band (FIG. 23 (b)). Therefore, Kim
The optical filters used as a means by M. et al. And Masuda et al.
It is essentially different from the optical filter used as the means of the optical amplifier of the present invention.

In the optical amplifier and the optical amplification medium of the present invention, the equivalent fiber (optical waveguide) length (Er-doped fiber (optical waveguide) length × Er-doped concentration) is an important parameter. As shown in the embodiment of the present invention, the gain is increased by increasing the equivalent fiber (optical waveguide) length, and in order to obtain the gain of 15 dB or more, the equivalent fiber (optical waveguide) length of a certain value or more is required. It is necessary (Fig. 3, Fig. 10, Fig. 13). That is, it is understood that the equivalent fiber (optical waveguide) length is important for realizing a practical 1500 nm band optical amplifier.

Although there exist optical amplifiers realized by utilizing the equivalent fiber (optical waveguide) length as the prior art (see, for example, Patent Documents 1 to 3), these have low noise and high output. Equivalent fiber (optical waveguide) length for realizing both functions (for example, refer to Patent Document 4), equivalent fiber (optical waveguide) length for realizing low noise property (for example, refer to Patent Document 5), 1580 nm An equivalent fiber (optical waveguide) length (see, for example, Patent Document 6) for realizing a band-pass optical amplifier, which is a means of the present invention 1500n
It is essentially different from the equivalent fiber (optical waveguide) length for realizing an m-band optical amplifier.

As described above, the optical amplifier or optical amplification medium of the present invention has an equivalent fiber length (fiber length and E
The product of the r-doped concentration (wt ppm) is set to a length such that the signal gain becomes a signal gain of a predetermined practical reference value or more, and the optical filter generates an Er-doped fiber or an Er-doped optical waveguide from 1530 nm to 1560 nm (especially 1530 nm
By reducing the signal light power (in the vicinity) or the ASE light power, it is possible to suppress saturation at 1530 nm to 1560 nm and amplify the 1500 nm band signal light with a gain value equal to or higher than the practical reference value.

The above is a description of an example of an Er-doped silica fiber, and the absolute value of the gain coefficient differs for each Er-doped fiber depending on the fiber parameter and Er ion doping concentration. However, even in various Er-doped fibers or Er-doped optical waveguides, 15
Since the spectral shape of the gain coefficient having a peak near 30 nm is almost the same, various doped fibers and E
It can be applied to r-doped optical waveguides.

[0108]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 shows a first embodiment of an optical amplifier according to the present invention.
In the block diagram showing the configuration of the embodiment, reference numeral 1-1,
Reference numeral 1-2 is an optical amplifier, and 2 is an optical filter. In the optical amplifiers 1-1 and 1-2 of this embodiment, Er is added to at least one of the core and the clad, or Er is added to at least one of the core and the clad formed on the substrate. An Er-doped optical waveguide is used as an optical amplification medium. Moreover, at least one optical amplifier 1-1, 1-2 is provided, and is composed of an optical amplification medium and a pumping light source. Further, at least one optical filter 2 is provided, and in the wavelength band in which the gain is obtained in the optical amplification medium, the light in the first wavelength band having the maximum gain is reduced to perform the optical amplification in the first wavelength band. Is configured to suppress. Due to this suppression, in the wavelength band where the gain is obtained in the optical amplification medium, the second wavelength that is located at the bottom of the low wavelength side and has a relatively small gain is promoted, and the amplified second wavelength is obtained. The optical signal in the band is output.

Further, FIG. 2 is a diagram showing an example of the structure of the optical amplifying section, in which reference numeral 3 is an Er-doped fiber as an amplifying medium, and 4
Is a multiplexer for combining pumping light and signal light, 5 is a pumping light source for generating pumping light to the Er-doped silica fiber 3, 6-1,
6-2 has shown the optical isolator.

The Er-doped fiber 3 is a silica-based fiber in which Al is co-doped in the core. Al 3 wt% and Er 1000 wt.
ppm. The multiplexer 4 was a bulk type WDM coupler, and the pumping light source was a 980 nm band LD. In the Er-doped optical fiber, the average population inversion ratio can be brought close to 1 by using the pumping light source in the 980 nm band, and the gain coefficient in the 1500 nm band can be increased.

FIG. 3 shows the signal light 1 of the optical amplifier of this embodiment.
It is a figure which shows the equivalent fiber length dependence of the gain in 490 nm and 1520 nm (sum of each amplification part). It can be seen that the equivalent fiber length for obtaining a practical gain of 15 dB or more is longer at the signal wavelength of 1490 nm, and the equivalent fiber length of 1.5 × 10 ⁴ m · wt ppm is required.

FIG. 4 is a diagram showing the loss spectrum of the optical filter. This loss spectrum excludes the loss of the filter itself and the loss between the filter and the fiber (collectively referred to as excess loss). The peak wavelength of the loss substantially coincides with the peak wavelength of the gain coefficient near 1530 nm, and has a large loss in the large gain coefficient of 1520 nm to 1560 nm. Due to such a loss spectrum shape,
Suppresses the growth of ASE in 0 nm to 1560 nm,
The 1500 nm band signal could be efficiently amplified.

FIG. 5 is a diagram showing the amplification characteristics of the optical filter. The total equivalent fiber length of each amplification section is 2 × 10 ⁴ m.multidot.m.
It was set to wt ppm. The measurement method of the amplification characteristic is to set 8 waves (the power of each wavelength is -15 dBm and the total power is -6 dBm) in the wavelength range of 1490 nm to 1505 nm as a saturated signal light, and sweep the probe light of power -30 dBm,
The method of measuring the gain and noise figure of the probe light was adopted. The amplification characteristic measured by this measuring method corresponds to the gain and noise characteristic when the WDM signal is amplified.

As shown in FIG. 5, the optical amplifier of this embodiment has a wavelength band of 1485 nm to 1520 nm, and
The gain was more than dB and the noise figure was less than 5.3 dB. Also, the total pump power is 140 mW, the total signal output power is 56 mW, and the power conversion efficiency is 40%.
Met.

As described above, according to the present embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber having excellent mechanical strength and weather resistance as an amplification medium can be realized.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the configuration of the optical amplifying section is as shown in FIG.
, The backward pumping type shown in FIG. 7, the bidirectional pumping type shown in FIG.
Similar results were obtained with each of the reflection type configurations shown in FIG. Incidentally, reference numerals 4-1 and 4-2 in the figure
Is a multiplexer, 5-1 and 5-2 are excitation light sources, 7 is an optical circulator, and 8 is a total reflection mirror. Further, in each of the configurations shown in FIGS. 2, 6, 7 and 8, even if some of the optical isolators were omitted, the amplification characteristics were not affected at all.

The Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer.

[Second Embodiment] FIG. 9 is a block diagram showing the configuration of a second embodiment of the optical amplifier according to the present invention.
Those having the same functions as those in the embodiment are designated by the same reference numerals as those in the first embodiment. This embodiment is similar to the first embodiment, except that the optical amplifiers 1-1, 1-2, ... 1-N and the optical filters 2-1 ... 2- (N-1) are used. The difference is that they are connected in multiple stages alternately. The configuration of each optical amplifier unit is a combination of the configurations shown in FIG. 2, FIG. 6, FIG. 7, and FIG.
The Er-doped fiber 3 is a silica-based fiber in which Al is co-doped in the core, and has an Al 3 wt% and Er 1000 wt ppm multiplexer 4.
Is a bulk WDM coupler, and the pumping light source is a 980 nm band LD.

The loss spectrum of the optical filter used in this embodiment is similar to that of the optical filter of the first embodiment.
It has a large loss in the range of 1520 nm to 1560 nm, effectively suppresses the ASE growth of 1520 nm to 1560 nm, and also has a loss in the range of 1500 nm to 1520 nm, and also gain flattening to reduce the wavelength dependence of the gain in the 1500 nm band. Is going. The total loss value of each filter is 30 dB or more in the vicinity of 1530 nm.

FIG. 10 is a diagram showing the equivalent fiber length dependence of the gain of the optical amplifier according to the present embodiment (the total of each amplifier). In the present embodiment, since gain flattening is also performed by the optical filter, the equivalent fiber length dependence of the gain in 1490 nm to 1520 nm is almost the same as in the first embodiment. It can be seen from FIG. 8 that an equivalent fiber length of 1.5 × 10 ⁴ m · wt ppm is required to obtain a practical gain of 15 dB or more.

FIG. 11 is a diagram showing the amplification characteristic of the optical amplifier of this embodiment. The total equivalent fiber length of each amplification section is 2 ×.
It was set to 10 ⁴ m · wt ppm. The optical amplifier according to the present embodiment has 20 dB in the wavelength band of 1485 nm to 1518 nm.
It has a gain (gain deviation of 1 dB) and a noise figure of 5.3d.
It was B or less. Further, the total pump power was 63 mW, the total signal output power was 28.4 mW, and the power conversion efficiency was 45%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

Further, as shown in FIG. 12, in each optical amplification section 1, similar amplification characteristics were obtained even if one pumping light source was shared by a plurality of optical amplification sections. In this case, the number of pumping light sources can be reduced, and the cost of the optical amplifier can be reduced.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the optical amplifier section has the backward pumping type shown in FIG. 6, the bidirectional pumping type shown in FIG. Similar results were obtained with each of the reflective configurations shown in FIG. 8 and their combinations. Further, in each of the configurations shown in FIGS. 2, 6, 7 and 8, even if some of the optical isolators were omitted, the amplification characteristics were not affected at all.

The Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer.

[Third Embodiment] The configuration of the optical amplifier of the third embodiment according to the present invention is the same as the configuration of the optical amplifier of the second embodiment, and the loss characteristics of the optical filter are different.
The loss spectrum of the optical filter used in this embodiment is 1520 nm as in the optical filter of the second embodiment.
Has a large loss at ~ 1560 nm and is effectively 1
In addition to suppressing ASE growth of 520 nm to 1560 nm, it also has a loss of 1490 nm to 1520 nm.
At the same time, gain flattening for reducing the wavelength dependence of the gain in the 00 nm band is performed, and 1520 nm to 1560 n
The loss of m is smaller than that in the second embodiment, and is 1520 nm
A gain of 20 dB or more is obtained even at 1560 nm. The total loss value of each filter is 1530
It is 25 dB or more in the vicinity of nm.

FIG. 13 is a diagram showing the equivalent fiber length dependence of the gain of the optical amplifier according to the present embodiment (the total of each amplifier). In the present embodiment, since gain flattening is also performed by the optical filter, the equivalent fiber length dependence of the gain in 1490 nm to 1520 nm is almost the same as in the first embodiment. It can be seen from FIG. 13 that an equivalent fiber length of 1.5 × 10 ⁴ m · wt ppm is required to obtain a practical gain of 15 dB or more.

FIG. 14 is a diagram showing the amplification characteristics of the optical amplifier of this embodiment, where the total equivalent fiber length of each amplifier is 2 ×.
It was set to 10 ⁴ m · wt ppm. The optical amplifier of the present embodiment has 20 dB in the wavelength band of 1485 nm to 1560 nm.
It has a gain (gain deviation of 1 dB) and a noise figure of 5.8d.
It was B or less. Further, the total pump power was 65 mW, the total signal output power was 27 mW, and the power conversion efficiency was 41.5%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the optical amplifier section has the backward pumping type shown in FIG. 6, the bidirectional pumping type shown in FIG. Similar results were obtained with each of the reflective configurations shown in FIG. 8 and their combinations. Further, in each of the configurations shown in FIGS. 2, 6, 7 and 8, even if some of the optical isolators were omitted, the amplification characteristics were not affected at all.

Note that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer.

[Fourth Embodiment] FIG. 15 is a block diagram showing the configuration of the fourth embodiment of the optical amplifier according to the present invention. In the figure, reference numeral 10 is a modularized optical amplification medium. Reference numerals of other components are the same as those in the first embodiment.

FIG. 16 is a diagram showing the structure of the optical amplification medium module. In the figure, reference numeral 11 is a multilayer film filter, and 12 is a fiber wiring board. This optical amplification medium module 10
Then, the Er-doped fiber 3 is bent at a radius that does not increase the bending loss, and the fiber wiring board 12 is reciprocated many times. A groove is cut in the fiber wiring board 12, and the multilayer filter 11 is inserted in this groove.

The loss characteristic of the multilayer filter 11 is similar to that of the filter of the second embodiment.
has a large loss in nm to 1560 nm, effectively suppresses the ASE growth of 1520 nm to 1560 nm, and also has a loss in 1500 nm to 1520 nm,
At the same time, gain flattening is performed to reduce the wavelength dependence of the gain in the 1500 nm band. The groove for the multilayer filter is obliquely arranged with respect to the fiber (with respect to the traveling direction of light) and has a return loss of 60 dB or more.
The deterioration of amplification characteristics due to reflection is prevented. The total loss during the passage of the optical power from the input end to the output end of the optical amplification medium is 30 dB or more in the vicinity of 1530 nm. E
The r-doped fiber 3 is a silica-based fiber in which Al is co-doped in the core and has Al 3 wt% and Er 1000 wt ppm.

In order to obtain a practical gain of 15 dB or more in the optical amplifying medium of this embodiment, an equivalent fiber of 1.5 ×
10 ⁴ m · wt ppm was required.

FIG. 17 is a diagram showing the amplification characteristics of the optical amplifier of this embodiment, and the total equivalent fiber length is 2 × 10 ⁴ m.
・ We set it as wt ppm. The multiplexer 4 was a bulk type WDM coupler, and the pumping light source was a 980 nm band LD. The optical amplifier of the present embodiment has a gain of 22 dB (gain deviation of 1 dB) in the wavelength band of 1485 nm to 1518 nm and a noise figure of 5.3 dB or less. Further, the total pump power was 172 mW, the total signal output power was 84 mW, and the power conversion efficiency was 48.8%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

The Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer. The optical filter also uses a multilayer filter in the present embodiment, but the filter is not limited to this as long as it has a similar loss characteristic. Further, the insertion form of the filter is not limited to that of this embodiment.

Although the optical amplifier of this embodiment uses a bidirectional type configuration, similar results were obtained with each of the forward pump type, backward pump type and reflective type configurations.

[Fifth Embodiment] The structure of the optical amplifier of the fifth embodiment according to the present invention is the same as that of the optical amplifier of the fourth embodiment, but the structure of the optical amplifying medium 10 is different.

FIG. 18 is a diagram showing the structure of the optical amplifying medium according to the present embodiment. FIG. 18 is a side view of the Er-doped fiber. Reference numeral 13 is a core and 14 is a clad. In the optical amplification medium according to the present embodiment, a grating is manufactured over the entire core (indicated by a striped pattern in the core diameter direction in FIG. 18). The loss characteristic of the grating formed in the core 13 is similar to that of the optical filter of the second embodiment, having a large loss at 1520 nm to 1560 nm, and effectively having a wavelength of 1520 nm to 1560 nm.
Suppresses ASE growth of 1,500 nm-152
At the same time, there is a loss even at 0 nm, and gain flattening is performed to reduce the wavelength dependence of the gain in the 1500 nm band. The total loss during the passage of the optical power from the input end to the output end of the optical amplification medium is 30d in the vicinity of 1530 nm.
It is B or more. Al is also co-added to the core.
3 wt% and Er 1000 wt ppm.

In the optical amplifying medium of this embodiment, an equivalent fiber length of 1.5 is required to obtain a practical gain of 15 dB or more.
× 10 ⁴ m · wt ppm was required. Further, by using this optical amplification medium module, an optical amplifier having the same amplification characteristic as that of the fourth embodiment can be realized. The total equivalent fiber length was 2 × 10 ⁴ m · wt ppm.

It should be noted that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained.

Further, as shown in FIG. 19, similar amplification characteristics were obtained even in an optical amplifying medium in which a core of an Er-doped fiber had a portion with and without a grating.

[Sixth Embodiment] The structure of the optical amplifier of the sixth embodiment according to the present invention is the same as that of the optical amplifier of the fourth embodiment, but the structure of the optical amplifying medium 10 is different.

FIG. 20 is a diagram showing the structure of the optical amplifying medium in the present embodiment. In the figure, reference numerals 11-1 and 11-2 are multilayer filters, 15 is an Er-doped optical waveguide, and 16-1 and 16.
Reference numeral -2 is a silica-based bigtail fiber, and 17 is a Si substrate.

In this optical amplification medium, Er on the Si substrate 17 was used.
The added optical waveguide 15 is formed. A groove is cut in the middle of the waveguide path 15, and the multilayer filter 11-1, 11-is formed in this groove.
Insert 2. The loss characteristics of the multilayer filters 11-1 and 11-2 are similar to the loss characteristics of the filter of the second embodiment, having a large loss at 1520 nm to 1560 nm, and effectively having an AS of 1520 nm to 1560 nm.
Suppresses E growth and 1500 nm to 1520 nm
At the same time, gain flattening is performed to reduce the wavelength dependence of the gain in the 1500 nm band. The total loss during the passage of the optical power from the input end to the output end of the optical amplification medium is 30 dB or more in the vicinity of 1530 nm. Er-doped optical waveguide is Al3wt%, Er5000
wt ppm.

In the optical amplifying medium of this embodiment, an equivalent optical waveguide length of 1.5 is required to obtain a practical gain of 15 dB or more.
× 10 ⁴ m · wt ppm was required.

By using this optical amplification medium, an optical amplifier having the same amplification characteristic as that of the fourth embodiment could be realized. The total equivalent optical waveguide length is 2 × 10 ⁴ m
・ We set it as wtppm.

Note that the Er-doped optical waveguide and the multiplexer used in this embodiment are merely examples, and as the Er-doped optical waveguide, a waveguide without Al co-doping, an Er-doped tellurite waveguide, or an Er-doped optical waveguide is used. Aluminosilicate Waveguide, Er-Doped Phosphate Waveguide, Er-Doped Phosphoric Acid Waveguide, Er-Doped Fluoride Waveguide, Er-Doped Bismuth Oxide Waveguide, E
Similar results were obtained using the r-doped chalcogenide waveguide. Similar results were obtained with a combination of these waveguides.

The optical filter also uses a multilayer film filter in the present embodiment, but it is not limited to this as long as it has a similar loss characteristic. Further, the insertion form of the filter is not limited to that of this embodiment.

[Seventh Embodiment] FIG. 21 is a diagram showing a table summarizing amplification characteristics when an optical fiber other than Er-doped silica fiber is used. The optical amplifier configuration is similar to that of the second embodiment.

When these Er-doped fibers are used as an amplifying medium, the joint between heterogeneous fibers with the silica-based fiber becomes large, and the mechanical strength and weather resistance are smaller than those of the silica-based fiber. We were able to realize highly efficient optical amplification equivalent to the case of using fiber as the amplification medium.

Further, in the optical amplifier and the optical amplification medium having the same configurations as those of the first and third to fifth embodiments, respectively,
Similarly, a highly efficient optical amplifier could be realized. Furthermore, the Er-doped silica-based fiber and the Er shown in FIG.
It was possible to realize a highly efficient 1500 nm band optical amplifier also in the optical amplifier having the configuration shown in FIG. 9 by combining a plurality of fibers from among the doped fibers.

[Eighth Embodiment] The structure of the optical amplifier of the eighth embodiment according to the present invention is the same as that of the optical amplifier of the second embodiment, and the loss characteristics of the optical filter are different.
The loss spectrum of the optical filter used in this embodiment is 1520 nm as in the optical filter of the second embodiment.
Has a large loss at ~ 1560 nm and is effectively 1
Suppresses ASE growth of 520 nm to 1560 nm and also has a loss of 1490 nm to 1520 nm.
An amplification gain is obtained in the 50 nm to 1490 nm band.

An Er-doped silica fiber (equivalent fiber length 1 × 10 ⁵ m · wt ppm) was used, and the total pumping power was 6
With respect to 3 mW, the total signal output power was 22 mW, and the power conversion efficiency was 31.7%. According to this embodiment, the Er-doped silica fiber having excellent mechanical strength and weather resistance was used as the amplification medium. It was possible to realize an efficient 1470 nm band optical amplifier.

[Ninth Embodiment] FIG. 24 is a block diagram showing the structure of an optical amplifier according to the ninth embodiment of the present invention. Reference numerals 21-1, 21-2, ..., 21-N in the figure denote optical amplifiers, 22-1, 22-2, ..., 22- (N-1) denote optical filters.

FIG. 25 is a diagram showing a configuration example of the optical amplifiers 21-1 to 21-N. In the figure, reference numeral 23 is an Er-doped fiber that is an amplification medium, 24 is a multiplexer that combines pumping light and signal light, 25 is a pumping light source that generates pumping light to the Er-doped silica fiber 23, 26-1, Reference numeral 26-2 indicates an optical isolator.

The Er-doped fiber 23 is a silica-based fiber in which Al is co-doped in the core. Al3 wt%, Er1000
wt ppm. The multiplexer 24 was a fiber type WDM coupler, and the pumping light source was a 980 nm band LD.

FIG. 26 shows the total Er used for the gains in the signal lights 1490 and 1520 of the optical amplifier of this embodiment.
The dependence of the doped fiber on the total loss at 1480 nm is shown. In order to obtain a practical gain of 15 dB or more, at the signal wavelength of 1520 nm, it is possible to obtain 1 of all Er-doped fibers.
It can be seen that the total loss at 480 nm needs to be 11 dB or more, and the total loss at 1480 nm of all Er-doped fibers needs to be 33 dB or more at the signal wavelength of 1490 nm.

Therefore, 148 of all Er-doped fibers
If the total loss at 0 nm is 33 dB or more, a gain of 15 dB or more can be obtained in the wavelength band of 1490 to 1520 nm.

FIG. 27 is a diagram showing a loss spectrum of the optical filter. This loss spectrum excludes the loss of the filter itself and the loss between the filter and the fiber (collectively referred to as excess loss). This optical filter is 1520
Has a large loss at 1560 nm and effectively
Suppresses ASE growth of 20 to 1560 nm and
There is a loss at 500 nm to 1520 nm and 1500 n
At the same time, gain flattening is performed to reduce the wavelength dependence of the gain in the m band. The total loss value of each filter is 15
It is 30 dB or more in the vicinity of 30 nm.

FIG. 28 is a diagram showing the amplification characteristic of the optical amplifier. The total loss at 1480 nm of all Er-doped fibers used in each amplification section is 44 dB. The measurement method of the amplification characteristic is 1490 to 150 as saturated signal light.
16 waves in the wavelength band of 5 nm (power of each wavelength -15 dB
m, total power -6 dBm) is input to the optical amplifier of the present embodiment, the probe light with power -30 dBm is wavelength-swept,
The method of measuring the gain and noise figure of the probe light was adopted. The amplification characteristic measured by this measuring method corresponds to the gain and noise characteristic when the WDM signal is amplified.

As shown in FIG. 28, the optical amplifier according to this embodiment has a wavelength band of 1485 to 1520 nm and a wavelength of 15d.
The gain was B or more and the noise figure was 5.1 dB or less. The total pump power is 138 mW, the total signal output power is 58 mW, and the power conversion efficiency is 42%.
Met.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the configuration of the optical amplifying section is as shown in FIG.
9, the backward pumping type shown in FIG. 9, the bidirectional pumping type shown in FIG.
Similar effects were obtained with each of the reflection type configurations shown in FIG. 31 and combinations thereof (27 indicates an optical circulator, and 28 indicates a total reflection mirror). Further, in each of the configurations of FIGS. 25 and 29 to 31, even if some of the optical isolators were omitted, the amplification characteristics were not affected at all.

It should be noted that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer. In addition, the number of optical filters may be N and the optical amplifiers 1-N may be arranged on the signal output side.

Furthermore, by changing the loss characteristic in the 1500 nm band of the optical filter, the signal wavelength band becomes 14
It was possible to expand to a short wavelength of 90 to 1520 nm and a long wavelength of about 10 nm.

In this embodiment, each optical amplifier 21-
1, 21-2, ..., 21-N, as shown in FIG.
Similar amplification characteristics were obtained even with a configuration in which one pumping light source was shared by a plurality of optical amplifiers. In this case, the number of pumping light sources can be reduced, and the cost of the optical amplifier can be reduced.

[Tenth Embodiment] FIG. 33 is a block diagram showing the structure of an optical amplifier according to the tenth embodiment of the present invention. Reference numeral 30 in the figure denotes an optical amplification component. Reference numerals of other components are the same as those in the ninth embodiment. FIG. 34 is a diagram showing the configuration of the optical amplification component. In the figure, reference numeral 23 is an Er-doped fiber, 31 is a multilayer film filter, and 32 is a fiber wiring board.

In this optical amplification component module, the Er-doped fiber 3 is bent at a radius that does not increase the bending loss, and the fiber wiring board 32 is reciprocated many times. A groove is cut in the fiber wiring board, and the multilayer filter 31 is inserted in this groove. The loss characteristic of the multilayer filter is similar to the loss characteristic of the filter of the ninth embodiment and is 1520 to 1560 nm.
Has a large loss in 1520 to 156 effectively
Suppresses 0 nm ASE growth and
At the same time, there is a loss at 20 nm, and gain flattening is performed to reduce the wavelength dependence of gain in the 1500 nm band.

The grooves for the multilayer film are arranged obliquely (with respect to the traveling direction of light) with respect to the fiber, and the groove is 60d.
It has a return loss of B or more to prevent deterioration of amplification characteristics due to reflection. The total loss during the passage of the optical power from the input end to the output end of the optical amplification component is 30 dB or more in the vicinity of 1530 nm. Er-doped fiber 3 has a core A
Quartz fiber co-doped with 1% Al, 3 wt%, Er
It is 1000 wtppm.

In order to obtain a practical gain of 15 dB or more in the optical amplifying component of this embodiment, 1 of Er-doped fiber is used.
The loss at 480 nm was 33 dB.

The amplification characteristics of the optical amplifier of this embodiment are shown below. The loss of the Er-doped fiber at 1480 nm was 44 dB, the multiplexers 24-1 and 24-2 were bulk type WDM couplers, and the pumping light source was a 980 nm band LD. The optical amplifier according to the present embodiment has wavelength bands 1485 to 15
At 18 nm, the gain was 22 dB (gain deviation 1 dB), and the noise figure was 5.3 dB or less. Also, the total pump power is 112 mW, while the total signal output power is 5
It was 6 mW and the power conversion efficiency was 50%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber having excellent mechanical strength and weather resistance as an amplification medium can be realized.

It should be noted that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer. The optical filter also uses a multilayer filter in the present embodiment, but the filter is not limited to this as long as it has a similar loss characteristic. Further, the insertion form of the filter is not limited to that of this embodiment.

Although the optical amplifier of this embodiment uses a bidirectional type configuration, similar results were obtained with each of the forward pump type, backward pump type and reflection type configurations.

[Eleventh Embodiment] The eleventh embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

FIG. 35 is a diagram showing the structure of the optical amplifying component of this embodiment. This figure is a side view of the Er-doped fiber, where 33 is a core and 34 is a clad. In the optical amplification component of this embodiment, a grating is formed in the core portion (indicated by a striped pattern in the core diameter direction in FIG. 35).

The loss characteristic of the grating formed on the core is similar to that of the optical filter of the ninth embodiment.
It has a large loss at 0 to 1560 nm, effectively suppresses the ASE growth of 1520 to 1560 nm, and has a loss at 1500 to 1520 nm as well.
At the same time, gain flattening is performed to reduce the wavelength dependence of gain in the nm band. The total loss during the passage of the optical power from the input end to the output end of the optical amplification component is 30 dB or more in the vicinity of 1530 nm. Al was also co-added to the core, and Al was 3 wt% and Er was 1000 wtppm.

In order to obtain a practical gain of 15 dB or more in the optical amplifying component of this embodiment, 1 of Er-doped fiber is used.
The loss at 480 nm was 33 dB.

This optical amplification component (148 of Er-doped fiber)
The loss at 0 nm was set to 44 dB), and an optical amplifier having the same amplification characteristics as the tenth embodiment could be realized.

Note that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained.

Further, as shown in FIG. 36, an Er-doped fiber having a chirped grating formed therein, and as shown in FIG. 37, an Er-doped fiber having a plurality of grating forming portions formed with a plurality of gratings having different periods,
As shown in FIG. 38, similar amplification characteristics were obtained when an Er-doped fiber having a grating formed in both the core and the clad was used as an optical amplification component.

[Twelfth Embodiment] The twelfth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

FIG. 39 is a view showing the optical amplification component of the optical amplifier of this embodiment. The optical amplifying component includes Er-doped fibers 36-1, 36-2 ... 36-N and an optical filter 37.
-1, 37-2 ... 37- (N-1) are alternately connected in series.

The loss characteristic of the optical fiber is similar to the loss characteristic of the filter of the ninth embodiment, and is 1520 to 156.
It has a large loss at 0 nm and is effectively 1520 to
Suppresses 1560nm ASE growth and 1500
At the same time, the gain is flattened to reduce the wavelength dependence of the gain in the 1500 nm band by also having a loss up to 1520 nm. Furthermore, the loss at the pump wavelength is small,
The transmittance of excitation light is also high.

The amplification characteristic of the optical amplifier using this optical amplification component was equivalent to that of the optical amplification component of the eleventh embodiment. The number of optical filters does not necessarily have to be the same as the number of Er-doped fibers.

[Thirteenth Embodiment] The thirteenth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

The present optical amplification component uses an Er-doped fiber in which Nd is co-doped in the core as an optical amplification medium. Nd
Has an absorption band near 1530 nm, it is possible to suppress ASE growth of 1520 to 1560 nm generated by Er. That is, there is the same effect as the optical filter of the eleventh embodiment.

The amplification characteristics of an optical amplifier using an Er-doped fiber containing 100 ppm of Nd as an optical amplification component are as follows.
It was equivalent to the optical amplification component of the eleventh embodiment.

The rare earth ions to be co-doped are Pr and N.
Similar effects were obtained with any one of d, Sm, Tb, Dy, Tm, or a combination thereof. Further, the same effect was obtained also in the Er-doped fiber in which these rare earth ions were co-doped only in the cladding and both the core and the cladding.

[Fourteenth Embodiment] The fourteenth embodiment of the present invention
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

This optical amplification component has a shape in which Er-doped fibers are wound (bundled) in a small diameter. By winding Er-doped fiber with a small diameter, bending losses are increased. The loss due to this bending increases as the wavelength becomes longer, and Er is generated by selecting the diameter appropriately.
ASE growth of 20 to 1560 nm can be suppressed. That is, there is the same effect as the optical filter of the third embodiment.

The amplification characteristic of the optical amplifier using the Er-doped fiber wound to a diameter of 1.5 cm as the optical amplification component was equivalent to that of the optical amplification component of the third embodiment.

[Fifteenth Embodiment] The fifteenth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

This optical amplification component uses an Er-doped fiber having a plurality of claddings as an optical amplification medium. A fiber having a plurality of claddings has a cutoff wavelength of the fundamental mode, and the cutoff wavelength of the fundamental mode is 1520n.
By designing the Er-doped fiber so as to be near m, the ASE of 1520 to 1560 nm generated by Er is generated.
Growth can be suppressed. That is, there is the same effect as the optical filter of the eleventh embodiment.

The amplification characteristic of an optical amplifier using an Er-doped fiber having a W-type refractive index distribution as an optical amplification component is as follows:
It was equivalent to the optical amplification component of one embodiment.

[Sixteenth Embodiment] The sixteenth embodiment of the present invention
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, but the configuration of the optical amplification component 30 is different.

FIG. 40 is a diagram showing the structure of the optical amplifying component of this embodiment. In the figure, reference numeral 35 is an Er-doped optical waveguide, 38-1 and 38-2 are silica-based pigtail fibers,
Reference numeral 39 is a Si substrate, and 31-1 is a multilayer filter.

In this optical amplification component, Er on the Si substrate 39
An added optical waveguide is formed. A groove is cut in the middle of the waveguide path, and the multilayer filter is inserted into this groove. The loss characteristic of the multilayer filter is similar to the loss characteristic of the filter of the tenth embodiment and has a large loss at 1520 to 1560 nm and effectively has an AS of 1520 to 1560 nm.
At the same time, the E-growth is suppressed and the gain is flattened to reduce the wavelength dependence of the gain in the 1500 nm band by having a loss in the range of 1500 to 1520 nm. The total loss during the passage of the optical power from the input end to the output end of the optical amplification component is 30 dB or more in the vicinity of 1530 nm.
Er-doped optical waveguide is Al3wt%, Er5000wtp
pm.

In order to obtain a practical gain of 15 dB or more in the optical amplifying component of the present embodiment, the Er-doped fiber 14
The loss at 80 nm was 33 dB.

By using this optical amplification component, an optical amplifier having amplification characteristics similar to those of the twelfth embodiment could be realized.
The loss of the Er-doped fiber at 1480 nm was 44 dB.

The examples of the Er-doped optical waveguide and the multiplexer used in this embodiment are only examples. As the Er-doped optical waveguide, a waveguide without Al co-doping, an Er-doped tellurite waveguide, or an Er-doped optical waveguide is used. Aluminosilicate Waveguide, Er-Doped Phosphate Waveguide, Er-Doped Phosphoric Acid Waveguide, Er-Doped Fluoride Waveguide, Er-Doped Bismuth Oxide Waveguide, E
Similar results were obtained using the r-doped chalcogenide waveguide. Similar results were obtained with a combination of these waveguides.

The optical filter also uses a multilayer filter in the present embodiment, but the filter is not limited to this as long as it has a similar loss characteristic. Further, the insertion form of the filter is not limited to that of this embodiment.

[Seventeenth Embodiment] FIG.
It is the figure which made the amplification characteristic when using other than the addition silica type fiber the tabular form. The optical amplifier configuration is similar to that of the ninth embodiment.

When these Er-doped fibers are used as an amplifying medium, the connection between different types of fibers with the silica-based fiber becomes large, and the mechanical strength and weather resistance are smaller than those of the silica-based fiber. We were able to achieve high-efficiency optical amplification equivalent to that when a fiber was used as the amplification medium.

Further, also in the optical amplifiers and the optical amplification components having the same configurations as those of the tenth and eleventh embodiments, the highly efficient optical amplifiers can be realized respectively.

Furthermore, an Er-doped silica-based fiber and FIG.
By similarly combining a plurality of fibers from the Er-doped fiber shown in 0 (a), a highly efficient 1500 nm band optical amplifier can be realized also in the optical amplifier having the configuration shown in FIG.

[Eighteenth Embodiment] The eighteenth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is the same as that of the optical amplifier of the ninth embodiment, but the configuration of the optical amplification unit is different.

FIG. 41 is a diagram showing an example of the structure of the optical amplification section. The optical amplification section of the present embodiment is similar to the optical amplification section of the ninth embodiment, except that the temperature of the Er-doped fiber 23 is controlled by the Peltier element 40.

The Er-doped fiber 23 is a silica-based fiber in which Al is co-doped in the core.
wt ppm. The multiplexer 24 was a fiber type WDM coupler, and the pumping light source was a 980 nm band LD.

FIG. 26 shows the signal light 1 of the optical amplifier of this embodiment.
The dependence of the gain at 490 and 1520 on the total loss at 1480 nm of the total Er-doped fiber used is shown. The temperature of the Er-doped fiber 3 was 65 ° C. When the temperature is raised, the amplification initial level of Er ( ⁴ I
_13/2 ), between the Stark levels of the final levels ( ⁴ I _15/2 ) (Each level is a level at which degeneracy is released by the Stark effect)
The population distribution changes and the gain coefficient of the Er-doped fiber increases.

Therefore, the loss at 1480 nm of the Er-doped fiber that can obtain a practical gain of 15 dB or more is smaller than that of the optical amplifier of the ninth embodiment (FIG. 42), and the total loss of all Er-doped fibers at 1480 nm at the signal wavelength of 1520 nm. Is required to be 8.3 dB or more, and when the signal wavelength is 1490 nm, it is 1 of all Er-doped fibers.
Gain of 15 at total loss of more than 25 dB at 480 nm
dB was obtained. Therefore, one of all Er-doped fibers
If the total loss at 480 nm is 25 dB or more,
A gain of 15 dB or more can be obtained in the wavelength band of 1490 to 1520 nm.

The loss spectrum of the optical filter 2 is similar to that of the optical filter of the ninth embodiment and is 1520 to 156.
It has a large loss at 0 nm and is effectively 1520 to
Suppresses 1560nm ASE growth and 1500
At the same time, there is a loss in the range of nm to 1520 nm, and gain flattening is performed to reduce the wavelength dependence of the gain in the 1500 nm band. The total loss during the passage of the optical power from the input end to the output end of the optical amplification component is 30 dB or more in the vicinity of 1530 nm.

FIG. 43 is a diagram showing the amplification characteristic of the optical amplifier. The total loss at 1480 nm of all Er-doped fibers used in each amplification section is 34 dB. Figure 2
As shown in FIG. 8, the optical amplifier of the present embodiment has a wavelength band 14
At 85 to 1520 nm, the gain was 15 dB or more and the noise figure was 5.1 dB or less. Also, the total pump power is 128 mW, while the total signal output power is 58 m
The power conversion efficiency was 45%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the configuration of the optical amplifying section is as shown in FIG.
9, the backward pumping type shown in FIG. 9, the bidirectional pumping type shown in FIG.
In each of the reflection type configurations shown in FIG. 31 and combinations thereof, as shown in FIG.
Similar results were obtained with a configuration equipped with a means for controlling the temperature.

Similar results were obtained by using a heater as a means for controlling the temperature of the Er-doped fiber 23.

Note that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doped or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer.

Furthermore, by using the optical amplifying component in which the temperature of the Er-doped fiber used in the optical amplifying components shown in the tenth to sixteenth embodiments is controlled in the same manner as in the present embodiment, a highly efficient 1500 nm is obtained. An optical amplifier was realized.

[Nineteenth Embodiment] The nineteenth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, and the loss characteristics of the optical filter are different. Like the optical filter of the ninth embodiment, the loss spectrum of the optical filter used in the present embodiment is 15
It has a large loss in 20 to 1560 nm, effectively suppresses the ASE growth of 1520 to 1560 nm, and also has a loss in 1465 to 1520 nm.
The amplification gain is obtained in the band of 1490 nm.

Using Er-doped quartz fiber (total loss 150 dB at 1480 nm of all Er-doped fiber), total pumping power was 63 mW, total signal output power was 22 mW, and power conversion efficiency was 31.7%. Therefore, according to the present embodiment, an Er-doped silica-based fiber excellent in mechanical strength and weather resistance is used as an amplification medium, and it is highly efficient.
A 470 nm band optical amplifier was realized. Even when a fiber other than the Er-doped quartz fiber is used as the optical amplification medium, as shown in FIG.
An optical amplifier was realized.

[Twentieth Embodiment] The twentieth embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the ninth embodiment, and the loss characteristics of the optical filter are different. The loss spectrum of the optical filter used in this embodiment is 152 as in the optical filter of the ninth embodiment.
It has a large loss at 0 to 1560 nm, effectively suppresses the ASE growth of 1520 to 1560 nm, and has a loss at 1500 to 1520 nm as well.
At the same time, the gain flattening for reducing the wavelength dependency of the gain in the nm band is performed, and the loss of 1520 to 1560 nm is made smaller than that of the tenth embodiment, and the gain is 1520 to 1560n.
Even at m, a gain of 20 dB or more is obtained. The total loss value of each filter is 30 dB or more in the vicinity of 1530 nm.

FIG. 44 is a diagram showing the amplification characteristic of the optical amplifier of this embodiment. The total loss at 1480 nm of all Er-doped fibers used in each amplifier is 44 dB.
Is. The optical amplifier of this embodiment has a wavelength band of 1485 to 1
At 560 nm, the gain was 20 dB (gain deviation 1 dB) and the noise figure was 5.8 dB or less. Also, the total pump power is 65 mW, while the total signal output power is 2
It was 7 mW and the power conversion efficiency was 41.5%.

As described above, according to this embodiment, a highly efficient 1500 nm band optical amplifier using an Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium can be realized.

Here, the optical amplifier of the present embodiment uses the forward pumping type configuration, but the configuration of the optical amplifying section is as shown in FIG.
9, the backward pumping type shown in FIG. 9, the bidirectional pumping type shown in FIG.
Similar results were obtained with the reflection-type configurations shown in FIG. 31 and combinations thereof. Also, FIG. 25 and FIG.
-In each structure of FIG. 31, some of the optical isolators were omitted and the amplification characteristics were not affected at all.

It should be noted that the Er-doped silica-based fiber and the multiplexer used in this embodiment are merely examples, and a fiber without Al co-doping or a P-doped fiber may be used as the Er-doped silica-based fiber. Similar results were obtained. Similar results were obtained with a fiber type WDM coupler as the multiplexer.

[Twenty-first Embodiment] The twenty-first embodiment of the present invention.
The configuration of the optical amplifier of the embodiment is similar to that of the optical amplifier of the tenth embodiment, and the loss characteristics of the optical filter are different. Like the optical filter of the ninth embodiment, the loss spectrum of the optical filter used in the present embodiment is 15
It has a large loss at 20 to 1560 nm and effectively suppresses the ASE growth at 1520 to 1560 nm, and
Not only the wavelength band of 490 to 1520 nm but also 1570 to
The amplification gain can be obtained even in the wavelength band of 1610 nm.

FIG. 45 is a diagram showing the amplification characteristic of the optical amplifier. 14 of all Er-doped fibers used in each amplification section
The total loss at 80 nm is 160 dB. Figure 45
As shown in FIG.
A gain of 15 dB or more and a noise figure of 5.5 dB at 5 to 1520 nm and 1570 to 1610 nm
It was below. Further, the total pumping power was 250 mW, the total signal output power was 100 mW (both wavelength bands matched), and the power conversion efficiency was 40%.

As described above, according to this embodiment, an optical amplifier which uses the Er-doped silica fiber excellent in mechanical strength and weather resistance as an amplification medium and simultaneously amplifies optical signals in the 1500 nm band and the 1580 nm band is realized. done.

[Twenty-second Embodiment] FIG. 46 shows an optical amplifier according to the twenty-second embodiment of the present invention. The optical amplifier of the present embodiment is a 1500 that amplifies a 1500 nm band optical signal.
It comprises a nm band amplification section 61 and a 1580 nm band amplification section 62 which amplifies a 1580 nm band optical signal. Incidentally, reference numeral 63 is a demultiplexer, and 64 is a multiplexer.

The 1500 nm band amplifying section 61 is almost the same as that of the ninth embodiment of the present invention, but some or all of the optical filters each have two output ports, and one port outputs a 1500 nm band optical signal. The other port transmits ASE light of 1520 to 1560 nm.

The 1580 nm band amplifying section 62 includes an Er-doped fiber 41, a multiplexer 42 for combining pumping light and signal light, a pumping light source 43, and optical isolators 44-1, 44-2, 15.
It is composed of a multiplexer 50 that multiplexes the 00 nm band optical signal and the 1525 to 1560 nm ASE light.

The 1580 nm band amplifying section 62 includes the pumping light source 4
In addition to 3, the ASE light of 1525 to 1560 nm is used as the excitation light, so that the power conversion efficiency is improved as compared to the case where the ASE light of 1525 to 1560 nm is not input (there is no input of ASE light of 1525 to 1560 nm). In 4
0%, 52% with ASE light input of 1525 to 1560 nm).

In the present embodiment, the wavelengths of 1500 nm and 1
Although the optical amplifier that amplifies the 580 nm band has been described, an optical amplifier in which an amplification unit that amplifies the 1550 nm band (approximately wavelength band 1530 to 1560 nm) is added to these wavelength bands can also be realized.

[Twenty-third Embodiment] FIG. 47 is a diagram showing a laser apparatus according to a twenty-third embodiment of the present invention. Reference numeral 4 in the figure
6 is an optical amplification component, 47-1 is an Er-doped silica fiber 3
Pumping light sources 48-1 and 48-2 for generating pumping light to the fiber gratings are fiber gratings.

As the optical amplification component 46, the optical amplification component shown in the twelfth embodiment is used. The reflectance at 1490 nm of each fiber grating is
-1 is 100%, and the fiber grating 48-
2 is 90%.

In this laser device, 2 at 1490 nm is used.
A laser light output of 0 mW was obtained. In addition, by using fiber gratings 28 having different reflection wavelengths,
Laser power was obtained in the wavelength range of 50 to 1520 nm.

Furthermore, by using a reflection mirror instead of the fiber grating and using a bandpass filter together, a wavelength tunable laser device was realized in the wavelength range of 1450 to 1520 nm.

[Twenty-fourth Embodiment] FIG. 48 is a block diagram showing the structure of a white light source according to a twenty-fourth embodiment of the present invention. In the figure, reference numeral 49 is a reflection mirror, 51 is an optical amplification component, 52-2 is a multiplexer, 53 is an excitation light source, and 54-2 is an optical isolator.

As the optical amplification component 51, the optical amplification component shown in the twelfth embodiment is used.

FIG. 49 is a diagram showing the output power density of the white light source of the present invention. Wavelength band 1486-1522nm
A power density of -10 dBm / nm was obtained.

As described above, according to this embodiment, a 1500 nm band white light source using an Er-doped silica fiber having excellent mechanical strength and weather resistance as an amplification medium can be realized.

It should be noted that the 1500-nm-band white light source could be realized by a structure in which the pumping light is transmitted through the reflection mirror and input to the optical amplification component instead of using the multiplexer. Further, the reflection mirror could realize a 1500 nm band white light source even with a fiber grating.

[0246]

As described above, according to the present invention, at least one optical amplification section including an optical amplification medium and a pumping light source, and at least one wavelength at which a gain can be obtained by the optical amplification medium are provided. In the band, an optical filter that reduces light in the first wavelength band having the maximum gain to suppress optical amplification in the first wavelength band, and a wavelength band in which gain is obtained in the optical amplification medium by suppression Among them, since it is located at the bottom of the low wavelength side, the gain of the second wavelength band having a relatively small gain is promoted, and the amplified optical signal of the second wavelength band is output, so Er addition is performed. Using a silica-based fiber or various Er-doped fibers, an optical filter is used to
By suppressing the SE, it is possible to efficiently achieve 1500 without causing gain saturation in the wavelength band having a large gain coefficient.
There is an advantage that a nm band signal can be amplified. Further, when the Er-doped silica fiber is used, there is an advantage that an optical amplifier and an optical amplification medium having excellent mechanical strength and weather resistance can be realized.

Further, the optical amplifier of the present invention uses Er-doped silica fiber or various Er-doped fibers and suppresses ASE in the wavelength band having a large gain coefficient by the optical filter, so that the gain in the wavelength band having a large gain coefficient is suppressed. There is an advantage that a 1500 nm band signal can be efficiently amplified without causing saturation. Furthermore, when an Er-doped silica-based fiber is used, it has excellent mechanical strength and weather resistance.
It has an advantage that a 00 nm band optical amplifier, an optical amplification component, and a white light source can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an optical amplifier according to the present invention.

FIG. 2 is a block diagram illustrating a configuration example of an optical amplification unit.

FIG. 3 is a diagram showing the equivalent fiber length dependence of the gain of the optical amplifier in the first embodiment.

FIG. 4 is a diagram showing a loss spectrum of an optical filter used in the optical amplifier of the first embodiment.

FIG. 5 is a diagram showing amplification characteristics of the optical amplifier according to the first embodiment.

FIG. 6 is a block diagram showing another configuration example (1) of the optical amplification section.

FIG. 7 is a block diagram showing another configuration example (No. 2) of the optical amplification section.

FIG. 8 is a block diagram showing another configuration example (3) of the optical amplification section.

FIG. 9 is a block diagram showing a configuration of a second embodiment of an optical amplifier according to the present invention.

FIG. 10 is a diagram showing the equivalent fiber length dependence of the gain of the optical amplifier in the second embodiment.

FIG. 11 is a diagram showing amplification characteristics of the optical amplifier according to the second embodiment.

FIG. 12 is a block diagram showing a configuration example of an optical amplification unit in which a pumping light source is shared by a plurality of optical amplification units.

FIG. 13 is a diagram showing the equivalent fiber length dependence of the gain of the optical amplifier in the third embodiment.

FIG. 14 is a diagram showing amplification characteristics of the optical amplifier according to the third embodiment.

FIG. 15 is a block diagram showing a configuration of a fourth embodiment of an optical amplifier according to the present invention.

FIG. 16 is a diagram showing a configuration of an optical amplification medium according to a fourth embodiment.

FIG. 17 is a diagram showing amplification characteristics of the optical amplifier according to the fourth embodiment.

FIG. 18 is a diagram showing a configuration of an optical amplification medium according to a fifth embodiment.

FIG. 19 is a diagram showing another configuration of the optical amplification medium in the fifth embodiment.

FIG. 20 is a diagram showing a configuration of an optical amplification medium according to a sixth embodiment.

FIG. 21 is a diagram showing a table summarizing amplification characteristics when an optical fiber other than an Er-doped silica fiber is used.

FIG. 22 is a diagram showing a gain coefficient of an Er-doped fiber.

FIG. 23 is a diagram showing an amplification characteristic of a conventional optical amplifier using an optical filter.

FIG. 24 is a block diagram showing a configuration of an optical amplifier according to a ninth embodiment.

FIG. 25 is a block diagram illustrating a configuration example of an optical amplification unit.

FIG. 26 is a diagram showing the dependence of the gain of the optical amplifier of the ninth embodiment on the total loss of the Er-doped fiber at 1480 nm.

FIG. 27 is a diagram showing a loss spectrum of the optical filter used in the optical amplifier of the ninth embodiment.

FIG. 28 is a diagram showing the amplification characteristic of the optical amplifier of the ninth embodiment.

FIG. 29 is a block diagram illustrating another configuration example of the optical amplification unit.

FIG. 30 is a block diagram illustrating another configuration example of the optical amplification unit.

FIG. 31 is a block diagram illustrating another configuration example of the optical amplification unit.

FIG. 32 is a block diagram showing a configuration example of an optical amplification unit in which a pumping light source is shared by a plurality of optical amplification units.

FIG. 33 is a block diagram showing a configuration of an optical amplifier according to a tenth embodiment.

FIG. 34 is a diagram showing a configuration of an optical amplification component of a tenth embodiment.

FIG. 35 is a diagram showing a configuration of an optical amplification component of the optical amplifier according to the eleventh embodiment.

FIG. 36 is a diagram showing a configuration of an optical amplification component of the optical amplifier according to the eleventh embodiment.

FIG. 37 is a diagram showing a configuration of an optical amplification component of the optical amplifier according to the eleventh embodiment.

FIG. 38 is a diagram showing a configuration of an optical amplification component of the optical amplifier of the eleventh embodiment.

FIG. 39 is a diagram showing a configuration of an optical amplification component of an optical amplifier according to a twelfth embodiment.

FIG. 40 is a diagram showing the configuration of the optical amplifier component of the sixteenth embodiment.

FIG. 41 is a block diagram showing a configuration of an optical amplification section used in the optical amplifier of the eighteenth embodiment.

FIG. 42 is a diagram showing the dependence of the gain of the optical amplifier of the eighteenth embodiment on the total loss of the Er-doped fiber at 1480 nm.

FIG. 43 is a diagram showing the amplification characteristic of the optical amplifier of the eighteenth embodiment.

FIG. 44 is a diagram showing the amplification characteristic of the optical amplifier of the twentieth embodiment.

FIG. 45 is a diagram showing an amplification characteristic of the optical amplifier of the twenty-first embodiment.

FIG. 46 is a block diagram showing the structure of an optical amplifier according to a twenty-second embodiment.

FIG. 47 is a block diagram showing the structure of a laser device according to a twenty-third embodiment.

FIG. 48 is a block diagram showing a configuration of a white light source according to a twenty-fourth embodiment.

FIG. 49 is a diagram showing the output characteristic of the white light source of the twenty-fourth embodiment.

FIG. 50 is a table showing the amplification characteristics of the optical amplification section,
(A) is an amplification characteristic when using a fiber other than the Er-doped silica fiber in the seventeenth embodiment, and (b) shows an amplification characteristic when a fiber other than the Er-doped silica fiber in the nineteenth embodiment is used as an optical amplification medium. FIG.

[Explanation of symbols]

1-1, 1-2, ... 1-N optical amplifier 2,2-1, 2- (N-1) optical filter 3 Er-doped fiber 4,4-1,4-2 multiplexer 5, 5-1 and 5-2 Excitation light source 6-1 and 6-2 Optical Isolator 7 Optical circulator 8 total reflection mirror 9 Optical power splitter 10 Optical amplification medium 11, 11-1 Multilayer filter 12 Fiber wiring board 13 cores 14 Clad 15 Er-doped waveguide 16-1, 16-2 Silica Pigtail Fiber 17 Si substrate 21-1, 21-2, ... 21-N optical amplifier 22-1, ... 22- (N-1) Optical filter 23 Er-doped fiber 24, 24-1, 24-2 multiplexer 25,25-1,25-2 Excitation light source 26-1, 26-2 Optical Isolator 27 Optical circulator 28 Total reflection mirror 30 Optical amplification parts 31 Multilayer filter 32 fiber wiring board 33 cores 34 Clad 35 Er-doped waveguide 36-1, 36-2, 36-N Er-doped fiber 37-1, 37-2, 37- (N-1) Optical Filter 38-1, 38-2 Silica-based pigtail fiber 39 Si substrate 40 Peltier element 41 Er-doped fiber 42 multiplexer 43 Excitation light source 44-1 and 44-2 optical isolator 45 Optical power splitter 46 Optical amplification parts 47-1 Excitation light source 48-1, 48-2 Fiber grating 49 reflective mirror 50 multiplexer 51 Optical amplification parts 52-2 Multiplexer 53 Excitation light source 54-2 Optical Isolator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04B 10/16 H04B 9/00 J 10/17 (72) Inventor Makoto Shimizu 2-chome, Otemachi, Chiyoda-ku, Tokyo 3-1, Nihon Telegraph and Telephone Corporation (72) Inventor Takuya Tanaka 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Jun Mori Otemachi, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Makoto Yamada (72) Inventor Makoto Yamada 1-12-1 Dogenzaka, Shibuya-ku, Tokyo NTT Electronics F Term (reference) 2H047 KA03 KA12 QA01 QA02 RA00 5F072 AB07 AB09 AK03 AK06 JJ02 JJ20 MM20 PP07 RR01 YY17 5K102 AA13 AA55 AD01 MB05 MC01 MC15 PC03 PH11

Claims (75)

[Claims] 1. Er in at least one of the core and the clad
An optical amplifier using an Er-doped fiber doped with or an Er-doped waveguide, which is formed on a substrate and in which at least one of a core and a clad is doped with Er, as an optical amplification medium, comprising at least one: An optical amplification unit including the optical amplification medium and a pumping light source; and a wavelength band in which a gain is obtained in the optical amplification medium, which is provided with at least one, and which reduces the light in the first wavelength band having the maximum gain Controlling means for suppressing the optical amplification of the first wavelength band, and the suppression is located at the skirt on the low wavelength side in the wavelength band where the gain is obtained in the optical amplification medium by the suppression, and the gain is relatively small. An optical amplifier, which promotes optical amplification in a second wavelength band and outputs the amplified optical signal in the second wavelength band. 2. The optical amplifier according to claim 1, further comprising an optical filter as a means for suppressing optical amplification in the first wavelength band. 3. The pumping light source is one unit, the optical amplification unit shares the pumping light source, and a branching unit for branching the pumping light generated by the pumping light source, and a pumping unit branched by the branching unit. The optical amplifier according to claim 1 or 2, further comprising: an optical unit that guides light to each optical amplification unit. 4. N optical amplification sections and (N-1) optical filters are provided, and the optical amplification sections and the optical filters are alternately arranged so that the optical amplification sections are provided at both ends. The optical amplifier according to claim 1, wherein the optical amplifier is connected in series. 5. The optical amplifier according to claim 1, wherein the total loss of the optical filters is 25 dB or more in the first wavelength band. 6. The optical amplifier according to claim 1, wherein the total loss of the optical filters is 30 dB or more in the first wavelength band. 7. The first wavelength band is 1520 to 156.
0 nm, and the second wavelength band is 1485 to 152
It is 0 nm, The optical amplifier in any one of Claim 1 thru | or 6 characterized by the above-mentioned. 8. The optical filter comprises 1490 to 1520.
The optical amplifier according to claim 7, which is an optical filter for flattening the optical power of nm. 9. The optical filter has an optical power attenuation amount in the first wavelength band and 1500 to 1520 nm so that a gain from the first wavelength band to the second wavelength band is flattened. 9. The optical filter in which the balance of the optical power attenuation amount in is adjusted, and the signal light in the first wavelength band is amplified and output in addition to the second wavelength band. The optical amplifier described. 10. The first wavelength band is 1490 to 15
60 nm, and the second wavelength band is 1450 to 14
It is 90 nm, The optical amplifier in any one of Claim 1 thru | or 6 characterized by the above-mentioned. 11. The first wavelength band is 1520 nm to
1560 nm, and the second wavelength band is 1485-
The optical amplifier according to any one of claims 1 to 6, which has a wavelength of 1520 nm and a wavelength of 1570 to 1610 nm. 12. An equivalent fiber length or equivalent waveguide length of the optical amplification medium (fiber length or waveguide length, E
The optical amplifier according to any one of claims 1 to 11, wherein a product of r-doped concentration (wt ppm) is a predetermined value with which a signal gain of 15 dB or more is obtained in the second wavelength band. 13. The optical amplification medium is an Er-doped silica-based fiber or waveguide having an equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 14. The optical amplification medium is an Er-doped tellurite fiber or waveguide having the equivalent fiber length or waveguide length of 0.7 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 15. The optical amplification medium is an Er-doped aluminosilicate fiber or waveguide having the equivalent fiber length or waveguide length of 1.2 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 16. The optical amplification medium is an Er-doped phosphate salt fiber or waveguide having an equivalent fiber length or waveguide length of 1.0 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 17. The optical amplification medium is an Er-doped fluorophosphate fiber or waveguide having the equivalent fiber length or waveguide length of 1.3 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 18. The optical amplification medium is an Er-doped fluoride fiber or waveguide having the equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 19. The optical amplification medium is an Er-doped bismuth oxide-based fiber or waveguide having the equivalent fiber length or waveguide length of 0.6 × 10 ⁻⁴ m · wt ppm or more. The optical amplifier according to claim 12. 20. The optical amplification medium is an Er-doped chalcogenide fiber or waveguide having an equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. Item 13. The optical amplifier according to item 12. 21. An electric means for controlling the temperature of the Er-doped fiber is provided.
0. The optical amplifier according to 0. 22. The Er of the optical amplification medium is 1480 nm.
The total loss in the second wavelength band is 15
22. The optical amplifier according to claim 1, wherein the optical amplifier has a predetermined value with which a signal gain of dB or more can be obtained. 23. The optical amplification medium is Er 1480n.
23. The optical amplifier according to claim 22, which is an Er-doped silica fiber or a waveguide having a total loss in m of 33 dB or more. 24. The optical amplification medium is Er 1480n.
The optical amplifier according to claim 22, which is an Er-doped tellurite fiber or a waveguide having a total loss in m of 32 dB or more. 25. The optical amplification medium is Er 1480n.
The optical amplifier according to claim 22, which is an Er-doped aluminosilicate fiber or waveguide having a total loss in m of 30 dB or more. 26. The optical amplification medium is Er 1480n.
3. An Er-doped phosphate fiber or waveguide having a total loss in m of 33 dB or more.
2. The optical amplifier according to item 2. 27. The optical amplification medium is Er 1480n.
23. The optical amplifier according to claim 22, which is an Er-doped fluorophosphate fiber or a waveguide having a total loss in m of 35 dB or more. 28. The optical amplification medium is Er 1480n.
3. An Er-doped fluoride fiber or waveguide having a total loss in m of 32 dB or more.
2. The optical amplifier according to item 2. 29. The optical amplification medium is Er 1480n.
23. The optical amplifier according to claim 22, which is an Er-doped bismuth oxide-based fiber or waveguide having a total loss in m of 30 dB or more. 30. The optical amplification medium is Er 1480n.
The optical amplifier according to claim 22, which is an Er-doped chalcogenide fiber or a waveguide having a total loss in m of 35 dB or more. 31. The optical amplifier according to claim 1, wherein the pumping light source is a 980 nm band semiconductor laser. 32. An optical amplification component comprising an Er-doped optical fiber having Er added to at least one of a core and a clad wired on a wiring board, wherein the Er-doped optical fiber is an optical amplification medium. In a wavelength band in which a gain is obtained in an optical fiber, at least one optical filter is provided that reduces light in the first wavelength band having the maximum gain to suppress optical amplification in the first wavelength band, Due to the suppression, in the wavelength band in which the gain is obtained in the optical amplification medium, the optical amplification is performed in the second wavelength band located at the bottom of the low wavelength side and having a relatively small gain, and the amplified second wavelength band is obtained. An optical amplification component that outputs an optical signal in the wavelength band. 33. E in at least one of the core and the clad.
An optical amplification component comprising an Er-doped optical fiber doped with r, wherein the Er-doped optical fiber is used as an optical amplification medium, wherein a grating is formed in the core or the clad,
The grating is an optical filter that suppresses light amplification in the first wavelength band by reducing light in the first wavelength band in which the gain is maximum in the wavelength band in which the gain is obtained in the Er-doped optical fiber. Which is a grating having a function of, and suppresses optical amplification of a second wavelength band having a relatively small gain, which is located at the skirt on the low wavelength side in the wavelength band in which the gain is obtained in the optical amplification medium. An optical amplification component, characterized in that the optical signal of the second wavelength band that is prompted and amplified is output. 34. The optical amplification component according to claim 33, wherein the grating is a chirped grating. 35. The grating is a plurality of gratings having different periods.
The optical amplification component according to item 3. 36. An optical amplification medium, comprising: an optical waveguide produced on a substrate and having Er added to at least one of a core and a clad; and a silica-based pigtail fiber connected to the optical waveguide. In the optical amplification component, the light in the first wavelength band having the maximum gain is reduced in the wavelength band in which the gain is obtained in the Er-doped optical waveguide, and the optical amplification in the first wavelength band is suppressed. At least one optical filter for controlling the optical amplification of the second wavelength band, which is located at the bottom of the low wavelength side and has a relatively small gain in the wavelength band in which the gain is obtained in the optical amplification medium by the suppression. And an amplified optical signal of the second wavelength band is output. 37. The optical amplification component according to claim 32, wherein a total loss of the optical filters is 25 dB or more in the first wavelength band. 38. The optical amplification component according to claim 32, wherein a total loss of the optical filters is 30 dB or more in the first wavelength band. 39. E in at least one of the core and the clad.
An optical amplification component comprising N Er-doped fibers doped with r, wherein the Er-doped fiber is used as an optical amplification medium, wherein the gain is maximum in a wavelength band in which the gain is obtained by the Er-doped fiber. At least N or (N-1) optical filters that reduce the light in the wavelength band of 1 to suppress the optical amplification in the first wavelength band, and the Er-doped fiber and the optical filter are alternately connected in series. Due to the suppression, in the wavelength band in which the gain is obtained in the optical amplification medium, the optical amplification is performed in the second wavelength band located at the skirt on the low wavelength side and having a relatively small gain, and the amplified light is amplified. An optical amplification component, wherein an optical signal in the second wavelength band is output. 40. E in at least one of the core and the clad
An optical amplification component comprising an Er-doped fiber to which r is added, wherein the Er-doped fiber is used as an optical amplification medium, Pr, Nd,
At least one kind of rare earth ion selected from Sm, Tb, Dy, and Tm is added, and the rare earth ion has a maximum gain in the wavelength band in which the gain is obtained in the Er-doped fiber. Is a rare earth ion having a function of an optical filter that reduces light in the wavelength band of 1 to suppress optical amplification of the first wavelength band, and in the wavelength band in which gain is obtained in the optical amplification medium by the suppression, An optical amplification component which is located at the bottom of the low wavelength side and promotes optical amplification in a second wavelength band with a relatively small gain, and outputs the amplified optical signal in the second wavelength band. . 41. E in at least one of the core and the clad
In an optical amplification component including an Er-doped fiber doped with r, wherein the Er-doped fiber is an optical amplification medium, the Er-doped fiber is bent with a radius of curvature of a reference value or less, and has a loss due to the bending, The loss due to bending has a function of reducing light in the first wavelength band in which the gain is maximum in the wavelength band in which the gain is obtained in the Er-doped fiber and suppressing optical amplification in the first wavelength band. In the wavelength band in which the gain is obtained in the optical amplification medium by the suppression, the optical amplification is performed in the second wavelength band located at the skirt on the low wavelength side and having a relatively small gain, and is amplified. An optical amplification component, wherein an optical signal in the second wavelength band is output. 42. E in at least one of the core and the clad.
An optical amplification component comprising an Er-doped fiber doped with r, wherein the Er-doped fiber is used as an optical amplification medium, comprising a plurality of claddings, and having a cutoff wavelength of a fundamental mode of light propagating through the Er-doped fiber, The loss on the longer wavelength side than the cutoff wavelength reduces the light in the first wavelength band in which the gain is maximum in the wavelength band in which the gain is obtained in the Er-doped fiber, and the optical amplification in the first wavelength band is performed. Of the second wavelength band having a relatively small gain, which is located at the bottom of the low wavelength side in the wavelength band in which the gain is obtained in the optical amplification medium by the suppression. An optical amplification component, characterized in that the optical signal of the second wavelength band that is prompted and amplified is output. 43. The Er-doped fiber is any one of a W-type fiber, a triple-clad type fiber, and a quadruple-clad type fiber.
The optical amplification component described in. 44. The function of suppressing optical amplification in the first wavelength band is a function of giving a loss to the first wavelength band, and the total loss is 30 dB or more in the first wavelength band. The optical amplification component according to claim 41, 42 or 43. 45. The first wavelength band is 1520-15.
60 nm, and the second wavelength band is 1485-15
The optical amplification component according to any one of claims 32 to 44, which has a thickness of 20 nm. 46. The optical filter comprises 1490-152.
The optical amplification component according to any one of claims 32 to 40, which is an optical filter that flattens the optical power of 0 nm. 47. The optical filter has an optical power attenuation amount in the first wavelength band and 1500 to 1520 nm so that a gain from the first wavelength band to the second wavelength band is flattened. 41. An optical filter in which the balance of the optical power attenuation amount in is adjusted, and the first wavelength band is amplified and output in addition to the second wavelength band. The optical amplification component described in. 48. The first wavelength band is 1490-15.
60 nm, and the second wavelength band is 1450 to 14
The optical amplification component according to any one of claims 32 to 44, which has a thickness of 90 nm. 49. The equivalent fiber length or equivalent waveguide length of the optical amplification medium is 1 in the second wavelength band.
49. The optical amplification component according to claim 32, which has a predetermined value that can obtain a signal gain of 5 dB or more. 50. The optical amplification medium is an Er-doped silica-based fiber or waveguide having an equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 51. The optical amplification medium is an Er-doped tellurite fiber or waveguide having an equivalent fiber length or waveguide length of 0.7 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 52. The optical amplification medium is an Er-doped aluminosilicate fiber or waveguide having the equivalent fiber length or waveguide length of 1.2 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 53. The optical amplification medium is an Er-doped phosphate salt fiber or waveguide having the equivalent fiber length or waveguide length of 1.0 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 54. The optical amplification medium is an Er-doped fluorophosphate fiber or waveguide having the equivalent fiber length or waveguide length of 1.3 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 55. The optical amplification medium is an Er-doped fluoride fiber or waveguide having the equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 56. The optical amplification medium is an Er-doped bismuth oxide-based fiber or waveguide having the equivalent fiber length or waveguide length of 0.6 × 10 ⁻⁴ m · wt ppm or more. The optical amplification component according to claim 49. 57. The optical amplifying medium is an Er-doped chalcogenide fiber or waveguide having the equivalent fiber length or waveguide length of 1.5 × 10 ⁻⁴ m · wt ppm or more. Item 49. The optical amplification component according to item 49. 58. The optical amplification component according to claim 32, further comprising electrical means for controlling the temperature of the Er-doped fiber. 59. The Er of the optical amplification medium is 1480 nm.
The total loss in the second wavelength band is 15
The optical amplification component according to any one of claims 32 to 58, which has a predetermined value with which a signal gain of dB or more is obtained. 60. The optical amplification medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped quartz fiber or a waveguide having a total loss in m of 33 dB or more. 61. The optical amplification medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped tellurite fiber or a waveguide having a total loss in m of 32 dB or more. 62. The optical amplifying medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped aluminosilicate fiber or waveguide having a total loss in m of 32 dB or more. 63. The optical amplification medium is Er 1480n.
6. An Er-doped phosphate fiber or waveguide having a total loss in m of 33 dB or more.
9. The optical amplification component according to item 9. 64. The optical amplification medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped fluorophosphate fiber or a waveguide having a total loss in m of 35 dB or more. 65. The optical amplification medium is Er 1480n.
6. An Er-doped fluoride fiber or waveguide having a total loss in m of 32 dB or more.
9. The optical amplification component according to item 9. 66. The optical amplification medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped bismuth oxide-based fiber or waveguide having a total loss in m of 30 dB or more. 67. The optical amplification medium is Er 1480n.
The optical amplification component according to claim 59, which is an Er-doped chalcogenide fiber or a waveguide having a total loss in m of 35 dB or more. 68. The optical amplification component according to any one of claims 32 to 67, a pumping light source for generating pumping light to the optical amplification component, pumping light from the pumping light source, and signal light in the second wavelength band. And an optical means for coupling the optical path and the optical path to the optical amplification component. 69. The optical amplifier according to claim 68, wherein the pumping light source is a 980 nm band semiconductor laser. 70. An optical amplifying component according to claim 32, a pumping light source for generating pumping light to the optical amplifying component, and 1.
A fiber grating that totally reflects a part of wavelengths in a wavelength band of 450 to 1520 nm, and 1450 to 1520n
A laser device comprising a fiber grating that reflects a part of light at a part of wavelengths in a wavelength band of m. 71. An optical amplification component according to any one of claims 32 to 67, a pumping light source for generating pumping light to the optical amplification component, and 1
A mirror that totally reflects a part or all of the wavelength band of 450 to 1520 nm, a mirror that reflects a part of the light of a part or all of the wavelength band of 1450 to 1520 nm, and a wavelength band of 1450 to 1520 nm. A laser device comprising a bandpass filter that transmits a part of the wavelengths of the above. 72. The laser device according to claim 70, wherein the excitation light source is a 980 nm band semiconductor laser. 73. A white light source, comprising: the optical amplification component according to any one of claims 32 to 67; and a pumping light source that generates pumping light for the optical amplification component. 74. The white light source according to claim 73, wherein the excitation light source is a 980 nm band semiconductor laser. 75. Any one of claims 1 to 31 or 6
The optical amplifier described in 8, 69 is provided as an amplifying unit, and 157
A signal light in the wavelength band of 1490 to 1520 nm and a demultiplexer for demultiplexing the signal light in the wavelength band of 1570 to 1610 nm; And a AS having a wavelength of 1520 to 1560 nm generated by the optical amplifier.
An optical amplifier comprising: an optical unit that guides the E light to an amplification unit that amplifies the signal light in the wavelength band of 1570 to 1610 nm.