JPH10123342A - Wavelength dispersion compensator and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized wavelength dispersion compensator which has low transmission loss and contains a long wide-band DCF so that no increase in transmission loss is caused even in high-temperature environment. SOLUTION: An optical fiber coil 32 after being manufactured by winding the wide-band DCF(dispesion compensating optical fiber) around a coil barrel is taken out of the coil barrel to manufacture an optical fiber coil 32 in a bundle state wherein winding strain is released. Resin 42 is used as a winding disorder preventive member to fix the optical fiber coil 32 to a storage box at four places. Both the ends of the optical fiber coil 32 are connected to pigtail fibers by fusion splicing parts 44 respectively. Even when the storage box is closed with its lid after the optical fiber coil 32 is fixed to the storage box 40 with the resin 42, a gap is left in the bundle of the optical fiber coil 32 and a space is left between the optical fiber coil 32 and storage box, so there is no increase in the transmission loss, etc., even when the bundled optical fiber coil 32 is stored in the storage box 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromatic dispersion compensator and a method of manufacturing the same, and more particularly, to a chromatic dispersion compensator for reducing chromatic dispersion in a 1.55 .mu.m band of an optical fiber transmission line and a method of manufacturing the same.

[0002]

2. Description of the Related Art If an optical amplifier operating in the 1.55 μm band is used by using an optical fiber doped with erbium (Er) as a rare earth element, long-distance large-capacity transmission in the 1.55 μm band is possible. However, when transmission is performed in the 1.55 μm band using a single mode optical fiber (1.3 SMF) having the zero dispersion wavelength in the 1.3 μm band, the zero dispersion wavelengths do not match, so that a large chromatic dispersion occurs and an optical signal is generated. Is distorted, thereby deteriorating the signal quality. Therefore, when transmission is performed in the 1.55 μm band using 1.3 SMF, a technique for suppressing chromatic dispersion is required. One of them is a dispersion compensating optical fiber (D) having a large chromatic dispersion with a sign opposite to that of 1.3 SMF.
There is a method of canceling chromatic dispersion in the 1.55 μm band using CF).

[0003] This DCF is roughly classified into two types. One is that the chromatic dispersion at a specific wavelength is 1.3SM.
Since it is opposite to F, it is a DCF that can compensate for chromatic dispersion at that wavelength. As a structure of this type of DCF, a matched clad type in which the refractive index of the clad portion is uniform (FIG. 18)
The DCF of (a)) is known. The other is a DCF capable of compensating for chromatic dispersion over a wide band because not only chromatic dispersion but also the wavelength dependence of chromatic dispersion (chromatic dispersion slope) is opposite to 1.3 SMF. This kind of broadband DC
The structure of F is a double clad type having a depressed portion between a core portion and a clad portion (FIG. 18B), and a depressed portion having a depressed portion between a clad portion and a core portion. 18 (c), and a segment core type (FIG. 18 (c), in which a portion having a higher refractive index is provided in the cladding portion). d)).
If a CF is used, a signal can be transmitted with a plurality of lights whose wavelengths are slightly shifted, so that wavelength multiplex transmission that can increase the transmission capacity per fiber can be easily performed.

[0004]

However, DC for wide band
Double-clad, double-core, and segment-core optical fibers suitable for F generally have poor bending loss characteristics.
Large transmission loss occurs in the 55 μm band. This bending loss can be reduced by increasing the diameter of the coil and reducing the number of winding layers. However, when the diameter of the coil is increased, the chromatic dispersion compensator is increased, which is not preferable.

A chromatic dispersion compensator is often used in combination with an optical amplifier using an erbium-doped optical fiber. In this case, the temperature of the chromatic dispersion compensator rises due to heat generated from the pumping laser inside the optical amplifier, and the coil thermally expands to generate distortion in the broadband DCF, thereby increasing transmission loss. The transmission loss in such a high temperature environment can be reduced by using a material having a small thermal expansion for the coil body. However, materials such as quartz glass, ceramics, and special alloys having a small coefficient of thermal expansion are difficult to process and expensive.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a small-sized chromatic dispersion compensator which efficiently stores therein a long wideband DCF which has low transmission loss and does not cause an increase in transmission loss even in a high-temperature environment, and a method of manufacturing the same. Is to provide.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted various studies to achieve the above object, and as a result, have accomplished the present invention focusing on the following points.

When a long DCF for a wide band is wound around a small coil, a large transmission loss increases in a 1.55 μm band which is a transmission wavelength band. By examining the wavelength dependence, it was found that a so-called macrobend loss in which the transmission loss increases as the wavelength becomes longer. Macro bend loss occurs when an optical fiber is bent with a small curvature. When a broadband DCF is wound around a coil, the coil is bent at a curvature corresponding to the diameter of the coil body, so that macrobend loss may occur. However, when the coil body was removed after winding the coil, the increased transmission loss almost disappeared. For this reason, it has been clarified that the main factor of the transmission loss caused by coil winding is the lateral pressure received from adjacent fibers due to the multilayer winding. Therefore, it is considered that the macrobend loss is caused by bending the optical fiber due to the lateral pressure. Thus, it was concluded that eliminating this lateral pressure would allow production of an optical fiber coil with low transmission loss.

Further, even if the temperature is changed in a state where the broadband DCF is housed in a small coil, a large transmission loss occurs in the 1.55 μm band. In addition, when the winding tension is increased when the broadband DCF is wound around the coil, or when the wideband DCF is wound around a coil having a small body diameter, the amount of temperature change in transmission loss increases. These facts indicate a deep relationship between the transmission loss change and the magnitude of the lateral pressure. Therefore, it was found that the side pressure should be eliminated in order to reduce the temperature dependence of the transmission loss.

Therefore, the present invention has the following configuration.

A chromatic dispersion compensator according to the present invention is a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line. An optical fiber coil in which a chromatic dispersion compensating optical fiber having a chromatic dispersion slope having the opposite sign to the optical fiber of the optical fiber transmission line is wound a plurality of times, and a state in which the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. And a storage case for storing the optical fiber coil.

As described above, since the optical fiber coil is stored in the storage case in a state where the winding distortion is substantially released, the side pressure generated by winding the broadband DCF in multiple layers is alleviated, and in a high temperature environment. In this case, the optical fiber coil is housed without being affected by the thermal expansion of the coil body.

A chromatic dispersion compensator according to the present invention is a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line. An optical fiber coil in which a chromatic dispersion compensating optical fiber having a chromatic dispersion slope having the opposite sign to the optical fiber of the optical fiber transmission line is wound a plurality of times, and a state in which the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. And a storage case for storing the optical fiber coils bundled in the bundle.

As described above, the unwinding optical fiber coil is housed in the housing case in a bundle state in which the winding distortion is substantially released, so that the side pressure generated by winding the broadband DCF in multiple layers is reduced, and The optical fiber coil is housed in a high temperature environment without being affected by the thermal expansion of the coil body.

A chromatic dispersion compensator according to the present invention is a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line, wherein a diameter of a body is reduced from a first diameter to a second diameter. A possible coil body and a chromatic dispersion compensating optical fiber having a chromatic dispersion of the opposite sign to the optical fiber of the optical fiber transmission line and a chromatic dispersion slope of the opposite sign to the optical fiber of the optical fiber transmission line are coiled at the first diameter. An optical fiber coil wound around the body a plurality of times, and an optical fiber coil in a state where the diameter of the coil body is substantially reduced to a second diameter and the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. And a storage case for storing.

As described above, after the optical fiber coil is manufactured, the body diameter is substantially contracted and unwound, and then the optical fiber coil is stored in the storage case.
The side pressure generated by winding F in multiple layers is reduced,
In addition, the optical fiber coil is accommodated in a high-temperature environment without being affected by the thermal expansion of the coil body.

The chromatic dispersion compensator according to the present invention may further include a collapse prevention member for preventing the collapse by fixing the optical fiber coil to the storage case.

As described above, when the optical fiber coil is fixed to the storage case by the winding prevention member, even if the optical fiber coil is stored in a state in which the winding distortion is substantially released, vibration and impact during transportation of the chromatic dispersion compensator and the like can be achieved. This can prevent breakage of the optical fiber, collapse of the optical fiber coil, and increase in transmission loss.

In the chromatic dispersion compensator according to the present invention, the collapse prevention member may be formed of a resin for fixing the optical fiber coil to the storage case at a plurality of locations.

As described above, if the optical fiber coil is fixed to the storage case by using the resin as the winding prevention member,
It is possible to easily prevent breakage of the optical fiber due to vibration or impact during transportation of the chromatic dispersion compensator, collapse of the optical fiber coil, and increase in transmission loss.

In the chromatic dispersion compensator according to the present invention, the winding prevention member may be a cushion member for fixing the optical fiber coil to the storage case.

As described above, if the optical fiber coil is fixed to the storage case by using the cushion material as the winding collapse preventing member, the optical fiber is broken due to vibration and impact during transportation of the chromatic dispersion compensator, and the optical fiber coil is wound. Collapse and an increase in transmission loss can be easily prevented.

In the chromatic dispersion compensator according to the present invention, the diameter of the optical fiber coil may be 100 mm or less at the minimum.

As described above, in a state in which the winding distortion is substantially released and in a state where the coil is not affected by the thermal expansion of the coil body even when placed in a high temperature environment, the diameter is 100 mm or less. When the optical fiber coil can be stored in the storage case, a small chromatic dispersion compensator having reduced transmission loss and temperature dependence of the transmission loss can be obtained.

The method of manufacturing a chromatic dispersion compensator according to the present invention is a method of manufacturing a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line.
A chromatic dispersion compensating optical fiber having a chromatic dispersion of the opposite sign to the optical fiber of the optical fiber transmission line and a chromatic dispersion slope of the opposite sign to the optical fiber of the optical fiber transmission line is wound around the coil body a plurality of times to form an optical fiber coil. A coil manufacturing step of manufacturing, and a coil removing step of removing the optical fiber coil from the coil body to form a bundled optical fiber coil in a state where the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. .

As described above, since the optical fiber coil in the bundle state in which the winding distortion is substantially released is formed by the coil removing step, the side pressure generated by winding the broadband DCF in multiple layers is loosened and relaxed. Thus, an optical fiber coil can be manufactured which is not affected by the thermal expansion of the coil body even when placed in a high temperature environment.

[0027] The method of manufacturing a chromatic dispersion compensator according to the present invention may further include a lubricating material applying step of applying a lubricating material to the coil body prior to any one of the coil manufacturing step and the coil removing step.

With the provision of the lubricating material application step, the friction between the coil body and the optical fiber coil can be reduced, so that the optical fiber coil can be easily removed from the coil body.

In the method of manufacturing a chromatic dispersion compensator according to the present invention, the coil manufacturing step includes a step of manufacturing the optical fiber coil by winding the chromatic dispersion compensating optical fiber around the coil body with a winding tension of 40 g weight or less. It may be.

When the winding tension is set at 40 g weight or less, the friction between the coil body and the optical fiber coil can be reduced, so that the optical fiber coil can be easily removed from the coil body.

A method of manufacturing a chromatic dispersion compensator according to the present invention is a method of manufacturing a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line.
A chromatic dispersion compensating optical fiber having a chromatic dispersion of the opposite sign to the optical fiber of the optical fiber transmission line and a chromatic dispersion slope of the opposite sign to the optical fiber of the optical fiber transmission line is wound around the coil body a plurality of times to form an optical fiber coil. A coil manufacturing process to be manufactured, and, after the coil manufacturing process, a body diameter that substantially reduces the diameter of the coil body compared to the diameter of the coil body in the coil manufacturing process so that winding distortion is substantially released. And a change step.

As described above, since the body diameter is substantially reduced in the body diameter changing step to form an optical fiber coil in the form of a bundle in which the wide band DCF is unwound, the side pressure generated due to the multilayer winding. And an optical fiber coil which is not affected by the thermal expansion of the coil body even when placed in a high temperature environment can be manufactured.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, in which an optical fiber coil is manufactured using a DCF for a wide band (hereinafter, simply referred to as DCF).

FIG. 1 is a cross-sectional view of a DCF used in the embodiment and shows a case where the number of coating layers is two. This DCF
Has two concentric cylindrical shell-shaped coating layers 13 and 15 on the side surface of the optical fiber 11 around the optical fiber 11 made of glass. The coating layer is not limited to two layers. A resin is used for the DCF coating material. In the embodiment, for manufacturing the optical fiber coil, the glass diameter c = 100 μm and the primary coating layer thickness d =
20 μm, secondary coating layer thickness e = 20 μm, fiber outer diameter f
A DCF (fiber A) having a double clad type (FIG. 18B) refractive index distribution of 180 μm is used. In addition, 2
At 0 ° C., the yank modulus of the primary coating layer is 0.06 kgf / mm ² and the Young's modulus of the secondary coating layer is 65 kgf / mm2.
mm ² .

FIG. 2 is a perspective view of a coil for winding the DCF, where the coil body diameter (hereinafter, referred to as body diameter) is g, the coil flange diameter is h, and the winding width of the coil is k. The coil is
It comprises a cylindrical coil body 20 around which DCF is wound in multiple layers and two disk-shaped coil flanges 21. Two coil tsuba 2
Numeral 1 sandwiches the coil cylinder 20 and both are arranged with their central axes coincident. According to FIG. 2, the coil cylinder is cylindrical, but is not limited to this. The coil is made of aluminum, but is not limited to this.

FIG. 3 is a data list showing the data of the DCF used in the embodiment. The refractive index distribution shape corresponds to FIG. 18B, and △ +, △ −, a and b correspond to the symbols in FIG. 18, respectively. Glass diameter c, primary coating thickness d, secondary coating thickness e, fiber outer diameter f are
Each corresponds to the reference numeral in FIG.

In the following description, a gravitational unit system is used as a unit of force and Young's modulus for easy understanding of numerical values.

(First Embodiment) In this embodiment,
A case where the optical fiber coils are bundled to substantially release the winding distortion of the optical fiber coils will be described.

In this embodiment, a fiber A having a fiber length of 10 km is prepared by using a fiber having a body diameter g = 100 mm and a coil flange diameter h.
= 200 mm and a winding width k = 18 mm were wound on an aluminum coil with a winding pitch of 0.4 mm and a winding tension of 40 g to produce an optical fiber coil.

FIG. 4 shows transmission loss values (after coil winding) measured after manufacturing the optical fiber coil, and transmission loss values (after heat cycle) measured after performing the heat cycle shown in FIG. 5 on the optical fiber coil. ), And the vertical axis indicates the loss change amount of the transmission loss value, and the horizontal axis indicates the wavelength. When measured at a wavelength of 1.55 μm, the loss change value after winding the coil was 1.7 dB. The loss change value after the heat cycle becomes smaller due to the relaxation of the side pressure,
It was 5 dB. In addition, this optical fiber coil is
When the transmission loss value was measured by heating to a temperature of up to 20 ° C. after the heat cycle, the change was 0.24 dB. When the transmission loss was measured after cooling again to 20 ° C., the value returned to the value after the heat cycle, and the change in the transmission loss disappeared.

In the heat cycle shown in FIG.
After leaving the measured optical fiber coil at a temperature of 20 ° C. for 1 hour, 80 ° C. and −40 ° C. are alternately repeated twice, left for 1 hour each, and finally left at 20 ° C. for 2 hours. The change between the temperatures is as follows.
The rate of change in temperature drop is -1 ° C / min.

Next, in order to eliminate the lateral pressure, the optical fiber coil was removed from the wound coil body, and the change in the transmission loss value was examined. First, an optical fiber coil was manufactured under the same conditions as above, and the transmission loss value (after winding the coil) of the optical fiber coil wound around the coil body was measured. Further, both coil flanges were removed, the coil body was carefully extracted, and the transmission loss value (after the coil body was removed) of the optical fiber coil that was unwrapped and bundled was measured.

FIG. 6 is a characteristic diagram showing a transmission loss value after winding the coil and a transmission loss value after removing the coil body. The change in the transmission loss value is plotted on the vertical axis, and the wavelength is plotted on the horizontal axis. . When measured at a wavelength of 1.55 μm after winding the coil, the loss change value was 1.7 dB. When measured after removing the coil body, the change in transmission loss caused by coil winding disappeared. The temperature of the optical fiber coil after removing the coil body is 70 ° C.
When the transmission loss value was measured at a wavelength of 1.55 μm, the transmission loss value was increased by 0.06 dB as compared with the value at 20 ° C.

The minute change in the transmission loss value is described in the literature (Tanaka et. Al., “TEMPERATU”.
RE DEPENDENCE OF INTRINSI
C TRANSMISSION LOSS FOR H
IGH SILICA FIBER ", Europea
n Conference on Optical C
communication, pp193-pp196,
1987), which is about the same as the value of 1.3 SMF. Therefore, this transmission loss is a value irrelevant to the lateral pressure, and is considered to be an essential temperature-dependent loss of the optical fiber.

As described above, since the optical fiber coil manufactured by winding the DCF around the coil body a plurality of times is removed from the coil body to form a bundle, the winding distortion of the optical fiber coil is substantially released. It was in a state of being. As a result, the side pressure generated by winding the DCF in multiple layers is reduced, and the effect of thermal expansion of the coil body in a high-temperature environment is eliminated, thereby reducing the transmission loss of the optical fiber coil and the temperature dependence of the transmission loss. it can. If this is stored in a storage case, the optical fiber coil can be stored in a state where the winding distortion of the chromatic dispersion compensating optical fiber is substantially released.

When removing the optical fiber coil from the coil body, it is preferable to apply a lubricant such as fine powder to the coil body before winding the DCF. This is because, when the lubricant is applied, the friction coefficient between the optical fiber coil and the surface of the coil body can be reduced, so that the optical fiber coil can be easily removed. For example, it took about 15 minutes to remove an optical fiber coil manufactured by winding a DCF under the same conditions as in the present embodiment without applying anything to the coil cylinder, from the coil cylinder. On the other hand, when talc (4th edition, physics and chemistry dictionary, pp. 239) used as a powdered inorganic filler was applied to the coil body, and a DCF was wound around to produce an optical fiber coil, the extraction time was about 4 minutes. The lubricating material is not limited to fine powder such as talc, but may be a liquid material as long as the coefficient of friction between the DCF and the surface of the coil body can be reduced when the optical fiber coil is removed from the coil body. It may be applied after winding.

It is preferable that the tension at the time of winding the DCF around the coil cylinder is small. If the tension is small, the friction between the optical fiber coil and the coil body surface can be reduced,
This is because the removal of the optical fiber coil becomes easy.
For example, when talc was applied to the coil body, and a DCF was wound with a winding tension of 50 g weight to produce an optical fiber coil, the extraction time was about 20 minutes. on the other hand,
When an optical fiber coil was manufactured with only the winding tension of 40 g weight, the extraction time was about 4 minutes. The winding tension is preferably as low as the DCF does not disturb the winding state, and is preferably about 40 g weight or less as a value derived from experience through experiments and the like.

The bundle of optical fiber coils is DCF
Is wound around the coil body, and then removed from the coil body. After the DCF is wound around a member corresponding to the coil body in the manufacturing process of the optical fiber coil to manufacture the optical fiber coil, the optical fiber coil may be removed from the member to manufacture the optical fiber coil.

(Second Embodiment) In this embodiment,
A description will be given of a case where the diameter of the optical fiber coil is substantially reduced after the DCF is wound around the coil body in order to substantially release the winding distortion of the optical fiber coil.

First, a description will be given of a structure of a coil capable of reducing a body diameter after winding of a DCF.

FIG. 7A is an exploded view of the coil. This coil has a cylindrical core member 22 and a coil flange 2.
6, a support member 28, and a wedge-shaped member 24. The coil flange 26 is a thin disk having an opening at the center for inserting the core member 22. The support member 28 has an opening at the center for inserting the core member 22. The wedge-shaped member 24 is shown in FIG.
As shown in the side view of (b), the shape is such that the disk is sufficiently divided by a line including the center, the protrusions 30 are provided on both side surfaces of the central portion, and the circumferential portion has the same dimensions as the winding width of the coil. It has a thick part. FIG. 7C is a cross-sectional view of the coil assembled with these components cut along a plane including the central axis. Two coil flanges 26 sandwich the support member 28 from both sides, and these are arranged on a concentric axis. Further, when the core member 22 is inserted into the opening at the center, the coil flange 26 and the support member 28 are fixed. The wedge-shaped member 24 is sandwiched and fixed between the support member 28 and the coil flange 26 from both sides, and is in contact with the core member 22 at the tip of the wedge portion.

FIG. 8A is a top view of the support member 28. FIG. 8B is a cross-sectional view of the cross section taken along the line AA ′ of FIG. The support member 28 has a structure in which two disks are bonded together by a connecting wall 34 provided from the circumferential side to the edge of the opening. In order to insert the wedge-shaped member 24 therebetween, ten connection walls 34 are provided in accordance with the wedge shape. In addition, each connection wall 3
At the center between the four, there is a groove 36 formed from the peripheral side toward the central side. FIG. 8C is an enlarged view of the groove 36. The groove 36 is formed by a depression having a rectangular parallelepiped shape. Groove 36
Inside, a spiral spring 38 having one end fixed to the peripheral side of the support member 28 is arranged. The reason why the spiral spring is used is that the structure is simple and a small one can be manufactured. The spiral spring 38 is not limited to this as long as it acts as an elastic body.

Next, a mechanism for reducing the body diameter after winding the DCF around the coil body will be described with reference to FIG. In FIG. 9, the coil flange 26 is shown so that the reduction mechanism can be easily understood.
Are omitted, and the wedge-shaped member 24 that is hidden behind the support member 28 and cannot be seen is indicated by a broken line.

FIGS. 9A and 9B are a side view and a top view, respectively, of the coil before the body diameter is reduced. Wedge-shaped member 24
Is inserted between the connection walls 34 of the support member 24 with the wedge part directed toward the center, and is in contact with the core member 22 at the tip of the wedge part. The protrusions 30 on both sides respectively press and compress the helical springs 38 and are fitted into the corresponding grooves 36. For this reason, the wedge-shaped member 24 receives a force in the center direction by the spiral spring 38, and is fixed by the core member 22 having a diameter of 10 mm. In this manner, a substantially cylindrical coil body is formed by the arcs of the ten wedge-shaped members 24. A DCF (not shown) is wound around this surface. In FIG. 9A, the body diameter is 100 m.
m and the winding width is 18 mm. 9 (c) and 9
(D) is the side view and top view of the coil after the trunk | drum diameter reduction, respectively. When the core member 22 is removed from the coil, the wedge-shaped member 24 moves toward the center by the force of the spiral spring 38 so that the wedge portions are aligned, so that a columnar reduced coil body is formed. In FIG. 9C, the trunk diameter after the reduction is 90 mm.

The structure in which the coil cylinder can be reduced is not limited to the structure described above. It is sufficient that the body diameter in the state accommodated in the chromatic dispersion compensator is substantially reduced as compared with the body diameter when the DCF is wound, and the specific mechanism is not limited. The number of the wedge-shaped members 24, the structure of the groove 36, and the like are merely examples,
Other configurations may be used as long as the respective functions can be exhibited. The term “substantially reduction” means a reduction in which the winding distortion is released and the transmission loss and the temperature dependence of the transmission loss can be reduced.

As can be seen from the above description, the degree of reduction of the body diameter can be changed by the diameter of the core member 22. The rate of reduction of the trunk diameter is preferably several percent of the trunk diameter.
With this degree, the winding distortion is substantially released,
Lateral pressure can be reduced. In addition, in order to sufficiently reduce the lateral pressure, it is more preferably 5 to 6%. Note that the degree of reduction does not exceed 10% at most.

Next, having such a structure, the body diameter is g =
100 mm, coil flange diameter h = 200 mm, winding width k
An optical fiber coil having a length of 10 km was wound around a coil having a length of 18 mm at a winding pitch of 0.4 mm and a winding tension of 40 g weight to produce an optical fiber coil. Wavelength 1.55
When the transmission loss value was measured in μm, a loss increase of 1.7 dB was observed.

Next, after reducing the body diameter to 90 mm, the optical fiber is unwound without changing its outer diameter, and
When the transmission loss value was measured after the coil was swung in order to equalize the winding condition or the state of the density of the entire optical fiber, the increase in the transmission loss value caused by the coil winding disappeared. When this coil was heated to 70 ° C. and the transmission loss was measured, the loss increase was 0.06 dB as compared with 20 ° C., and no other increase occurred except for the loss increase inherent in the optical fiber.

As described above, when the coil body is reduced after the optical fiber coil is manufactured by winding the DCF a plurality of times, the winding distortion of the optical fiber coil is substantially released. For this reason, the side pressure generated by winding the DCF in multiple layers is alleviated, and the temperature is not affected by the thermal expansion of the coil body even in a high-temperature environment. Dependency can be reduced. That is, the optical fiber coil can be housed in the coil in a state where the winding distortion of the chromatic dispersion compensating optical fiber is substantially released.

(Third Embodiment) In order to manufacture a chromatic dispersion compensator using an optical fiber coil, it is necessary to simply store the optical fiber coil in a storage case and connect a pigtail fiber to the chromatic dispersion compensator. Vibration or impact during transportation of the container may cause breakage of the optical fiber coil or fluctuation in characteristics. Therefore, it is necessary to take measures to prevent the optical fiber from partially jumping out due to vibration or shock, or to prevent the optical fiber from becoming unwinding due to an increase in the winding outer diameter.

In the present embodiment, a case will be described in which the optical fiber coil described in the first embodiment is fixed to a storage case by using a resin as a winding prevention member.

FIG. 10 is a top view when the bundle of optical fiber coils 32 is stored in a storage box 40 which is a storage case. A bundle of optical fiber coils 32 is fixed to the storage box 40 at four locations by a resin 42. Both ends of the optical fiber coil 32 are respectively connected to the pigtail fiber at a fused portion 44. Resin is used to suppress the increase in transmission loss value and temperature dependence of the optical fiber coil.
Those having an adhesive property with a small coefficient of thermal expansion and a small shrinkage rate after application are preferable. In this embodiment, a silicone resin is used. Examples of the silicone resin include KE45T manufactured by Shin-Etsu Chemical Co., Ltd. Thus, the optical fiber coil 32 is fixed at a plurality of locations from the surroundings. It is preferable that four or more resin-fixed portions are provided at substantially equal intervals. This is because the optical fiber coil can be sufficiently fixed to the storage box if there are four or more places. It is more preferable that the number of the fixed portions be eight or more at substantially equal intervals, because they can withstand a considerable impact. The width of the fixed portion of the resin is 5
mm is preferable. This is because with such a degree, it is not unreasonable to apply with an applicator.

FIG. 11 shows a case where the optical fiber coil is stored in the storage box 40.
FIG. Optical fiber coil 32
Is fixed to the storage box 40 with a resin (not shown), and then the lid 46 of the storage box 40 is closed, so that the fiber coil 32 is stored in the storage box 40 in a state in which winding collapse is prevented. Lid 4
Even when the DCF 6 is closed, there is a space in the DCF bundle of the optical fiber coil, and there is a space between the DCF bundle and the storage box 40. Not affected by

An impact test was performed on the optical fiber coil housed as described above. The impact test was performed according to IEC68-2-
The test was performed under the conditions of an acceleration of 98 m / sec ² , a shock application time of 16 msec, and the number of times of shock application of 1,000 times in accordance with the regulations of 29Eb. As shown in FIG. 11, the direction of impact application is a direction perpendicular to the plane including the wound optical fiber coil. Even after the impact test, the optical fiber coil did not collapse. When the transmission loss was measured at a wavelength of 1.55 μm, there was no increase in the transmission loss, and when measured at a temperature of 70 ° C., there was no increase other than the loss essentially present in the optical fiber.

As described above, if the bundle of optical fiber coils 32 is fixed to the storage box 40 with the resin 42, the bundle does not collapse and the winding distortion of the optical fiber coil is substantially released. Can be stored in the storage box. Accordingly, it is possible to obtain a small-sized chromatic dispersion compensator in which the destruction of the optical fiber coil and fluctuation in characteristics due to vibration, impact, and the like are prevented, and the transmission loss value and the temperature dependence of the transmission loss are reduced.

(Fourth Embodiment) In the present embodiment,
A case will be described in which the optical fiber coil described in the second embodiment is fixed to the coil using a resin as the collapse prevention member.

FIG. 12 is a side view of a coil used in the second embodiment. In the case of the present embodiment, the coil flange 26 is made of resin applied to the four resin applied portions 52.
, An optical fiber coil is fixed, and the DCF 50 is pulled out from the optical fiber coil. Although the portion to which the resin is applied is not visible in FIG. 12 which is a side view, it is explicitly illustrated for explanation.

FIG. 13 is a sectional view taken along the line BB 'of FIG. The resin 54 is applied to the inside of the two coil flanges 26 so as to fix the optical fiber coil 48 to the coil flange 26. Since the characteristics as the resin are the same as those of the third embodiment, the details are omitted. Thus, the optical fiber coil 48 is fixed at a plurality of locations from the surroundings. It is preferable that four or more resin-fixed portions are provided at substantially equal intervals. This is because if there are four or more fixing portions, the optical fiber coil can be sufficiently fixed to the coil flange. It is more preferable that the fixing portions are provided at substantially equal intervals at eight or more positions, because they can withstand a considerable impact. The width of the resin 54 is preferably about 5 mm. This is because with such a degree, it is not unreasonable to apply with an applicator.

The stored optical fiber coil was subjected to an impact test under the same conditions as in the third embodiment. The direction in which the impact is applied is a direction perpendicular to the plane including the optical fiber coil 48, as shown in FIG. Even after the impact test, the optical fiber coil did not collapse. Even if the transmission loss value is measured at a wavelength of 1.55 μm, there is no increase in the transmission loss,
And no increase other than the increase in loss inherently present in the optical fiber.

As described above, if the body diameter is reduced after the DCF is wound and the optical fiber coil 48 is fixed to the coil flange 26 with the resin 42, the collapse of the optical fiber coil does not occur and The optical fiber coil 48 can be stored in the coil which is the storage case in a state where the winding distortion of the optical fiber coil is substantially released. Accordingly, it is possible to obtain a small-sized chromatic dispersion compensator in which the destruction of the optical fiber coil and fluctuation in characteristics due to vibration, impact, and the like are prevented, and the transmission loss value and the temperature dependence of the transmission loss are reduced.

(Fifth Embodiment) In the present embodiment,
A cushion material, which is an anti-collapse member, is disposed,
A case where the bundled optical fiber coil described in the above embodiment is fixed to a storage box will be described.

FIG. 14A is a perspective view of a cushion material for housing an optical fiber coil. In order to store the optical fiber coil, the cushion material 60 is cut out according to the size of the storage box 62, and an optical fiber coil storage portion is formed on the upper surface of the cushion material 60. The optical fiber coil accommodating portion is formed by penetrating a portion of the cushion material 60 including a cylindrical shell region having the shape of the optical fiber coil 32 and an optical fiber coil lead-out region. The depth is preferably such that the optical fiber coil is housed and a lid of a cushion material can be formed on the upper part. With this configuration, the periphery of the optical fiber coil can be surrounded by the cushion material. In FIG. 14A, the shape of the bottom is U-shaped or semicircular in cross section, but is not limited to this shape. Further, the shape of the cushion material is not limited to the shape shown in FIG. As in a cushion material 67 shown in FIG. 15, the cushion material 60 may have a shape in which a part is cut out. With such a shape, the optical fiber coil is supported at a plurality of locations by the cushion material.

FIG. 14B is a schematic view when the optical fiber coil 32 is stored using the cushion material 60. The cushion material 60 is put in the storage box 62, the optical fiber coil 32 is stored in the optical fiber storage section, and the drawn DCF is connected to the pigtail fiber by the fusion portion 44. Thereafter, the cover 66 of the cushion material is placed in alignment with the optical fiber storage section, and the cover 64 of the storage box is closed, whereby the optical fiber coil 32 is fixed. The shape of the lid 66 preferably covers the opening area of the optical fiber storage section. This is because the optical fiber coil 32 can be covered with the cushion material. It is more preferable that the shape of the optical fiber coil housing is substantially the same. This is because the optical fiber coil 32 can be covered with the cushion material in accordance with the optical fiber coil housing portion.

The cushioning material is required to be easily processed, to be soft enough not to damage the optical fiber, and to be elastically deformed so as to wrap the optical fiber with a small pressing force when housed with a small Young's modulus. As such a cushioning material, soft polyurethane and foamed polyethylene are preferable, but foamed polyethylene is particularly preferable in practical use because of easy processing. It is not limited to this as long as the above requirements are satisfied. In the present embodiment, PE No. PE light manufactured by Inoac Corporation and B4 were used as the foamed polyethylene. The density of the expanded polyethylene is 0.027 g / c.
m is ^3.

The stored optical fiber coil was subjected to an impact test under the same conditions as in the third embodiment. The direction of impact application is a direction perpendicular to the plane including the optical fiber coil 32, as shown in FIG. Even after the impact test, the optical fiber coil did not collapse. Even if the transmission loss value at a wavelength of 1.55 μm is measured, there is no increase in the transmission loss.
There was no increase in loss measured at ° C other than the loss inherent in the optical fiber.

As described above, the cushion material 60
When the optical fiber coil 32 is housed in the optical fiber coil housing portion formed by cutting through the storage box, the storage box can be stored in a bundle in which the winding distortion of the optical fiber coil 32 is substantially released and the optical fiber coil 32 is not substantially collapsed. 62. Therefore, it is possible to obtain a small-sized chromatic dispersion compensator in which the destruction of the optical fiber coil and fluctuation in characteristics due to vibration, impact, and the like are prevented, and the transmission loss value and the temperature dependence of the transmission loss are reduced.

(Sixth Embodiment) In this embodiment,
A cushion material as an anti-collapse member is disposed,
A case will be described in which the optical fiber coil described in the embodiment is fixed to a coil which is a storage case.

FIG. 16 is a schematic diagram when the optical fiber coil 48 is housed in the coil by using the cushion material 68. An optical fiber coil 48 is formed by sandwiching a cushion material 68 between the coil flanges 26 on both sides of the coil body and winding the cushion material 68 over the entire circumference in accordance with the outer periphery of the coil flange 26.
Is fixed to the coil flange. The cushion material 68 is fixed to the coil flange 26 by a resin. The resin is preferably applied so as not to adhere to the optical fiber coil 48. The dimensions of the cushion material vary depending on the size of the coil flange 26 used, the number of turns of the DCF, and the like. In the present embodiment, the thickness is 3 mm, the width is 18 mm according to the winding width of the coil, and the length is about 6 mm according to the outer peripheral length of the coil flange 26.
A 28 mm rectangular parallelepiped is preferred. The shape of the cushion material is not limited to the shape shown in FIG. As shown in FIG. 17, a plurality of thin rectangular parallelepiped cushion members 72 may be arranged at a plurality of positions, and the optical fiber coil 48 may be fixed to the coil flange. Further, it is preferable that the cushion 68 be provided with an outlet for the DCF wound around the coil. FIG.
6, the cushioning material 6
A hole 70 penetrating in the thickness direction 8 is provided as an outlet.

The characteristics of the cushioning material are the same as those of the fifth embodiment, so that the details are omitted. As the resin, a silicone resin is preferable. However, the resin is not limited to this as long as it is a resin that does not peel off even when a heat history is added in a range of about 0 ° C. to 70 ° C. assumed as a use environment.

The stored optical fiber coil was subjected to an impact test under the same conditions as in the third embodiment. The impact application direction is a direction perpendicular to the plane including the optical fiber coil 48, as shown in FIG. Even after the impact test, the optical fiber coil did not collapse. Even if the transmission loss value is measured at a wavelength of 1.55 μm, there is no increase in the transmission loss,
And no increase other than the increase in loss inherently present in the optical fiber.

As described above, if the bundle of optical fiber coils 48 is fixed by the cushion material 68, the winding does not collapse and the winding distortion of the optical fiber coil 48 is substantially released. , Can be stored in a coil. Accordingly, it is possible to obtain a small-sized chromatic dispersion compensator in which the destruction of the optical fiber coil and fluctuation in characteristics due to vibration, impact, and the like are prevented, and the transmission loss value and the temperature dependence of the transmission loss are reduced.

In the first embodiment and the second embodiment, the optical fiber coils are bundled in a state where the winding distortion is substantially released, and after the coil body of the optical fiber coil is wound up. The case of substantially reducing the size has been described. Means for substantially releasing winding distortion are not limited to these.

In the first to sixth embodiments, the case where the chromatic dispersion compensator is manufactured using the double clad type DCF has been described. The present invention is not limited to this, and can be similarly applied to dual-core and segment-core DCFs.

In the prior art, it was impossible to produce a practical level chromatic dispersion compensator for a small coil having a diameter of 100 mm or less. However, from the first embodiment to the sixth
As described in the embodiment, according to the present invention, since the winding distortion can be stored in the storage case in a substantially released state, the transmission loss and the small wavelength with reduced temperature dependence of the transmission loss are reduced. A dispersion compensator can be realized.

Japanese Patent Application Laid-Open No. Sho 62-91810 discloses that a resin is filled and solidified in a gap and around an optical system including an optical coupling portion between an optical fiber and an optical element, and the optical system is embedded in the resin. Is disclosed in the field of optical fiber gyros, and there is no description about a chromatic dispersion compensator. Japanese Patent Application Laid-Open No. 8-75477 discloses an invention of an optical fiber coil having excellent vibration characteristics, but is related to the field of an optical fiber gyro.
There is no description about the chromatic dispersion compensator.

[0086]

As described above in detail, when a chromatic dispersion compensator is manufactured by winding a DCF for a wide band around a small coil, a storage case in which the winding distortion of the DCF for a wide band is substantially released is provided. To be stored. As a result, a small chromatic dispersion compensator with reduced transmission loss can be manufactured, and the chromatic dispersion compensator that does not increase transmission loss even when exposed to high temperatures when used in combination with an optical amplifier or the like. It is possible to make vessels.

Further, since the optical fiber coil is fixed to the storage case by the collapse prevention member, vibration,
It is possible to prevent destruction of the optical fiber coil and fluctuation in characteristics due to impact or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chromatic dispersion compensating optical fiber having a two-layer coating layer.

FIG. 2 is a perspective view of a coil for winding a chromatic dispersion compensating optical fiber.

FIG. 3 is a data list showing data of a chromatic dispersion compensating optical fiber in a list.

FIG. 4 is a characteristic diagram illustrating wavelength dependence of a transmission loss value of the optical fiber A;

FIG. 5 is a temperature change diagram of a heat cycle applied to a coil after winding.

FIG. 6 is a characteristic diagram illustrating a wavelength dependence of a transmission loss value after the coil is removed from the body;

FIG. 7 (a) is an exploded view of a coil capable of reducing a body diameter. FIG. 7B is a side view of the wedge-shaped member. FIG. 7C is a cross-sectional view after assembling a coil capable of reducing the body diameter.

FIG. 8A is a top view of the coil support member. FIG. 8B is a cross-sectional view taken along line AA ′ of FIG. FIG. 8C is an enlarged view of the groove.

FIGS. 9A and 9B are a side view and a top view of the coil before the coil body is reduced, respectively. FIG.
(C) and FIG. 9 (d) are a side view and a top view of the coil after the coil body is reduced.

FIG. 10 is a schematic diagram when an optical fiber coil is fixed to a storage box with a resin.

FIG. 11 is a schematic diagram when the optical fiber coil is stored in a storage box.

FIG. 12 is a side view of the coil after fixing the optical fiber coil with a resin.

FIG. 13 is a sectional view taken along line BB ′ of FIG. 12;

FIG. 14 (a) is a perspective view of a cushion material for housing an optical fiber coil. FIG. 14B is a schematic diagram when the optical fiber coil is stored using the cushion material.

FIG. 15 is a perspective view of a cushion material for housing an optical fiber coil.

FIG. 16 is a schematic diagram when an optical fiber coil is fixed with a cushion material.

FIG. 17 is a schematic diagram when an optical fiber coil is fixed with a cushion material.

FIGS. 18A to 18D are schematic diagrams showing the refractive index distribution in the cross-sectional direction of the chromatic dispersion compensating optical fiber.

[Explanation of symbols]

11: Optical fiber, 13: Primary coating layer, 15: Secondary coating layer, 20: Coil cylinder, 21: Coil flange, 22: Core member,
24: wedge-shaped member, 26: coil flange, 28: support member, 3
0: protrusion, 32: optical fiber coil, 34: connecting wall of left and right support members, 36: groove of support member, 38: spiral spring,
40: storage box, 42: resin, 44: fused part, 46: lid of storage box, 48: optical fiber coil, 50: DCF, 5
2 ... Resin coated part, 54 ... Resin, 60, 67 ... Cushion material for storage, 62 ... Storage box, 64 ... Lid of storage box, 66 ...
Cushion material for lid, 68, 72 ... Cushion material for coil

Claims (11)

[Claims] 1. A chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line, wherein the chromatic dispersion has a sign opposite to that of an optical fiber of the optical fiber transmission line, and a light of the optical fiber transmission line. An optical fiber coil in which a chromatic dispersion compensating optical fiber having a chromatic dispersion slope having the opposite sign to the fiber is wound a plurality of times; and the optical fiber coil in a state where winding distortion of the chromatic dispersion compensating optical fiber is substantially released. And a storage case for storing the wavelength dispersion compensator. 2. A chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line, wherein the chromatic dispersion has the opposite sign to that of the optical fiber of the optical fiber transmission line and the light of the optical fiber transmission line. An optical fiber coil in which a chromatic dispersion compensating optical fiber having a chromatic dispersion slope of the opposite sign to the fiber is wound a plurality of times, and bundled in a state where the winding distortion of the chromatic dispersion compensating optical fiber is substantially released And a storage case for storing the optical fiber coil. 3. A chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line, comprising: a coil body whose diameter can be reduced from a first diameter to a second diameter; A chromatic dispersion compensating optical fiber having a chromatic dispersion of the opposite sign to the optical fiber of the fiber transmission line and a chromatic dispersion slope of the opposite sign to the optical fiber of the optical fiber transmission line is provided on the coil body a plurality of times at the first diameter. The wound optical fiber coil, and the optical fiber coil in a state where the diameter of the coil body is substantially reduced to the second diameter and the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. A chromatic dispersion compensator, comprising: a storage case for storing. 4. The chromatic dispersion compensator according to claim 2, further comprising a collapse prevention member that prevents the collapse by fixing the optical fiber coil to the storage case. 5. The chromatic dispersion compensator according to claim 4, wherein the collapse prevention member is formed of a resin that fixes the optical fiber coil to the storage case at a plurality of locations. 6. The chromatic dispersion compensator according to claim 4, wherein the collapse prevention member is a cushion material for fixing the optical fiber coil to the storage case. 7. The optical fiber coil according to claim 1, wherein the diameter of the optical fiber coil is 100 mm or less at a minimum portion.
The chromatic dispersion compensator according to claim 2 or 3. 8. A method of manufacturing a chromatic dispersion compensator for reducing chromatic dispersion in a wavelength band of 1.55 μm of an optical fiber transmission line, comprising: a chromatic dispersion having a sign opposite to that of an optical fiber of the optical fiber transmission line; A coil manufacturing step of manufacturing an optical fiber coil by winding a chromatic dispersion compensating optical fiber having a chromatic dispersion inclination having an opposite sign to the optical fiber of the path around the coil body, and removing the optical fiber coil from the coil body. A coil removing step of forming the optical fiber coil bundled in a state in which the winding distortion of the chromatic dispersion compensating optical fiber is substantially released. 9. The chromatic dispersion compensation according to claim 8, further comprising a lubricant applying step of applying a lubricant to the coil body prior to at least one of the coil manufacturing step and the coil removing step. Method of manufacturing the vessel. 10. The coil manufacturing process according to claim 1, wherein the chromatic dispersion compensating optical fiber is wound around the coil body a plurality of times with a winding tension of 40 g or less to manufacture an optical fiber coil. A method for manufacturing a chromatic dispersion compensator according to claim 8 or 9. 11. The wavelength of an optical fiber transmission line is 1.55 μm.
A method of manufacturing a chromatic dispersion compensator for reducing chromatic dispersion in a band, comprising: a chromatic dispersion having an opposite sign to an optical fiber of the optical fiber transmission line and a chromatic dispersion slope having an opposite sign to an optical fiber of the optical fiber transmission line. A coil manufacturing step of winding the chromatic dispersion compensating optical fiber around the coil body a plurality of times to manufacture an optical fiber coil; and, after the coil manufacturing step, a diameter of the coil body in the coil manufacturing step compared to the diameter of the coil body. A diameter changing step of substantially reducing the diameter so that winding distortion is substantially released.