JP3616983B2 - 2-wavelength optical multiplexer / demultiplexer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-wavelength optical multiplexer / demultiplexer, and more particularly to a two-wavelength optical multiplexer / demultiplexer used for FTTH.
[0002]
[Prior art]
In the FTTH concept in Japan, 31 μm wavelength light; Wavelength multiplexing communication using two-wavelength light of 55 μm wavelength light is planned. 1. The 31 μm wavelength light is used as a digital communication signal for bidirectional communication between the base station and the user's home. And 1. The 55 μm wavelength light is used as an analog video signal for one-way broadcasting from the base station to the user's house. Therefore, 1. 31 μm wavelength light / 1. Separating two wavelengths of 55 μm wavelength light; The 55 μm wavelength light is guided to the image receiving unit and 1. A 31-μm wavelength light is required to have a two-wavelength optical multiplexer / demultiplexer that guides to a digital communication transmission unit and reception unit. Hereinafter, a conventional example of a wavelength optical multiplexer / demultiplexer for FTTH will be described in detail with reference to the drawings.
[0003]
3 and 4, reference numeral 1 denotes an optical waveguide substrate made of silicon Si. Three V-shaped grooves 40 are formed on the surface of one end of the optical waveguide substrate 1. A cross-sectional rectangular groove 6 is formed on the surface of one end of the optical waveguide substrate 1 in a direction orthogonal to the cross-sectional V-shaped groove 40. On the surface of the other end portion of the optical waveguide substrate 1, one V-shaped groove 30 having the same cross section as that formed at one end portion is formed. On the surface of the other end portion of the optical waveguide substrate 1, an inclined cross-section rectangular groove 60 that intersects with the cross-section V-shaped groove 30 without being orthogonal is formed.
[0004]
A right-angle end face optical fiber 4 whose end face is perpendicular to the fiber extending direction is fitted and fixed to each of the three V-shaped grooves 40 formed on the surface of one end of the optical waveguide substrate 1. Reference numeral 41 denotes an optical fiber core wire. An inclined end-face optical fiber 3 that forms an inclined surface whose end face is not orthogonal to the fiber drawing direction is fitted and fixed to one cross-section V-shaped groove 30 formed on the surface of the other end of the optical waveguide substrate 1. Yes. Reference numeral 21 denotes a linear optical waveguide, which is formed on the surface of the optical waveguide substrate 1 across a rectangular groove 6 at one end of the optical waveguide substrate 1 and an inclined rectangular groove 60 at the other end. The end face of the straight optical waveguide 21 is exposed to the cross-sectional rectangular groove 6 opposite to the cross-sectional V-shaped groove 40 to which the right-angle end face optical fiber 4 constituting the port P1 is fitted and fixed, and is inclined to form the port P2. Opposing to the cross-sectional V-shaped groove 30 to which the end face optical fiber 3 is fitted and fixed, it is exposed to the inclined cross-sectional rectangular groove 60. Reference numeral 22 denotes a Y-branch optical waveguide, which includes a straight line part 221 and a branch part 222. The Y-branch optical waveguide 22 is formed on the surface of the optical waveguide substrate 1 across the rectangular groove 6 at one end of the optical waveguide substrate 1 and the inclined rectangular groove 60 at the other end. One end face of the branching portion 222 is exposed to the rectangular groove 6 facing the cross-sectional V-shaped groove 40 to which the right-angle end face optical fiber 4 constituting the port P31 is fitted and fixed, and the other end face of the branching portion 222 is exposed. Opposed to the cross-sectional V-shaped groove 40 to which the right-angle end face optical fiber 4 constituting the port P32 is fitted and fixed is exposed to the cross-sectional rectangular groove 6. The end face of the straight portion 221 of the Y branch optical waveguide 22 is exposed to the inclined section rectangular groove 60 so as to face the section V-shaped groove 30 to which the inclined end face optical fiber 3 constituting the port P2 is fitted and fixed. The end face of the straight optical waveguide 21 and the end face of the straight portion 221 of the Y-branch optical waveguide 22 constitute a common end face. Reference numeral 5 denotes a dielectric multilayer filter. The dielectric multilayer filter 5 includes an end face of the straight optical waveguide 21 exposed in the inclined cross-section rectangular groove 60 at the other end of the optical waveguide substrate 1 and a common end face of the end face of the straight portion 221 of the Y branch optical waveguide 22; Between the inclined end face of the inclined end face optical fiber 3 fitted and fixed in the V-shaped cross section 30, it is inserted and fixed in the inclined section rectangular groove 60 in a state in contact with both end faces.
[0005]
As the oblique end face optical fiber 3 and the right end face optical fiber 4, a multicore tape fiber having a pitch of 250 μm is usually used. Further, the alignment between the optical fibers and the optical waveguide is performed by aligning the optical fibers by the V-shaped grooves 30 and 40 formed in the optical waveguide substrate 1 with high accuracy.
Here, 1. 31 μm wavelength light / 1. The wavelength multiplexed signal of 55 μm wavelength light is introduced into the straight optical waveguide 21 via the right-angle end face optical fiber 4 constituting the port P 1 and separated by the dielectric multilayer filter 5. Here, 1. The 55 μm wavelength light passes through the dielectric multilayer filter 5 and is input to the video receiving unit at the user's home via the inclined end face optical fiber 3 constituting the port P2. On the other hand, The 31 μm light is reflected by the dielectric multilayer filter 5, is introduced into the straight portion 221 of the Y branch optical waveguide 22, is divided into the branch portions 222, and is received at the user's home via the right end face optical fiber 4 constituting the port P 31. Introduced into the unit. On the contrary, it is introduced from the transmission unit at the user's home via the right-angle end face optical fiber 4 constituting the port P32. The 31 μm light is transmitted to the base station via the Y branch optical waveguide 22, the dielectric multilayer filter 5, the linear optical waveguide 21, and the port P1.
[0006]
[Problems to be solved by the invention]
In the conventional example of the above two-wavelength optical multiplexer / demultiplexer, the linear optical waveguide 21 and the Y-branch optical waveguide 22 are formed in parallel on the surface of the optical waveguide substrate 1, so that they have substantially the same waveguide length. Will result in The linear optical waveguide 21 and the Y branch optical waveguide 22 are made of polymer.
[0007]
However, most of optical waveguides composed of polymers are as follows. It exhibits practical performance with low loss for 31 μm wavelength light. The loss is large for 55 μm wavelength light. Acrylic polymers that are typical waveguide materials are: The loss for 31 μm wavelength light is 0. Whereas it is 3 dB / cm or less, The loss with respect to light having a wavelength of 55 μm is as large as several dB / cm. Recently, a polyimide polymer having a low loss as compared with an acrylic polymer has been developed. It is 0. 3 dB / cm, For light of 55 μm wavelength, 0. Indicating 9 dB / cm; The loss in the 55 μm band is large.
[0008]
When a polymer optical waveguide is applied to a two-wavelength optical multiplexer / demultiplexer for FTTH, from the above-described characteristics, The length of the linear optical waveguide 21 through which light having a wavelength of 55 μm circulates is preferably as short as possible. However, in the two-wavelength optical multiplexer / demultiplexer of FIG. 3, the lengths of the straight optical waveguide 21 and the Y branch optical waveguide 22 must be substantially equal.
On the other hand, in order to reduce the loss of the Y-branch optical waveguide 22, it is desirable to make the optical waveguide length longer to make a gentle curve, and the branch width of the Y-branch is 250 μm in accordance with the pitch of the multi-core tape optical fiber. Since it is convenient to use the pitch, the optical waveguide length of the Y branch optical waveguide 22 cannot be made shorter than a certain limit. Therefore, in this embodiment: The length of the linear optical waveguide 21 that transmits 55 μm wavelength light cannot be made shorter than this fixed limit.
[0009]
Here, it is possible to employ a configuration in which only the length of the linear optical waveguide 21 is shortened as in the conventional example of FIG. In the conventional example of FIG. 5, the V-shaped groove 40 for fitting and fixing the right-angle end optical fiber 4 constituting the port P1 in the conventional example of FIG. The fiber 4 is extended, and the substantially straight optical waveguide 21 is shortened as shown. The extended end face of the right end face optical fiber 4 is formed by newly processing a rectangular groove 61 in the cross section to expose it.
[0010]
In the case of the conventional example shown in FIG. 5, the V-shaped groove 40 having a cross-section for fitting and fixing the right-angle end face optical fiber 4 constituting the port P1 needs to be greatly extended. Furthermore, it becomes necessary to newly form the cross-sectional rectangular groove 61. Satisfying both of these needs is not always easy in terms of anisotropic etching and dicing saw processing techniques.
The present invention provides a two-wavelength optical multiplexer / demultiplexer that eliminates the above-described problems and employs an optical waveguide made of a low-priced and highly productive polymer.
[0011]
[Means for Solving the Problems]
Claim 1: Dielectric multilayer filter 5 for multiplexing and demultiplexing light of two wavelengths, linear optical waveguide 21 constituting one optical waveguide for dielectric multilayer filter 5, and Y constituting the other optical waveguide In the two-wavelength optical multiplexer / demultiplexer in which the branched optical waveguide 22 is formed on the optical waveguide substrate 1, the linear optical waveguide 21 constituting one optical waveguide and the Y branched optical waveguide 22 constituting the other optical waveguide are an optical waveguide substrate. A two-wavelength optical multiplexer / demultiplexer having different formation directions in 1 was configured.
[0012]
Then, comprising a V-shaped cross section groove 30 formed laterally in the right upper portion of the optical waveguide substrate 1, this V-shaped cross section groove 30 is inclined end face optical fiber 3 forming the port P2 fitted and fixed The optical waveguide substrate 1 has a V-shaped groove 40 formed in the transverse direction in the upper left portion of the optical waveguide substrate 1, and the right-angled end face optical fiber 4 constituting the port P 1 is fitted in the V-shaped groove 40. The cross-section V-shaped groove 40 is fixed and formed in the lower part of the optical waveguide substrate 1 in the vertical direction. The cross-section V-shaped groove 40 includes the right-angle end face light that constitutes the port P31 and the port P32. The fiber 4 is fitted and fixed, and includes a cross-sectional rectangular groove 6 formed in the lateral direction on the lower side of the optical waveguide substrate 1, and a cross-sectional rectangular groove 62 formed in the vertical direction on the left side of the optical waveguide substrate 1. Of the optical waveguide substrate 1 An inclined cross-section rectangular groove 60 formed to be inclined with respect to the vertical direction is provided at the upper portion, and a linear optical waveguide 21 formed extremely short in the horizontal direction is provided at the upper portion of the optical waveguide substrate 1. One end face is exposed in the rectangular groove 62 facing the right-angle end face optical fiber 4 constituting the port P1, and the other end face is opposed to the inclined end face optical fiber 3 constituting the port P2 in the inclined section rectangular groove 60. The Y branch optical waveguide 22 is formed in the vertical direction from the upper part to the lower part of the optical waveguide substrate 1, and the inclined end face of the straight part 221 constitutes the port P 2 in the inclined sectional rectangular groove 60. The end surfaces of the branching portions 222 and 223 are opposed to the right-angled end surface optical fibers 4 constituting the ports P31 and P32 in the rectangular grooves 6 in the transverse direction. Exposed bookmarks by, it comprises a dielectric multilayer film filter 5 to be inserted and fixed in contact with the common exposed end faces the inclined rectangular section groove 60 of the linear portion 221 of the straight waveguide 21 and the Y branch optical waveguide 22, the optical waveguide substrate Reference numeral 1 is made of silicon, and the V-shaped groove, which is an optical fiber fixing groove, constituted a two-wavelength optical multiplexer / demultiplexer formed by performing anisotropic etching on a silicon optical waveguide substrate .
[0013]
Further, to constitute a two-wavelength optical multiplexing demultiplexer, wherein the straight Senkoshirube waveguides 21 and Y branch optical waveguide 22 is formed using the polymer material.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. In FIG. 1 and FIG. 2, the same reference numerals are given to the members common to the members in FIG. 3 to FIG.
In FIG. 1, reference numeral 30 denotes a rectangular groove formed in the transverse direction in the upper right part of the optical waveguide substrate 1, and the inclined end face optical fiber 3 constituting the port P2 is fitted and fixed.
[0015]
Reference numeral 40 denotes a V-shaped cross section formed in the horizontal direction in the upper left portion of the optical waveguide substrate 1 and two in the vertical direction in the lower portion. A right-angle end face optical fiber 4 constituting the port P1 is fitted and fixed to the upper left cross-section V-shaped groove 40. A right-angled end face optical fiber 4 constituting the port P31 and the port P32 is fitted and fixed in a V-shaped groove 40 formed in the lower part of the optical waveguide substrate 1.
[0016]
Reference numeral 6 denotes a cross-sectional rectangular groove formed in the lateral direction on the lower side of the optical waveguide substrate 1, and reference numeral 62 denotes a cross-sectional rectangular groove formed in the vertical direction on the left side of the optical waveguide substrate 1.
Reference numeral 60 denotes an inclined cross-sectional rectangular groove formed to be inclined with respect to the vertical direction in the upper right portion of the optical waveguide substrate 1.
The straight optical waveguide 21 is formed extremely short in the lateral direction in the upper part of the optical waveguide substrate 1, and the end faces are exposed in the inclined cross-section rectangular groove 60 and the cross-section rectangular groove 62.
[0017]
The Y-branch optical waveguide 22 is formed in the vertical direction from the upper part to the lower part of the optical waveguide substrate 1, and the inclined end face of the linear part 221 is exposed to the inclined sectional rectangular groove 60 . The inclined end surface of the linear portion 221 constitutes an exposed end surface that is common with the inclined end surface of the linear optical waveguide 21. The branch part 222 and the branch part 223 of the Y branch optical waveguide 22 have end faces exposed in the rectangular groove 6.
[0018]
The dielectric multilayer filter 5 is inserted into and fixed to the inclined section rectangular groove 60 in contact with the common exposed end face of the straight portion 221 of the straight optical waveguide 21 and the Y branch optical waveguide 22.
In the above two-wavelength optical multiplexer / demultiplexer, an input is made from the right end face optical fiber 4 fitted and fixed in a V-shaped groove 40 which is an optical fiber fixing groove formed in the horizontal direction in the upper left part of the optical waveguide substrate 1. 1. 31 μm wavelength light / 1. A wavelength multiplexed signal composed of 55 μm wavelength light is incident on the dielectric multilayer filter 5 through a short straight optical waveguide 21 formed in the lateral direction. Of the wavelength multiplexed signals incident on the dielectric multilayer filter 5. The 55 μm wavelength light is transmitted through the dielectric multilayer filter 5, and the inclined end face light is fitted and fixed to the V-shaped groove 30 which is an optical fiber fixing groove formed in the horizontal direction in the upper right part of the optical waveguide substrate 1. It is fed into the fiber 3 and introduced into the video receiving unit. On the other hand, among the wavelength multiplexed signals, 1. The 31 μm wavelength light is incident on the dielectric multilayer filter 5 and reflected by the dielectric multilayer filter 5, and is transmitted to the receiving unit via the straight end portion optical fiber 4 constituting the straight portion 221 and the branch portion 222 of the Y branch optical waveguide 22 and the port P 31. be introduced. Contrary to this, 1. is inputted through the right-angle end face optical fiber 4 constituting the port P32. The 31 μm wavelength light signal enters the dielectric multilayer filter 5 via the Y branch optical waveguide 22, is reflected here, is introduced into the linear optical waveguide 21, and is output via the port P 1.
[0019]
【The invention's effect】
As described above, in the two-wavelength optical multiplexer / demultiplexer of the present invention, the linear optical waveguide 21 is formed in the optical waveguide substrate 1 in the lateral direction, while the Y branch optical waveguide 22 is formed in the direction in which it is formed. The vertical direction is different from the direction in which the straight optical waveguide 21 is formed. Here, the length of the straight optical waveguide 21 is about the branch width of the Y branch optical waveguide 22, and the length of the Y branch optical waveguide 22 is independent of the length of the straight optical waveguide 21. The length can also be set. That is: An optical waveguide through which light having a wavelength of 55 μm is transmitted is extremely short. Even if a polymer optical waveguide having a large loss with respect to the light wavelength of 55 μm is used, there is no problem. Therefore: An optical waveguide can be formed of a polymer material having a large loss with respect to light having a wavelength of 55 μm, and a two-wavelength optical multiplexer / demultiplexer that is inexpensive and has good productivity can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment.
FIG. 2 is a diagram illustrating an optical waveguide substrate.
FIG. 3 is a diagram illustrating a conventional example.
FIG. 4 is a diagram illustrating a conventional example of an optical waveguide substrate.
FIG. 5 is a diagram for explaining another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical waveguide board | substrate 21 Linear optical waveguide 22 Y branch optical waveguide 5 Dielectric multilayer filter

Claims (1)

A dielectric multilayer filter that transmits light having a larger transmission loss rate in incident light of two wavelengths and reflects light having a smaller transmission loss and can multiplex / demultiplex light of two wavelengths; dielectric multilayer film straight waveguide and the other two wavelengths optical multiplexing demultiplexer the Y branch optical waveguide polymer material forming the optical waveguide substrate constituting the optical waveguide of the polymer material constituting the one optical waveguide to the filter In
Constitute one optical waveguide, a straight waveguide 21 against the light of the large wavelength of the transmission loss ratio, constitute the other optical waveguide, a Y branch optical waveguide 22 against the light of a small wavelength transmission loss index Differ in the direction of formation on the optical waveguide substrate,
A second cross-section V-shaped groove 30 formed in the lateral direction in the upper right portion of the optical waveguide substrate is provided, and the inclined end-face optical fiber 3 constituting the second port is formed in the second cross-section V-shaped groove 30. Are fitted and fixed,
A first cross-section V-shaped groove 40 formed in the lateral direction in the upper left portion of the optical waveguide substrate is provided, and the first cross-section V-shaped groove 40 has a first right-angled end face light constituting a first port. The fiber 4 is fitted and fixed,
Third and fourth cross-section V-shaped grooves 40 and 40 formed in the vertical direction at the lower portion of the optical waveguide substrate are provided, and the cross-section V-shaped grooves 40 and 40 constitute two ports. The third and fourth right end face optical fibers 4 and 4 are fitted and fixed, respectively.
Comprising a first cross-sectional rectangular groove 6 formed laterally on the lower side of the optical waveguide substrate;
A second cross-sectional rectangular groove 62 formed in the vertical direction on the left side of the optical waveguide substrate;
An inclined cross-sectional rectangular groove 60 formed to be inclined with respect to the vertical direction in the upper right part of the optical waveguide substrate,
The linear optical waveguide 21 is formed in the upper part of the optical waveguide substrate so as to be extremely short in the lateral direction, and one end face of the linear optical waveguide 21 is a first port that forms a first port in the second cross-sectional rectangular groove 62. The other end face is exposed to the inclined end face optical fiber 3 constituting the second port in the inclined section rectangular groove 60, and is exposed to the right end face optical fiber 4.
A Y-branch optical waveguide 22 formed in the vertical direction from the upper part to the lower part of the optical waveguide substrate is provided, and an inclined end face of the straight part 221 has an inclined end face optical fiber constituting a second port in the inclined section rectangular groove 60. thereby exposed against toward the 3, end surface and the third perpendicular end face of the fourth constituting the third and fourth ports to the first transverse cross-sectional rectangular groove 6 of the two branch portions 222 and 223 Exposed facing the optical fibers 4 and 4 respectively,
A dielectric multilayer filter 5 that is in contact with the common exposed end face of the straight portion 221 of the straight optical waveguide 21 and the Y-branch optical waveguide and is inserted and fixed in the inclined cross-section rectangular groove 30;
In addition, the optical waveguide substrate is made of silicon, and the V-shaped groove that is the optical fiber fixing groove is formed by performing anisotropic etching on the silicon optical waveguide substrate. Wave demultiplexer.

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