JP4692424B2 - Waveguide array for multicore bidirectional communication, method for manufacturing the same, and bidirectional communication module - Google Patents

Description

  The present invention relates to a waveguide array for multicore bidirectional communication, a manufacturing method thereof, and a bidirectional communication module, and more particularly, a waveguide array for multicore bidirectional communication using a multicore array of optical fibers and a manufacturing method thereof. And a bidirectional communication module.

  In the data transmission field of high-end servers and large-scale supercomputers that perform parallel computation, for example, transmission / reception modules using a multicore array of optical fibers represented by SNAP12 are being put into practical use. SNAP 12 is a standard for high-speed data transfer in a single direction using a 12-core optical fiber array with a pitch of 250 μm. In order to improve the data transfer density, the technology for bidirectionalizing the flow of optical signals is to determine the upstream and downstream wavelengths separately, and then use a collimating lens or waveguide to create a dielectric multilayer film, etc. In general, light from a light-emitting element such as an optical fiber or a VCSEL array is guided to a wavelength selection filter to be configured so that reflection / transmission can be selected according to the wavelength.

  In the bi-directional transmission method using the collimating lens, the microlens array is installed corresponding to at least all of the optical fiber array, the VCSEL array, and the light receiving element (PD) array, and the positional angular relationship with the dielectric multilayer filter. Must be established. For this reason, there are the problems that the number of assembling steps is extremely increased and that a high degree of assembling accuracy is required. Furthermore, since adjacent light sources are arranged at a narrow pitch of 250 μm, precise component accuracy and assembly accuracy are required to prevent crosstalk. Furthermore, it is difficult to reduce the size of the entire module.

  On the other hand, in the bidirectional transmission method using the waveguide, it is possible to bond and integrate the filter and the light emitting / receiving element to the waveguide, and therefore, it is possible to reduce the number of parts, and thus the assembly accuracy and Cost reduction can be achieved from both viewpoints of assembly man-hours. For example, a single-core optical fiber has been proposed as one using such a waveguide. As an example, for example, a dielectric multilayer filter is inserted into a groove provided so as to cross the branch portion of the Y-branch waveguide, and a single-core optical fiber and a light-emitting element are inserted at the end of the branched waveguide. There is a waveguide-type optical multiplexer / demultiplexer having a configuration in which a light receiving element can be connected to the opposite waveguide end (see, for example, Patent Document 1).

  In the conventional waveguide-type optical multiplexer / demultiplexer as described in Patent Document 1, the arrangement position of the light emitting element and the light receiving element is set so that crosstalk does not occur even if the branching angle of the branching waveguide is small. It is determined with respect to the dielectric multilayer filter surface. This conventional technique is intended for a single-core optical fiber. However, in a waveguide fabrication technique using a photolithography technique that is generally performed, the core pattern of the waveguide is fabricated only on the same plane, and is three-dimensional. That is, it is difficult to fabricate in the waveguide thickness direction. Therefore, when the conventional branching waveguide structure as described in Patent Document 1 is applied to an optical fiber array in which multiple cores, particularly three or more cores are arranged in parallel, the following (1) to (5) There were various problems as explained in).

(1) When Y branch waveguides are arranged in parallel on the same plane, one end of the optical fiber and one end of the light emitting element are aligned at the end of the branched waveguide. For this reason, when a VCSEL array having three or more light emitting points is used as a light emitting element, it interferes with the arrangement position of the optical fiber (if the light emitting point is up to two, the optical fiber is connected outside, It is possible to place a VCSEL array inside.) As an example for preventing this, it is conceivable to use a configuration in which, for example, all waveguide ends are connected to an optical fiber and then light is guided to an arbitrary place by bending the optical fiber one by one. (For example, refer to Patent Document 2). However, compared with the method of directly connecting the VCSEL array to the end of the waveguide, there is a problem that the number of parts and the number of assembling steps increase and the cost increases. Even if a single VCSEL or edge emitting laser is used instead of the VCSEL array, the number of parts and the number of assembly steps will increase. Considering the size of the element itself, the arrangement interference with the optical fiber is reduced. There was a problem that it was difficult to prevent.

(2) A Y-branch waveguide is arranged in parallel in the plane direction, and the waveguide and the light emitting element toward the optical fiber are separated in order to separate the waveguide end connected to the optical fiber and the waveguide end connected to the light emitting element. There is a waveguide having a configuration in which the waveguide toward the crossing is crossed (see, for example, Patent Document 3). However, in consideration of bending the waveguide within a 250 μm pitch, there is a problem in that crosstalk increases because the crossing angle cannot be increased. Furthermore, since the number of crossings differs for each waveguide, there is a problem that the optical loss characteristic varies.

(3) Thus, in the conventional waveguide structure as described in the above (1) and (2), the waveguide core toward the optical fiber and the waveguide core toward the light emitting element on the same plane, As a result, various problems as described above will occur. Therefore, it is considered desirable to adopt a configuration in which the waveguide structure is extended in the thickness direction. That is, the single-core bidirectional Y-branch waveguide described in Patent Document 1 and the like can be laminated using the method of manufacturing a laminated polymer optical waveguide previously proposed by the present applicants. (For example, refer to Patent Document 4). However, in this case, there is a problem that the process time increases as the number of stacked layers increases in order to ensure the dimensional accuracy in the stacking direction. In addition, since it is difficult to mount a VCSEL array or a PD array on a plane and connect it to the waveguide end, another substrate for mounting is required. In addition, after all the lamination of the waveguide is completed, it is necessary to process the filter insertion groove for inserting the dielectric multilayer filter again. For this reason, there is a problem that the difficulty of filter insertion groove processing that can be performed simultaneously with the waveguide outer shape cutting processing by a dicing saw is increased, and the number of manufacturing steps increases.

(4) On the other hand, as an example of configuring the light propagation in the waveguide thickness direction without depending on the waveguide structure, for example, the waveguide structure is configured by a simple linear waveguide array, and a dielectric is provided in the middle of the linear waveguide. By inserting the multilayer filter obliquely in the vertical direction, the dielectric multilayer filter is arranged so that the normal of the dielectric multilayer filter is outside the waveguide surface, and the light emitting element or light receiving element is on the extension of the normal There exists a structure which arrange | positions (for example, refer patent document 5). However, in the conventional waveguide structure described in Patent Document 5, there is no waveguide with respect to the light emitting element or the light receiving element disposed outside the waveguide surface, so that light is free in a portion where the waveguide does not exist. Will propagate. There is a problem that adjacent crosstalk increases as the distance of the portion where the waveguide does not exist becomes longer. Further, when the light emitting element is disposed outside the waveguide surface, it is necessary to align the direction of the light emitting element with respect to the dielectric multilayer filter, and thus there is a problem that the planar mounting is difficult. Furthermore, if the light receiving element is arranged on the optical fiber side of the dielectric multilayer filter, there is a problem that light from the light emitting element that passes through the dielectric multilayer filter is likely to enter, causing crosstalk.

(5) In order to minimize the distance between the light emitting element disposed outside the waveguide surface and the dielectric multilayer filter, for example, the vertical tilt angle of the dielectric multilayer filter is set to 45 degrees, and the dielectric multilayer film is A light emitting element may be disposed immediately below the filter. However, when a multimode waveguide is used, the light incident on the dielectric multilayer filter from the light emitting element and the optical fiber is not parallel light, unlike the case where a collimating lens is used. It is extremely difficult to exhibit predetermined transmission / reflection characteristics. In addition, since the polarization dependency is increased by tilting the dielectric multilayer filter by 45 degrees in the vertical direction, it is difficult to exhibit transmission / reflection characteristics. In such a configuration, if the upstream and downstream wavelengths used in bidirectional communication are very different, for example, if the ratio of the two is 1: 2, the transmission / reflection characteristics of the incident light component can be improved. Although it is not impossible in principle, the dielectric multilayer filter itself is extremely expensive, and the VCSEL array and the PD array that can be used for the filter are similarly expensive. There was a problem. In addition, when the wavelengths are very different, it is unavoidable to select light emitting elements and light receiving elements having different compositions. Therefore, there is a high possibility that the characteristics over time are different, and the performance of the bidirectional communication module is likely to vary. There was a problem.
JP-A-63-33707 Japanese Patent Laid-Open No. 10-282350 JP-A-6-59143 JP 2004-69742 A JP 2003-232944 A

  As described above, the conventional waveguide structures described in Patent Documents 1 to 5 have a problem that it is extremely difficult to realize economical two-way communication with respect to the multicore fiber array. .

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and a multi-core bidirectional communication waveguide array capable of bidirectionalizing a narrow-pitch multi-core optical fiber array and its manufacture. It is to provide a method and a bidirectional communication module.

[1] The present invention, multicore both the waveguide core of the Y branch shape, the pair of branch side cores disposed in parallel three or more on the same plane as the same direction having a pair of branch side core A waveguide array for directional communication, wherein a wavelength selective filter disposed across a branching portion of the waveguide core and every other one on a branching side core of the waveguide core; A multi-core bidirectional communication waveguide characterized by comprising a plurality of mirrors capable of reflecting guided light in the same direction out of the plane, and the plurality of mirrors being arranged on the same straight line In the array.

  By adopting the above configuration, it is possible to rationally bidirectionalize a narrow-pitch multi-core optical fiber array using a waveguide array and a wavelength selection filter, and improve the data transfer density in the same installation area. Is possible.

[2] In the present invention, the cross-sectional shape of the waveguide core is formed in a substantially rectangular shape, and the length of one side thereof is 70 to 100% of the core diameter of the multimode optical fiber. It is preferable that the numerical aperture of the waveguide core is larger than the numerical aperture of the optical fiber. Multimode optical fiber for two-way communication with a large connection tolerance can be used while minimizing loss during transmission and reception, and low cost and highly reliable multi-core two-way communication can be obtained. be able to.

[3] In the present invention, it is preferable that the wavelength selection filter is a dielectric multilayer film, and an angle between a waveguide optical axis and a normal line of the wavelength selection filter is 2.5 degrees or more and 10 degrees or less. It is. The angle formed between the normal line of the wavelength selective filter and the optical axis of the waveguide can be narrowed according to the two-wavelength separation characteristics. When the angle is smaller than 2.5 degrees, it is difficult to produce the branch side core, and the branch characteristics are adversely affected. If the angle exceeds 10 degrees, the characteristics of the wavelength selection filter are deteriorated, which is not preferable.

[4] The waveguide array for multi-core bidirectional communication according to the present invention includes three or more pairs of Y-branch waveguides arranged in parallel on the same plane so that a pair of Y-branch cores are in the same direction. A mold having a core-forming concave groove formed on a molding surface having a form corresponding to a core and a form corresponding to a plurality of mirrors capable of reflecting guided light in the same direction out of the plane from the waveguide core The mold surface side of the mold is closely attached to the lower clad material, and the core-forming groove is filled and cured with an ultraviolet curable resin, and after the ultraviolet curable resin is cured, a metal thin film is attached to the mirror. Forming a film and forming an upper cladding material on the waveguide core, and disposing a wavelength selection filter across the branch of the waveguide core , wherein the plurality of mirrors includes: A branch side core of the waveguide core A method for manufacturing a multi-core bidirectional communication waveguide array, characterized in that it is formed every other line and arranged on the same straight line.

  According to the above configuration, the use of a template having a core-forming concave groove portion can eliminate complicated processes such as patterning, exposure / development, etching, and the like. It can be produced stably with a simple process. By simplifying the process and improving productivity, cost reduction can be achieved easily and reliably.

[5] As another manufacturing method of the present invention , three or more pairs of Y-branch-shaped waveguide cores arranged in parallel on the same plane so that a pair of Y-branch-shaped branch-side cores have the same direction are supported. Using a mold having a core-forming concave groove formed on the molding surface and having a form, the molding surface side of the mold is brought into close contact with the lower clad material, and the core-forming concave groove is filled and cured with an ultraviolet curable resin After the UV curable resin is cured, an upper clad material is formed on the waveguide core, and light is guided to the branch side core portion of the waveguide core in the same direction out of the plane from the waveguide core. Forming a plurality of mirror portions capable of reflecting the light beam by laser irradiation, and disposing a wavelength selection filter so as to traverse the branching portion of the waveguide core , wherein the plurality of mirror portions include: Branch of waveguide core In the method of manufacturing a waveguide array for multi-core bidirectional communication, wherein every other core is formed on the side core and arranged on the same straight line.

  According to the above configuration, after producing the waveguide core and the upper clad material, the mirror part capable of reflecting the guided light in the out-of-plane direction from the waveguide core can be formed in the adjacent branch side core part by laser irradiation. The mirror portion can operate as a total reflection mirror due to a difference in refractive index between the waveguide core and air, and does not require a metal thin film.

[6] The material of the waveguide array is preferably made of an epoxy-based, acrylic-based, or polyimide-based polymer resin material.

[7] Further, the present invention provides the waveguide array for multi-core bidirectional communication according to any one of claims 1 to 3, and a light emitting element arranged so that a light emitting point coincides with a position corresponding to the mirror. The light receiving point coincides with the array, the optical fiber array disposed at the end of the branching core other than the branching core where the mirror is disposed, and the end of the waveguide core opposite to the branching core. The bidirectional communication module includes a light receiving element array arranged in such a manner.

  In the bidirectional communication module of the present invention, for example, the light emitting element array and the light receiving element array can be mounted on the same submount, and the optical fiber array is mounted with a required pitch interval and an arbitrary number of cores. It becomes possible.

[8] The bidirectional communication module of the present invention has a configuration in which normal directions of the light receiving and emitting surfaces of the light receiving element array and the light emitting element array are arranged in the same direction. Is preferred.

  According to the present invention, transmission / reception using a multi-core array of optical fibers can be bidirectional, and the data transfer density in the same installation area can be improved. In addition, a product with high reliability and low price can be obtained.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
(Configuration of waveguide array for multicore bidirectional communication)
FIG. 1 schematically shows an example of the configuration of a multi-core bidirectional communication waveguide array according to a first embodiment of the present invention. FIG. 1A is a top view of a waveguide array for multicore bidirectional communication, and FIG. 1B is a cross-sectional view as seen from the portion corresponding to the arrowed line II in FIG. 1A. FIG. 2 is an enlarged partial cross-sectional view schematically showing a mirror structure capable of reflecting the guided light in the direction outside the waveguide surface. In FIG. 1, the illustration of the upper clad material 14 is omitted.

  In FIG. 1, the code | symbol 10 has shown the structure of the waveguide array for multi-core bidirectional | two-way communication. As shown in FIG. 1, the basic configuration of the waveguide array 10 includes a lower clad material 11 serving as a clad layer, a Y-branch-shaped waveguide core 12 formed on the lower clad material 11, and a waveguide core surface. A mirror 13 that can reflect light outward, an upper clad material 14 that is a clad layer covering the waveguide core 12, and a wavelength selection that transmits light of a specific wavelength band and reflects light of other wavelengths It consists of a polymer optical waveguide film having a filter 15.

  As shown in FIG. 1, the waveguide array 10 includes a plurality of curved waveguides in which two branch cores (branch-side waveguide cores) 12 a and 12 a are branched via a branch portion of the waveguide core 12. Consists of cores. In the illustrated example, three or more sets of waveguide cores 12 are arranged in parallel on the same plane of the lower clad material 11 with a predetermined array interval. The waveguide core 12 is made of a material having a high refractive index, and the cross section of the waveguide core 12 with respect to the light traveling direction is substantially rectangular. As a material of the waveguide core 12, for example, an epoxy-based, acrylic-based, or polyimide-based polymer resin material can be used. The clad materials 11 and 14 are made of a material having a refractive index lower than that of the waveguide core 12. As a material of these clad materials 11 and 14, for example, an epoxy-based, acrylic-based, or polyimide-based polymer resin material can be used.

  In the middle of the branch core 12a, as shown in FIG. 2, a stepped step portion including an inclined surface inclined at 45 degrees from the flat upper surface of the core and a thin flat surface is formed. The inclined surface of the stepped portion can have a mirror structure for inputting external input light perpendicularly to the clad materials 11 and 14. In the mirror structure of the first embodiment, every other mirror 13 having a 45-degree inclined surface serving as an optical path conversion surface for bending the waveguide optical axis at 90 degrees is formed on the branch core 12a. It is arranged on a straight line. The 45-degree inclined surface of the mirror 13 can deposit a metal thin film 13a having a high reflectance. As the metal thin film 13a, various metal materials such as aluminum, gold, silver, and titanium can be used. The end face of the waveguide core 12 opposite to the branch core 12a is an inclined mirror surface 13b that is inclined obliquely alternately with the mirror 13 at an inclination angle of 45 degrees with respect to the light traveling direction.

  The optical fiber optically coupled to the waveguide core 12 is formed in a circular cross section, and the cross section of the waveguide core 12 is formed in a rectangle. Therefore, when applied to multicore bidirectional communication, the rectangular dimension of the waveguide core cross section is preferably about 70 to 100%, preferably about 80 to 90% of the core diameter of the optical fiber. More desirable is. The length of the waveguide core 12 is about 5 cm at the maximum, and since there is no arc-shaped core portion with a large curvature, it is possible to prevent excitation of higher-order modes of guided light. By setting the numerical aperture NA of the waveguide core 12 to be larger than the numerical aperture NA of the optical fiber, there is no leakage mode of the received light from the optical fiber, and the transmitted light from the VCSEL array is also substantially the emission characteristics of the VCSEL array itself. It is possible to reach the optical fiber array while maintaining the numerical aperture NA coming from.

  As shown in FIG. 1, the wavelength selective filter 15 is inserted into a linear groove formed so as to cross the branch portions arranged in parallel. The wavelength selection filter 15 is preferably made of a dielectric multilayer film from the viewpoint of performance and price. In the wavelength selection filter 15 (dielectric multilayer filter 15), it is preferable that the angle formed between the normal line and the waveguide optical axis is as small as possible in view of polarization characteristics. However, when the angle is too small, it is difficult to manufacture the branch core 12a, which may adversely affect the branch characteristics, which is not preferable. If the angle is too large, the characteristics of the wavelength selection filter 15 will be deteriorated. Therefore, the angle formed by the waveguide optical axis and the normal line of the wavelength selection filter 15 is preferably 2.5 degrees or more and 10 degrees or less. More preferably, it is within the range of 4 to 8 degrees. As a result, the wavelength range used for bidirectional transmission can be selected from those having excellent VCSEL characteristics that are light emitting element arrays. Instead of the commonly used combination of wavelengths 850 nm and 780 nm, it is possible to use two types of VCSEL arrays with very narrow wavelength intervals and similar life characteristics as multimode light of 850 nm and 820 nm.

[Second Embodiment]
(Configuration of waveguide array for multicore bidirectional communication)
FIG. 3A is a top view schematically showing a configuration example of the waveguide array for multicore bidirectional communication according to the second embodiment of the present invention, and FIG. ) Is a cross-sectional view seen from the portion corresponding to the arrowed portion of the III-III line, and FIG. 4 is an enlarged partial cross-sectional view schematically showing the mirror structure of the waveguide array according to the second embodiment. . In these figures, the main difference from the first embodiment is that the mirror is formed by a cut portion, and the remaining configuration is the same as that of the first embodiment. Accordingly, in these drawings, substantially the same members as those in the first embodiment are denoted by the same member names and reference numerals, and detailed description thereof will be omitted.

  In the middle of the branch core 12a of the waveguide array 10 according to the second embodiment, as shown in FIG. 3 and FIG. 4 (a), the upper clad material 14 serving as a flat clad layer is downward from the upper surface. A wedge-shaped cut portion 13 c is formed, which is composed of an inclined surface inclined at 45 degrees toward the upper surface and a vertical surface orthogonal to the upper clad material 14. The inclined surface of the cut portion 13c can be configured as a 45 ° inclined mirror. This cut part 13c is formed in every other branch core 12a, and is arranged on the same straight line. The 45-degree inclined surface of the cut portion 13c can operate as a total reflection mirror due to a difference in refractive index between the waveguide core 12 and air. For this reason, a metal thin film is not formed in the cut portion 13c. In addition, since the mirror function by this notch part 13c is comprised from the inclined surface of about 45 degree | times, and an air interface, depending on a processing method, the shape like FIG.4 (b) may be sufficient, for example.

  According to the multi-core bidirectional communication waveguide array 10 configured as in the first and second embodiments, the dielectric multilayer filter 15 can be configured in accordance with the requirement of two-wavelength (850 nm, 820 nm) separation characteristics. Configuration in which the angle between the normal line and the optical axis of the waveguide can be made as narrow as possible, a configuration in which the light emitting element array and the light receiving element array can be mounted on the same submount, and an arbitrary number of cores with an optical fiber pitch of 250 μm It has a main feature that it can have a compatible configuration. The waveguide array 10 can transmit and receive light from the optical fiber array using the same waveguide core 12. For this reason, it becomes possible to use a multimode optical fiber for bidirectional communication having a large connection tolerance while maintaining a loss during transmission and reception to the minimum, and low-cost multi-core bidirectional communication can be obtained. . Of course, the structure, shape, and components of the multi-core bidirectional communication waveguide array 10 configured as in the first and second embodiments are not limited to the illustrated examples. .

  The multi-core bidirectional communication waveguide array 10 according to the first and second embodiments having the above-described configuration can be efficiently manufactured as follows.

(Manufacturing method of waveguide array for multi-core bidirectional communication)
The multi-core bidirectional communication waveguide array 10 needs to have a local mirror structure in the middle of the waveguide core 12. In order to manufacture the waveguide array 10 for multi-core bidirectional communication, the mold manufacturing technique described in Japanese Patent Application Laid-Open No. 2004-86144 and the like previously proposed by the present applicants can be used. This mold has a convex shape for forming a waveguide core formed in a form corresponding to the waveguide core 12 having a Y-branch shape and a form corresponding to a mirror 13 portion capable of reflecting guided light from the waveguide core 12 in the out-of-plane direction. It can be produced using a master having a strip. Even in the production of this master, it can be obtained by a manufacturing method using a technique for producing a master described in JP 2004-86144 A and the like. For example, polydimethylsiloxane is particularly suitable as the material of the mold.

  A multi-core bidirectional communication waveguide array is manufactured using a mold having a groove for forming a waveguide core formed in a form corresponding to the Y-branch-shaped waveguide core 12 and a form corresponding to the mirror 13 part. In order to do this, first, the molding surface side of the mold is brought into intimate contact with the lower clad material 11, and the waveguide core forming concave groove portion is filled and cured with an ultraviolet curable resin. After the ultraviolet curable resin is cured, a metal thin film 13a is deposited on the mirror 13 part. Then, by applying the upper clad material 14 to the waveguide core 12, the entire Y-branch-shaped waveguide core 12 can be formed to be embedded in the clads 11 and 14.

  As shown in FIG. 2, the mirror-shaped cut portion 13c is formed slightly thinner than the thickness of the waveguide core 12, so that the concave groove portion for forming the waveguide core of the rubber mold does not have a dead end structure. It becomes easy to fill the resin. In addition, the excess loss slightly increases, but does not particularly affect the performance as a two-way communication module. Note that, after the waveguide core shape is fabricated, when the upper and side surfaces of the waveguide core 12 are filled with the clad material 14, the difference in refractive index between the waveguide core 12 and the clad 14 is such that the waveguide core 12 and the air are refracted. Since it is not large compared with the rate difference, the mirror effect does not occur as it is. In order to demonstrate the function of the 45 degree mirror 13 part, after covering the surface other than the mirror part with a metal mask having a window corresponding to the mirror 13 part, aluminum, gold is applied to the 45 degree mirror 13 part by metal vapor deposition means. By vapor-depositing a metal thin film 13a such as silver or titanium, the function of the waveguide array 10 can be sufficiently exhibited even in the buried structure of the clad materials 11 and 14.

  Further, even after the waveguide core 12 and the upper clad material 14 are fabricated without considering the mirror structure as in the waveguide array 10 according to the second embodiment, an epoxy-based, acrylic-based, or polyimide-based high As shown in FIGS. 4A and 4B, the waveguide array 10 made of a molecular material can be processed by cutting the surface of the waveguide by means such as laser irradiation. Specifically, the branch core of the waveguide core 12 to be processed using an excimer laser such as a fourth harmonic of YAG or ArF or KrF at an angle of 45 degrees with respect to the normal line of the waveguide film surface. 12a can be irradiated. At this time, since the processing range can be limited to only the required branch core 12a using the optical system, it is possible to process every other branch core. The cut portion 13c can operate as a total reflection mirror due to a difference in refractive index between the waveguide core 12 and air, and a metal thin film is not necessarily required.

[Third Embodiment]
(Configuration of bidirectional communication module)
Next, a bidirectional communication module using the waveguide array 10 manufactured by the above manufacturing method will be specifically described. FIG. 5 schematically shows a configuration example of the bidirectional communication module according to the third embodiment of the present invention, and FIG. 5A is a top view of the bidirectional communication module. (B) is sectional drawing seen from the site | part corresponded to the arrow part of the VV line of Fig.5 (a). In these drawings, substantially the same members as those in the first embodiment are given the same member names and symbols. Therefore, the detailed description regarding these members is omitted.

  In FIG. 5, reference numeral 20 indicates the structure of a bidirectional communication module having the waveguide array 10. As shown in FIG. 5, the two-way communication module 20 has a branch except for the light emitting element array 21 arranged so that the light emitting points coincide with the positions corresponding to the mirror 13 and the branch core 12a where the mirror 13 is arranged. An optical fiber array 22 arranged at the end of the core 12 and a light receiving element array 23 arranged so that the light receiving point coincides with the end of the waveguide core 12 opposite to the branch core 12a. Yes. The optical fiber array 22 composed of fiber cables is arranged in a line at a pitch of 250 μm. The light emitting element array 21 and the light receiving element array 23 have elements arranged in a line with substantially the same pitch as the optical fiber array 22.

  In the bidirectional communication module 20, the light emitting element array 21 is arranged so that the light emitting points coincide with the positions corresponding to the mirrors 13, and the light receiving element array 23 is arranged at the end of the waveguide core 12 opposite to the branch core 12a. By arranging so that the light receiving points coincide with each other, the influence of crosstalk on the light receiving element array 23 can be minimized. In such a configuration, it is desirable to reduce the branch angle of the branch core 12a in order to exhibit the performance of the dielectric multilayer filter 15, but the positional relationship between the light receiving and emitting element arrays 23 and 21 is reversed. When the branching angle of the branch core 12a is small, in order to prevent the light from the light emitting element from being easily branched to the light receiving element side in the same module, that is, a structure that is likely to cause crosstalk. It was made.

  As shown in FIG. 5, the bidirectional communication module 20 includes a ceramic package 25 that hermetically seals the waveguide array 10 and the submount 24. An MT connector 26 made of an attachment of the fiber array 22 and an MT compatible connector 28 connected to the MT connector 26 via two guide pins 27 and 27 are provided on the end face of the branch core 12a of the waveguide array 10. A fiber array 22 is attached via the cable. The submount 24 is electrically connected to a light emitting element array 21, a light receiving element array 23, a light emitting element array driving circuit 30, a light receiving element array amplifier (TIA) 31, and the like via an electric circuit 24a printed on the submount 24. It is connected to the. A portion corresponding to the mirror 13 portion of the waveguide array 10 is bonded and fixed to the light emitting element array 21 and the light receiving element array 23.

  In the bidirectional communication module 20, the light receiving element array 21 and the light emitting element array 23 can be arranged so that the normal directions of the light receiving and emitting surfaces are in the same direction. This eliminates the need to stand the element in the 90-degree direction. Therefore, mounting on the same submount 24 or mounting on a circuit board printed on the ceramic package 25 is facilitated, and the mounting cost can be reduced. Furthermore, it is possible to reduce the possibility that light from a light emitting element that is not coupled to the waveguide array 10 will erroneously enter the light receiving element due to errors in mounting, and to improve data transfer density.

(Bidirectional communication module operation)
FIG. 6 is a schematic diagram schematically illustrating an example of a bidirectional communication module. FIG. 7 is a graph showing the transmittance characteristics of the dielectric multilayer filter, wherein transmittance (%) is represented on the vertical axis and wavelength band (nm) is represented on the horizontal axis.

  In FIG. 6, each of the first and second bidirectional communication modules is optically coupled through an optical fiber array 22 (ribbon fiber 22). The first bidirectional communication module 20 (left side of FIG. 6) has a wavelength transmission filter whose wavelength transmission characteristic when light with a wavelength of 820 nm is vertically incident is approximately 90% or more as shown in FIG. 15, a light emitting element array 21 having a wavelength of 850 nm, and a light receiving element array 23. The second bidirectional communication module 40 (right side in FIG. 6) has a wavelength transmission filter 41 having a wavelength transmission characteristic of approximately 90% or more as shown in FIG. 7B when light having a wavelength of 850 nm is vertically incident. And a light emitting element array 42 having a wavelength of 820 nm and a light receiving element array 43.

  In the first two-way communication module 20, the signal light L1 from the light emitting point of the light emitting element array 21 having a wavelength of 820 nm is optically path-converted by the 45 degree mirror surface, and then guided through the branch core 12a on the light emitting element array side. To wave. The optical path of the signal light L1 is converted again by the wavelength selection filter 15 and is emitted to the ribbon fiber 22 via the fiber-side branch core 12a by changing the propagation direction. The signal light L1 from the ribbon fiber 22 propagates through the branch core 44a and the wavelength selection filter 41 of the other party's second bidirectional communication module 40. The signal light L1 is reflected by the inclined mirror surface formed on the end face of the waveguide core 44 opposite to the branch core 44a, and is received by the light receiving point of the light receiving element array 43 through the lower clad material by changing the propagation direction. Is done.

  On the other hand, in the second bidirectional communication module 40, the signal light L2 from the light emitting point of the light emitting element array 42 having a wavelength of 850 nm is optically path-converted by the 45-degree mirror surface, and then the branching core 44a on the light emitting element array side Is guided. The optical path of the signal light L2 is converted again by the wavelength selection filter 41, propagates in the opposite direction along the same optical path as the light from the light emitting element array 21 having the wavelength of 820 nm, and passes through the fiber-side branch core 44a. It propagates through the ribbon fiber 22, the branch core 12 a of the counterpart first bidirectional communication module 20, and the wavelength selection filter 15. The signal light L2 is reflected by the inclined mirror surface formed on the end face of the waveguide core 12, and is received by the light receiving point of the light receiving element array 23 through the lower clad material.

  In the bidirectional communication modules 20 and 40 configured as described above, the light emitting element array 21 can be arranged on the lower surface or the upper surface instead of the side surface of the waveguide array 10. Therefore, it becomes possible to prevent the arrangement interference between the light emitting element array 21 and the optical fiber array 22, and there is no influence of crosstalk. As a result, it is possible to use a VCSEL array having a light emitting point of 250 μm pitch as a light emitting element array, a PD array having a light receiving point of 250 μm pitch as a light receiving element array, and an optical fiber array having a 250 μm pitch. A transmission / reception module using a multicore array of optical fibers used for high-speed data transmission between electrical and electronic devices can be bidirectionalized. In addition, since the multimode VCSEL in the 850 nm band and the nearby multimode VCSEL in the wavelength of 820 nm can be used because they are highly reliable and less expensive than other wavelengths, the module as a whole is also reliable. Improvement and price reduction can be achieved.

  Hereinafter, more specific embodiments of the present invention will be described with reference to FIGS.

In producing a polymer optical waveguide as shown in FIG. 1, first, a concave groove corresponding to a core shape in which 12 sets of Y branch shapes having a core cross-sectional dimension of 45 μm square and a branch angle of 12 degrees are arranged in parallel, Every other book, a silicone rubber mold having a depth of 42 μm and having a cut forming convex part of 45 degrees was prepared. After an Arton film (refractive index of 1.51) having a thickness of 100 μm is brought into close contact with the molding surface of the mold, a waveguide core is formed in the concave groove portion of the mold through a resin filling hole and a resin suction port provided in the mold. A waveguide core pattern is formed by filling an ultraviolet curable resin (refractive index of 1.525 at the time of curing), irradiating with ultraviolet rays having a wavelength of 365 nm and an intensity of 50 mW / cm ² through a mold for 15 minutes to cure. Formed. In the mold, every other branch core has a 45-degree cut portion having a depth of 42 μm, and the shape of the hardened waveguide core pattern reflects the shape of the mold. Filling the mold with resin from the waveguide core side with no notch, so that the notch is very narrow, so there is almost no UV curable resin in the unnecessary part from that part to the end of the branch core. Not filled.

  Next, a metal mask having 12 through holes of 100 μm square in series with a pitch of 250 μm is prepared, and the waveguide is formed with 12 through holes aligned with each of the 12 45 degree mirror portions of the branch core. The other part of the core pattern was covered, and aluminum was vapor-deposited to a thickness of about 100 nm from the metal mask side toward the 45-degree mirror part of the branch core through the vapor deposition source.

Next, an ultraviolet curable resin (refractive index at the time of curing 1.51) serving as an upper clad material was applied onto the Arton film on which the waveguide core pattern was formed. With a 100 μm thick Arton film laminated on the waveguide core pattern, UV light having a wavelength of 365 nm and an intensity of 50 mW / cm ² is irradiated for 3 minutes to cure, and an NA of 0.21 including a mirror structure is embedded. A waveguide structure was completed.

  Next, a dicing blade having a blade edge of 90 degrees and a thickness of 40 μm is attached to the dicing saw, and a 40 μm wide groove reaching the depth of the waveguide core is produced so as to cross the branching portion of the waveguide core. Further, the side portion of the waveguide core and the end portion of the branch core were cut. Finally, using a dielectric multilayer filter having a wavelength transmission characteristic of 30 μm as shown in FIG. 7A when the light having a wavelength of 820 nm is vertically incident, the normal line of the filter and the waveguide core The dielectric multilayer filter is inserted into an insertion groove that crosses the branching portion of the waveguide core so that the angle formed by the optical axis of the waveguide becomes 6 degrees, and an ultraviolet curable resin (refractive index at curing 1.525) The waveguide array for multi-core bi-directional communication was completed by bonding and fixing.

  The characteristics of the waveguide array in Example 1 were evaluated. FIG. 8A is a top view for explaining the arrangement relationship of the components of the waveguide array, and FIG. 8B corresponds to the arrow VIII-VIII line in FIG. 8A. It is sectional drawing seen from the site | part.

  As shown in FIG. 8, a VCSEL array 21 and a PD array 23 having a wavelength of 850 nm and a GI type multimode fiber having a numerical aperture NA of 0.2 and a core diameter of 50 μm are 250 μm with respect to the waveguide array 10. When a plurality of optical fiber arrays 22 arranged at a pitch are installed, the light emitted from the emission point of the VCSEL array 21 reaches the fiber with a loss of 2 dB or less with respect to the optical fiber, and the stray light on the PD array 23 side is − It was 40 dB, and sufficient attenuation characteristics could be obtained. Further, the crosstalk between adjacent channels was 40 dB or less, and good performance could be exhibited. On the other hand, when light having a wavelength of 820 nm is input from the optical fiber array 22 to the waveguide array 10, the light reaches the PD array 23 with a loss of 2 dB or less. On the other hand, the stray light for the VCSEL array 21 side is -40 dB, and a sufficient attenuation characteristic can be obtained.

  The waveguide core pattern was changed to a waveguide core pattern with a waveguide core diameter of 40 μm, and a multi-core bidirectional communication waveguide array was produced in the same manner as in Example 1. As a result, substantially the same performance as that of the waveguide array for multicore bidirectional communication in Example 1 could be exhibited. Even when the core refractive index was 1.53 and the numerical aperture NA was 0.25, the performance was not changed.

  The width of the insertion groove for inserting the dielectric multilayer filter is changed to 60 μm, a multi-core bidirectional communication waveguide array is produced in the same manner as in the first embodiment, and the dielectric multilayer filter is inserted into the insertion groove. Made it easier. As a result, a mounting angle fluctuation of about ± 0.6 degrees occurred, but the performance substantially equivalent to that of the waveguide array for multicore bidirectional communication in Example 1 could be exhibited.

Similar to Example 1, a polymer optical waveguide as shown in FIG. 3 was produced. A silicone rubber mold having a groove portion corresponding to a core shape in which 12 sets of Y-branched shapes having a core cross-sectional dimension of 45 μm square and a branching angle of 12 degrees are arranged in parallel was prepared. After an Arton film (refractive index of 1.51) having a thickness of 100 μm is brought into close contact with the molding surface of the mold, a waveguide core is formed in the concave groove portion of the mold through a resin filling hole and a resin suction port provided in the mold. A waveguide core pattern is formed by filling an ultraviolet curable resin (refractive index of 1.525 at the time of curing), irradiating with ultraviolet rays having a wavelength of 365 nm and an intensity of 50 mW / cm ² through a mold for 15 minutes to cure. Formed.

Next, an ultraviolet curable resin (refractive index at the time of curing of 1.51) serving as an upper clad material is applied on the ARTON film on which the waveguide core pattern is formed to a thickness of 70 μm by spin coating, the wavelength is 365 nm, the strength The film was irradiated with ultraviolet rays having a power of 50 mW / cm ² for 3 minutes to be cured, and a buried waveguide structure was completed. Next, a YAG fourth harmonic laser with an oscillation output of 300 mW and a wavelength of 266 nm was irradiated for 3 seconds per location, so that a 45-degree cut portion was produced for every other branch core. Next, a dicing blade having a blade edge of 90 degrees and a thickness of 40 μm is attached to the dicing saw, and a 40 μm wide groove reaching the depth of the waveguide core is produced so as to cross the branching portion of the waveguide core. Further, the side portion of the waveguide core and the end portion of the branch core were cut.

  Finally, using a dielectric multilayer filter having a thickness of 30 μm as shown in FIG. 7 (a), the wavelength transmission characteristics when light having a wavelength of 820 nm is vertically incident, the normal line of the filter and the waveguide The dielectric multilayer filter is inserted into an insertion groove that crosses the branching portion of the waveguide core so that the angle formed by the waveguide optical axis of the core is 6 degrees, and an ultraviolet curable resin (refractive index 1.525 at the time of curing is set). ) To complete the waveguide array for multi-core bidirectional communication.

  When a VCSEL array having a wavelength of 850 nm, a PD array, and an optical fiber array in which a plurality of GI type multimode fibers having a numerical aperture NA of 0.2 and a core diameter of 50 μm are arranged at a pitch of 250 μm are installed on the waveguide array, the optical fiber On the other hand, the light emitted from the light emitting point of the VCSEL array reached the fiber with a loss of 2 dB or less, and the stray light with respect to the PD array side was −40 dB, and sufficient attenuation characteristics could be obtained. Further, the crosstalk between adjacent channels was 40 dB or less, and good performance could be exhibited. On the other hand, when light having a wavelength of 820 nm was input from the optical fiber array to the waveguide array, it reached the PD ray with a loss of 2 dB or less. On the other hand, the stray light with respect to the VCSEL array side is −40 dB, and a sufficient attenuation characteristic can be obtained.

  A waveguide array was prepared as in Example 1 above, and a 45-degree inclined mirror surface was formed on the waveguide core end surface on the light receiving element array side by cutting a dicing saw. Next, a ceramic package having a submount with a predetermined electrical circuit printed on the surface was prepared, and a 1 × 12 wavelength 850 nm VCSEL array, a 1 × 12 PD array, and a driving IC were mounted on the submount. The part corresponding to the mirror part of the waveguide array is bonded and fixed to the light emitting element array and the light receiving element array, and the MT connector, the guide pin and the adapter compatible with the core position are inserted into the end of the branch core, and the bidirectional communication module. (See FIG. 5).

  Wavelength transmission characteristics when light with a wavelength of 850 nm is vertically incident are shown in FIG. 7B, and a bidirectional multilayer communication according to the first embodiment using a dielectric multilayer filter as shown in FIG. 7B and a 1 × 12 VCSEL array with a wavelength of 820 nm. A two-way communication module that is paired with the module was fabricated. These two modules were connected by a ribbon fiber having a length of 30 m in which 12 GI type multimode fibers having a core diameter of 50 μm were arranged at a pitch of 250 μm and both ends were attached to MT connectors. Two-way communication of 3 Gbps × 2 per optical fiber was possible between these modules without any trouble.

  The optical waveguide and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, modifications, and examples, and various design changes can be made without departing from the spirit of the invention. It is.

BRIEF DESCRIPTION OF THE DRAWINGS One structural example of the waveguide array for multi-core bidirectional communication which is the 1st Embodiment in this invention is shown typically, (a) is a top view, (b) is sectional drawing. It is a partial section enlarged view showing typically the mirror structure of the waveguide array of the present invention. The structural example of the waveguide array for multi-core bidirectional | two-way communication which is the 2nd Embodiment in this invention is shown typically. (A) is a top view, (b) is a sectional view. (A), (b) is the fragmentary sectional enlarged view which shows typically the other mirror structure of the waveguide array of this invention. The structural example of the bidirectional | two-way communication module which is the 3rd Embodiment in this invention is shown typically, (a) is a top view, (b) is sectional drawing. It is a schematic diagram which shows an example of a bidirectional | two-way communication module typically. (A), (b) is a graph which shows the transmittance | permeability characteristic of a dielectric multilayer filter. (A) is a top view for demonstrating arrangement | positioning relationship of the component of the bidirectional | two-way communication module in this invention, (b) is the sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Waveguide array 11 Lower clad material 12,44 Waveguide core 12a, 44a Branch core 13 Mirror 13a Metal thin film 13b Inclined mirror surface 13c Cut part 14 Upper clad material 15,41 Wavelength selection filter 20,40 Bidirectional communication module 21, 42 Light-Emitting Element Array 22 Optical Fiber Arrays 23 and 43 Light-Receiving Element Array 24 Submount 24a Electric Circuit 25 Package 26 MT Connector 27 Guide Pin 28 MT-Compatible Connector 30 Light-Emitting Element Array Drive Circuit 31 Light-Receiving Element Array Amplifiers L1 and L2 Signal Light

Claims (8)

Waveguide core Y-branch shape having a pair of branch side core, with said pair of multi-core bidirectional communication waveguide array branch side cores disposed in parallel three or more on the same plane as the same direction There,
A wavelength selective filter disposed across the branch of the waveguide core;
A plurality of mirrors formed on every other branch side core of the waveguide core and capable of reflecting the guided light in the same direction out of the plane from the waveguide core;
A waveguide array for multi-core bidirectional communication, wherein the plurality of mirrors are arranged on the same straight line. The waveguide core has a substantially rectangular cross-sectional shape, and the length of one side thereof is 70 to 100% of the core diameter of the multimode optical fiber,
The waveguide array for multi-core bidirectional communication according to claim 1, wherein the numerical aperture of the waveguide core is larger than the numerical aperture of the optical fiber. The wavelength selective filter is a dielectric multilayer;
The waveguide array for multicore bidirectional communication according to claim 1 or 2, wherein an angle formed by a waveguide optical axis and a normal line of the wavelength selection filter is 2.5 degrees or more and 10 degrees or less. A form corresponding to a Y-branch-shaped waveguide core arranged in parallel on the same plane so that a pair of Y-branch-shaped branch-side cores are in the same direction, and the same direction out of the plane from the waveguide core Using a mold having a groove for forming a core formed on a molding surface with a configuration corresponding to a plurality of mirrors capable of reflecting guided light,
The mold surface side of the mold is brought into close contact with the lower clad material, and the core forming concave groove is filled and cured with an ultraviolet curable resin,
After curing of the ultraviolet curable resin, to-deposit a metal film on the mirror, and the upper clad layer be formed on the waveguide core,
Disposing a wavelength selective filter across the bifurcation of the waveguide core ;
The plurality of mirrors are formed on every other branch side core of the waveguide core and are arranged on the same straight line. . For forming a core formed on a molding surface having a form corresponding to a Y-branch-shaped waveguide core arranged in parallel in the same plane so that a pair of Y-branch-shaped branch-side cores have the same orientation Using a mold having a concave groove,
The mold surface side of the mold is brought into close contact with the lower clad material, and the core forming concave groove is filled and cured with an ultraviolet curable resin,
After the UV curable resin is cured, an upper clad material is formed on the waveguide core, and the waveguide light can be reflected in the same direction out of the plane from the waveguide core to the branch core portion of the waveguide core. Forming a plurality of mirror parts by laser irradiation ,
Disposing a wavelength selective filter across the bifurcation of the waveguide core ;
The plurality of mirror portions are formed on every other branch side core of the waveguide core and arranged on the same straight line, and the waveguide array for multicore bidirectional communication is manufactured. Method.   6. The method of manufacturing a waveguide array for multi-core bidirectional communication according to claim 5, wherein a material of the waveguide array is made of an epoxy-based, acrylic-based, or polyimide-based polymer resin material. The waveguide array for multicore bidirectional communication according to any one of claims 1 to 3,
A light emitting element array arranged so that the light emitting points coincide with the positions corresponding to the mirrors;
An optical fiber array disposed at an end of the branch-side core other than the branch-side core in which the mirror is disposed;
A bidirectional communication module, comprising: a light receiving element array arranged so that a light receiving point coincides with an end portion of the waveguide core opposite to the branch side core.   8. The bidirectional communication module according to claim 7, wherein the light receiving element array and the light emitting element array have a configuration in which normal directions of light receiving and emitting surfaces are the same.

Images