JP2008281695A - Light guide and light guide substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide and a light guide substrate having small light loss even when having a curvature part. <P>SOLUTION: The end of a polymer light guide film 3 is inserted between a heating member 7 and a support member 8 provided by corresponding to the thickness of the polymer light guide film 3 on a working bench 9 as shown in Fig.4(a). Subsequently, the polymer light guide film 3 is heated by the heating member 7, deformation is performed by being curved in a direction of A of Fig.4(a), and a curvature part 32A hold the shape by returning the polymer light guide film 3 to a room temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical waveguide and an optical waveguide substrate.

  As a conventional technique, an optical waveguide having a mirror surface having an angle of 45 degrees with respect to the optical axis is provided at one end, a substrate having an optical waveguide provided therein, a light emitting unit, and a substrate And a flexible optical waveguide provided with an end portion having a mirror surface having an angle of 45 degrees with respect to the optical axis and another end portion where the core is exposed. A formed optical waveguide substrate is known (see, for example, Patent Document 1).

  The optical waveguide is provided such that the end having the mirror surface is in the inner direction of the substrate and the other end is in the outer direction of the substrate, and the substrate is provided with a groove at a position corresponding to the mirror surface. ing.

The flexible optical waveguide is curved over the entire length by applying external force, and the end where the core is exposed directly abuts against the light emitting part of the surface optical element and is bonded, and the end having the mirror surface is The optical waveguide is inserted into a groove provided in the substrate and optically connected to an end portion having a mirror surface of the optical waveguide.
JP 2001-188146 A

  An object of the present invention is to propose an optical waveguide and an optical waveguide substrate which have a curved portion and have a small optical loss.

  In order to achieve the above object, an aspect of the present invention provides the following optical waveguide and optical waveguide substrate.

(1) An optical device having a curved portion having a core and a cladding provided around the core, having an NA of 0.25 to 0.45, and maintaining a predetermined radius of curvature without any external force Waveguide.

(2) The optical waveguide according to (1), wherein a difference in refractive index between the core and the clad is 1 to 5%.

(3) The optical waveguide according to (2), wherein the core and the clad are formed of a thermoplastic resin.

(4) The optical waveguide according to (1), wherein the curved portion is curved at 90 degrees.

(5) The optical waveguide according to (1), wherein the curvature radius of the curved portion is 1 to 1.5 mm.

(6) The optical waveguide according to (1), wherein the curved portion is provided between 10 mm from an optical input / output end.

(7) The optical waveguide according to (1), wherein at least the glass transition temperature of the curved portion is 100 to 200 ° C.

(8) The optical waveguide according to (1), wherein the core has a rectangular cross section.

(9) The optical waveguide according to (1), wherein the core has a circular cross section.

(10) A substrate having a pair of positioning grooves, a pair of spherical or cylindrical fixing members positioned by the pair of positioning grooves, and an optical input / output end side inserted between the pair of fixing members to be fixed. An optical waveguide substrate comprising the optical waveguide described in any one of 1 to 7 above.

  According to the optical waveguide of the first aspect, the optical loss can be reduced even if the curved portion is provided.

  According to the optical waveguide of the second aspect, the optical loss can be suppressed even if the optical waveguide is curved.

  According to the optical waveguide of the third aspect, the curved portion can be easily formed by heating.

  According to the optical waveguide of the fourth aspect, mounting becomes easy.

  According to the optical waveguide of the fifth aspect, a product on which the optical waveguide is mounted can be reduced in size.

  According to the optical waveguide of the sixth aspect, the height when mounted can be reduced.

  According to the optical waveguide of the seventh aspect, the curved portion can be easily formed at a low heating temperature.

  According to the optical waveguide substrate of the eighth aspect, a film-shaped optical waveguide can be used as the optical waveguide.

  According to the optical waveguide substrate of the ninth aspect, an optical fiber can be used as the optical waveguide.

  According to the optical waveguide substrate of the tenth aspect, the optical loss can be reduced even if the curved portion is provided.

[First embodiment]
FIG. 1 is a schematic view of an optical substrate according to the first embodiment of the present invention, and FIG. 2 is a perspective view of an optical waveguide according to the first embodiment of the present invention. 1A is a plan view of the optical substrate, FIG. 1B is a cross-sectional view taken along the line AA in FIG. 1A, FIG. 1C is a cross-sectional view along the line BB in FIG. It is line sectional drawing. 2A is a perspective view of the polymer optical waveguide film, and FIG. 2B is a cross-sectional view taken along the line CC of FIG. 2A.

  An optical substrate 1 as an optical waveguide substrate has a submount 2A installed on an electronic circuit board (not shown) including various electronic components, power supply circuit components, etc., and thermoplasticity is provided on the submount 2A. Polymer optical waveguide film 3 made of resin, light emitting element 4A that outputs a light signal by converting a drive signal transmitted from an electronic component on an electronic circuit board, and a light signal that is received is converted into an electric signal The light receiving element 5A, for example, fixing members 20a, 20b, 20c and 20d having a spherical shape, and a height adjusting member 200 for adjusting the height when the polymer optical waveguide film 3 is mounted are arranged.

(Submount)
The submount 2A has a rectangular shape and U grooves 21a, 21b, 21c, and 21d formed in a U shape on the upper surface. The material is, for example, a metal such as Si, Ni, or Cu, glass, or acrylic. Plastic such as polycarbonate is used.

  As shown in FIG. 1A, in the present embodiment, the pads 22a and 22b are provided on the submount 2A. For example, the pads 22a and 22b are not provided on the submount 2A, but directly from the electronic circuit board. You may wire to the pad 41 and the pad 51 of the light receiving element 5A. Further, when the submount 2A has conductivity, it may be directly wired to the pads 41 and 51, or an insulator may be interposed between the pads 22a and 22b and the submount 2A.

(Fixing member)
FIG. 3A is a plan view of the intersection of the U grooves according to the first embodiment of the present invention, and FIG. 3B is a cross-sectional view of the U groove according to the first embodiment of the present invention. FIG. 3C is a cross-sectional view of the V-groove according to the first embodiment of the present invention.

  As shown in FIG. 3A, the fixing member 20a is arranged at the intersection of the U groove 21a and the U groove 21c, the fixing member 20b is arranged at the intersection of the U groove 21a and the U groove 21d, and the fixing member 20c is The fixing member 20d is disposed at the intersection of the U groove 21b and the U groove 21c.

  As shown in FIGS. 3A and 3B, each of the fixing members 20a to 20d is supported by four corners that can be intersections, and is fixed to the submount 2A. In addition, the lower surfaces of the fixing members 20a to 20d may be embedded and fixed so as to be in contact with the lower surfaces of the grooves 21a to 21d. Moreover, each fixing member 20a-20d may be fixed to each groove | channel 21a-21d using an epoxy-type adhesive agent etc., for example.

  Moreover, each fixing member 20a-20d may be not only a spherical member but also a cylindrical member, and the shape thereof is not limited. The material is not limited to glass, but may be metal or plastic, and is not limited thereto.

  Further, the U grooves 21a, 21b, 21c and 21d may be V-shaped as shown in FIG. 3 (c), for example, semicircular or other shapes, or a combination thereof. A shape may be sufficient and the shape is not ask | required.

(Polymer optical waveguide film)
The polymer optical waveguide film 3 has, for example, a thickness of 100 μm, a glass transition temperature of 100 to 200 ° C., and a rectangular cross section extending in the film length direction as shown in FIG. As shown in FIG. 2B, for example, the first and second cores 31a and 31b having a thickness of 50 μm and the first and second cores 31a and 31b are surrounded, for example, the cladding 30 having a thickness of 25 μm. And grooved. Further, the polymer optical waveguide film 3 is formed with a curved portion 32 </ b> A having a constant radius of curvature 33, and both end portions are formed at 90 degrees with respect to the optical axis of the polymer optical waveguide film 3.

  The NA (numerical aperture) of the polymer optical waveguide film 3 is preferably 0.25 to 0.45 and more preferably 0.35 to 0.45 in order to reduce bending loss. The glass transition temperature of the polymer optical waveguide film 3 is preferably 100 ° C. or higher, and more preferably 100 to 200 ° C. In other words, the refractive index difference between the first and second cores 31a and 31b and the clad 30 is preferably 1 to 5% and 3 to 5% from the viewpoint of optical loss in the curved portion 12A. More preferred. For example, when the refractive index difference is 3%, even if the radius of curvature is 1.5 mm, the optical loss can be 0.1 dB or less, and when the refractive index difference is 4%, the radius of curvature is 1 mm. The optical loss can be reduced to 0.1 dB or less.

  As shown in FIG. 2B, the bending portion 32A has θ of 90 degrees in the present embodiment, where θ is the angle from the light input / output end of the polymer optical waveguide film 3 to the end of bending. Thus, the curved portion 32A is formed. However, for example, in the case where θ is produced at 80 degrees with an error of 10 degrees, a gap is formed between the light emitting section 40 of the light emitting element 4A and the light receiving section 50 of the light receiving element 5A and the polymer optical waveguide film 3. However, since the polymer optical waveguide film 3 has a large NA, the use of the adhesive 6A, gel, or the like can suppress the connection loss equivalent to θ of 90 degrees.

  As the adhesive 6A, a photo-curing adhesive such as an ultraviolet curable resin, a thermosetting adhesive, or the like can be used. It is desirable to use a material having the same refractive index as the second cores 31a and 31b. Moreover, as the adhesive 6B used when fixing the polymer optical waveguide film 3 and the fixing member, for example, an epoxy adhesive is used.

(Production of polymer optical waveguide film)
The polymer optical waveguide film 3 can be produced by, for example, a method using photolithography or RIE (reactive ion etching) which is generally used. The polymer optical waveguide film 3 in the present embodiment can be efficiently produced, for example, by the following steps (1) to (6).
(1) A mold formed from a cured layer of a mold-forming curable resin and provided with a concave portion corresponding to the core convex portion of the optical waveguide and two or more through holes communicating with one end and the other end of the concave portion, respectively. Step to prepare.
(2) A step of adhering a flexible film base material for clad having good adhesion to the mold to the mold.
(3) Fill the through hole at one end of the recess of the mold with the clad flexible film substrate in close contact with the core forming curable resin, and suck it under reduced pressure from the through hole at the other end of the recess of the mold. Filling the recesses of the mold with the core-forming curable resin.
(4) A step of curing the filled core-forming curable resin and peeling the mold from the clad flexible film substrate.
(5) A step of forming a clad layer on the clad flexible film substrate on which the core is formed.
(6) The process of forming the end surface of a polymer optical waveguide film with a dicing saw.

  The material of the flexible film base material for clad takes into consideration optical properties such as refractive index and light transmission, mechanical strength, heat resistance, adhesion to the mold, and flexibility depending on the application of the optical element. Is selected. Examples of the film include an alicyclic acrylic resin film, an alicyclic olefin resin film, a cellulose triacetate film, an epoxy resin film, and a fluorine-containing resin film. Further, the thickness of the film substrate is appropriately selected in consideration of flexibility, rigidity, ease of handling, etc., and generally about 0.02 to 0.1 mm is preferable.

  As the core-forming curable resin, resins such as radiation curable, electron beam curable, and thermosetting can be used. Of these, ultraviolet curable resins and thermosetting resins are preferred. As the ultraviolet curable resin or thermosetting resin for forming the core, for example, an ultraviolet curable or thermosetting monomer, an oligomer, or a mixture of a monomer and an oligomer is preferably used. Moreover, as an ultraviolet curable resin, an epoxy type, a polyimide type, and acrylic type ultraviolet curable resin are used preferably, for example. The refractive index of the cured product of the core-forming curable resin needs to be larger than that of the film substrate serving as the cladding.

  As the curable resin for cladding, for example, an ultraviolet curable resin or a thermosetting resin is preferably used, and an ultraviolet curable or thermosetting monomer, an oligomer, or a mixture of a monomer and an oligomer is used. In addition, it is preferable from the viewpoint of light confinement that the refractive index of the clad be the same as that of the film substrate.

  According to the method for producing the polymer optical waveguide film 3 described above, the production process is greatly simplified, and the polymer optical waveguide film can be easily produced. Accordingly, it is possible to produce the polymer optical waveguide film 3 at an extremely low cost as compared with the conventional method for producing the polymer optical waveguide film 3. Furthermore, although it is a simple method, optical loss of the obtained polymer optical waveguide film 3 is reduced, it is highly accurate, and can be freely loaded into various devices.

(Formation of curved part)
4A and 4B are schematic diagrams relating to the formation of the bending portion according to the first embodiment of the present invention. FIGS. 4A and 4B are side views and FIG. 4C is a perspective view. .

  As shown in FIG. 4A, the polymer optical waveguide film 3 has an end portion between a heating member 7 and a support member 8 provided on the work table 9 corresponding to the thickness of the polymer optical waveguide film 3. Is inserted.

  The heat generating member 7 has a cylindrical shape with a radius of curvature of 0.5 to 5 mm, has a member that generates heat when energized with a nichrome wire or the like, or a member that generates heat, and the target polymer optical waveguide film 3 has. It generates heat in the glass transition temperature range of 100-200 ° C. In addition, although the heat generating member 7 and the supporting member 8 have a cylindrical shape in FIG. 4C, the heat generating member 7 is not limited to this, and the heat generating member 7 transfers heat to the curved portion 32 </ b> A of the polymer optical waveguide film 3. As long as the heat generating member 7 and the supporting member 8 are grooved, the shapes thereof are not limited.

  The polymer optical waveguide film 3 is deformed by being bent in the direction of A in FIG. 4A while being heated by the heat generating member 7, and the polymer optical waveguide film 3 is returned to room temperature to be bent. Holds the shape of 32A.

  The entire polymer optical waveguide film 3 does not need to be made of a thermoplastic resin, and a portion between 10 mm from the end of the polymer optical waveguide film 3 may be made of a thermoplastic resin. As a result, the mounting height when the light emitting element 4A and the light receiving element 5A and the polymer optical waveguide film 3 are connected and used can be reduced. As the thermoplastic resin, an acrylic resin, an epoxy resin, and a polyolefin resin are used. Moreover, the polymer optical waveguide film 3 may be made of a polyimide-based resin, and may be made up to 10 mm from the end portion using the thermoplastic resin.

(Light emitting element)
As the light emitting element 4A, for example, a plurality of light emitting elements (surface optical elements) such as a surface light emitting diode and a surface laser can be used. In the present embodiment, a VCSEL (surface emitting laser) is used as the light emitting element 4A.

  In this surface emitting laser, for example, an n-type upper reflective layer, an active layer, a current confinement layer, a p-type lower reflecting mirror layer, a p-type contact layer, and a p-type electrode are formed on an n-type GaAs substrate. An n-type electrode is formed on the front side.

  In the light emitting element 4A, the pad 41 and the pad 22a are electrically connected via the wire 23a, and the pad 22a is, for example, a groove so as to be electrically connected to the circuit pattern of the electronic circuit board on which the submount 2A is mounted. It is made.

(Light receiving element)
As the light receiving element 5A, for example, a planar optical element such as a planar photodiode can be used. In the present embodiment, a GaAs PIN photodiode excellent in high-speed response is used as the light receiving element 5A.

  The light receiving element 5A includes, for example, a P-layer, an I-layer, and an N-layer that are PIN-bonded on a GaAs substrate, a p-type electrode connected to the P-layer, and an n-type electrode formed on the N-layer. ing.

  In the light receiving element 5A, the pad 51 and the pad 22b are electrically connected via the wire 23b, and the pad 22b is, for example, a groove so as to be electrically connected to the circuit pattern of the electronic circuit board on which the submount 2A is mounted. It is made.

  As shown in FIG. 1B, the light receiving portion 50 of the light receiving element 5A is grooved so as to be optically coupled to the first core 31a of the polymer optical waveguide film 3 via the transparent adhesive 6A. The light emitting portion 40 of the light emitting element 4A is grooved so as to be optically coupled to the second core 31b of the polymer optical waveguide film 3 via the transparent adhesive 6A.

(Mounting polymer optical waveguide film)
In the polymer optical waveguide film 3 in which the curved portion 12A is formed as described above, the adhesive 6A is applied to the light input / output end on the side where the curved portion 12A is formed. Subsequently, the adhesive 6 </ b> B is applied to the fixing members 20 c and 20 d and the height adjusting member 200. The light input / output end to which the adhesive 6A is applied is inserted between the fixing members 20a and 20d and 20b and 20c, and is fixed to the submount 2A by the fixing members 20a to 20d and the height adjusting member 200. After the polymer optical waveguide film 3 is fixed, each optical element and each fixing member are sealed with a sealant.

(Operation of the first embodiment)
Hereinafter, the operation of the optical substrate according to the first embodiment of the present invention will be described with reference to FIGS.

(Transmission and reception of optical signals)
In the light emitting element 4A of the submount 2A, for example, a drive signal for driving the light emitting element 4A transmitted from the electronic circuit board on which the submount 2A is mounted is input via the pad 22a, the wire 23a, and the pad 31. The light emitting element 4A outputs an optical signal based on the input drive signal and propagates it to the polymer optical waveguide film 3.

  The optical path of the optical signal propagated to the polymer optical waveguide film 3 is converted by the core of the curved portion 32A from the direction perpendicular to the surface of the submount 2A to the direction parallel to the surface of the submount 2A. The optical signal is received by a light receiving element (not shown) via an optical connector (not shown) provided at the other end of the polymer optical waveguide film 3 and converted into an electrical signal, for example. Are transmitted to a predetermined electronic circuit.

[Second Embodiment]
FIG. 5 is a perspective view of an optical substrate according to the second embodiment of the present invention. In the following description, portions having the same groove and function as those in the first embodiment are denoted by common reference numerals.

  Compared to the first embodiment, the polymer optical waveguide film 3 newly has a curved portion 12B, and the curved portion 12B is formed by the same process as the curved portion 12A in the first embodiment.

  The submount 2B newly has U grooves 21e and 21f as compared with the first embodiment. In the present embodiment, the light-emitting element 4A and the light-receiving element 5B arranged so that the light-emitting element 4A and the light-receiving element 5A of the first embodiment are point-symmetric are added, and the height adjusting member 200 is The polymer optical waveguide film 3 is supported at the center.

(Mounting polymer optical waveguide film)
In the polymer optical waveguide film 3 in which the curved portions 12A and 12B are formed as described above, the adhesive 6A is applied to both ends. Subsequently, the adhesive 6B is applied to the fixing members 20c and 20d and the height adjusting member 200 on both sides. Both ends of the polymer optical waveguide film 3 to which the adhesive 6A is applied are respectively inserted between fixing members 20a and 20d and 20b and 20c provided on both sides of the submount 2A, and fixed on both sides of the submount 2A. The member 20a to 20d and the height adjusting member 200 are fixed to the submount 2A. After the polymer optical waveguide film 3 is fixed, each optical element and each fixing member are sealed with a sealant.

(Transmission and reception of optical signals)
In the light emitting element 4A, for example, a drive signal transmitted from the electronic circuit board on which the submount 2B is mounted is input via the pad 22a, the wire 23a, and the pad 41, and the light emitting element 4A is based on the input drive signal. The optical signal propagates through the polymer optical waveguide film 3.

  The optical signal propagated to the polymer optical waveguide film 3 is converted in its optical path from the direction perpendicular to the surface of the submount 2B to the direction parallel to the surface of the submount 2B by the bending portion 32A. The optical signal propagates through the polymer optical waveguide film 3, and the optical path is changed from the direction parallel to the surface of the submount 2B to the direction perpendicular to the surface of the submount 2B by the curved portion 32B.

  The optical signal whose optical path has been converted is received by a light receiving unit (not shown) of the light receiving element 5B and converted into an electrical signal, and then the converted electrical signal is transmitted via the pad 51, the wire 23, and the pad 22b. Are transmitted to a predetermined electronic circuit.

[Third embodiment]
6A and 6B are schematic views of an optical substrate according to the third embodiment of the present invention. FIG. 6A is a plan view, and FIG. 6B is a DD line in FIG. It is sectional drawing.

  The optical substrate 1 has a submount 2C installed on an electronic circuit board (not shown) including various electronic components, power supply circuit components, etc., and the electronic components on the electronic circuit board are placed on the submount 2C. The light emitting element 4A that converts the drive signal transmitted from the light source and outputs an optical signal, for example, fixing members 20A and 20B having a cylindrical shape, and the optical fiber 300 are disposed.

(Submount)
The submount 2C has a rectangular shape and has U grooves 21A and 21B formed in a U shape on the upper surface.

  The optical fiber 300 is made of, for example, the same material as the polymer optical waveguide film 3 in the first embodiment, and includes a core 301 having a circular cross section and a clad 302 formed around the core 301. Has been.

  The curved portion 12C of the optical fiber 300 is produced in the same process as the curved portion 12C of the polymer optical waveguide film 3 in the first embodiment.

(Optical fiber mounting)
In the optical fiber 300, the adhesive 6A is applied to the light input / output end on the curved portion 12C side, and the adhesive 6B is applied to the fixing member 20B. The light input / output end of the optical fiber 300 coated with the adhesive 6A is inserted between the fixing members 20A and 20B and fixed to the submount 2C by the fixing members 20A and 20B. After the optical fiber 300 is fixed, the light emitting element 4A and each fixing member are sealed with a sealant.

(Transmission and reception of optical signals)
The light emitting element 4A provided in the submount 2C inputs, for example, a drive signal transmitted from the electronic circuit board on which the submount 2C is mounted via the pad 22a, the wire 23a, and the pad 41. An optical signal based on the input drive signal is output to propagate the optical signal to the optical fiber 300.

  The optical path of the optical signal propagated to the optical fiber 300 is converted by the bending portion 12C from a direction perpendicular to the surface of the submount 2C to a direction parallel to the surface of the submount 2C. The optical signal is received by a light receiving element (not shown) via an optical connector (not shown) provided at the other end of the optical fiber 300, converted into an electric signal, and then transmitted to a predetermined electronic circuit.

  Example 1 corresponding to the first exemplary embodiment of the present invention will be described.

(Production of polymer optical waveguide film)
The core of the polymer optical waveguide film 3 was prepared using an epoxy film (thickness 50 μm, refractive index 1.57, glass transition temperature 120 ° C.) having a high refractive index.

  Subsequently, an acrylic ultraviolet curable resin (glass transition temperature 120 ° C.) having a refractive index of 1.51 is applied on both sides (thickness 20 μm), the acrylic ultraviolet curable resin is cured by irradiating with ultraviolet rays, and a three-layer film is formed. Produced.

  The produced three-layer film was cut from the side surface with an accuracy of 75 μm ± 5 μm from the upper surface by a dicing saw, and then the dicing saw was moved by 50 μm in a direction perpendicular to the optical axis, and moved and moved by 450 μm from the moved position.

  Subsequently, when the dicing saw is moved by 50 μm in the direction perpendicular to the optical axis and cut from the moved position, a two-core optical waveguide core having a core diameter of 50 μm and a width of 500 μm is formed so as to fill the cut recess. An acrylic ultraviolet curable resin having a refractive index of 1.51 was applied, and the acrylic ultraviolet curable resin was cured by being irradiated with ultraviolet rays. The cured two-core optical waveguide core was cut with a dicing saw to obtain a predetermined polymer optical waveguide film 3.

(Submount)
Using a dicing saw using a 300 μm thick blade from a 500 μm thick Si wafer, 300 μm deep U grooves 21 a to 21 d are produced, and subsequently, a glass having a diameter of 350 μm is formed at a position where the U grooves 21 a to 21 d intersect. Embedded beads.

(Light emitting element and light receiving element)
A VCSEL element is used as the light emitting element 4A, and a photodiode element is used as the light receiving element 5A. Each optical element was mounted at a predetermined position of the submount 2A using a flip chip bonder.

(Mounting polymer optical waveguide film)
The polymer optical waveguide film 3 is coated with an ultraviolet curable resin, which is the same material as the first and second cores 31a and 31b, at the light input / output end on the curved portion 12A side in order to suppress optical loss loss. As shown in FIG. 1, one end is inserted between the fixing members 20a, 20b and 20c20d, and the light emitting part 40 of the light emitting element 4A and the light receiving part 50 of the light receiving element 5A are connected to the first and second cores 31a, 31b. Positioning was performed by passive alignment so that the end faces coincided. As the fixing members 20a to 20d, glass beads having a diameter of 350 μm were used. Subsequently, each optical element and each fixing member were sealed with a sealant and fixed.

  As a result, the core is an epoxy film (thickness 50 μm, refractive index 1.57, glass transition temperature 120 ° C.), and the clad is an acrylic ultraviolet curable resin (thickness 20 μm, refractive index 1.51, glass transition temperature 120). C.) was obtained.

  Example 2 corresponding to the first embodiment of the present invention will be described.

(Production of polymer optical waveguide film)
A thick film resist (SU-8, manufactured by Micro Chemical Co., Ltd.) is applied to a Si substrate by spin coating, then pre-baked at 80 ° C., exposed through a photomask, developed, and formed into a square cross section. Convex portions (width: 50 μm, height: 50 μm, length: 80 mm) were formed. The interval between the protrusions was 250 μm. Next, this was post-baked at 120 ° C. to prepare a master for preparing a polymer optical waveguide.

  Next, after applying a mold release agent to this master, a thermosetting liquid dimethylsiloxane rubber (manufactured by Dow Corning Asia Co., Ltd .: SYLGARD 184, viscosity of 5000 mPa.s) and a mixture of the curing agent are poured, and 120 ° C. After being cured by heating for 30 minutes, it was peeled off to produce a mold having a concave portion corresponding to a convex portion having a rectangular cross section (mold thickness: 5 mm).

  Further, a mold was produced by punching through-holes having a tapered cross-sectional shape in the thickness direction in a mold having a circular planar shape so as to communicate with the recess at one end and the other end of the recess.

This mold and a clad film substrate (Arton film, manufactured by JSR Corporation, refractive index 1.510) having a film thickness of 20 μm, which is slightly larger than the mold, were brought into close contact with each other. Next, the viscosity is 500 mPa.s in the entrance side through hole of the mold. When a few drops of the ultraviolet curable resin of s were dropped and sucked under reduced pressure from the discharge side (vacuum suction side) through-hole, the ultraviolet curable resin was filled in the recess in 10 minutes. Next, 50 mW / cm ² of UV light was irradiated from the upper part of the mold for 5 minutes to be cured by ultraviolet rays. When the mold was peeled off from the Arton film, a core having the same shape as the master disc protrusion was formed on the Arton film.

Next, an ultraviolet curable resin having a refractive index after curing of 1.510, which is the same as that of the ARTON film, is applied to the core forming surface of the ARTON film, and then a 20 μm clad film base material is laminated, and 50 mW / cm ² By irradiating with UV light for 5 minutes and curing with ultraviolet rays, the two films were bonded to form a polymer optical waveguide film 3 having a width of 1.5 mm and a film thickness of 90 μm.

  Next, using a dicing saw, both ends of the polymer waveguide film were cut at an angle of 90 degrees with respect to the optical axis to obtain a polymer optical waveguide film 3.

  As a result, a polymer optical waveguide film 3 having a core of 50 μm (refractive index: 1.560, glass transition temperature 130) and a clad of 20 μm (refractive index: 1.510 glass transition temperature 171) was obtained.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from or changing the technical idea of the present invention.

(A) is a top view of the optical substrate which concerns on the 1st Embodiment of this invention, (b) is AA sectional view taken on the line of the optical substrate which concerns on the 1st Embodiment of this invention. (C) is an example of a cross-sectional view along the line BB according to the first embodiment of the present invention. (A) is a perspective view of a polymeric optical waveguide film, (b) is CC sectional view taken on the line of Fig.2 (a). (A) is a top view of the intersection of the U groove which concerns on the 1st Embodiment of this invention, (b) is sectional drawing of the U groove which concerns on the 1st Embodiment of this invention, (C) is sectional drawing of the V-groove which concerns on the 1st Embodiment of this invention. (A), (b) and (c) is the schematic regarding formation of the curved part which concerns on the 1st Embodiment of this invention. It is a perspective view of the optical board | substrate which concerns on the 2nd Embodiment of this invention. (A) is a top view of the optical board | substrate which concerns on the 3rd Embodiment of this invention, (b) is the DD sectional view taken on the line of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical substrate, 2A, 2B, 2C ... Submount, 3 ... Polymer optical waveguide film, 4A, 4B ... Light emitting element, 5A, 5B ... Light receiving element, 6A, 6B ..Adhesive, 7 ... heat generating member, 8 ... support member, 9 ... workbench, 12A, 12B, 12C ... curved portion, 20A, 20B, 20a-20d ... fixing member, 21A ... V-groove, 21a-21f ... U-groove, 22a, 22b ... pad, 23a, 23b ... wire, 30 ... cladding, 31a ... first core, 31b ... Second core, 32A, 32B ... curved portion, 33 ... radius of curvature, 40 ... light emitting portion, 41 ... pad, 50 ... light receiving portion, 51 ... pad, 200 ..Adjusting member, 300 ... optical fiber

Claims (10)

A core and a cladding provided around the core, the NA being 0.25 to 0.45;
An optical waveguide having a curved portion that maintains a predetermined radius of curvature in the absence of external force.   The optical waveguide according to claim 1, wherein a difference in refractive index between the core and the clad is 1 to 5%.   The optical waveguide according to claim 2, wherein the core and the clad are formed of a thermoplastic resin.   The optical waveguide according to claim 1, wherein the curved portion is curved at 90 degrees.   The optical waveguide according to claim 1, wherein the curvature radius of the curved portion is 1 to 1.5 mm.   The optical waveguide according to claim 1, wherein the curved portion is provided between 10 mm from an optical input / output end.   The optical waveguide according to claim 1, wherein at least the glass transition temperature of the curved portion is 100 to 200 ° C.   The optical waveguide according to claim 1, wherein the core has a rectangular cross section.   The optical waveguide according to claim 1, wherein the core has a circular cross section. A substrate having a pair of positioning grooves;
A pair of spherical or cylindrical fixing members positioned by the pair of positioning grooves;
An optical waveguide substrate comprising: the optical waveguide according to claim 1, wherein an optical input / output end side is inserted and fixed between the pair of fixing members.

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