JP2007334236A - Optical waveguide and manufacturing method therefor, and optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide that makes improvement in flexibility and light weight possible, without accompanying of change in materials, that can be mounted with high accuracy, and that makes low cost and simple manufacturing possible, and to provide its manufacturing method and an optical communication module. <P>SOLUTION: In the optical waveguide 10, inside a space formed between waveguide cores 12 and between a lower substrate 11 and an upper substrate 13, there are formed cavities 15 that extend along the waveguide cores 12, in a state with a clad 14 not being filled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical waveguide and a method for manufacturing the same, and an optical communication module, and in particular, an optical waveguide that can ensure flexibility without changing materials and can be reduced in weight, and a method for manufacturing the same. And an optical communication module.

As an example of a conventional method for producing a polymer optical waveguide, for example, (1) a method in which a film is impregnated with a monomer, a core portion is selectively exposed, and a film is laminated by changing a refractive index (selective polymerization method) ,
(2) A method of forming a clad portion using reactive ion etching after applying a core layer and a clad layer (RIE method),
(3) A method of exposing and developing an ultraviolet curable resin obtained by adding a photosensitive material in a polymer material by photolithography (direct exposure method),
(4) Method using injection molding,
(5) Various methods such as a method of changing the refractive index of the core part by exposing the core part after applying the core layer and the clad layer (photo bleaching method) have been proposed.

  However, the selective polymerization method (1) has a problem in film lamination. The RIE method (2) and the direct exposure method (3) are expensive because they use a photolithography method. The injection molding method (4) has a problem in the accuracy of the obtained core diameter. The photo bleaching method (5) has a problem that the difference in refractive index between the core layer and the clad layer cannot be sufficiently obtained. Practical production methods include the RIE method (2) and the direct exposure method (3), but there is a problem in production cost as described above. In any of the production methods (1) to (5), it is practically unsuitable for forming a polymer optical waveguide on a flexible plastic substrate having a large area.

On the other hand, as an example of a method for producing a polymer optical waveguide that is completely different from the conventional production method, there is a method for producing a polymer optical waveguide using a mold called, for example, a micromold method (for example, Patent Documents 1 to 3). reference.). According to the polymer optical waveguide manufacturing methods described in these Patent Documents 1 to 3, the mold having the core-forming recess and the film base for cladding are in close contact with each other so as to be peeled off, and the capillary phenomenon is utilized. The waveguide core is formed on the film substrate by filling and curing the core-forming curable resin in the concave portion of the mold. And after peeling a casting_mold | template, a clad layer is formed in the whole surface of the core formation surface of a film base material. As a result, it is possible to mass-produce optical waveguides at a low cost and extremely easily, and it is possible to stably produce an optical waveguide with a small optical waveguide loss despite the simple manufacturing method. . Furthermore, it becomes possible to produce an optical waveguide on a flexible plastic substrate that has been difficult to produce. In addition, the manufacturing method of the polymer optical waveguide described in the said patent documents 1-3 is what the present applicant etc. proposed previously.
JP 2004-29507 A JP 2004-86144 A JP 2004-109927 A

  By the way, for example, in an optical waveguide disposed across a rotation axis of a hinge inside a portable device or an information device that can be opened and closed by a hinge, it is necessary to use a flexible optical waveguide rich in flexibility. In the optical waveguide manufactured by the above-described conventional optical waveguide manufacturing technology, sufficient flexibility cannot be obtained with a material having poor flexibility. Therefore, when it is necessary to give the optical waveguide further flexibility, it has been frequently performed to manufacture the optical waveguide using a material having high flexibility.

  However, when making flexible optical waveguides by changing the material, the bending performance of the optical waveguide is more important than the thermal characteristics and optical transmission characteristics of the optical waveguide. In the process of producing a 45 ° micromirror surface with a dicing saw, it is difficult to process the micromirror surface to a flat surface with high accuracy. There were various problems that became difficult. For this reason, the manufacturing method of the optical waveguide which is cheap and can provide flexibility easily without changing the material of an optical waveguide was calculated | required.

  On the other hand, when the entire optical waveguide is made highly flexible by changing the material, if an external force is applied to the optical waveguide by pick-up or bonding during the mounting process, the optical waveguide itself is easily deformed. Therefore, when the optical waveguide is optically coupled to the light emitting element and the light receiving element, the distance between these elements and the optical waveguide core cannot be stably maintained, and the optical waveguide is mounted with the required accuracy. There was a problem that it became difficult. Further, since the clad material is densely filled between the waveguide cores and around the waveguide core, there is a problem that the weight of the optical waveguide increases. There has been a demand for reducing the weight of all components mounted on mobile devices and the like, and it is also desired to reduce the weight of the optical waveguide that is the component.

  In the polymer optical waveguide manufacturing methods described in Patent Documents 1 to 3, the flexibility of the polymer optical waveguide is improved and the polymer optical waveguide is reduced in weight without changing the material of the optical waveguide. Is not mentioned.

  The present invention has been made in order to solve the above-described conventional problems, and can improve the flexibility and reduce the weight without changing the material, and can be mounted with high accuracy. At the same time, it is an object to provide an optical waveguide, a manufacturing method thereof, and an optical communication module which are inexpensive and can be easily manufactured.

[1] The present invention includes a lower substrate, a waveguide core formed on the lower substrate, a clad formed so as to surround the waveguide core, and an upper substrate for the lower substrate. A cavity extending along the waveguide core without filling the cladding in a space formed between the waveguide cores and between the lower base material and the upper base material. The optical waveguide is characterized by being formed.

  According to the above configuration, when the optical waveguide is bent, it is possible to absorb and mitigate deformation due to distortion or bending in the cavity, and the flexibility of the optical waveguide can be increased regardless of the material of the optical waveguide. The use efficiency of the material can be drastically increased, and the weight reduction of the optical waveguide can be achieved.

[2] In the invention described in [1], the waveguide core and the cavity are formed in an array structure extending to each other. In addition to the effect [1], high-density mounting of optical circuits can be achieved.

[3] In the invention described in [2] above, the widths of the cross sections in the light traveling direction in the plurality of cavities arranged in an array are set to different width dimensions. In addition to the effect [2], it is possible to obtain a shape capable of efficiently and reliably capturing an optical signal without reducing the mounting density of the optical waveguide array.

[4] In the invention according to any one of [1] to [3], the cavity penetrates from one end face to the other end face in the light traveling direction along the waveguide core. It is characterized by being formed. In addition to the effects [1] to [3] above, it is possible to rationally absorb and relax excessive external force due to bending or twisting.

[5] In the invention described in [4] above, a curable resin is filled and cured in at least one open end of the cavity. In addition to the function and effect of [4] above, it is possible to impart flexibility to only the necessary part of the optical waveguide. The rigidity of the end portion of the optical waveguide can be increased, and the light emitting portion for making the light incident on the waveguide core and the light receiving portion for receiving the light emitted from the waveguide core can be easily attached.

[6] In the invention described in [4] above, the curable resin is filled and cured at a predetermined position in both side opening ends of the cavity, and between the filling start position and the filling end position of the curable resin. The distance is set to a different dimension. In addition to the effect [4], since the cavity can be blocked from the outside air, it is possible to prevent the optical transmission characteristics from being hindered even under high temperature and high humidity environmental conditions. In addition, since the distance between the filling start position and the filling end position of the curable resin filled in the cavity can be set to different dimensions, the flexibility of the optical waveguide can be adjusted.

[7] In the invention described in [5] or [6] above, the curable resin is made of a material different from that of the clad. In addition to the effects [5] and [6] described above, a flexible optical waveguide excellent in mechanical characteristics and optical transmission characteristics can be obtained.

[8] In the invention according to any one of [5] to [7], the curable resin is made of a polymer material. In addition to the effects [5] to [7] described above, the flexibility of the optical waveguide and the adhesion to the cladding can be further enhanced.

[9] In the invention described in [1] above, the lower base material and the upper base material have the same refractive index as that of the cladding, or a refractive index difference within 0.02, and are flexible. It is characterized by being comprised by the film material which has property. In addition to the effect [1], a highly reliable flexible optical waveguide excellent in optical transmission characteristics can be obtained.

[10] In the invention described in [1] or [9] above, the lower base material and the upper base material are made of a polymer film material. In addition to the effects [1] and [9], thermal characteristics, optical transmission characteristics, flexibility, and the like can be further enhanced.

[11] In the invention described in [1] or [9] above, the clad is made of a curable polymer material. In addition to the effects [1] and [9] above, the uncured thin film cladding can be adhered to the side surface of the waveguide core by utilizing resin migration. A cavity extending along the waveguide core can be produced by a simple process.

[12] In the invention described in [1] above, a clad layer is formed on at least one of the opposing inner wall surfaces between the lower base material and the upper base material. As the upper substrate and the lower substrate, for example, a clad film substrate or a clad substrate coated with a clad layer can be used. In addition to the effect [1], the degree of freedom in selecting the material for the lower substrate and the upper substrate is increased.

[13] The present invention further includes a step of forming a waveguide core on the lower cladding film, a step of forming an uncured thin film cladding on the upper cladding film, and a thin film cladding on the upper cladding film on the waveguide core. A step of covering the formation surface, the thin film clad flows to cover the side surface of the waveguide core, and a cavity penetrating along the waveguide core is formed between the lower clad film, the upper clad film and the thin film clad And a method of manufacturing the optical waveguide, comprising: a step of curing the thin film clad.

  According to the above configuration, complicated processes such as patterning, exposure / development, and etching can be eliminated, and a waveguide core and a cavity penetrating along the waveguide core can be stably mass-produced by a simple process. . Simplification of the process can be achieved, and cost reduction can be easily and reliably achieved by improving productivity.

[14] The present invention further includes a step of forming a waveguide core on the lower cladding film, a step of forming an uncured thin film cladding on the upper cladding film, and a thin film cladding on the upper cladding film on the waveguide core. A step of covering the surface side, the thin film clad flows to cover the side surface of the waveguide core, and a cavity penetrating along the waveguide core is formed between the lower clad film, the upper clad film and the thin film clad And a step of curing the thin film cladding, and a step of filling and curing the curable resin in the cavity.

  According to the said structure, in addition to the effect of said [13], the flexible optical waveguide which can provide the flexibility etc. of an optical waveguide to a required site | part can be manufactured easily.

[15] In the invention described in [14] above, in the step of filling and curing the curable resin in the cavity, the curable resin is brought into a predetermined position in the cavity by capillary action and / or vacuum suction. It is characterized by comprising the process of filling. In addition to the above effect [14], the curable resin can easily enter the cavity.

[16] In the invention described in [14] above, a step of forming a through hole for capillary action and / or vacuum suction in a portion of the lower clad film or the upper clad film corresponding to the cavity And the step of filling and curing the curable resin in the cavity includes the step of curing with heat or light after filling the curable resin to a predetermined position in one open end of the cavity, and the curing And a step of curing by heat or light after filling the resin with a predetermined position in the other open end of the cavity. In addition to the above effect [14], the curable resin can be surely entered into the cavity without generating voids or mixing bubbles.

[17] Furthermore, the present invention provides a light emitting unit that makes light incident on the waveguide core of the optical waveguide according to any one of claims 1 to 12, and a light receiving unit that receives light emitted from the waveguide core. It is in the optical communication module characterized by having.

  According to the above configuration, since the flexibility of the hollow portion can be increased, for example, optical coupling can be easily and accurately performed without being restricted by assembly between electrical modules in electrical equipment or between electrical equipment. .

  By adopting an optical waveguide having a cavity along the waveguide core, the present invention makes it possible to improve flexibility without changing the material and achieve weight reduction. It can be mounted with high accuracy, and at the same time, the cost is low, the manufacturing process can be simplified, and stable mass production is possible.

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

[First Embodiment]
(Configuration of optical waveguide)
FIG. 1 is a cross-sectional view schematically showing a configuration example of an optical waveguide according to the first embodiment of the present invention.

  In FIG. 1, the code | symbol 10 has shown the structural example of the optical waveguide. As shown in FIG. 1, the basic configuration of the optical waveguide 10 includes a lower base material 11 serving as a cladding layer, a waveguide core 12 formed on the lower base material 11, and the waveguide core 12 interposed therebetween. The upper substrate 13 is a clad layer facing the lower substrate 11, a thin film clad 14 formed on the side surface of the waveguide core 12, and a cavity 15 formed between the opposed clads 14. The lower base material 11 and the upper base material 13 are formed of, for example, a film material or a sheet material in a rectangular shape. The waveguide core 12 and the cavity 15 have an array structure extending mutually with a predetermined array interval. The waveguide cores 12 having this array configuration extend in the light traveling direction with different array intervals. On the other hand, the cavity 15, which is a characteristic configuration of the first embodiment, is formed so as to penetrate along the waveguide core 12 from one end face to the other end face in the light traveling direction. The section of the cavities 15 of the array configuration in the light traveling direction has a substantially rectangular shape, and the widths of the sections are different from each other. The height of the cavity 15 is substantially equal to the height of the waveguide core 12.

  The waveguide core 12 is made of a material having a high refractive index, and the lower base material 11 and the upper base material 13 are made of a material having a lower refractive index than the waveguide core 12. As the lower base material 11 and the upper base material 13, for example, a polymer film base material excellent in optical characteristics such as refractive index and light transmittance, mechanical strength, heat resistance and flexibility, or a clad layer is coated. The base material etc. which were made can be used. As the substrate, various materials such as silicone, glass, ceramic, or plastic can be used. In the case of a substrate having an appropriate refractive index, it can be used as it is as a clad substrate. For those requiring control of the refractive index, a resin coat or an inorganic material is deposited on the entire surface of the clad substrate by the PVD method, or a resin coat or an inorganic material is partially deposited on the clad substrate by the PVD method The above can be used as a cladding layer.

  In the optical waveguide 10, a structure in which a closing member (reference numeral 16 in FIG. 3) made of a curable resin is embedded in at least one open end of the cavity 15 can be formed. The refractive index of the curable resin is not limited. Thereby, the opening end of the cavity 15 is closed by the curable resin filled and cured in the opening end portion of the cavity 15, and the inside of the cavity 15 can be blocked from the outside air. A highly reliable flexible optical waveguide 10 having excellent mechanical characteristics and light transmission characteristics can be obtained even under high temperature and high humidity environmental conditions. Further, the distance between the filling start position and the filling end position of the curable resin filled in the cavity 15 can be set to different dimensions. Thereby, the position of the bent part of the optical waveguide 10 can be adjusted.

  Of course, the structure, shape, and constituent members of the optical waveguide 10 configured as described above are not limited to the illustrated examples. According to the first embodiment, the waveguide cores 12 are formed with different array intervals, and the cross-sectional widths of the cavities 15 are formed with different width dimensions. It is not limited. In the present invention, for example, the waveguide cores 12 with the array configuration can be extended in the light traveling direction with the same array spacing, and the width of the cavity 15 with the array configuration can be configured with the same spacing. . The shape of the waveguide core 12 can be appropriately set depending on the shape of the optical element to be optically coupled.

  In the optical waveguide 10 according to the first embodiment, the peripheral surface of the cavity 15 formed therein is not configured as the side surface of the waveguide core 12. The cavity 15 does not have a function as a clad having a refractive index of 1.0. The cavity 15 of the optical waveguide 10 according to the first embodiment has a main feature in that it has a function of absorbing and mitigating excessive deformation caused by bending or twisting in the optical waveguide 10, The width of the cavity 15 can be freely set according to the demand for flexibility of the optical waveguide 10.

(Optical waveguide manufacturing method)
The optical waveguide 10 according to the first embodiment having the above configuration is efficiently manufactured as follows by the manufacturing method of the present invention shown in FIG. In the following production example, the optical waveguide 10 using a polymer film material having high flexibility for the lower base material 11 and the upper base material 13 will be described, but the present invention is not limited to the polymer film material. . In this manufacturing example, the case where the waveguide cores 12 having the array configuration are manufactured with the same array interval will be described, but the case where the waveguide cores 12 having the array configuration are manufactured with different array intervals is also included.

  FIG. 2 conceptually shows a manufacturing process of the optical waveguide 10. 2 (a) and 2 (b) are conceptual diagrams showing a process for producing a template 1 for producing a waveguide core, and FIGS. 2 (c) to 2 (f) produce a waveguide core 12. FIG. 2 (g) and FIG. 2 (h) are conceptual diagrams showing a process for producing the thin film cladding 14a, and FIGS. 2 (i) to 2 (k) show the waveguide core 12. FIG. 2 (l) is a conceptual diagram showing a process of filling and curing the curable resin 16 in the cavity 15. FIG. 3 shows a state in which a curable resin is filled and cured in the open end of the cavity 15 of the optical waveguide 10. 3A and 3B are cross-sectional views taken along line III-III in FIG.

(Mold making process)
The mold 21 shown in FIG. 2 (c) has convex portions 20a corresponding to the form of the waveguide core, similar to the mold manufacturing technique described in Patent Documents 1 to 3 previously proposed by the present applicants. It can be manufactured using the formed master 20. Even in the production of the master 20, it can be obtained by substantially the same manufacturing method as that for the master described in Patent Documents 1 to 3.

  As shown in FIGS. 2A and 2B, the mold 21 is first formed on a surface on which a convex portion 20a corresponding to the shape of the waveguide core of the master 20 is formed. Apply or cast. Next, after performing a drying treatment as necessary, the curable resin is cured. Next, by peeling the cured curable resin from the master 20, a mold structure having a concave portion 21a corresponding to the convex shape of the waveguide core can be produced as shown in FIG.

  As the curable resin for forming the mold, for example, liquid silicone rubber that becomes rubber after curing can be used. As the liquid silicone rubber, for example, liquid dimethylsiloxane rubber is particularly preferably used from the viewpoints of adhesion, peelability, dimensional stability, strength, hardness, and the like. In the mold 21 using such a liquid silicone rubber, deformation of the concave structure can be prevented. The waveguide core shape of the master 20 can be stably copied with high accuracy, and the mixing of bubbles can be reduced. Further, even if the cross-sectional area of the concave portion 21a of the mold 21 is extremely small, for example, about 10 × 10 μm, the inside of the concave portion 21a of the mold 21 can be obtained by utilizing the capillary phenomenon of the curable resin for forming the waveguide core. Can be filled immediately.

(Process for producing a waveguide core on the lower clad film substrate)
The process of producing the waveguide core 12 on the lower clad film base material 11 (lower base material 11) made of a polymer film material is as follows. First, as shown in FIGS. The lower clad film base material 11 is brought into close contact with the mold, and a curable resin for forming a waveguide core is filled into the recess 21a of the mold 21 with the lower clad film base material 11 brought into close contact therewith. Next, the filled curable resin for core formation is cured by heat or light. Next, the mold 21 is peeled from the lower clad film substrate 11. In this step, it is preferable to fill the recess 21a of the mold 21 with a curable resin for forming the waveguide core, for example, by capillary action. In order to promote the filling of the curable resin into the recess 21a of the mold 21 by utilizing capillary action, for example, a suction port (not shown) is provided at a predetermined position communicating with the recess 21a of the mold 21. Therefore, it is desirable to reduce the pressure of the entire suction system to about 0.1 to 200 Pa.

  Of course, even in the waveguide core 12 on the lower clad film base material 11, it can be obtained by substantially the same manufacturing method as the manufacturing techniques of the above-mentioned Patent Documents 1 to 3 previously proposed by the present applicants. The present invention is not limited to this, and for example, a method for producing the waveguide core 12 by a direct exposure method, an etching method, or the like can be used. Even in the present invention, manufacturing the waveguide core 12 on the lower clad film substrate 11 using the manufacturing techniques of Patent Documents 1 to 3 described above reduces the manufacturing man-hour and the manufacturing cost. And it is suitable at the point which can form the convex part of the waveguide core 12 directly on a flexible polymer film base material.

  As the curable resin for forming the waveguide core, for example, a resin having radiation curable property, electron beam curable property, thermosetting property or the like is suitable. It is particularly preferable to use an ultraviolet curable resin or a thermosetting resin. As the ultraviolet curable resin or the thermosetting resin, for example, an ultraviolet curable or thermosetting monomer, an oligomer, a mixture of a monomer and an oligomer, or the like can be used. As the ultraviolet curable resin, for example, an epoxy-based, polyimide-based, or acrylic-based ultraviolet curable resin can be preferably used.

(Process for producing an uncured thin film clad on the upper clad film substrate)
The process of producing the uncured clad thin film layer 14a (thin film clad 14a) on the upper clad film base material 13 (upper base material 13) made of a polymer film material is shown in FIGS. 2 (g) and 2 (h). As shown in the drawing, first, an appropriate amount of uncured resin for clad is dropped on the upper clad film substrate 13 to produce an uncured clad thin film layer 14a. The uncured clad thin film layer 14a can be formed by, for example, a spin coating method.

  As the resin for forming the clad, for example, various resin materials such as radiation curable, electron beam curable, and thermosetting can be used. An ultraviolet curable resin or a thermosetting resin is particularly suitable. As the ultraviolet curable resin or the thermosetting resin, for example, an ultraviolet curable or thermosetting monomer, an oligomer, a mixture of a monomer and an oligomer, or the like can be used. As the ultraviolet curable resin, for example, an epoxy-based, polyimide-based, or acrylic-based ultraviolet curable resin is preferably used. In order to cure the ultraviolet curable resin, an ultraviolet lamp, an ultraviolet LED, a UV irradiation device or the like is used. Further, heating in an oven or the like is used to cure the thermosetting resin.

  As the lower clad film base 11 and the upper clad film base 13, it is preferable to use a film material having flexibility. When using an ultraviolet curable resin for the waveguide core forming resin or the thin film clad forming resin, it is important to select a material having high transparency in the ultraviolet region. The difference in refractive index between the clad film bases 11 and 13 and the thin clad 14 is preferably within 0.02. More preferably, it is particularly desirable that they are the same or within 0.005. On the other hand, when using a clad base material with a thin film clad coated on the base material, it is possible to improve the flatness of the base material and use a base material made of a material that is inferior in transparency and not limited by the refractive index. It becomes possible to do.

(Process for producing thin-film cladding and cavity on side surface of waveguide core)
The step of forming the cavity 15 penetrating along the waveguide core 12 between the clad 14 on the side surface of the waveguide core 12 and the lower clad film base material 11, the upper clad film base material 13 and the clad 14 is shown in FIG. As shown in FIG. 2 (k), first, the uncured clad thin film layer 14a of the upper clad film substrate 13 is laminated on the waveguide core 12 on the lower clad film substrate 11. In this state, the uncured clad thin film layer 14a is deposited on the side surface of the waveguide core 12 by leaving it for several minutes and using resin migration. After several minutes, the uncured clad thin film layer 14a is cured by ultraviolet rays or heat, whereby the clad 14 and the cavity 15 can be formed on the side surface of the waveguide core 12.

(Process of filling and curing curable resin in the cavity)
The process of filling and curing the curable resin to be the closing member 16 in the cavity 15 is performed by dropping an uncured curable resin into the cavity 15 and then by capillary action and / or vacuum suction to a desired position in the cavity 15. The curable resin filled in the cavity 15 and filled in the cavity 15 can be cured by heat or light. FIG. 3A shows a state in which the curable resin is filled and cured in one open end of the cavity 15, and FIG. 3B is a diagram in which the curable resin is filled and cured in the open ends on both sides of the cavity 15. Indicates the state. Using the capillary phenomenon, the uncured curable resin can be naturally diffused toward the suction port side. It is also possible to suction under reduced pressure from the suction port side and forcibly diffuse the uncured curable resin toward the suction port side. As the curable resin, a material different from that of the clad 14 can be selected, and in order to reinforce the end, selecting a material having higher rigidity after curing facilitates bonding with other devices. It is preferable because it can be used. Further, the refractive index of the curable resin is not limited.

  When the curable resin is filled and cured in the opening end portions on both sides of the cavity 15, as shown in FIG. 3B, the lower cladding film substrate 11 or the upper cladding film substrate 13 corresponding to the cavity 15 is formed. It is preferable to form the through holes 17 which are air vents / suction ports for capillary action and / or vacuum suction by laser processing or the like. It is preferable to close the through-hole after filling and curing the curable resin in the opening end of the cavity 15. By closing the through-hole 17 after filling and curing with the curable resin, it is possible to prevent the flexibility of the optical waveguide as the initial target from being reduced, and the through-hole 17 is repeatedly formed by repeating the bending operation of the optical waveguide 10. It is possible to prevent the peripheral portion from being damaged or deformed. It is preferable to form the through-hole 17 in a portion separated from a portion where the optical waveguide 10 is easily bent.

(Process of cutting the end of the optical waveguide)
Both ends in the longitudinal direction of the optical waveguide are cut at right angles or obliquely with a dicing saw or the like to form a flexible polymer optical waveguide 10. Needless to say, the method of cutting both end faces of the optical waveguide is not limited to the cutting method using a dicing saw.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(A) Regardless of the material of the optical waveguide 10, the flexibility of the optical waveguide 10 can be increased, and deformation due to distortion or bending can be absorbed and relaxed in the cavity 15.
(B) The material of the optical waveguide 10 can be saved and the weight can be reduced.
(C) A light emitting unit that can provide flexibility only to a necessary portion of the optical waveguide 10 and can increase the rigidity of the end of the optical waveguide 10 so that light is incident on the waveguide core 12. In addition, it is possible to easily attach the light receiving unit that receives the light emitted from the waveguide core 12.
(D) The material usage efficiency can be increased and the material cost can be reduced.
(E) It is possible to obtain a shape capable of efficiently and reliably capturing optical signals without reducing the mounting density of the optical waveguide array.
(F) It is a simple manufacturing method, which can reduce the production process and improve the yield, and can stably mass-produce.
(G) Cost reduction and simplification of the manufacturing process can be achieved easily and reliably.

[Second Embodiment]
(Configuration of optical communication module)
FIG. 4 shows an example of the structure of an optical communication module according to the second embodiment of the present invention. FIG. 4 is a conceptual diagram showing the configuration of the optical communication module. In the figure, members substantially the same 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. 4, the code | symbol 30 has shown the optical communication module provided with the flexible polymer optical waveguide 10 which is the said 1st Embodiment. The optical communication module 30 has an array structure in which the waveguide core 12 and the cavity 15 serving as an optical wiring pattern extend to each other. The curable resin shown in FIG. 3B is filled and cured in the open end of the cavity 15. The optical communication module 30 is provided with a light emitting portion of a single light emitting element 31 (surface emitting laser array 31) on one end side of the polymer optical waveguide 10 and a single light receiving element 32 on the other end side. A light receiving portion of (photodiode 32) is provided. Both end faces of the polymer optical waveguide 10 are inclined mirror surfaces that are alternately inclined with an inclination angle of about 45 degrees with respect to the light traveling direction.

(Operation of optical communication module)
The optical signal emitted from the surface emitting laser array 31 enters the polymer optical waveguide 10 through the lower clad film substrate 11 as shown in FIG. The incident optical signal is reflected by the inclined mirror surface and propagates along the polymer optical waveguide 10. The optical signal is reflected again by the other inclined mirror surface, and enters the photodiode 32 through the lower clad film substrate 11 by changing the propagation direction. The optical signal is converted into an electric signal and then transmitted to the outside through an electric component (not shown). Thus, the surface emitting laser array 31 and the photodiode 32 can be optically coupled.

(Effect of the second embodiment)
According to the second embodiment, the following effects can be obtained in addition to the operational effects of the first embodiment.
(A) Since the cavity 15 can be bent, it is possible to relax assembly restrictions in various devices such as between electronic modules in electronic devices or between electronic devices.
(B) Since the rigidity of the end of the optical waveguide 10 can be increased, the surface emitting laser array 31 and the photodiode 32 can be easily optically coupled with high accuracy.

  Hereinafter, a more specific embodiment of the present invention will be described with reference to FIG.

  A thick film resist (SU-8 manufactured by Micro Chemical Co., Ltd.) was applied to the surface of the silicon substrate by spin coating, and then prebaked at 80 ° C. Next, the thick film resist on the silicon substrate was exposed and developed through a photomask, and a convex portion corresponding to the form of the waveguide core was formed on the silicon substrate. Then, the convex part on the silicon substrate was post-baked at 120 ° C. to produce a master for producing a waveguide core (see FIG. 2A).

  Next, after applying a release agent on the master, a thermosetting dimethylsiloxane resin (SYLGARD 184 manufactured by Dow Corning Asia Co., Ltd.) is poured and left for a certain period of time, followed by vacuum defoaming for about 10 minutes at 120 ° C. It was solidified by heating for 30 minutes (see FIG. 2B). Thereafter, the master was peeled off to produce a mold having a recess (mold thickness 5 mm) corresponding to the form of the waveguide core. Further, a hole having a diameter of 3 mm was drilled at both ends communicating with the concave portion of the mold, and a filling port and a suction port were formed, respectively, to produce a mold (see FIG. 2C). The template is composed of four waveguide cores (concave portions) formed in parallel with each other, the waveguide core has a cross-sectional size of 50 × 50 μm, and the waveguide core spacing is 250 μm. Formed.

Next, the produced mold and a lower film substrate (Arton film manufactured by JSR Co., Ltd., refractive index 1.51) having a film thickness of 100 μm to be the lower clad film were brought into close contact (see FIG. 2D). Next, the filling hole of the mold was sufficiently filled with an ultraviolet curable resin (manufactured by JSR, refractive index 1.56 after curing) and sucked through the suction port of the mold with a suction pump. And filled in the recess of the mold (see FIG. 2 (e)). Next, 50 mW / cm ² of ultraviolet light was irradiated through the mold for 5 minutes to cure the ultraviolet curable resin filled in the concave portions of the mold. Thereafter, the mold was peeled off to produce a waveguide core on the lower film substrate (see FIG. 2 (f)).

Next, an ultraviolet curable resin (manufactured by JSR Corp., refractive index 1 after curing) is formed on an upper film substrate (Arton film manufactured by JSR Corporation, refractive index 1.51) having a film thickness of 100 μm to be an upper clad film. .51) was dropped in an appropriate amount (see FIG. 2 (g)), and an uncured thin film clad layer having a thickness of 40 μm was formed by a spin coating method (see FIG. 2 (h)). Next, the uncured thin film clad layer applied to the upper film base material is bonded to the waveguide core on the lower film base material (see FIG. 2 (i)). It migrated to the side part of the waveguide core on a lower film base material, and was left for several minutes until other parts were maintained as a cavity (refer FIG.2 (j)). Thereafter, 50 mW / cm ² of ultraviolet light was irradiated through the upper film substrate for 15 minutes to be cured (see FIG. 2 (k)). Finally, in order to form the end portion of the waveguide core, it was cut out by a dicing saw, and the waveguide length was set to 60 mm. Through the above steps, a cavity having a height of 50 μm and a width of about 200 μm was formed so as to penetrate between the waveguide cores, and a flexible polymer optical waveguide was obtained.

  The central part of the produced polymer optical waveguide was attached to a cylindrical jig having a radius of 5 mm, bent at 90 degrees with the central part of the polymer optical waveguide as a fulcrum, and loss measurement was performed. As a result, the insertion loss was 1.0 dB, which was confirmed to be a practical level.

  According to the same procedure as in the first embodiment, four waveguide cores having a waveguide core cross-sectional size of 50 × 50 μm and waveguide core intervals of 250 μm, 500 μm, and 750 μm can be manufactured. A mold was made and formed through the cavity along the waveguide core. As a result, a flexible polymer optical waveguide having a cavity with a height of 50 μm and a width of about 200 μm, 450 μm, and 700 μm was obtained.

According to the same procedure as in the first embodiment, the waveguide core has a cross-sectional size of 50 × 50 μm, an interval between the waveguide cores of 250 μm, and a length of 60 mm and three waveguide cores. A flexible polymer optical waveguide having a cavity was fabricated. Then, using capillary action, 10 mm of ultraviolet curable resin was filled from one open end of the cavity, and immediately cured by irradiating with 50 mW / cm ² of ultraviolet light. Next, a through hole having a diameter of 100 μm was formed by laser processing at a portion corresponding to the cavity of the polymer optical waveguide to form a gas hole. Next, using capillary action, 20 mm of ultraviolet curable resin was filled from the other open end of the cavity, and immediately cured by irradiating with 50 mW / cm ² of ultraviolet light. Finally, it was cut out with a dicing saw to form the end of the waveguide core. Through the above steps, a polymer optical waveguide having a cavity along the waveguide core and partially filling the opening ends on both sides of the cavity with curable resins having different lengths and having flexibility was obtained. .

  The optical waveguide, the manufacturing method thereof, and the optical communication module according to the present invention are not limited to the above embodiments and examples, and various design changes can be made without departing from the spirit of the invention. Is possible.

  The present invention can be used for an optical circuit, an optical waveguide and an optical waveguide, an optical switch, and the like when propagating an optical signal, such as an optical fiber connector and a splitter.

It is sectional drawing which shows typically the example of 1 structure of the optical waveguide which is the 1st Embodiment in this invention. (A)-(l) is a process figure which shows notionally the preparation process of the optical waveguide in this invention. (A), (b) is an expanded sectional view which shows the state which filled and hardened the curable resin in the opening edge part of the cavity of the optical waveguide in this invention. It is a conceptual diagram which shows the structure of the optical communication module which is the 2nd Embodiment in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical waveguide 11 Lower base material 12 Waveguide core 13 Upper base material 14 Clad 14a Clad thin film layer 15 Cavity 16 Closing member 17 Through hole 20 Master 20a Protrusion part 21 Mold 21a Concavity 30 Optical communication module 31 Surface emitting laser array 32 Photodiode

Claims (17)

An optical waveguide comprising a lower substrate, a waveguide core formed on the lower substrate, a clad formed so as to surround the waveguide core, and an upper substrate for the lower substrate,
In the space formed between the waveguide cores and between the lower base material and the upper base material, a cavity extending along the waveguide core is formed without filling the cladding. An optical waveguide.   2. The optical waveguide according to claim 1, wherein the waveguide core and the cavity are formed in an array structure extending to each other.   3. The optical waveguide according to claim 2, wherein widths of cross sections in the light traveling direction in the plurality of cavities arranged in an array are set to different width dimensions.   4. The optical device according to claim 1, wherein the cavity is formed so as to penetrate along the waveguide core from one end surface to the other end surface in the light traveling direction. Waveguide.   The optical waveguide according to claim 4, wherein a curable resin is filled and cured in at least one open end of the cavity.   The curable resin is filled and cured at a predetermined position in both side opening ends of the cavity, and the distance between the filling start position and the filling end position of the curable resin is set to different dimensions. The optical waveguide according to claim 4.   The optical waveguide according to claim 5, wherein the curable resin is made of a material different from that of the clad.   The optical waveguide according to claim 5, wherein the curable resin is made of a polymer material.   The lower base material and the upper base material have the same refractive index as that of the clad, or a refractive index difference within 0.02, and are made of a flexible film material. The optical waveguide according to claim 1.   10. The optical waveguide according to claim 1, wherein the lower base material and the upper base material are made of a polymer film material.   10. The optical waveguide according to claim 1, wherein the clad is made of a curable polymer material.   2. The optical waveguide according to claim 1, wherein a clad layer is formed on at least one of the opposed inner wall surfaces between the lower substrate and the upper substrate. Forming a waveguide core on the lower cladding film;
Forming an uncured thin film clad on the upper clad film;
Covering the waveguide core with a thin-film clad forming surface on the upper clad film;
Forming a cavity penetrating along the waveguide core between the lower clad film, the upper clad film and the thin film clad, wherein the thin film clad flows to cover a side surface of the waveguide core; and A method for producing an optical waveguide, comprising a step of curing a clad. Forming a waveguide core on the lower cladding film;
Forming an uncured thin film clad on the upper clad film;
Covering the thin film clad surface side of the upper clad film on the waveguide core;
Forming a cavity penetrating along the waveguide core between the lower clad film, the upper clad film and the thin film clad by flowing the thin film clad to cover a side surface of the waveguide core;
A method of manufacturing an optical waveguide, comprising: a step of curing the thin film clad; and a step of filling and curing a curable resin in the cavity.   The step of filling and curing the curable resin in the cavity includes a step of filling the curable resin into a predetermined position in the cavity by capillary action and / or vacuum suction. 14. A method for producing an optical waveguide according to 14. Further comprising a step of forming a through hole for capillary action and / or vacuum suction at a portion corresponding to the cavity of the lower clad film or the upper clad film,
The step of filling and curing the curable resin in the cavity includes the step of curing by heat or light after filling the curable resin to a predetermined position in one open end of the cavity, and the curable resin. 15. The method of manufacturing an optical waveguide according to claim 14, further comprising a step of curing with heat or light after filling a predetermined position in the other opening end of the cavity.   The light guide according to any one of claims 1 to 12, further comprising: a light emitting portion that makes light incident on the waveguide core; and a light receiving portion that receives light emitted from the waveguide core. Optical communication module.

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