JP2019028115A - Optical waveguide, optical waveguide connected body, and electronic apparatus - Google Patents

Abstract

To provide an optical waveguide having high propagation efficiency, and an optical waveguide connected body and an electronic apparatus including the optical waveguide.SOLUTION: An optical waveguide 1 has: a core part 14 comprising a first compound having a functional group that can be dimerized by irradiation with light; and a side cladding part 15 disposed to be adjacent to a side face of the core part 14 and comprising a second compound formed by dimerizing the first compound via the functional group. It is preferable that the functional group contains an unsaturated bond that induces a [2+2] cyclization reaction, and more preferably, the functional group is a maleimide group. It is preferable that the first compound contains a cyclic olefin structure in the main chain and contains the functional group in a side chain.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical waveguide, an optical waveguide connector, and an electronic device.

A method of manufacturing an optical waveguide from a polymer material using a photocuring method is known.
For example, Patent Document 1 discloses an optical waveguide including a core portion obtained by crosslinking maleimide groups by irradiating light. In this optical waveguide, the core is formed by curing the polymer by utilizing cross-linking by photodimerization reaction of maleimide groups.

  In addition, the region not irradiated with light can be dissolved in a solvent or the like. For this reason, the core part of the target pattern can be efficiently formed by appropriately setting the light irradiation region.

  Furthermore, in the photodimer reaction, curing occurs without including a photoreaction accelerator such as a radical generator, so that a highly transparent core part can be obtained.

JP 2008-233362 A

  However, in the method described in Cited Document 1, after the core portion is formed, the polymer in the unexposed area is removed. Thereafter, a separately prepared polymer for the clad part is supplied so as to cover the core part to form the clad part. For this reason, the manufacturing process becomes complicated, and there is a possibility that foreign matter adheres to the interface between the core part and the clad part, or a gap is formed. When such a state occurs, the light propagation efficiency in the core may be reduced.

  An object of the present invention is to provide an optical waveguide having high propagation efficiency, and an optical waveguide connector and an electronic apparatus including the optical waveguide.

Such an object is achieved by the present inventions (1) to (8) below.
(1) a core portion containing a first compound having a functional group dimerizable by light irradiation;
A side clad part including a second compound that is provided adjacent to a side surface of the core part and is formed by dimerizing the first compound via the functional group;
An optical waveguide comprising:

(2) The optical waveguide according to (1), wherein the functional group includes an unsaturated bond that causes a [2 + 2] cyclization reaction.
(3) The optical waveguide according to (2), wherein the functional group is a maleimide group.

  (4) The optical waveguide according to any one of (1) to (3), wherein the first compound includes a cyclic olefin structure in a main chain and includes the functional group in a side chain.

  (5) The optical waveguide according to any one of (1) to (4), wherein the waveguide mode is a single mode.

  (6) The optical waveguide according to any one of (1) to (5), wherein the content of the polymerization initiator in the side clad portion is 0.01% by mass or less.

(7) The optical waveguide according to any one of (1) to (6) above,
An optical component optically connected to the optical waveguide;
An optical waveguide connector comprising:
(8) An electronic apparatus comprising the optical waveguide connector according to (7).

According to the present invention, an optical waveguide with high propagation efficiency can be obtained.
In addition, according to the present invention, a highly reliable optical waveguide connector and electronic device can be obtained.

It is a perspective view which shows embodiment of the optical waveguide connection body of this invention. It is a perspective view which shows a mode that the optical waveguide connection body shown in FIG. 1 and an optical fiber are connected. It is a longitudinal cross-sectional view of the optical waveguide connector shown in FIG. It is the elements on larger scale of the optical waveguide connector shown in FIG. FIG. 5 is a cross-sectional view of the optical waveguide connector shown in FIG. It is a top view of the upper surface of the optical waveguide contained in the optical waveguide connector shown in FIG. It is sectional drawing which shows the modification of the optical waveguide shown in FIG. It is a permeation | transmission perspective view of the optical waveguide shown in FIG. It is a figure for demonstrating the method to manufacture the optical waveguide shown to FIG. It is a figure for demonstrating the method to manufacture the optical waveguide shown to FIG.

  Hereinafter, the optical waveguide, the optical waveguide connector, and the electronic device of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<Optical waveguide connector>
First, an embodiment of the optical waveguide connector of the present invention will be described.

  FIG. 1 is a perspective view showing an embodiment of the optical waveguide connector of the present invention, FIG. 2 is a perspective view showing a state of connecting the optical waveguide connector shown in FIG. 1 and an optical fiber, and FIG. 1 is a longitudinal sectional view of the optical waveguide connector shown in FIG. 1, and FIG. 4 is a partially enlarged view of the optical waveguide connector shown in FIG. 5 is a cross-sectional view of the optical waveguide connector shown in FIG. 1 and is a partial cross-sectional view of a cross-section different from FIG. In the following description, for convenience of explanation, the upper part of FIGS. 3 and 4 will be described as “upper” and the lower part will be described as “lower”.

  An optical waveguide connector 10 shown in FIG. 1 includes an optical waveguide 1 (an embodiment of the optical waveguide of the present invention), an optical connector 5 provided at an end of the optical waveguide 1, and an optical interposer 2 (optical component). And a mounting substrate 3.

  The optical waveguide 1 shown in FIG. 1 is connected to an optical fiber 9 with an optical connector 91 as shown in FIG. That is, the right end surface 102 of the optical waveguide 1 is a light incident / exit surface for inputting / extracting an optical signal, and the optical connector 5 and the optical connector 91 are fastened to each other, whereby the optical input / output surface of the optical fiber 9 and the optical surface are optically coupled. Combined.

  The optical waveguide 1 shown in FIG. 1 is long and has a sheet shape. In the optical waveguide 1, an optical signal can be transmitted between one end and the other end in the longitudinal direction.

  As shown in FIG. 4, such an optical waveguide 1 includes a laminated body in which a lower clad layer 11, a core layer 13, and an upper clad layer 12 are laminated in this order from below. In the present specification, of the two main surfaces of the core layer 13 in FIG. 4 that are in a front-back relationship, the lower surface is referred to as the “lower surface 103” and the upper surface is also referred to as the “upper surface 104”.

  On the other hand, the optical interposer 2 includes an interposer substrate 21, a light guide portion 22, a conductive portion 23, a bump 24, a semiconductor element 25, and a light emitting / receiving element 26.

  The upper clad layer 12 is not laminated on a portion of the upper surface 104 of the core layer 13 of the optical waveguide 1 in the vicinity of the left end surface 101 (hereinafter, this portion is referred to as a “left upper surface 105”) (FIG. 4). reference). On the left upper surface 105, as shown in FIG. 4, the optical interposer 2 is provided in contact with the adhesive 6 therebetween. As a result, an adiabatic coupling is formed between the core portion 14 and the optical interposer 2 on the left upper surface 105. This adiabatic coupling means that they are optically connected via a leaking light (evanescent light). As a result, optical signals can be transmitted between the optical waveguide 1 and the optical interposer 2.

  Thus, the optical waveguide connector 10 includes the optical waveguide 1 and the optical interposer 2 that is optically connected to the optical waveguide 1.

  In order to manufacture the optical waveguide connector 10, as shown in FIG. 5, the center of the width of the core portion 14 of the optical waveguide 1 and the center of the width of the light guide portion 22 of the optical interposer 2 are matched. Place both. Thereby, optical coupling efficiency can be improved.

FIG. 6 is a plan view of the upper surface of the optical waveguide included in the optical waveguide connector shown in FIG.
As shown in FIG. 6, the core layer 13 includes eight long core portions 14 provided in parallel, and a side cladding portion 15 adjacent to the side surface of each core portion 14. . The core part 14 is surrounded by clad parts (side clad part 15, lower clad layer 11 and upper clad layer 12), and light can be confined and propagated in the core part 14. That is, these core portions 14 function as a transmission path for transmitting an optical signal in the optical waveguide 1. And the right end surface 102 of each core part 14 becomes a light entrance / exit surface for entering and exiting an optical signal at the right end of the optical waveguide 1 when the optical fiber 9 and the like shown in FIG. 2 are connected.

  On the other hand, on the left upper surface 105 of the core layer 13, the core portion 14 and the optical interposer 2 are optically connected. As a result, optical signals can be transmitted between the optical waveguide 1 and the optical interposer 2.

Hereinafter, the optical waveguide connector 10 will be further described in detail.
(Optical waveguide)
As described above, the core part 14 is surrounded by the clad parts (the side clad part 15, the lower clad layer 11, and the upper clad layer 12), and light can be confined and propagated in the core part 14.

  The refractive index distribution in the cross section of the core layer 13 may be any distribution. This refractive index distribution may be a so-called step index (SI) type distribution in which the refractive index changes discontinuously, but at least a so-called graded in which the refractive index in the width direction of the core portion 14 continuously changes. It is preferably an index (GI) type distribution. Thereby, even if there is some manufacturing variation, it becomes difficult to affect the optical coupling loss, so that the optical transmission efficiency of the core portion 14 is improved regardless of the manufacturing conditions, and the optical coupling between the optical waveguide 1 and the optical interposer 2 is improved. Efficiency is improved.

  Further, the optical waveguide 1 and the core portion 14 formed therein may be linear or curved in a plan view. Furthermore, the optical waveguide 1 and the core part 14 formed therein may be branched or intersected in the middle.

  The cross-sectional shape of the core portion 14 is not particularly limited, and may be, for example, a circle such as a perfect circle, an ellipse, or an oval, or a polygon such as a triangle, a rectangle, a pentagon, or a hexagon. By being (rectangular), there is an advantage that the core portion 14 can be easily formed.

  On the other hand, the waveguide mode of the core portion 14 may be multimode, but is preferably single mode. As a result, the adiabatic coupling using evanescent light can be coupled with high efficiency. In addition, the optical waveguide 1 is obtained which can be optically connected with an optical coupling efficiency to an optical component whose waveguide mode is a single mode.

  The width and height of the core portion 14 (thickness of the core layer 13) are not particularly limited, but are preferably about 1 to 15 μm, more preferably about 2 to 12 μm, and about 3 to 10 μm. More preferably. Thereby, a reduction in transmission efficiency can be suppressed. Further, by setting the width and height of the core portion 14 within the above range, the waveguide mode of the core portion 14 can be easily changed to the single mode.

  Moreover, as shown in FIG. 6, when the several core part 14 is located in parallel, although the width | variety of the side clad part 15 located between core parts 14 is not specifically limited, it is about 0.5-500 micrometers. Is more preferable, about 1 to 300 μm is more preferable, and about 2 to 250 μm is further preferable. Thereby, it is possible to reduce the pitch of the core portions 14 while preventing optical signals from being mixed (crosstalk) between the core portions 14.

  Moreover, the number of the core parts 14 formed in the optical waveguide 1 is not particularly limited, but is preferably about 1 to 100. When the number of core portions 14 is large, the optical waveguide 1 may be multilayered as necessary. Specifically, a multilayer can be formed by alternately overlapping a core layer and a clad layer on the upper clad layer 12 shown in FIG.

  As a constituent material (main material) of the core layer 13 as described above, for example, acrylic resin, methacrylic resin, polycarbonate, polystyrene, cyclic ether resin such as epoxy resin or oxetane resin, polyamide, polyimide, Polybenzoxazole, polysilane, polysilazane, silicone resin, fluorine resin, polyurethane, polyolefin resin, polybutadiene, polyisoprene, polychloroprene, polyester such as PET and PBT, polyethylene succinate, polysulfone, polyether, benzocyclobutene In addition to various resin materials based on a component such as a cyclic olefin resin such as a base resin or a norbornene resin, various glass materials such as quartz glass and borosilicate glass may be used. The resin material may be a composite material or a polymer alloy in which different compositions are combined.

  Further, as the constituent material of the lower clad layer 11 and the upper clad layer 12, for example, the same material as the constituent material of the core layer 13 described above can be used, and in particular, (meth) acrylic resin, epoxy resin It is preferably at least one selected from the group consisting of a silicone resin, a polyimide resin, a fluorine resin, and a polyolefin resin.

  The optical waveguide 1 is preferably made of a resin material. As a result, the optical waveguide 1 is inexpensive and rich in flexibility and lightness, and handling and mounting work can be facilitated.

  The optical waveguide 1 shown in FIG. 4 includes a cover layer 17 laminated on the upper surface of the upper cladding layer 12.

  Examples of the constituent material of the cover layer 17 include various resin materials such as polyolefin such as polyethylene terephthalate (PET), polyethylene and polypropylene, polyimide and polyamide, and various glass materials such as quartz glass and borosilicate glass. .

The average thickness of the cover layer 17 is not particularly limited, but is preferably about 5 to 500 μm, and more preferably about 10 to 400 μm. Thereby, since the cover layer 17 has moderate rigidity, the core layer 13 can be reliably supported, and the core layer 13 and the upper cladding layer 12 can be reliably protected from external force and external environment.
In addition, the cover layer 17 should just be provided as needed, and may be abbreviate | omitted.

  On the other hand, the optical waveguide 1 shown in FIG. 4 includes a support layer 16 laminated on the lower surface of the lower clad layer 11 (on the side opposite to the core layer 13). Thereby, since the core layer 13 is reinforced by the support layer 16, the optical waveguide 1 with high reliability is obtained.

  Although it does not specifically limit as a constituent material of the support layer 16, It can select from what was mentioned as a constituent material of the cover layer 17. FIG.

The average thickness of the support layer 16 is not particularly limited, but is preferably about 10 to 3000 μm, and more preferably about 20 to 1500 μm. Thereby, the above-described function of the support layer 16 is sufficiently exhibited while preventing the optical waveguide 1 from becoming too thick.
In addition, the support layer 16 should just be provided as needed and may be abbreviate | omitted.

  Further, optional layers may be interposed between the support layer 16 and the lower clad layer 11 and between the cover layer 17 and the upper clad layer 12, respectively, as necessary.

  On the other hand, the upper clad layer 12 laminated on the upper surface 104 of the core layer 13 is not necessarily provided and may be omitted. However, by providing the upper cladding layer 12 as shown in FIG. 4, for example, when the optical waveguide 1 is connected to an optical fiber, the coupling efficiency with the optical fiber is improved, and the core portion 14 is protected from external force and external environment. can do. Therefore, the reliability of the optical waveguide 1 can be further improved.

  In the optical waveguide 1 shown in FIG. 4, as described above, the upper cladding layer 12 is not laminated on the left upper surface 105 of the upper surface 104 of the core layer 13. That is, in the optical waveguide 1 shown in FIG. 4, the left end surface 121 of the upper clad layer 12 is retreated to the right from the left end surface 101 of the core layer 13. Due to the retreat of the upper clad layer 12, when the optical interposer 2 is disposed with respect to the optical waveguide 1, interference between the upper clad layer 12 and the optical interposer 2 is avoided. For this reason, it becomes easy to arrange the optical waveguide 1 and the optical interposer 2, and the connectivity between the optical waveguide 1 and the optical interposer 2 is ensured while the core portion 14 is reliably protected by the upper cladding layer 12 except for the upper left surface 105. Can be increased.

  The upper cladding layer 12 may be laminated so as to cover the entire upper surface 104 of the core layer 13.

  Moreover, since the core part 14 is also exposed when the upper surface 104 of the core layer 13 is exposed, the distance between the core part 14 and the optical interposer 2 can be reduced. Thereby, the optical coupling efficiency between both can be raised more.

  The core portion 14 and the optical interposer 2 are preferably in contact with each other, but may be separated from each other as long as the adiabatic coupling is not inhibited. In that case, inclusions such as the adhesive 6 as shown in FIG. 4 may be interposed. The separation distance between the core portion 14 and the optical interposer 2 (thickness of the adhesive 6) is appropriately set according to the width of the core portion 14, but is preferably about 0.3 to 10 μm. More preferably, it is about 5 to 5 μm. Thereby, sufficiently high optical coupling efficiency can be ensured.

  Examples of the adhesive 6 used include an epoxy adhesive, an acrylic adhesive, a urethane adhesive, a silicone adhesive, an olefin adhesive, and various hot melt adhesives (polyester and modified olefin). Can be mentioned.

  The elastic modulus of the adhesive 6 is not particularly limited, but is preferably about 100 to 20000 MPa, more preferably about 300 to 15000 MPa, still more preferably about 500 to 12500 MPa, and particularly preferably about 1000 to 10,000 MPa. Is done. By setting the elastic modulus of the adhesive 6 within the above range, it is possible to alleviate the concentration of stress generated at the adhesive interface while securing the adhesive force. Thereby, the reliability of an adhesion part can be raised more.

  The elastic modulus of the adhesive 6 is measured at a temperature of 25 ° C. in accordance with the method defined in JIS K 7127.

  Here, the core part 14 and the side clad part 15 have the same base polymer as the constituent material. The base polymers being the same as each other means that the structures of the main (largest molar ratio) repeating units contained in the polymer having the highest blending ratio in both constituent materials are the same. Thereby, physical properties, such as a thermal expansion coefficient and an elasticity modulus, approximate each other between the core part 14 and the side clad part 15. As a result, even when the environment in which the optical waveguide 1 is placed changes or the optical waveguide 1 is bent, the core portion 14 is deformed, the transmission efficiency in the core portion 14 is reduced, or the core portion 14 and the optical It can suppress that the optical coupling efficiency with the interposer 2 falls. In addition, there is an advantage that the core layer 13 can be easily manufactured and the dimensional accuracy of the core portion 14 can be easily increased.

  The core portion 14 includes a first compound having a functional group that can be dimerized by light irradiation (hereinafter also referred to as “photodimerizable functional group”). On the other hand, the side clad portion 15 is provided so as to be adjacent to the side surface of the core portion 14 and includes a second compound obtained by dimerizing the first compound via a photodimerizable functional group.

  Such a core part 14 and the side clad part 15 are simultaneously formed using the dimerization reaction by light irradiation. That is, the first compounds are cross-linked by the photodimerization reaction, and a second compound that is a cross-linked product is generated. For this reason, it is suppressed that a foreign material adheres to the interface of the core part 14 and the side surface clad part 15, or a clearance gap is made. As a result, an increase in propagation loss due to the interface between the core portion 14 and the side cladding portion 15 is suppressed, and the optical waveguide 1 having high propagation efficiency is obtained.

  In addition, by providing such an optical waveguide 1, a highly reliable optical waveguide connector 10 can be obtained due to high propagation efficiency in the optical waveguide 1.

-Core part-
Next, the core part 14 is demonstrated.

The first compound contained in the core portion 14 has a photodimerizable functional group as described above.
Examples of the photodimerizable functional group include functional groups containing unsaturated bonds such as N = N group, C = C group, C = N group, and C = O group.

  Specifically, N = N group such as azobenzene group, azonaphthalene group, aromatic heterocyclic azo group, bisazo group, formazan group, maleimide group, indene group, coumarin group, cinnamate group, polyene group, stilbene group, C = C group such as stilbazole group, stilbazolium group, cinnamoyl group, cinnamyl group, cinnamylidene group, hemithioindigo group, chalcone group, anthryl group, cinnamic acid group, aromatic Schiff base, aromatic hydrazone structure, etc. Examples include C═O groups such as C═N groups, benzophenone groups, anthraquinone groups, ester groups such as allyl ester groups, acylphenol structures, and the like, and at least one of these is used.

  Among these, as the photodimerizable functional group, those containing an unsaturated bond that causes a [2 + 2] cyclization reaction are preferably used. Since the [2 + 2] cyclization reaction is a highly selective reaction, the core portion 14 and the side clad portion 15 can be formed with high accuracy by appropriately selecting the light irradiation region. As a result, even the core portion 14 having a complicated pattern can be formed with high accuracy, and the optical waveguide 1 having high propagation efficiency and high optical coupling efficiency with other optical components can be obtained.

  As the photodimerizable functional group, a maleimide group is particularly preferably used. The maleimide group has a relatively high sensitivity in the dimerization reaction by light irradiation. For this reason, even if it is the core part 14 which has a complicated pattern by using a maleimide group as a photodimerization functional group, it can be formed with high precision and in a short time. As a result, the optical waveguide 1 having high propagation efficiency and higher optical coupling efficiency with other optical components can be obtained.

  Here, the maleimide group used as the photodimerizable functional group according to the present embodiment is represented, for example, by the following formula (1).

［式中、Ｒ^１およびＲ^２は、独立して、水素原子または炭素数１〜４のアルキル基である。］

[Wherein, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]

  Such a photodimerizable functional group is preferably contained in the side chain of the polymer in the first compound. That is, the first compound has a main chain and a side chain containing a photodimerizable functional group.

  The main chain is not particularly limited. For example, cyclic olefins, acrylic esters, methacrylic esters, acrylamides, methacrylamides, vinyl esters, styrenes, acrylic acids, methacrylic acids, acrylonitriles, anhydrous Examples include those containing structural units derived from monomers such as maleic acids and maleic imides, and those containing one or more of these are used.

  Among these, a main chain containing a structural unit (cyclic olefin structure) derived from cyclic olefins is preferably used. That is, the first compound preferably contains a cyclic olefin structure in the main chain and a photodimerizable functional group in the side chain. Since such a first compound has better light transmittance, the optical waveguide 1 having higher propagation efficiency can be obtained.

  Examples of the cyclic olefins include monocyclic compounds such as cyclohexene and cyclooctene, norbornene, norbornadiene, dicyclopentadiene, dihydrodicyclopentadiene, tetracyclododecene, tricyclopentadiene, dihydrotricyclopentadiene, tetracyclopentadiene, Examples include polycyclic compounds such as dihydrotetracyclopentadiene, and those containing one or more of these are used.

  As for the 1st compound used for this embodiment, what contains the structural unit represented by following formula (2) especially is preferable.

［式中、Ｘは、単結合または二価の有機基であり、Ｒ^１およびＲ^２は、独立して水素原子または炭素数１〜４のアルキル基である。］

[Wherein, X is a single bond or a divalent organic group, and R ¹ and R ² are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]

  When X is a divalent organic group, examples of the organic group include a hydrocarbon group having 1 to 12 carbon atoms, an ether bond, an ester bond, an amide bond, a carbonyl group, and a vinylidene group. One or two or more of them are combined.

  Among these, the C1-C12 hydrocarbon contained in X may be either linear or branched, and may be either saturated or unsaturated. In addition, it is preferable that carbon number of a hydrocarbon is 1-8, and it is more preferable that it is 1-4. Thereby, since the mechanical characteristics of the core layer 13 are optimized, for example, the optical waveguide 1 having excellent folding resistance can be obtained.

  The hydrogen atom of the hydrocarbon group may be substituted with a substituent such as an alkyl group having 1 to 2 carbon atoms, a hydroxyl group, an amino group, a carboxyl group, or a halogen atom.

On the other hand, when R ¹ and R ² are an alkyl group having 1 to 4 carbon atoms, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, Examples thereof include a tert-butyl group. Among these, any one of R ¹ and R ² is preferably a methyl group, and more preferably both are methyl groups. In the first compound containing such a photodimerizable functional group having R ¹ and R ² , the radical polymerization reaction hardly proceeds or does not proceed at all. For this reason, the probability that a polymerization reaction other than the photodimerization reaction proceeds can be reduced, and the refractive index can be easily controlled.

  Since the first compound represented by the formula (2) has a particularly high sensitivity and a good light transmittance, the optical waveguide 1 having a particularly high propagation efficiency can be realized. .

  The weight average molecular weight of the first compound is not particularly limited, but is preferably 10,000 or more, and more preferably about 20,000 to 150,000. Such a first compound has necessary and sufficient mechanical properties and good light transmittance. That is, it is possible to obtain the optical waveguide 1 having high transmission efficiency while maintaining the mechanical characteristics that give flexibility while maintaining the shape of the core portion 14.

  Furthermore, when the molecular weight is within such a range, volatilization of the first compound can be suppressed when the optical waveguide 1 is manufactured, and therefore it is necessary to give excessive consideration to the time required for the manufacturing and the drying conditions. Disappear. For this reason, while the ease of a manufacturing process increases, the freedom degree of a manufacturing process can be raised, and improvement of manufacturing efficiency and cost reduction can be aimed at.

  For the calculation of the weight average molecular weight of the first compound, for example, a polystyrene conversion value obtained from a standard polystyrene (PS) calibration curve obtained by GPC (Gel Permeation Chromatography) measurement is used. As the apparatus, a high-performance liquid chromatograph HLC-8020 system manufactured by Tosoh Corporation, which uses a TSK-gel GML column, a TSK-gel G2000H column, a differential refractometer, and tetrahydrofuran as a mobile phase is used. Then, measurement was performed under the conditions of 40 ° C. and a flow rate of 1.0 ml / min, and a calibration curve of retention time and molecular weight was prepared using a Tosoh PS-oligomer kit as standard polystyrene, and the polystyrene equivalent weight of the first compound Average molecular weight can be determined.

  Further, the first compound may be in any form such as a monomer, a prepolymer, an oligomer, a polymer, a mixture thereof or a multimer thereof, but is preferably a polymer or an oligomer, and is a polymer. Is more preferable.

  Moreover, the 1st compound may have other structural units other than the structural unit containing the photodimerizable functional group mentioned above. Examples of other structural units include structural units derived from arbitrary monomers, and are not particularly limited.

  Such other structural units are preferably 50 mol% or less, and more preferably 30 mol% or less, of all the structural units in the first compound.

  The core portion 14 is composed of components other than the first compound described above, for example, a second compound and other polymers described later, other monomers, sensitizers, reaction accelerators, antioxidants, adhesion assistants, and surfactants. In addition, additives such as dyes may be included. The content of such components other than the first compound is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10% by mass or less of the core part 14. preferable.

  Among these, as the adhesion assistant, for example, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, Examples include silane coupling agents such as trimethoxysilyl norbornene, triethoxysilyl norbornene, trimethoxysilylethyl norbornene, and one or more of these are used.

  Moreover, it is preferable that it is about 0.1-5 mass% of resin solid content, and, as for the addition amount of adhesion | attachment adjuvant, it is more preferable that it is about 0.3-3 mass%.

-Side cladding-
Next, the side clad part 15 will be described.

  As described above, the side clad portion 15 is provided so as to be adjacent to the side surface of the core portion 14, and includes the second compound obtained by dimerizing the first compound via the photodimerizable functional group.

  Therefore, the second compound is a dimer of the first compound including a structure (dimerization structure) formed by dimerizing the photodimerizable functional groups.

  The following formula (3) is a formula representing a dimerization reaction when the photodimerizable functional group is a maleimide group.

  With such a dimerization reaction, the double bond contained in the photodimerizable functional group decreases. Thereby, the refractive index of a 2nd compound shows the tendency to fall rather than the refractive index of a 1st compound. For this reason, the refractive index of the side cladding 15 is smaller than the refractive index of the core 14. As a result, the core unit 14 functions as an optical transmission line.

  From the above viewpoint, the core part 14 should just contain the 1st compound, and the side surface clad part 15 should just contain the 2nd compound. The second compound may be included in the core portion 14, and the first compound may be included in the side clad portion 15.

  At this time, it is preferable that the content rate of the 2nd compound in the side clad part 15 is larger than the content rate of the 2nd compound in the core part 14. FIG. Thereby, the refractive index of the side clad part 15 becomes lower than the refractive index of the core part 14.

  On the other hand, the content ratio of the first compound in the side cladding portion 15 is preferably smaller than the content ratio of the first compound in the core portion 14.

  Such a difference in the content of each compound is reflected in the difference in refractive index between the core portion 14 and the side cladding portion 15.

  The relative refractive index difference between the core portion 14 and the side clad portion 15 is not particularly limited, but is preferably 0.1 to 2%, and more preferably 0.2 to 1%. Thereby, the optical transmission efficiency in the core part 14 can fully be improved, and the reliable optical waveguide connector 10 is obtained. That is, it is possible to reduce the power consumption, speed, and size of the optical waveguide connector 10. In particular, when the waveguide mode of the core portion 14 is a single mode, optimization of the refractive index difference is required. Therefore, if the relative refractive index difference is within the above range, high optical transmission efficiency can be realized. it can. Moreover, since the waveguide mode of the core part 14 is likely to be a single mode, for example, the optical coupling efficiency between the core part 14 and the optical interposer 2 can be further increased.

The relative refractive index difference is expressed by the following equation when the refractive index of the core portion 14 is n ₁ and the refractive index of the side cladding portion 15 is n ₂ .
Relative refractive index difference (%) = 100 × (n ₁ ² −n ₂ ² ) / 2n ₁ ²

  Since such a second compound is a dimer of the first compound, it will exhibit physical properties similar to those of the first compound. For this reason, the core part 14 and the side clad part 15 have physical properties close to each other in mechanical characteristics and thermal characteristics, for example, and have high affinity as structures adjacent to each other. Therefore, for example, even if the optical waveguide 1 is bent or a thermal load is applied to the optical waveguide 1, there is a probability that a gap is generated between the core portion 14 and the side cladding portion 15 or a crack is generated. It can be lowered sufficiently.

  Further, the weight average molecular weight of the second compound is not particularly limited, but is larger than the weight average molecular weight of the first compound, specifically, preferably 20,000 or more, and about 40,000 to 250,000. More preferably. Such a second compound has necessary and sufficient mechanical properties and good light transmittance. That is, a mechanical characteristic that provides flexibility while maintaining the shape of the side clad portion 15 is obtained.

  Furthermore, if the molecular weight is within such a range, volatilization of the second compound can be suppressed when the optical waveguide 1 is manufactured, and therefore it is necessary to give excessive consideration to the time required for manufacturing, the drying conditions, and the like. Disappear. For this reason, while the ease of a manufacturing process increases, the freedom degree of a manufacturing process can be raised and manufacturing efficiency can be improved and cost reduction can be achieved.

  In addition, for the calculation of the weight average molecular weight of the second compound, for example, a polystyrene conversion value obtained from a standard polystyrene (PS) calibration curve obtained by GPC (Gel Permeation Chromatography) measurement is used. As the apparatus, a high-performance liquid chromatograph HLC-8020 system manufactured by Tosoh Corporation, which uses a TSK-gel GML column, a TSK-gel G2000H column, a differential refractometer, and tetrahydrofuran as a mobile phase is used. Then, measurement is performed under the conditions of 40 ° C. and a flow rate of 1.0 ml / min, and a calibration curve of retention time and molecular weight is prepared using a Tosoh PS-oligomer kit as standard polystyrene. The weight of the second compound in terms of polystyrene Average molecular weight can be determined.

  The second compound may be in any form such as a monomer, a prepolymer, an oligomer, a polymer, a mixture thereof or a multimer thereof, but is preferably a polymer or an oligomer, and is a polymer. Is more preferable.

  Moreover, the 2nd compound may have other structural units other than the dimerization structure mentioned above. Examples of other structural units include structural units derived from arbitrary monomers, and are not particularly limited.

  In addition, such other structural units are preferably 30 mol% or less, more preferably 10 mol% or less, among all the structural units in the second compound.

  Further, the side clad portion 15 is composed of components other than the above-described second compound, for example, the above-described first compound and other polymers, other monomers, sensitizers, reaction accelerators, antioxidants, adhesion assistants, surface activity Additives such as agents and dyes may be included. The content of such components other than the second compound is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10% by mass or less of the side clad portion 15. Further preferred.

  Among these, as the adhesion assistant, for example, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, Examples include silane coupling agents such as trimethoxysilyl norbornene, triethoxysilyl norbornene, trimethoxysilylethyl norbornene, and one or more of these are used.

  Moreover, it is preferable that it is about 0.1-5 mass% of resin solid content, and, as for the addition amount of adhesion | attachment adjuvant, it is more preferable that it is about 0.3-3 mass%.

  In addition, it is preferable that the core part 14 and the side clad part 15 do not contain the polymerization initiator substantially, respectively. Thereby, the malfunction which deterioration of the material by a polymerization initiator, etc. progresses with time can be suppressed. That is, when unintentional light hits the optical waveguide 1 afterwards, the refractive index of the core portion 14 or the side cladding portion 15 changes or the mechanical characteristics deteriorate, so that the reliability of the optical waveguide 1 is improved. It can suppress that it falls. As a result, the optical waveguide 1 having good environmental test resistance is obtained.

The content of the polymerization initiator in the core portion 14 and the side cladding portion 15 is not particularly limited as long as it is as small as possible, but is preferably 0.01% by mass or less, and more preferably 0.005% by mass or less. preferable.
Examples of the polymerization initiator include a photoacid generator.

(Optical connector)
As shown in FIG. 3, the optical connector 5 includes a connector main body 51 and a through hole 50 formed in the connector main body 51.

  The optical waveguide 1 is bonded to the inner wall surface of the through hole 50 through an adhesive or the like. As a result, the optical connector 5 is fixed to the end of the optical waveguide 1. The optical connector 5 is configured to engage with an optical connector 91 as shown in FIG. 2, for example. Thereby, the optical waveguide 1 to which the optical connector 5 is attached and the optical fiber 9 to which the optical connector 91 is attached can be optically connected.

  The outer shape of the connector main body 51 is not particularly limited, and may be a shape conforming to a rectangular parallelepiped as shown in FIGS. Further, the connector main body 51 may include a part conforming to various connector standards. Examples of such connector standards include a miniature MT connector, an MT connector specified in JIS C 5981, a 16MT connector, a two-dimensional array MT connector, an MPO connector, and an MPX connector.

  Further, the optical connector 5 may include an engaging means for engaging with the optical connector 91. Examples of the engaging means include a means including a guide pin and a guide hole, a means using locking by a claw, a clip, an adhesive, and the like.

  Examples of the constituent material of the connector body 51 include various resin materials such as phenol resin, epoxy resin, olefin resin, urea resin, melamine resin, unsaturated polyester resin, polyphenylene sulfide resin, stainless steel, and the like. And various metal materials such as an aluminum alloy.

  In addition, the optical connector 5 should just be provided as needed, and may be abbreviate | omitted. In that case, it may be connected to the optical fiber 9 without going through the optical connector 5, or may be connected to a light emitting / receiving element or an optical interposer (not shown).

(Mounting board)
The mounting substrate 3 is a substrate for mounting the optical waveguide 1, the optical connector 5, and the optical interposer 2. By using such a mounting substrate 3, the optical waveguide 1 and the optical interposer 2 can be stably held. At the same time, the mounting substrate 3 includes LSI (Large-Scale Integration), IC (Integrated Circuit), CPU (Central Processing Unit), RAM (Random Access Memory) and other active components, capacitors, coils, resistors, diodes, etc. Electronic components such as passive components, and optical components such as light emitting diodes, laser diodes, and light receiving sensors can be mixed. Thereby, the optical waveguide connector 10 having higher functionality can be constructed.

The mounting substrate 3 includes an insulating substrate 31 and a conductive layer 32 (electric wiring).
Of these, any substrate can be used as the insulating substrate 31 as long as it has insulating properties and rigidity suitable for handling. Specific examples include various resin materials such as polyimide resins, polyamide resins, epoxy resins, various vinyl resins, and polyester resins such as polyethylene terephthalate resins. In addition, paper, glass cloth, resin film, etc. are used as a base material, and this base material is impregnated with a resin material such as a phenol resin, polyester resin, epoxy resin, cyanate resin, polyimide resin, or fluorine resin. In addition to insulating substrates used for composite copper-clad laminates such as glass cloth / epoxy copper-clad laminates, glass nonwoven fabrics / epoxy copper-clad laminates, polyetherimide resin substrates, Examples thereof include heat-resistant and thermoplastic organic rigid substrates such as ether ketone resin substrates and polysulfone resin substrates, and ceramic rigid substrates such as alumina substrates, aluminum nitride substrates, and silicon carbide substrates.

  In addition, the conductive layer 32 is provided inside or on the surface of the insulating substrate 31. Examples of the constituent material of the conductive layer 32 include simple metals such as copper, aluminum, nickel, chromium, zinc, tin, gold, and silver, or alloys containing these metal elements.

  Note that the mounting substrate 3 may be provided as necessary. For example, the mounting substrate 3 may be omitted when only the connection body of the optical waveguide 1 and the optical interposer 2 has sufficient rigidity.

(Optical interposer)
The optical interposer 2 includes an interposer substrate 21, a light guide part 22, a conductive part 23, a bump 24, a semiconductor element 25, and a light emitting / receiving element 26.

  The interposer substrate 21 may be any substrate as long as the light guide portion 22 and the conductive portion 23 can be mixedly mounted thereon.

  The light guide unit 22 optically connects the light emitting / receiving element 26 and the optical waveguide 1. That is, the light guide unit 22 is provided so as to extend from the vicinity of the light emitting / receiving element 26 to a region in contact with the optical waveguide 1.

  Moreover, it is preferable that the light guide part 22 is arrange | positioned so that the center of the width | variety and the center of the width | variety of the core part 14 may correspond when the core layer 13 is planarly viewed (refer FIG. 5). By arranging in this way, it becomes easy to ensure the area where both overlap in plan view. Thereby, the optical coupling efficiency between the optical waveguide 1 and the optical interposer 2 can be further increased.

  Note that the fact that the center of the width of the light guide portion 22 and the center of the width of the core portion 14 coincide with each other indicates a state where the positional deviation is 20% or less of the width of the core portion 14.

  Furthermore, it is preferable that the optical axis of the light guide part 22 and the optical axis of the core part 14 are parallel to each other. By arranging in this way, it becomes easy to ensure the area where both overlap in plan view. Thereby, the optical coupling efficiency between the optical waveguide 1 and the optical interposer 2 can be further increased.

  In addition, the optical axis of the light guide part 22 and the optical axis of the core part 14 being parallel to each other means a state where the angle deviation is 1 ° or less.

  The conductive portion 23 electrically connects the semiconductor element 25 or the light emitting / receiving element 26 and the bump 24. That is, the conductive portion 23 is provided so as to extend from the vicinity of the semiconductor element 25 and the light emitting / receiving element 26 to the bump 24.

  The semiconductor element 25 and the light emitting / receiving element 26 do not have to be separate elements, and may be a composite element in which both are combined.

  The optical waveguide connector 10 including the optical interposer 2 as described above is controlled by a control element such as an LSI mounted on the mounting substrate 3, for example, and functions as an optical transceiver that transmits or receives an optical signal. That is, it is inserted between the control element and the optical fiber 9 and is responsible for electrical / optical conversion, thereby contributing to the construction of optical communication between chips, between boards, and between servers.

<Modified example of optical waveguide>
Next, a modification of the optical waveguide according to the embodiment will be described.

  FIG. 7 is a cross-sectional view showing a modification of the optical waveguide shown in FIG. FIG. 8 is a transparent perspective view of the optical waveguide shown in FIG.

  Hereinafter, modifications of the above-described embodiment will be described. However, in the following description, differences from the above-described embodiment will be mainly described, and description of similar matters will be omitted.

  The optical waveguide 1 shown in FIG. 7 is provided with a marked substrate 7 while the support layer 16 and the cover layer 17 are omitted. The marked base material 7 is provided on the lower surface of the lower clad layer 11, and includes a base material 71 and a mark 72 provided on the upper surface of the base material 71.

  The mark 72 is provided at least in a region that is separated from the core layer 13 and overlaps the core portion 14 in plan view. In this modification, as shown in FIG. 8, the mark 72 is provided only in a region overlapping the core portion 14. In addition, planar view means a visual field when it sees along the normal line of the upper surface 104 of the core layer 13, and it sees through as needed.

  Such a mark 72 indicates a pattern that matches the position and shape of the core portion 14. For this reason, even when the visibility of the core part 14 is low, the mark 72 can reinforce the visibility instead of the core part 14.

  That is, the core part 14 has a relatively high light transmittance in terms of its function. For this reason, even if it tries to visually recognize the core part 14, it may be difficult to visually recognize correctly.

  On the other hand, since the mark 72 is provided, even if it is difficult to visually recognize the core portion 14 directly, the mark 72 can be visually recognized instead of the core portion 14. The shape can be grasped. As a result, it is possible to perform a connection operation between the optical waveguide 1 and another optical component while grasping the position and shape of the core portion 14. Thereby, alignment can be performed more accurately and the optical coupling efficiency between the optical waveguide 1 and other optical components can be easily increased.

  Further, it is preferable that the mark 72 has lower light transmittance than the core portion 14 in order to improve visibility. For this reason, the mark 72 also functions as a light shielding film that suppresses deterioration of the core portion 14 due to unintended light irradiation in the manufactured optical waveguide 1. In other words, since the mark 72 and the core portion 14 overlap each other in plan view, it is possible to suppress the light from hitting the core portion 14 located behind the mark 72 when light is irradiated from the mark 72 side. Deterioration due to light can be suppressed.

  The distance between the mark 72 and the core part 14 is not particularly limited, but is preferably about 2 to 50 μm, and more preferably about 5 to 40 μm. By setting the separation distance within the above range, the core portion 14 and the mark 72 are sufficiently close to each other regardless of the direction in which the optical waveguide 1 is viewed. Therefore, the position and shape of the core part 14 can be visually recognized more easily. Further, an increase in propagation loss due to the core portion 14 and the mark 72 being too close can be suppressed.

  When the separation distance is less than the lower limit, depending on the thickness of the mark 72, the unevenness of the mark 72 may affect the core layer 13. Moreover, since the thickness of the lower cladding layer 11 becomes too thin, there is a possibility that propagation loss increases. On the other hand, if the separation distance exceeds the upper limit value, the core portion 14 and the mark 72 are too far apart, and depending on the viewing angle, the recognition error due to parallax may increase.

  Moreover, although it is preferable that the mark 72 is provided only in a region overlapping the core part 14 in a plan view as illustrated, the mark 72 may be provided in other regions. Even in this case, although the accuracy is somewhat lowered, the position and shape of the core portion 14 can be grasped, and the above-described effects can be obtained.

  The mark 72 has a light transmission property lower than that of the core portion 14, and the constituent material is not particularly limited. However, for example, a metal material such as chromium, chromium alloy, nickel, nickel alloy, chromium oxide, nickel oxide, etc. Examples thereof include oxide materials, various nitride materials, and various carbide materials.

  Among these, the mark 72 preferably includes a metal material. As a result, the mark 72 having a high light shielding property can be obtained even if it is thin. Therefore, the thickness of the mark 72 can be further reduced while further improving the visibility of the mark 72. For this reason, the optical waveguide 1 in which the position and shape of the core portion 14 can be easily grasped can be obtained while reducing the probability that the unevenness of the mark 72 affects the core layer 13.

  The thickness of the mark 72 is appropriately set according to the constituent material of the mark 72, but is preferably about 20 to 2000 nm, and more preferably about 50 to 500 nm. By setting the thickness of the mark 72 within the above range, it is possible to minimize the influence of the unevenness of the mark 72 on the core layer 13 while ensuring the visibility of the mark 72 sufficiently.

  Such a mark 72 may be in any form, for example, a member formed by patterning a plate material, or a member formed by various film forming methods.

  The base material 71 shares part of the mechanical strength of the optical waveguide 1 and contributes to increasing the rigidity of the optical waveguide 1. Thereby, the optical waveguide 1 which is thin but hardly bent is obtained. Since the shape of the optical waveguide 1 is easily maintained, for example, this contributes to more accurate alignment with other optical components.

  The base material 71 will not be specifically limited if it has a light transmittance. Examples of the constituent material of the substrate 71 include acrylic resins, methacrylic resins, polycarbonates, polystyrenes, cyclic ether resins such as epoxy resins and oxetane resins, polyamides, polyimides, polybenzoxazoles, polysilanes, polysilazanes, Silicone resin, fluorine resin, polyurethane, polyolefin resin, polybutadiene, polyisoprene, polychloroprene, polyester such as PET and PBT, polyethylene succinate, polysulfone, polyether, benzocyclobutene resin, norbornene resin, etc. In addition to various resin materials using a component such as a cyclic olefin-based resin as a base polymer, various glass materials such as quartz glass, borosilicate glass, and soda lime glass can be used. The resin material may be a composite material or a polymer alloy in which different compositions are combined.

  Among these, it is preferable that the constituent material of the base material 71 is a glass material. Thereby, the base material 71 becomes compatible with the outstanding light transmittance and sufficient rigidity. For this reason, the shape of the core layer 13 is easily maintained, and the mark 72 is more easily visually recognized by illuminating from the base 71 side. And since it becomes easy to suppress that the core part 14 deform | transforms with the dead weight of the optical waveguide 1, etc., it contributes also to raising the optical coupling efficiency of the optical waveguide 1 and another optical component.

  The shape of the base material 71 is, for example, a flat plate shape. Thereby, the light transmittance in the thickness direction is increased, and the straightness of light is also increased. For this reason, the mark 72 can be easily visually recognized when viewed from the substrate 71 side.

  Although the thickness of the base material 71 is appropriately set according to the constituent material of the base material 71, the thickness is preferably about 0.01 to 5 mm, more preferably about 0.05 to 3 mm. More preferably, it is about 10 to 1 mm. If the thickness is set within such a range, the base material 71 having both excellent light transmittance and sufficient rigidity can be obtained.

  The light transmittance of the substrate 71 is preferably as high as possible, but the total light transmittance at a wavelength of 550 nm is preferably 85% or more, and more preferably 90% or more. Thereby, even when viewed from the base material 71 side, the mark 72 can be easily visually recognized.

  Further, as the base material 71, a material having a bending elastic modulus larger than that of the lower clad layer 11 described later is preferably used. Such a base material 71 can improve the flatness of the marked base material 7 even if the thickness of the base material 71 is reduced, so that the accuracy of the pattern of the mark 72 can also be improved. Thereby, the precision of the pattern of the core part 14 to be formed can be increased, and the optical waveguide 1 having high optical coupling efficiency with other optical components can be efficiently manufactured.

  In addition, it is preferable that the bending elastic modulus of the base material 71 is 110% or more of the bending elastic modulus of the lower clad layer 11, and it is more preferable that it is about 120 to 1000%.

  The flexural modulus is a measured value at 25 ° C. obtained in accordance with, for example, the method for obtaining the bending characteristics of plastics specified in JIS K 7171: 2016.

  In addition, such a base material 71 should just be provided as needed, and may be abbreviate | omitted, for example, when the mechanical strength of another site | part is sufficiently large.

<Optical waveguide manufacturing method>
Next, a method for manufacturing the optical waveguide 1 will be described. The optical waveguide 1 may be manufactured by any method, but an example thereof will be described here. Further, in the following description, a method for manufacturing the optical waveguide 1 according to the modification shown in FIGS.

  9 and 10 are diagrams for explaining a method of manufacturing the optical waveguide shown in FIGS. 7 and 8, respectively. In the following description, the upper part of FIGS. 9 and 10 is referred to as “upper” and the lower part is referred to as “lower”.

  The method of manufacturing the optical waveguide 1 includes a step of preparing a light-transmitting marked base material 7, a step of forming a lower cladding layer 11 on the upper surface side (one surface side) of the marked base material 7, A step of forming the core forming layer 130 on the upper surface side of the lower clad layer 11 (the side opposite to the marked substrate 7 side), and irradiating the core forming layer 130 with the active radiation L from the lower surface side. Forming the core portion 14 and the side clad portion 15 to obtain the core layer 13 and forming the upper clad layer 12 on the upper surface side of the core layer 13.

[1] Step of Preparing Marked Substrate 7 First, as shown in FIG. 9A, a marked substrate 7 including a light-transmitting substrate 71 and a mark 72 is prepared.

  As the mark 72, for example, various photomasks such as a chrome mask, an emulsion mask, and a film mask, various stencil masks such as a metal mask, and a silicon mask can be used.

  Further, the mark 72 may be separate from the base material 71, may be formed on the upper surface of the base material 71, or may be formed on the lower surface of the base material 71. Good. Of these, the mark 72 is preferably formed on the upper surface of the substrate 71. Since such a mark 72 can be formed relatively easily with high accuracy, it contributes to manufacturing an optical waveguide including the core portion 14 with high dimensional accuracy at low cost.

  In addition, the film-forming method of the mark 72 is not specifically limited, For example, the vapor phase film-forming method, the liquid phase film-forming method, the plating method etc. are mentioned.

[2] Step of Forming Lower Clad Layer 11 Next, as shown in FIG. 9B, the lower clad layer 11 is formed on the upper surface of the marked substrate 7.

  The lower clad layer 11 can be formed by, for example, a method of attaching a film, a method of applying a raw material liquid, or the like. Of these, the method of applying the raw material liquid is preferably used. In this method, it is possible to prevent the thickness of the mark 72 from affecting the upper surface of the lower clad layer 11 by applying the raw material liquid so as to cover the mark 72. As a result, the core forming layer 130 formed in the process described later is flattened, and the dimensional accuracy of the core portion 14 can be further increased.

  The coating method is not particularly limited, and examples thereof include a doctor blade method, a spin coating method, a dipping method, a table coating method, a spray method, an applicator method, a curtain coating method, a die coating method, and an ink jet method.

Also, the method for drying the liquid film formed by such a method is not particularly limited. For example, a method of heating the liquid film, placing it under reduced pressure, or spraying a dry gas is used.
Thereafter, a process for curing the dry film may be added as necessary.

  Such a process is, for example, heat treatment, and the conditions are a temperature of 50 to 230 ° C. and a time of about 1 minute to 3 hours. Further, the heat treatment may be performed in a plurality of times.

  The average thickness of the lower cladding layer 11 is not particularly limited, but is preferably about 2 to 50 μm, and more preferably about 5 to 40 μm. By setting the average thickness of the lower clad layer 11 within the above range, a sufficient distance between the core forming layer 130 and the mark 72 can be secured. Thereby, the probability that the light propagating through the formed core part 14 leaks to the mark 72 side can be sufficiently reduced, which contributes to the realization of the optical waveguide 1 having high propagation efficiency. In addition, it is possible to prevent the unevenness of the mark 72 from affecting the core layer 13. Further, it is possible to prevent the lower clad layer 11 from becoming too thick, thereby preventing a decrease in the straightness of the active radiation and preventing the optical waveguide 1 from being thickened.

  The average thickness of the lower clad layer 11 means an average value of measured values when the thickness of the lower clad layer 11 is measured at arbitrary 10 points or more.

  Further, although depending on the constituent material of the mark 72, the average thickness of the lower clad layer 11 is preferably about 2 to 200 times the average thickness of the mark 72, and about 3 to 150 times. More preferred. Thereby, the lower clad layer 11 can be sufficiently flattened, and the influence of the unevenness of the mark 72 on the core layer 13 can be suppressed. Further, it is possible to prevent the lower clad layer 11 from becoming too thick, prevent a reduction in the straightness of the active radiation, and form the core portion 14 with high dimensional accuracy.

[3] Step of Forming Core Forming Layer 130 Next, as shown in FIG. 9C, the core forming layer 130 is formed on the upper surface side of the lower clad layer 11 (the side opposite to the marked substrate 7 side). Form.

  The core forming layer 130 has a characteristic (refractive index modulation ability) in which the refractive index changes when irradiated with active radiation such as light or ultraviolet rays. For this reason, when a specific region of the core forming layer 130 is irradiated with active radiation, a refractive index difference is formed between the irradiated region and the non-irradiated region. As a result, the region on the high refractive index side becomes the core portion 14, and the region on the low refractive index side becomes the side cladding portion 15.

  The principle of refractive index modulation includes, for example, monomer diffusion, photobleaching, photoisomerization and the like in addition to photodimerization, and the principle of combining one or more of these is used.

  Among these, in monomer diffusion, a layer composed of a material in which a photopolymerizable monomer having a refractive index different from that of the polymer is dispersed in a polymer is partially irradiated with light to polymerize the photopolymerizable monomer. In addition to the occurrence, the photopolymerizable monomer is moved and unevenly distributed, thereby causing the refractive index in the layer to form the core portion 14 and the side cladding portion 15.

  Examples of a material that causes such monomer diffusion include a photosensitive resin composition described in Japanese Patent Application Laid-Open No. 2010-090328.

  In photobleaching, the molecular structure in the material is cut by light irradiation, and the leaving group is detached from the main chain. Thereby, the refractive index of the material is changed, and the core portion 14 and the side cladding portion 15 are formed.

  Examples of the material that causes photobleaching include core film materials described in JP-A-2009-145867.

  Moreover, in photoisomerization and photodimerization, photoisomerization or photodimerization of a material occurs by light irradiation, respectively. Thereby, the refractive index of the material is changed, and the core portion 14 and the side cladding portion 15 are formed.

  Examples of materials that cause photoisomerization include norbornene resins described in JP-A-2005-164650.

  Examples of the material that causes photodimerization include compounds having a functional group (photodimerizable functional group) that can be dimerized by the actinic radiation described above.

  In addition, in the case of refractive index modulation based on the principles of photobleaching, photoisomerization, and photodimerization, the amount of change in refractive index can be adjusted according to the amount of irradiated light (radiation amount). By gradually changing the light irradiation amount according to the irradiation position, an arbitrary refractive index distribution, for example, a refractive index distribution with a smooth refractive index change can be formed. Thereby, a graded index type refractive index distribution can be easily formed.

  As a method of gradually changing the amount of light irradiation according to the irradiation position, for example, a method using a multi-tone mask such as a gray-tone mask or a half-tone mask, a method of scanning a light beam having a distribution of light intensity, or a region For example, a method of irradiating while changing the irradiation time or the irradiation intensity for each.

  The core forming layer 130 can be formed by, for example, a method of attaching a film or a method of applying a raw material solution. The application method is appropriately selected from the methods described above.

[4] Step of irradiating the core forming layer 130 with the active radiation L Next, as shown in FIG. 10A, the core forming layer 130 is irradiated with the active radiation L from the lower surface side. Thereby, the core part 14 and the side clad part 15 are formed in the core formation layer 130.

  When the active radiation L is irradiated on the lower surface side, that is, through the marked substrate 7, the active radiation L is irradiated to the core forming layer 130 via the mark 72. For this reason, the active radiation L is shielded in the region where the mark 72 is provided, while the active radiation L reaches the core forming layer 130 in the region where the mark 72 is not provided.

  The actinic radiation L is appropriately selected according to the type of radiation that the core forming layer 130 reacts in the above-described refractive index modulation ability, and examples thereof include light such as visible light, electromagnetic waves such as infrared light and ultraviolet light, and the like. It is done.

  In the present embodiment, the core forming layer 130 having a refractive index modulation ability that reduces the refractive index of the irradiated region will be described as an example. That is, the refractive index of the core forming layer 130 according to the present embodiment is lowered by the irradiation with the active radiation L. Therefore, as shown in FIG. 10A, the mark 72 is provided in a region where the core portion 14 is to be formed. When the actinic radiation L is irradiated through such a mark 72, the refractive index decreases in the irradiated region, and the side cladding portion 15 is formed. Moreover, since the area | region which overlaps with the mark 72 turns into a non-irradiation area | region, the core part 14 will be formed.

The core forming layer 130 may have a refractive index modulation ability that increases the refractive index of the irradiated region. In this case, the mark 72 is provided in a region where the side clad portion 15 is to be formed.
Thereafter, a process for curing the core forming layer 130 may be added as necessary.

  Such a process is, for example, heat treatment, and the conditions are a temperature of 50 to 230 ° C. and a time of about 1 minute to 3 hours. Further, the heat treatment may be performed in a plurality of times.

  As described above, the core layer 13 including the core portion 14 and the side cladding portion 15 is formed (see FIG. 10B).

  The core part 14 and the side cladding part 15 formed in this way can have the same base polymer as the constituent material. The same base polymer means that the structures of main repeating units contained in the polymer having the largest blending ratio in both constituent materials are the same. Thereby, physical properties, such as a thermal expansion coefficient and an elasticity modulus, approximate each other between the core part 14 and the side clad part 15. As a result, even when the environment in which the optical waveguide 1 is placed is changed or the optical waveguide 1 is bent, the core portion 14 is deformed, the transmission efficiency in the core portion 14 is reduced, the core portion 14 and the like. It can suppress that the optical coupling efficiency with this optical component falls. In addition, there is an advantage that the core layer 13 can be easily manufactured and the dimensional accuracy of the core portion 14 can be easily increased.

  Moreover, such a core part 14 and the side clad part 15 are formed simultaneously by light irradiation. For this reason, it is suppressed that a foreign material adheres to the interface of the core part 14 and the side surface clad part 15, or a clearance gap is made. As a result, an increase in propagation loss due to the interface between the core portion 14 and the side cladding portion 15 is suppressed, and the optical waveguide 1 having high propagation efficiency is obtained.

[5] Step of Forming Upper Cladding Layer 12 Next, the upper cladding layer 12 is formed on the upper surface side of the core layer 13.

  The upper clad layer 12 can be formed by, for example, a method of attaching a film, a method of applying a raw material liquid, or the like. Specifically, it can be performed in the same manner as the formation of the lower clad layer 11.

  As described above, the optical waveguide 1 including the lower clad layer 11, the core layer 13, and the upper clad layer 12 is obtained (see FIG. 10C).

  The upper cladding layer 12 may be provided as necessary and may be omitted. In that case, this step can also be omitted.

In such a manufacturing method, in principle, the core part 14 in which the pattern of the mark 72 is faithfully reflected is formed. In other words, the pattern of the mark 72 substantially matches the pattern of the core part 14. For this reason, the mark 72 can be a mask for controlling the irradiation region of the active radiation in addition to the original function of grasping the position and shape of the core portion 14. As a result, the optical waveguide 1 includes the core portion 14 in which the shape of the mark 72 is faithfully reflected, and can be more accurately aligned with other optical components.
Note that “substantially match” means that a deviation of about a manufacturing error is allowed.

  Further, in the above manufacturing method, the mark 72 is provided inside the optical waveguide 1 and the light irradiation area is controlled by the mark 72. However, the arrangement of the mark 72 is not limited to this. It may be provided outside.

  Further, a process of forming a plurality of optical waveguides 1 and finally separating them into individual pieces may be added. As this process, the process of cut | disconnecting so that the optical waveguides 1 may be isolate | separated separately using the cutting tool like a diamond cutter, for example is mentioned.

<Electronic equipment>
As described above, the optical waveguide connector 10 as described above is connected to the optical waveguide 1 having high transmission efficiency and the optical interposer 2 and has high reliability. Therefore, by providing the optical waveguide connector 10, a highly reliable electronic device (embodiment of the electronic device of the present invention) that can perform high-quality optical communication is obtained.

  Examples of such electronic devices include smart devices, tablet terminals, mobile phones, game machines, router devices, WDM (Wavelength Division Multiplex) devices, personal computers, televisions, home servers, and other electronic devices. In any of these electronic devices, it is necessary to transmit a large amount of data at high speed between an arithmetic device such as an LSI and a storage device such as a RAM. Therefore, by providing such an electronic device with the optical waveguide connector 10, problems such as noise and signal deterioration peculiar to the electrical wiring are eliminated, and a dramatic improvement in performance can be expected.

  In addition, the amount of heat generated in the optical waveguide portion is significantly reduced compared to the electrical wiring. For this reason, the electric power required for cooling can be reduced and the power consumption of the whole electronic device can be reduced.

  As mentioned above, although the optical waveguide of this invention, the optical waveguide connector, and the electronic device were demonstrated based on embodiment of illustration, this invention is not limited to these.

  For example, an arbitrary element may be added to the embodiment, and an element included in the embodiment may be replaced with an element having an equivalent function.

Next, examples of the present invention will be described.
1. Production of optical waveguide An optical waveguide was produced as follows.
Example 1
(1) Production of core layer-forming resin composition First, in a glove box filled with dry nitrogen, a monomer capable of forming a unit structure of dimethylmaleimide norbornene (DMMINB) represented by the following formula (4), A 500 mL vial was weighed, mesitylene was added thereto, and the mixture was sealed with a silicon sealer and stirred. The photodimerizable functional group of dimethylmaleimide norbornene is a dimethylmaleimide group, and the main chain is norbornene.

  Subsequently, 3-glycidoxypropyltrimethoxysilane (adhesion aid) was added and dissolved by stirring. The addition amount of the adhesion assistant was 0.9% by mass of the resin solid content.

  The obtained solution was filtered through a PTFE filter having a pore size of 0.2 μm to obtain a resin composition for forming a core layer. In addition, the content rate of the polymerization initiator in the resin composition for core formation was 0.005 mass% or less.

(2) Production of Cladding Layer Forming Resin Composition Next, in a glove box filled with dry nitrogen, hexyl norbornene (HxNB) and diphenylmethylnorbornene methoxysilane (diPhNB) are weighed into a 500 mL vial. After mesitylene was added thereto, the mixture was sealed with a silicon sealer and stirred.

  The obtained solution was filtered with a PTFE filter having a pore size of 0.2 μm to obtain a resin composition for forming a cladding layer.

(3) Production of lower clad layer Next, a marked substrate was prepared. In addition, the glass substrate was used for the base material, and the chromium-type thin film vapor-deposited on the glass substrate was used for the mark. The mark pattern was the same as the core part to be formed, and the mark was used as a mask.

Next, the clad layer forming resin composition was uniformly applied to the mark side of the marked substrate by spin coating, and then heated at 50 ° C. for 10 minutes. After removing the solvent, the entire surface was irradiated with ultraviolet rays with a UV exposure machine to cure the coated resin composition for forming a clad layer. Furthermore, it heated for 10 minutes with a 150 degreeC hotplate. As a result, a lower cladding layer having a thickness of 10 μm was obtained. The cumulative amount of ultraviolet light was 1000 mJ / cm ² .

(4) Preparation of core formation layer Next, the resin composition for core layer formation was apply | coated to the upper surface of a lower clad layer, and it heated at 50 degreeC for 10 minute (s). Thereby, the solvent was removed to obtain a core forming layer.

(5) Irradiation of ultraviolet rays Next, the obtained core forming layer was irradiated with ultraviolet rays from the marked substrate side. The cumulative amount of ultraviolet light was 1000 mJ / cm ² .

Next, the core forming layer and the like irradiated with ultraviolet rays were heated on a hot plate at 150 ° C. for 30 minutes. As a result, a core layer having a thickness of 10 μm formed by forming a core portion having a width of 10 μm and a side cladding portion having a width of 250 μm was formed.
An optical waveguide was obtained as described above.

(Examples 2 to 11)
An optical waveguide was obtained in the same manner as in Example 1 except that the compounds contained in the core layer forming resin composition were changed as shown in Tables 1 and 2.

(Comparative example)
First, a lower clad layer was produced in the same manner as in Example 1.
Next, in the same manner as in Example 1, a core forming layer was produced on the upper surface of the lower clad layer.

  Next, in the same manner as in Example 1, the core forming layer was irradiated with ultraviolet rays. The core forming layer after ultraviolet irradiation was heated at 45 ° C. for 20 minutes.

Next, the core forming layer was immersed in the developer for 2 minutes to dissolve the non-irradiated area.
Next, the core forming layer was heated on a hot plate at 150 ° C. for 30 minutes to obtain a core part having a thickness of 10 μm.
The abbreviations shown in Tables 1 and 2 are the structural units shown below.

2. 2. Evaluation of optical waveguide 2.1 Propagation loss The obtained optical waveguide was compliant with the 4.6.2.1 cut-back method of “Testing method for polymer optical waveguide (JPCA-PE02-05-01S-2008)”. Thus, the propagation loss was obtained. In the measurement, light having a wavelength of 850 nm was used.
Then, the obtained propagation loss was evaluated in light of the following evaluation criteria.

<Evaluation criteria for propagation loss>
A: Propagation loss is less than 0.05 [dB / cm] O: Propagation loss is 0.05 [dB / cm] or more and less than 0.1 [dB / cm] Δ: Propagation loss is 0.1 [dB / cm] dB / cm] or more and less than 0.2 [dB / cm] x: Propagation loss is 0.2 [dB / cm] or more Tables 1 and 2 show the above evaluation results.

2.2 Folding resistance test Regarding the obtained optical waveguide, 6.1.2 of “Testing method for polymer optical waveguide (JPCA-PE02-05-01S-2008)” prescribed by Japan Electronic Circuits Association. A test for bending while applying a tensile force was performed in accordance with a folding test. And the increment of the insertion loss after the test with respect to the insertion loss before the test was calculated, and this was evaluated against the following evaluation criteria.

  In the measurement, light having a wavelength of 850 nm was used. The tensile load was 5 N, the rotation speed was 90 times per minute, the bending angle was 135 °, the number of bendings was 1000 times, and the bending radius was 2 mm.

<Evaluation criteria for folding resistance test>
A: The increment is very small (less than 0.2 dB)
B: Small increment (0.2 dB or more and less than 0.5 dB)
C: Increment is slightly small (0.5 dB or more and less than 1.0 dB)
D: Slightly large increment (1.0 dB or more and less than 1.5 dB)
E: The increment is large (1.5 dB or more and less than 2 dB)
F: The increment is very large (2 dB or more)
The above evaluation results are shown in Tables 1 and 2.

  As is clear from Tables 1 and 2, the optical waveguide of each example had a small propagation loss, and a significant increase in insertion loss was suppressed even after undergoing a bending resistance test. From this, it has been recognized that according to the present invention, an optical waveguide with high propagation efficiency can be realized even in a harsh environment.

DESCRIPTION OF SYMBOLS 1 Optical waveguide 2 Optical interposer 3 Mounting board 5 Optical connector 6 Adhesive 7 Marked base material 9 Optical fiber 10 Optical waveguide connector 11 Lower clad layer 12 Upper clad layer 13 Core layer 14 Core part 15 Side clad part 16 Support layer 17 Cover layer 21 Interposer substrate 22 Light guide portion 23 Conductive portion 24 Bump 25 Semiconductor element 26 Light emitting / receiving element 31 Insulating substrate 32 Conductive layer 50 Through hole 51 Connector body 71 Base material 72 Mark 91 Optical connector 101 Left end surface 102 Right end surface 103 Lower surface 104 Upper surface 105 Left upper surface 121 Left end surface 130 Core forming layer L Actinic radiation

Claims (8)

A core portion containing a first compound having a functional group dimerizable by light irradiation;
A side clad part including a second compound that is provided adjacent to a side surface of the core part and is formed by dimerizing the first compound via the functional group;
An optical waveguide comprising:   The optical waveguide according to claim 1, wherein the functional group includes an unsaturated bond that causes a [2 + 2] cyclization reaction.   The optical waveguide according to claim 2, wherein the functional group is a maleimide group.   The optical waveguide according to any one of claims 1 to 3, wherein the first compound includes a cyclic olefin structure in a main chain and the functional group in a side chain.   The optical waveguide according to claim 1, wherein the waveguide mode is a single mode.   The optical waveguide according to any one of claims 1 to 5, wherein a content of the polymerization initiator in the side clad portion is 0.01% by mass or less. The optical waveguide according to any one of claims 1 to 6,
An optical component optically connected to the optical waveguide;
An optical waveguide connector comprising:   An electronic apparatus comprising the optical waveguide connector according to claim 7.

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