JP4024729B2 - Manufacturing method of optical waveguide - Google Patents

Manufacturing method of optical waveguide Download PDF

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JP4024729B2
JP4024729B2 JP2003290915A JP2003290915A JP4024729B2 JP 4024729 B2 JP4024729 B2 JP 4024729B2 JP 2003290915 A JP2003290915 A JP 2003290915A JP 2003290915 A JP2003290915 A JP 2003290915A JP 4024729 B2 JP4024729 B2 JP 4024729B2
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refractive index
photocurable resin
optical path
resin liquid
path portion
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JP2005062365A (en
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達弥 山下
学 各務
幸利 伊縫
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Toyoda Gosei Co Ltd
Toyota Central R&D Labs Inc
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Toyota Central R&D Labs Inc
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Description

本発明は簡便・安価な光伝送路の製造方法並びにその製法に好適な材料の組成に関する。本発明の光導波路の製造方法は、光ファイバー通信分野における安価で低損失な光インターコネクション、光分波器あるいは合波器等の光導波路部品の製造に応用可能である。   The present invention relates to a simple and inexpensive method for producing an optical transmission line and a composition of a material suitable for the production method. The optical waveguide manufacturing method of the present invention can be applied to the manufacture of optical waveguide components such as inexpensive and low-loss optical interconnections, optical demultiplexers, and multiplexers in the field of optical fiber communications.

光硬化性樹脂液にビーム状の所定波長光を導入し、自己集光現象を利用して、光導波路デバイスを形成する技術が注目されている。例えば、本願共同出願人による下記特許文献１、２に記載された光導波路の製造方法がある。また、本願出願人以外の出願人によるものとしては下記特許文献３、４に記載された技術が知られている。これら各案件は、コアを高屈折率とし、当該コアを覆う外部を全て低屈折率のクラッドとするものである。この際、高屈折率の光硬化性樹脂液を硬化させてコアとしたのち、コア外部の低屈折率の光硬化性樹脂液、又は外部の高屈折率の光硬化性樹脂液と低屈折率の光硬化性樹脂液の混合溶液を硬化させるものである。尚、本願で「光硬化性樹脂液」とは、光重合開始剤と、それにより重合及び硬化可能なモノマー、オリゴマー、及び／又はコポリマーの混合物を言うものとする。
特開２０００−３４７０４３号公報 特開２００２−１６９０３８号公報 特開２００２− ３１７３３号公報 特開２００２−２５８０９５号公報 一方、本願共同出願人による特願２００２−３１３４２１においては、高屈折率の光硬化性樹脂液と低屈折率の光硬化性樹脂液の混合溶液において、高屈折率の光硬化性樹脂液を取り込んだ形で低屈折率の光硬化性樹脂液を選択的に硬化させ、外周部に低屈折率の光硬化性樹脂硬化物を漏光により付着させたのち、全体を硬化させる製造方法を出願した。これは、上記４文献記載の技術とは全く別の光導波路の製造方法であって、当該混合溶液が硬化した高屈折率の光路部分と、その外周に形成されたより低屈折率の樹脂成分の多い低屈折率部分と、更にその外部の当該混合溶液が硬化した高屈折率の部分を有する光導波路の製造方法である。 A technique for forming an optical waveguide device by introducing a light beam having a predetermined wavelength into a photocurable resin liquid and utilizing a self-condensing phenomenon has attracted attention. For example, there is an optical waveguide manufacturing method described in the following Patent Documents 1 and 2 by the present applicant. Moreover, the technique described in the following patent documents 3 and 4 is known as a thing by applicants other than the present applicant. In each of these cases, the core has a high refractive index, and the outside covering the core is all made of a low refractive index cladding. At this time, after curing a high refractive index photocurable resin liquid to form a core, a low refractive index photocurable resin liquid outside the core, or an external high refractive index photocurable resin liquid and a low refractive index. The photo-curable resin liquid mixed solution is cured. In the present application, the “photocurable resin liquid” refers to a mixture of a photopolymerization initiator and monomers, oligomers, and / or copolymers that can be polymerized and cured thereby.
JP 2000-347043 A JP 2002-169038 A JP 2002-31733 A On the other hand, in Japanese Patent Application No. 2002-313421 by the joint applicant of the present application, a high refractive index mixed solution of a high refractive index photocurable resin liquid and a low refractive index photocurable resin liquid is used. The photocurable resin liquid with a low refractive index is selectively cured in the form of taking in the photocurable resin liquid, and the cured product with a low refractive index is attached to the outer periphery by light leakage, and then the whole is cured. Filed a manufacturing method. This is an optical waveguide manufacturing method that is completely different from the technique described in the above four literatures, in which a high refractive index optical path portion obtained by curing the mixed solution and a resin component having a lower refractive index formed on the outer periphery thereof. This is a method of manufacturing an optical waveguide having many low refractive index portions and a high refractive index portion obtained by curing the mixed solution outside thereof.

上記特許文献１乃至４の従来技術である、高屈折率の光硬化性樹脂液を硬化させてコアとしたのち、コア外部の高屈折率の光硬化性樹脂液と低屈折率の光硬化性樹脂液の混合溶液を硬化させるとの技術においては、高屈折率の光硬化性樹脂液を選択的に硬化させる必要がある。ここで、高屈折率の光硬化性樹脂液と低屈折率の光硬化性樹脂液の混合溶液を用いて高屈折率の光硬化性樹脂液を選択的に硬化させてコアとするとき、当該コアにできるだけ低屈折率の光硬化性樹脂液が含まれないように、即ち低屈折率の光硬化性樹脂液を外部へ拡散させるためには、コア形成の速度を所定値以上に大きくすることができない。また、高屈折率の光硬化性樹脂液のみを用いてコアを形成し、洗浄したのちに外部のクラッドを形成する場合は、更に製造時間が長くなる。   The prior art disclosed in Patent Documents 1 to 4 is obtained by curing a high-refractive index photocurable resin liquid to obtain a core, and then a high-refractive index photocurable resin liquid outside the core and a low-refractive index photocurable property. In the technique of curing a mixed solution of resin liquids, it is necessary to selectively cure a photocurable resin liquid having a high refractive index. Here, when a high refractive index photocurable resin solution is selectively cured using a mixed solution of a high refractive index photocurable resin solution and a low refractive index photocurable resin solution, In order to prevent the core from containing a low refractive index photocurable resin liquid as much as possible, that is, to diffuse the low refractive index photocurable resin liquid to the outside, the core formation speed should be increased to a predetermined value or more. I can't. Further, in the case where the core is formed using only the high refractive index photocurable resin liquid and the outer cladding is formed after cleaning, the manufacturing time is further increased.

本発明者らは鋭意検討の結果、当該特願２００２−３１３４２１の技術を更に改良し、光導波路の製造をより容易にし且つその生産性を向上させることができた。即ち本発明は、混合溶液が硬化した高屈折率の光路部分と、その外周に形成されるより低屈折率の樹脂成分の多い低屈折率部分と、更にその外部の当該混合溶液が硬化した高屈折率の部分を有する光導波路の製造方法である。   As a result of intensive studies, the present inventors have further improved the technique of the Japanese Patent Application No. 2002-31421, making it easier to manufacture an optical waveguide and improving its productivity. That is, the present invention provides a high-refractive index optical path portion in which the mixed solution is cured, a low-refractive index portion having a higher amount of a resin component having a lower refractive index formed on the outer periphery thereof, and a high-cured portion in which the mixed solution outside is further cured. This is a method of manufacturing an optical waveguide having a refractive index portion.

本発明は、硬化機構の異なる低屈折率の第１の光硬化性樹脂液と高屈折率の第２の光硬化性樹脂液の混合溶液を用い、第１の光硬化性樹脂液を硬化させるが第２の光硬化性樹脂液を硬化させない第１の光照射により、第２の光硬化性樹脂液を取り込む形で第１の光硬化性樹脂液を硬化させ、光が透過する光路部分を形成する第１の光硬化工程と、光路部分を形成した後、第１の光照射を止めて所定時間静置することで、前記光路部分の表層へ光路部分の外部の混合溶液から未硬化の第１の光硬化性樹脂液を拡散させる拡散工程と、第１の光硬化性樹脂液と第２の光硬化性樹脂液の両方を硬化させる第２の光照射により、少なくとも前記光路部分の表層へ拡散した未硬化の第１の光硬化性樹脂液及び前記光路部分の第２の光硬化性樹脂液を硬化させる第２の光硬化工程とから成り、屈折率の高い光路部分と、その表層の低屈折率部分とを有する光導波路を製造する方法である。また、関連発明は、第１の光照射は、光ファイバにより供給されることを特徴とする。尚、本発明において、屈折率の高い光路部分とその表層部分の低屈折率部分との構成は、いわゆるステップインデックス型の屈折率分布を形成することに限定されない。即ち、屈折率が連続的に変化するもの、たとえばいわゆるグレーデッドインデックス型の屈折率分布のものであっても本願発明に包含される。   The present invention cures a first photocurable resin liquid using a mixed solution of a low refractive index first photocurable resin liquid and a high refractive index second photocurable resin liquid having different curing mechanisms. However, the first photo-curable resin liquid is cured by taking in the second photo-curable resin liquid by the first light irradiation that does not cure the second photo-curable resin liquid, and an optical path portion through which light passes is formed. After forming the first light curing step to be formed and the optical path part, the first light irradiation is stopped and left for a predetermined time, so that the surface layer of the optical path part is uncured from the mixed solution outside the optical path part. At least the surface layer of the optical path portion by the diffusion step of diffusing the first photocurable resin liquid and the second light irradiation for curing both the first photocurable resin liquid and the second photocurable resin liquid. Cured uncured first photocurable resin liquid and second photocurable resin liquid in the optical path portion It composed of a second photo-curing step of the high light path portion refractive index, a method of manufacturing an optical waveguide having a low refractive index portion of the surface layer. The related invention is characterized in that the first light irradiation is supplied by an optical fiber. In the present invention, the configuration of the optical path portion having a high refractive index and the low refractive index portion of the surface layer portion is not limited to forming a so-called step index type refractive index distribution. That is, even those whose refractive index continuously changes, for example, a so-called graded index type refractive index distribution are also included in the present invention.

本発明の作用を説明する。まず光学的に透明な光路部分を選択的に形成する。ただし当該光路部分は、未硬化の高屈折率の第２の光硬化性樹脂液が低屈折率の第１の光硬化性樹脂の硬化物中に取り込まれたままであって、のちの全体の硬化で初めて設計された屈折率、即ち当初の混合溶液をそのまま硬化させた場合の屈折率を有する光路となるものである。この際、低屈折率の第１の光硬化性樹脂の硬化物中には未硬化の第１の光硬化性樹脂液が存在しなくても良く、また存在していてもかまわない。   The operation of the present invention will be described. First, an optically transparent optical path portion is selectively formed. However, in the optical path portion, the uncured high-refractive-index second photo-curable resin liquid is still taken into the cured product of the low-refractive-index first photo-curable resin, and the entire curing is performed later. The optical path has a refractive index designed for the first time, that is, a refractive index when the original mixed solution is cured as it is. At this time, the uncured first photocurable resin liquid may or may not exist in the cured product of the low refractive index first photocurable resin.

この後光照射を止めた際、低屈折率の第１の光硬化性樹脂の硬化物中に取り込まれた液状成分において、未硬化の第１の光硬化性樹脂液の濃度の、未硬化の第２の光硬化性樹脂液の濃度に対する比は、当該第１の光硬化性樹脂液が硬化して固形分となった分だけ、当初の混合溶液における未硬化の第１の光硬化性樹脂液の濃度の、未硬化の第２の光硬化性樹脂液の濃度に対する比よりも小さくなっている。一方、光路部分の外部は当初の混合溶液であり、未硬化の第１の光硬化性樹脂液の濃度の、未硬化の第２の光硬化性樹脂液の濃度に対する比は変化が無い。すると光照射を止めた際、光路表面を境界として、未硬化の第１の光硬化性樹脂液と未硬化の第２の光硬化性樹脂液について、当初の混合溶液の濃度比を有する光路部分外部と、当該濃度比よりも未硬化の第１の光硬化性樹脂液の濃度が小さい光路部分の表層とが隣接することとなる。   Thereafter, when the light irradiation is stopped, in the liquid component taken into the cured product of the low refractive index first photocurable resin, the concentration of the uncured first photocurable resin liquid is uncured. The ratio to the concentration of the second photocurable resin liquid is the uncured first photocurable resin in the original mixed solution by the amount that the first photocurable resin liquid is cured to become a solid content. The ratio of the liquid concentration to the concentration of the uncured second photocurable resin liquid is smaller. On the other hand, the outside of the optical path portion is the original mixed solution, and the ratio of the concentration of the uncured first photocurable resin liquid to the concentration of the uncured second photocurable resin liquid does not change. Then, when the light irradiation is stopped, the optical path portion having the concentration ratio of the initial mixed solution with respect to the uncured first photocurable resin liquid and the uncured second photocurable resin liquid with the optical path surface as the boundary The outside and the surface layer of the optical path portion where the concentration of the uncured first photocurable resin liquid is smaller than the concentration ratio are adjacent to each other.

この濃度の差により、光路部分外部の混合溶液から光路部分の表層へ未硬化の第１の光硬化性樹脂液が拡散し、光路部分の表層から光路部分外部の混合溶液へ未硬化の第２の光硬化性樹脂液が拡散することとなる。こうして、光路部分の表層においては、その液状成分において、未硬化の第１の光硬化性樹脂液の濃度と未硬化の第２の光硬化性樹脂液の濃度が、光路部分外部と極めて近いものとなる。この拡散は、光路部分の内部へも伝播していくが、第１の光硬化性樹脂の硬化物が障害となるため、光路部分表層以外の光路部分では極めて拡散速度が遅い。一方、光路部分外部においては、混合溶液の粘度に依存するが比較的拡散速度は速いものと考えられる。   Due to the difference in concentration, the uncured first photocurable resin liquid diffuses from the mixed solution outside the optical path portion to the surface layer of the optical path portion, and the second uncured second liquid from the surface layer of the optical path portion to the mixed solution outside the optical path portion. The photocurable resin liquid will diffuse. Thus, in the surface layer of the optical path portion, in the liquid component, the concentration of the uncured first photocurable resin liquid and the concentration of the uncured second photocurable resin liquid are very close to the outside of the optical path portion. It becomes. Although this diffusion propagates also to the inside of the optical path portion, the cured product of the first photocurable resin becomes an obstacle, so that the diffusion speed is extremely slow in the optical path portion other than the optical path portion surface layer. On the other hand, the diffusion rate is considered to be relatively fast outside the optical path portion, depending on the viscosity of the mixed solution.

上記拡散は、液状成分での未硬化の第１の光硬化性樹脂液と未硬化の第２の光硬化性樹脂液の濃度比の差が小さくなるように生じるものである。さて、光路部分の表層においては既に硬化した低屈折率の第１の光硬化性樹脂の硬化物が存在する。すると、第２の光照射により残余の未硬化の光硬化性樹脂液を硬化させた場合、光路部分の表層の硬化物における第１の光硬化性樹脂硬化物の濃度は、光路部分外部の硬化物における第１の光硬化性樹脂硬化物の濃度よりも大きくなる。すると光路部分の表層においては、低屈折率の第１の光硬化性樹脂硬化物の濃度が、光路部分外部の硬化物における低屈折率の第１の光硬化性樹脂硬化物の濃度よりも大きい。これは光路部分の表層の屈折率が、光路部分外部の硬化物における屈折率よりも小さくなることを意味する。   The diffusion occurs so that the difference in the concentration ratio between the uncured first photocurable resin liquid and the uncured second photocurable resin liquid in the liquid component becomes small. By the way, in the surface layer of the optical path portion, there is a cured product of the first photocurable resin having a low refractive index that has already been cured. Then, when the remaining uncured photocurable resin liquid is cured by the second light irradiation, the concentration of the first photocurable resin cured product in the cured product of the surface layer of the optical path portion is the curing outside the optical path portion. It becomes larger than the density | concentration of the 1st photocurable resin hardened | cured material in a thing. Then, in the surface layer of the optical path portion, the concentration of the low refractive index first photocurable resin cured product is higher than the concentration of the low refractive index first photocurable resin cured product in the cured product outside the optical path portion. . This means that the refractive index of the surface layer of the optical path portion is smaller than the refractive index of the cured product outside the optical path portion.

光路部分の中心軸付近では、上述の液状成分での未硬化の第１の光硬化性樹脂液の拡散の影響は小さい。すると硬化後の光路部分の第１の光硬化性樹脂硬化物の濃度は、光路部分の外部の第１の光硬化性樹脂硬化物の濃度とほぼ等しい。以上総合すると、光路部分は高屈折率、光路部分の表層は低屈折率、光路部分の外部は高屈折率となる、光導波路が形成される。本発明はいわゆるステップインデックス型とは異なるが、以下の記載で光路部分の表層以外をコア、光路部分の表層をクラッドと呼ぶことがある。尚、第１の光照射により形成される「光路部分」は、のちの工程でコア及びクラッドとなるものであって、光路部分の表層は、光路部分の内側に形成される。   In the vicinity of the central axis of the optical path portion, the influence of diffusion of the uncured first photocurable resin liquid with the above-described liquid component is small. Then, the density | concentration of the 1st photocurable resin hardened | cured material of the optical path part after hardening is substantially equal to the density | concentration of the 1st photocurable resin hardened | cured material outside the optical path part. In summary, an optical waveguide is formed in which the optical path portion has a high refractive index, the surface layer of the optical path portion has a low refractive index, and the outside of the optical path portion has a high refractive index. Although the present invention is different from the so-called step index type, in the following description, a portion other than the surface layer of the optical path portion may be called a core, and a surface layer of the optical path portion may be called a clad. The “optical path portion” formed by the first light irradiation becomes a core and a clad in a later process, and the surface layer of the optical path portion is formed inside the optical path portion.

光路部分の形成においては、未硬化の高屈折率の第２の光硬化性樹脂液が低屈折率の第１の光硬化性樹脂の硬化物中に取り込まれるよう、速い光硬化が行われ、且つ、その光硬化後、所定時間光照射を停止して静置するだけで光路部分表層に低屈折率樹脂の濃度が元の混合溶液に比べて大きな部分が形成できる。こののち全体を光硬化させれば良い。このように本発明によれば、本発明者らが開発した以前のいずれの技術よりも、容易且つ生産性良く光導波路を形成することができる。本発明はコアを形成したのちの洗浄工程を必要としないので、比較的粘度の高いモノマー等を光硬化性樹脂液として用いることが可能であって、且つ小型の光モジュール等の大量生産に適している。   In the formation of the optical path portion, fast photocuring is performed so that the uncured high refractive index second photocurable resin liquid is taken into the cured product of the low refractive index first photocurable resin, Moreover, after the photocuring, a portion where the concentration of the low refractive index resin is larger than that of the original mixed solution can be formed on the surface layer of the optical path only by stopping the light irradiation for a predetermined time and allowing to stand. After that, the whole may be photocured. Thus, according to the present invention, an optical waveguide can be formed more easily and with higher productivity than any of the previous techniques developed by the present inventors. Since the present invention does not require a cleaning step after forming the core, it is possible to use a monomer having a relatively high viscosity as the photocurable resin liquid, and suitable for mass production of small optical modules and the like. ing.

更に、光ファイバで第１の光照射を行えば、当該光ファイバと整合する、細いコアを有する光導波路を容易に製造することができる。   Furthermore, if the first light irradiation is performed with an optical fiber, an optical waveguide having a thin core that matches the optical fiber can be easily manufactured.

本発明を実施するための個々の構成の具体例は次のようなものが例示される。まず、硬化機構の異なる２つの光硬化性樹脂液を用意する必要がある。ここで、硬化機構の異なるとは、たとえばラジカル重合、カチオン重合、アニオン重合から２種類選択すると良い。低屈折率の光硬化性樹脂液の光重合開始剤は、高屈折率の光硬化性樹脂液の光重合開始剤よりも、低波長の光で活性化されるものを選択すると良い。   Specific examples of individual configurations for carrying out the present invention are as follows. First, it is necessary to prepare two photocurable resin liquids having different curing mechanisms. Here, two different curing mechanisms may be selected from radical polymerization, cationic polymerization, and anionic polymerization, for example. As the photopolymerization initiator for the low-refractive index photocurable resin liquid, a photopolymerization initiator that is activated by light having a lower wavelength than the photopolymerization initiator for the high-refractive index photocurable resin liquid may be selected.

光ラジカル重合を行うモノマーとしては、（メタ）アクリル酸エステル、（メタ）アクリル酸アミドが好ましい。具体的には（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸２−ブトキシエチル等の１官能性（メタ）アクリル酸エステル（モノ（メタ）アクリレート）を用いることができる。また、エチレングリコール、ネオペンチルグリコール、１，６−ヘキサンジオール等のジオールと２等量の（メタ）アクリル酸とのエステル（ジ（メタ）アクリレート）を用いることができる。同様に、アルコール性水酸基を複数有する有機化合物と（メタ）アクリル酸とのエステル（トリ、テトラ、…（メタ）アクリレート）を用いることができる。尚、これらのモノマーにおいて、（メタ）アクリロイル基及びその他の有機骨格のメチル水素、メチレン水素、メチン水素の一部をハロゲンで置換したものでも良い。又、これらモノマーを適当に組み合わせて用いても良い。   As a monomer which performs radical photopolymerization, (meth) acrylic acid ester and (meth) acrylic acid amide are preferable. Specifically, monofunctional (meth) acrylic acid esters (mono (meth) acrylates) such as 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-butoxyethyl (meth) acrylate are used. Can do. Further, an ester (di (meth) acrylate) of diol such as ethylene glycol, neopentyl glycol, 1,6-hexanediol and 2 equivalents of (meth) acrylic acid can be used. Similarly, an ester (tri, tetra,... (Meth) acrylate) of an organic compound having a plurality of alcoholic hydroxyl groups and (meth) acrylic acid can be used. In these monomers, a part of methyl hydrogen, methylene hydrogen and methine hydrogen in the (meth) acryloyl group and other organic skeletons may be substituted with halogen. These monomers may be used in appropriate combinations.

光ラジカル重合を行うオリゴマー（マクロモノマー）としては、末端又は分岐に（メタ）アクリロイル基を有するウレタン系オリゴマー、ポリエーテル系オリゴマー、エポキシ系オリゴマー、ポリエステル系オリゴマーなどが好ましい。尚、これらのオリゴマーにおいて、（メタ）アクリロイル基及びその他の有機骨格のメチル水素、メチレン水素、メチン水素の一部をハロゲンで置換したものでも良い。又、これらオリゴマーを前記モノマーと適当に組み合わせたものを用いても良い。   As the oligomer (macromonomer) for performing radical photopolymerization, a urethane-based oligomer, a polyether-based oligomer, an epoxy-based oligomer, a polyester-based oligomer having a (meth) acryloyl group at the terminal or branch is preferable. In these oligomers, a part of methyl hydrogen, methylene hydrogen, and methine hydrogen in the (meth) acryloyl group and other organic skeletons may be substituted with halogen. Moreover, you may use what combined these oligomers with the said monomer suitably.

光ラジカル重合開始剤としては、ベンジルジメチルケタール系化合物としては２，２−ジメトキシ−２−フェニルアセトフェノン、α−ヒドロキシケトン系化合物としては２−ヒドロキシ−２−メチル−フェニルプロパン−１−オン、（１−ヒドロキシシクロヘキシル）−フェニルケトン、α−アミノケトン系化合物としては２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタン−１−オン、２−メチル−１−（４−（メチルチオ）フェニル）−２−モルホリノプロパン−１−オン、ビスアシルホスフィンオキシド系化合物としてはビス（２，６−ジメトキシベンゾイル）−２，４，４−トリメチル−ペンチルホスフィンオキシド、ビス（２，４，６−トリメチルベンゾイル）−フェニルホスフィンオキシド、メタロセン系化合物としてはビス（η−シクロペンタジエニル）−ビス（２，６−ジフルオロ−３−（Ｎ−ピロイル）フェニル）チタンなどを用いることができる。これらを複数種類用いても良い。   As a radical photopolymerization initiator, 2,2-dimethoxy-2-phenylacetophenone as a benzyldimethyl ketal compound, 2-hydroxy-2-methyl-phenylpropan-1-one as an α-hydroxyketone compound, ( 1-hydroxycyclohexyl) -phenyl ketone and α-aminoketone compounds include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- (4- ( Methylthio) phenyl) -2-morpholinopropan-1-one, and bisacylphosphine oxide compounds include bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, bis (2,4,4) 6-Trimethylbenzoyl) -phenylphosphine oxide, metallo As the senic compound, bis (η-cyclopentadienyl) -bis (2,6-difluoro-3- (N-pyroyl) phenyl) titanium or the like can be used. A plurality of these may be used.

光カチオン重合を行うモノマー或いはオリゴマーとしては、エポキシ環、オキセタン環ほか環状エーテルを有する化合物、環状ラクトン化合物、環状アセタール化合物、ビニルエーテル化合物等のモノマー或いはオリゴマーを用いることができる。又、これらモノマー或いはオリゴマーを適当に組み合わせたものを用いても良い。   As the monomer or oligomer for performing cationic photopolymerization, monomers or oligomers such as an epoxy ring, an oxetane ring, a compound having a cyclic ether, a cyclic lactone compound, a cyclic acetal compound, and a vinyl ether compound can be used. Moreover, you may use what combined these monomers or oligomers appropriately.

光カチオン重合開始剤としては、４，４’−ビス（ジ（２−ヒドロキシエトキシ）フェニルスルホニオ）フェニルスルフィド二ヘキサフルオロアンチモン酸、η−シクロペンタジエニル−η−クメン鉄（１＋）−ヘキサフルオロリン酸（１−）などを用いることができる。   As a photocationic polymerization initiator, 4,4′-bis (di (2-hydroxyethoxy) phenylsulfonio) phenyl sulfide dihexafluoroantimonic acid, η-cyclopentadienyl-η-cumene iron (1 +)-hexa Fluorophosphoric acid (1-) or the like can be used.

上記述の光ラジカル重合開始剤又は光カチオン重合開始剤に、光増感剤を加えても良い。更に、必要に応じて、重合禁止剤、紫外線吸収剤、光安定剤、酸化防止剤、レベリング剤、消泡剤その他の添加剤を配合することができる。以上のような組み合わせにより、本発明に用いる光硬化性液状樹脂組成物とすることができる。また、光アニオン重合性の重合開始剤とモノマー又はオリゴマーの組み合わせを用いても良く、チオール・エン付加による重合を用いても良い。   A photosensitizer may be added to the above-mentioned photo radical polymerization initiator or photo cationic polymerization initiator. Furthermore, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, a leveling agent, an antifoaming agent and other additives can be blended as necessary. By the combination as described above, the photocurable liquid resin composition used in the present invention can be obtained. Further, a combination of a photoanion polymerizable polymerization initiator and a monomer or oligomer may be used, or polymerization by thiol / ene addition may be used.

光が透過する光路部分の表層部分に未硬化の第１の光硬化性樹脂液を拡散させる拡散工程における静置する所定時間については、短ければ急峻な低屈折率部分が形成される。また、静置する所定時間が長ければ、光が透過する光路部分の表層部分から光路部分の中心部に向けて、なだらかに屈折率が上昇するような屈折率分布となる。   A steep low refractive index portion is formed if the predetermined time for standing in the diffusion step of diffusing the uncured first photocurable resin liquid on the surface layer portion of the optical path portion through which light passes is shorter. Further, if the predetermined time for standing still is long, the refractive index distribution is such that the refractive index gradually increases from the surface layer portion of the optical path portion through which light is transmitted toward the center portion of the optical path portion.

第１の光硬化性樹脂液として、ラジカル重合性モノマーであるサートマー社製商品名「SR-454」（屈折率1.471）を60部、ラジカル重合型可視光重合開始剤を0.5部、第２の光硬化性樹脂液として、カチオン重合性モノマーとして、ジャパンエポキシレジン社製商品名「エピコート828」（屈折率1.574）を40部、カチオン重合型紫外光重合開始剤を3.0部混合し、光硬化性樹脂液の混合溶液を調製した。この混合溶液の硬化前の屈折率は1.514、紫外線照射により混合溶液全体を硬化させた場合の硬化物の屈折率は1.543であった。本実施例では、ラジカル重合性モノマーである商品名「SR-454」（屈折率1.471）とラジカル重合型可視光重合開始剤との混合物が第１の光硬化性樹脂液にあたり、カチオン重合性モノマーである商品名「エピコート828」とカチオン重合型紫外光重合開始剤との混合物が第２の光硬化性樹脂液にあたる。尚、各商品名と主要成分の化学名を表１に示す。   As a first photocurable resin liquid, 60 parts of a trade name “SR-454” (refractive index: 1.471) manufactured by Sartomer, which is a radical polymerizable monomer, 0.5 parts of a radical polymerization type visible light polymerization initiator, a second As a photocurable resin liquid, as a cationic polymerizable monomer, 40 parts of the product name “Epicoat 828” (refractive index of 1.574) manufactured by Japan Epoxy Resin Co., Ltd. and 3.0 parts of a cationic polymerization type ultraviolet photoinitiator are mixed and photocured. A mixed solution of the resin liquid was prepared. The refractive index of the mixed solution before curing was 1.514, and the refractive index of the cured product when the entire mixed solution was cured by ultraviolet irradiation was 1.543. In this example, a mixture of a trade name “SR-454” (refractive index 1.471), which is a radical polymerizable monomer, and a radical polymerization type visible light polymerization initiator is the first photocurable resin liquid, and the cationic polymerizable monomer. A mixture of the product name “Epicoat 828” and a cationic polymerization type ultraviolet photopolymerization initiator corresponds to the second photocurable resin liquid. The trade names and chemical names of main components are shown in Table 1.

Figure 0004024729
図１は、本実施例の工程を示す工程図である。まず、図１の（ａ）のように、透明容器１に上記混合溶液２を充填し、プラスチック製光ファイバ３の片側を浸漬した。プラスチック製光ファイバ３としては三菱レイヨン社製の商品名「エスカミウ」（コア径0.73mm、開口数0.25）を用いた。
Figure 0004024729
 FIG. 1 is a process diagram showing the steps of the present embodiment. First, as shown in FIG. 1A, the transparent solution 1 was filled with the mixed solution 2, and one side of the plastic optical fiber 3 was immersed. As the plastic optical fiber 3, a trade name “Escamiu” (core diameter 0.73 mm, numerical aperture 0.25) manufactured by Mitsubishi Rayon Co., Ltd. was used.

次に、プラスチック製光ファイバ３の他端から波長458nmのレーザー光λ1を入射させ、プラスチック製光ファイバ３の浸漬した先端から混合溶液２に射出させた。レーザー光λ1のパワーは5mWとした。こうして、自己集光現象により、プラスチック製光ファイバ３の浸漬した先端から混合溶液２のうち、ラジカル重合開始剤のみが活性化して、屈折率1.471のラジカル重合性モノマー（第１の光硬化性樹脂液）が、未硬化の屈折率1.574のカチオン重合性モノマー（第２の光硬化性樹脂液）を取り込みながら、軸状に硬化して、一部未硬化の光路部分４が成長した（図１の（ｂ））。こうして、16秒で長さ18mmの一部未硬化の光路部分４が形成された。次に、波長458nmのレーザー光λ1を止めて15分間、静置した。この時、一部未硬化の光路部分４の表層６には、以下に述べるように、未硬化のラジカル重合性モノマーが拡散していたことが明らかとなった。一方、一部未硬化の光路部分４の表層以外の部分５には未硬化のラジカル重合性モノマーが余り拡散していないことが明らかとなった。（図１の（ｃ））。 Next, a laser beam λ 1 having a wavelength of 458 nm was made incident from the other end of the plastic optical fiber 3, and emitted from the immersed tip of the plastic optical fiber 3 to the mixed solution 2. The power of the laser beam λ 1 was 5 mW. Thus, due to the self-condensing phenomenon, only the radical polymerization initiator in the mixed solution 2 is activated from the immersed tip of the plastic optical fiber 3, and the radical polymerizable monomer (first photocurable resin having a refractive index of 1.471) is activated. Liquid) was cured into an axial shape while taking in an uncured cationically polymerizable monomer (second photocurable resin liquid) having a refractive index of 1.574, and a partially uncured optical path portion 4 was grown (FIG. 1). (B)). Thus, a partially uncured optical path portion 4 having a length of 18 mm was formed in 16 seconds. Next, the laser beam λ 1 having a wavelength of 458 nm was stopped and left for 15 minutes. At this time, it was revealed that the uncured radical polymerizable monomer was diffused in the surface layer 6 of the partially uncured optical path portion 4 as described below. On the other hand, it became clear that the uncured radical polymerizable monomer was not diffused so much in the portion 5 other than the surface layer of the partially uncured optical path portion 4. ((C) of FIG. 1).

次に、透明容器１の外部から、高圧水銀ランプにより紫外線を照射し、混合溶液２のラジカル重合開始剤及びチオン重合開始剤のいずれをも活性化して、残余の未硬化のラジカル重合性モノマー及びカチオン重合性モノマーを全て硬化させた。こうして、一部未硬化であった光路部分４の表層以外の部分５及び光路部分４の表層６並びに混合溶液２は、高屈折率のコア部５'と低屈折率のクラッド部６'、それを取り囲む高屈折率部分である混合溶液の硬化物２'の３重構造となった。こうして光導波路１０を形成した（図１の（ｄ））。尚、第２の光硬化工程では、透明容器の外部からの照射に限られず、光路部分から入射しても良い。これにより、用途に応じて、混合溶液の硬化物２'を有さない光導波路を形成できる。   Next, ultraviolet rays are irradiated from the outside of the transparent container 1 with a high-pressure mercury lamp to activate both the radical polymerization initiator and the thione polymerization initiator of the mixed solution 2, and the remaining uncured radical polymerizable monomer and All cationically polymerizable monomers were cured. Thus, the portion 5 other than the surface layer of the optical path portion 4 and the surface layer 6 of the optical path portion 4 and the mixed solution 2 that were partially uncured are the high refractive index core portion 5 ′, the low refractive index cladding portion 6 ′, It became the triple structure of the hardened | cured material 2 'of the mixed solution which is the high refractive index part which surrounds. Thus, the optical waveguide 10 was formed ((d) in FIG. 1). In the second photocuring step, the irradiation is not limited to the irradiation from the outside of the transparent container, but may be incident from the optical path portion. Thereby, according to a use, the optical waveguide which does not have the hardened | cured material 2 'of a mixed solution can be formed.

光導波路１０の伝送損失と接続損失をカットバック法により測定したところ、各々2.1dB/cm、0.42dBであった。また、二光束干渉顕微鏡により屈折率分布を測定したところ、光導波路１０の長さ方向（コア部５'の中心軸方向）と垂直方向に屈折率分布が見られた。図２は、光導波路１０のコア部５'の中心軸（断面半径0μm）から垂直方向（断面半径方向）の屈折率分布を示すグラフ図である。コア部５'の中心軸付近は、上記混合溶液２をそのまま硬化させた場合の屈折率1.543と等しい屈折率であり、中心軸から離れるに従って若干の単調減少ののち、クラッド部６'において1.535まで急激に屈折率が低下する。次に混合溶液２をそのまま硬化させた場合の屈折率1.543よりも若干高い屈折率1.544の部分７を経て、混合溶液２をそのまま硬化させた場合の屈折率1.543の部分２'が透明容器１に達するまで続く。尚、屈折率変化は、極めて連続的に変化するものであって、いわゆるステップインデックス型とは異なるが、一方、いわゆるグレーデッドインデックス型にも当てはめがたいものであった。ただし、この分布は一例であって、使用する材料（特に粘度、モノマー等の分子量その他）と静置条件（温度、時間）に大きく依存するため、本願発明が図２の分布を生じさせるものに限定されるわけではない。   When the transmission loss and connection loss of the optical waveguide 10 were measured by the cut-back method, they were 2.1 dB / cm and 0.42 dB, respectively. Further, when the refractive index distribution was measured with a two-beam interference microscope, a refractive index distribution was found in the direction perpendicular to the length direction of the optical waveguide 10 (the central axis direction of the core portion 5 ′). FIG. 2 is a graph showing the refractive index distribution in the vertical direction (cross-sectional radial direction) from the central axis (cross-sectional radius 0 μm) of the core portion 5 ′ of the optical waveguide 10. In the vicinity of the central axis of the core portion 5 ′, the refractive index is equal to the refractive index of 1.543 when the mixed solution 2 is cured as it is, and after a slight monotonic decrease as the distance from the central axis increases, it reaches 1.535 in the cladding portion 6 ′. The refractive index decreases rapidly. Next, after passing through the portion 7 having a refractive index of 1.544, which is slightly higher than the refractive index of 1.543 when the mixed solution 2 is cured as it is, the portion 2 ′ of the refractive index of 1.543 when the mixed solution 2 is cured as it is is transferred to the transparent container 1. Continue until it reaches. Note that the refractive index change changes extremely continuously and is different from the so-called step index type, but it is not applicable to the so-called graded index type. However, this distribution is merely an example, and since the present invention greatly depends on the material used (particularly viscosity, molecular weight of monomers, etc.) and the standing conditions (temperature, time), the present invention causes the distribution shown in FIG. It is not limited.

さらに、FT-IRにより、コア部５'中心軸付近から半径方向にかけての樹脂組成について分析した。これによると、コア部５'中心軸付近においては、ラジカル重合性硬化物とカチオン重合性硬化物との組成比が0.6:0.4であったが、最も屈折率の低い部分においては、組成比が0.69:0.31であった。   Further, the resin composition from the vicinity of the central axis of the core 5 ′ to the radial direction was analyzed by FT-IR. According to this, in the vicinity of the central axis of the core portion 5 ′, the composition ratio of the radical polymerizable cured product to the cationic polymerizable cured product was 0.6: 0.4, but in the lowest refractive index portion, the composition ratio was It was 0.69: 0.31.

この組成分析から次のようなことが考察される。λ1の光照射を止めると、一部未硬化の光路部分４の表層６には、低屈折率のラジカル重合性硬化物(第１の光硬化性樹脂の硬化物)とその中に取り込まれた高屈折率のカチオン重合性モノマー（未硬化の第２の光硬化性樹脂液）が存在する。ここに低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）が存在したとしても、低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）と高屈折率のカチオン重合性モノマー（未硬化の第２の光硬化性樹脂液）の組成比は、低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）の一部が硬化により消費されたことにより６：４よりも小さくなっている。場合によっては０：４、即ち低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）が存在しない可能性もある。 The following is considered from this composition analysis. When the light irradiation of λ 1 is stopped, the surface layer 6 of the partially uncured optical path portion 4 is taken into the low-refractive-index radical polymerizable cured product (cured product of the first photo-curable resin). In addition, there is a high refractive index cationically polymerizable monomer (an uncured second photocurable resin liquid). Even if a low refractive index radical polymerizable monomer (uncured first photocurable resin liquid) is present here, a low refractive index radical polymerizable monomer (uncured first photocurable resin liquid). The composition ratio of the high refractive index cationic polymerizable monomer (uncured second photocurable resin liquid) is one of the low refractive index radical polymerizable monomer (uncured first photocurable resin liquid). Part is smaller than 6: 4 due to consumption by curing. In some cases, there is a possibility that 0: 4, that is, a low-refractive-index radical polymerizable monomer (uncured first photocurable resin liquid) does not exist.

しかし光路部分４の外部には、組成比６：４で、低屈折率のラジカル重合性モノマー（及びその重合開始剤、未硬化の第１の光硬化性樹脂液）と高屈折率のカチオン重合性モノマー（及びその重合開始剤、未硬化の第２の光硬化性樹脂液）が存在する。この光路部分４の表面を境界とした低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）と高屈折率のカチオン重合性モノマー（未硬化の第２の光硬化性樹脂液）の濃度の差が拡散を生じさせる。即ち、光路部分４の外部から光路部分４の表層６へ未硬化の第１の光硬化性樹脂液が拡散し、光路部分４の表層６から光路部分４の外部へ未硬化の第２の光硬化性樹脂液が拡散する。これにより、光路部分４の表面を境界として低屈折率のラジカル重合性モノマー（未硬化の第１の光硬化性樹脂液）と高屈折率のカチオン重合性モノマー（未硬化の第２の光硬化性樹脂液）の濃度の差が小さくなる。   However, outside of the optical path portion 4, the composition ratio is 6: 4, and a low refractive index radical polymerizable monomer (and its polymerization initiator, uncured first photocurable resin liquid) and a high refractive index cationic polymerization. Monomer (and its polymerization initiator, uncured second photocurable resin liquid) is present. A low-refractive-index radical polymerizable monomer (uncured first photocurable resin liquid) and a high-refractive index cationically polymerizable monomer (uncured second photocuring property) with the surface of the optical path portion 4 as a boundary. The difference in the concentration of the (resin solution) causes diffusion. That is, the uncured first photocurable resin liquid diffuses from the outside of the optical path portion 4 to the surface layer 6 of the optical path portion 4, and the uncured second light from the surface layer 6 of the optical path portion 4 to the outside of the optical path portion 4. The curable resin liquid diffuses. As a result, a radically polymerizable monomer (uncured first photocurable resin liquid) having a low refractive index and a cationically polymerizable monomer (uncured second photocured) having a high refractive index with the surface of the optical path portion 4 as a boundary. Difference in the concentration of the conductive resin liquid) is reduced.

上記は光路部分４の表層６の液状部分と光路部分４の外部の濃度（組成）の話であるが、光路部分４の表層６には低屈折率のラジカル重合性硬化物（第１の光硬化性樹脂の硬化物）が存在する。すると残余の未硬化の光硬化性樹脂を紫外線照射により全体を硬化させた後は、光路部分４の表層６の低屈折率のラジカル重合性硬化物（第１の光硬化性樹脂の硬化物）の組成比は、光路部分４の外部の低屈折率のラジカル重合性硬化物（第１の光硬化性樹脂の硬化物）の組成比よりも多い。即ち、光路部分４の表層６は、低屈折率部分となる。一方光路部分４の内部、少なくとも中心軸近傍は、上記拡散の影響が少ないために、当初の混合溶液を硬化させた場合の第１及び第２の光硬化性樹脂硬化物の組成比と同じとなる。拡散による濃度変化が極めて連続的であることを考えると、このような作用により図２のような屈折率分布を生じるような、第１及び第２の光硬化性樹脂硬化物の組成変化が生じたものと考察される。   The above is the story of the liquid portion of the surface layer 6 of the optical path portion 4 and the concentration (composition) outside the optical path portion 4. The surface layer 6 of the optical path portion 4 has a low refractive index radical polymerizable cured product (first light A cured product of a curable resin). Then, after the entire remaining uncured photocurable resin is cured by ultraviolet irradiation, a low-refractive-index radically cured product (cured product of the first photocurable resin) of the surface layer 6 of the optical path portion 4 is obtained. Is higher than the composition ratio of the low-refractive-index radically polymerizable cured product (cured product of the first photocurable resin) outside the optical path portion 4. That is, the surface layer 6 of the optical path portion 4 is a low refractive index portion. On the other hand, the inside of the optical path portion 4, at least in the vicinity of the central axis, is less affected by the diffusion, and therefore has the same composition ratio of the first and second photocurable resin cured products when the original mixed solution is cured. Become. Considering that the concentration change due to diffusion is extremely continuous, the composition changes of the first and second photo-curing resin cured products that cause the refractive index distribution as shown in FIG. Is considered.

〔比較例〕
実施例１において、15分間の静置をせずに、波長458nmのレーザー光λ1の照射を止めて一部未硬化の光路部分４の形成を終了させると同時に、透明容器１の外部から高圧水銀ランプにより紫外線を照射して光導波路を作製した。この光導波路は光導波路としては充分に機能しない、光閉じ込めができないものであった。二光束干渉顕微鏡により屈折率分布を測定したが、この光導波路の内部での屈折率差は0.001以下であった。ここから、上記考察で述べた「拡散」は、所定時間の静置を行わなければ生じないことがわかった。 [Comparative Example]
In Example 1, the irradiation of the laser beam λ 1 having a wavelength of 458 nm was stopped without standing for 15 minutes to complete the formation of the partially uncured optical path portion 4 and at the same time a high pressure was applied from the outside of the transparent container 1. An optical waveguide was produced by irradiating ultraviolet rays with a mercury lamp. This optical waveguide does not function sufficiently as an optical waveguide and cannot confine light. The refractive index distribution was measured with a two-beam interference microscope, and the refractive index difference inside this optical waveguide was 0.001 or less. From this, it has been found that the “diffusion” described in the above consideration does not occur unless it is allowed to stand for a predetermined time.

〔検証実験〕
次のような方法によって、一部硬化させたコアを形成し、当該コア中の未硬化モノマーと、その外部の混合溶液中の未硬化モノマーとが相互に拡散を生じることを確認した。まず、表２のように、混合溶液Ａ、Ｂ、Ｃ及びＤを調製した。尚、重合開始剤は実施例１と同じものを用いた。 [Verification experiment]
A partially cured core was formed by the following method, and it was confirmed that the uncured monomer in the core and the uncured monomer in the mixed solution outside the core diffused with each other. First, as shown in Table 2, mixed solutions A, B, C and D were prepared. The same polymerization initiator as that used in Example 1 was used.

Figure 0004024729
各混合溶液をガラス板２枚で挟んで厚さ150μm、面積1cm2の円盤状に保持した。次に波長458nmのレーザー光を照射パワー3mWで、石英ファイバ（コア径600μm、開口数0.37）を介して中央部に15秒間照射した。この時の、光照射部とその周辺部分の屈折率分布の経時的な変化の様子を二光束干渉顕微鏡により観測した。この結果を概念図として図３に示す。光が照射された部分ではラジカル重合性モノマーが硬化するが、カチオン重合性モノマーは硬化せずに当該光照射部分（一部未硬化のコア）に取り込まれたままである。光照射を停止した場合、その直後の屈折率分布はステップ状の屈折率分布であった。これは光照射を停止した直後において、光照射の無いコア外部においては混合溶液はラジカル重合性モノマーとカチオン重合性モノマーとが当初の混合比率で存在し、光照射されたコアにおいてはラジカル重合性硬化物とカチオン重合性モノマーとが当初の混合比率で存在することを意味する。尚、当該硬化した樹脂（固体）は硬化前（液体）よりも屈折率が上昇することはごく一般的なことである。よって混合物の一部硬化であっても、硬化前の混合物（液体）よりも一部硬化後の混合物（固液混合物）の屈折率の方が高い。これを図３の（ａ）に示す。
Figure 0004024729
 Each mixed solution was held between two glass plates and held in a disk shape having a thickness of 150 μm and an area of 1 cm 2 . Next, a laser beam with a wavelength of 458 nm was irradiated at a central portion for 15 seconds through a quartz fiber (core diameter 600 μm, numerical aperture 0.37) with an irradiation power of 3 mW. At this time, the temporal change in the refractive index distribution of the light irradiation part and its peripheral part was observed with a two-beam interference microscope. The result is shown in FIG. 3 as a conceptual diagram. The radically polymerizable monomer is cured at the portion irradiated with light, but the cationic polymerizable monomer is not cured but remains taken into the light irradiated portion (partially uncured core). When light irradiation was stopped, the refractive index distribution immediately after that was a step-shaped refractive index distribution. This is because immediately after the light irradiation is stopped, outside the core without light irradiation, the mixed solution contains the radical polymerizable monomer and the cationic polymerizable monomer in the initial mixing ratio, and in the light irradiated core, the radical polymerizable property is present. It means that the cured product and the cationic polymerizable monomer are present in the initial mixing ratio. Note that it is very common that the cured resin (solid) has a higher refractive index than before curing (liquid). Therefore, even if the mixture is partially cured, the refractive index of the partially cured mixture (solid-liquid mixture) is higher than that of the mixture (liquid) before curing. This is shown in FIG.

この後、静置時間の経過とともに光照射部分の外周付近で屈折率が変化する様子が確認できた。即ち、表２で※欄をＷと示した混合溶液Ａ、Ｂ、Ｄを用いたものについては、図３の（ａ）のようなステップ状の屈折率分布から、図３の（ｂ）のように変化した。この現象は実施例１でも同様であるものと考えられる。一方、表２で※欄をＭと示した混合溶液Ｃを用いたものについては、図３の（ａ）のようなステップ状の屈折率分布から、図３の（ｃ）のように変化した。   Thereafter, it was confirmed that the refractive index changed in the vicinity of the outer periphery of the light irradiation portion as the standing time passed. That is, for those using the mixed solutions A, B, and D whose * column is marked W in Table 2, from the step-shaped refractive index distribution as shown in FIG. Changed. This phenomenon is considered to be the same in the first embodiment. On the other hand, in the case of using the mixed solution C whose M column is indicated in Table 2 as shown in FIG. 3, the step-like refractive index distribution as shown in FIG. 3A changed as shown in FIG. .

本発明の具体的な一実施例に係る光導波路の製造方法を示す工程図（断面図）。Process drawing (sectional drawing) which shows the manufacturing method of the optical waveguide which concerns on one specific Example of this invention. 実施例１の光導波路のコア部の中心軸から垂直方向の屈折率分布を示すグラフ図。FIG. 3 is a graph showing a refractive index distribution in the vertical direction from the central axis of the core portion of the optical waveguide of Example 1. 検証実験における、屈折率分布の概略を示すグラフ図であって、（ａ）は光照射を停止した直後、（ｂ）は混合溶液Ａ、Ｂ、Ｄの場合の所定時間経過後、（ｃ）は混合溶液Ｃの場合の所定時間経過後。In the verification experiment, it is a graph which shows the outline of refractive index distribution, Comprising: (a) is immediately after stopping light irradiation, (b) is after the predetermined time progress in the case of mixed solution A, B, D, (c) Is after a predetermined time in the case of the mixed solution C.

符号の説明Explanation of symbols

１：透明容器
２：硬化機構の異なる低屈折率の第１の光硬化性樹脂液と高屈折率の第２の光硬化性樹脂液の混合溶液
２'：混合溶液の硬化物
３：光ファイバ
４：一部未硬化の光路部分
５：一部未硬化の光路部分の表層以外の部分
６：一部未硬化の光路部分の表層
５'：コア（完全に硬化した光路部分の表層以外の部分）
６'：クラッド（完全に硬化した光路部分の表層）
７：光路部分の表層部分の外部の高屈折率部分 1: Transparent container 2: Mixed solution 2 ′ of low refractive index first photocurable resin liquid and high refractive index second photocurable resin liquid having different curing mechanisms 2 ′: Cured product of mixed solution 3: Optical fiber 4: Partially uncured optical path part 5: Part other than the surface layer of the partially uncured optical path part 6: Surface layer 5 ′ of the partially uncured optical path part: Core (Part other than the surface layer of the completely cured optical path part) )
6 ': Cladding (surface layer of a completely hardened optical path part)
7: High refractive index part outside the surface layer part of the optical path part

Claims (2)

硬化機構の異なる低屈折率の第１の光硬化性樹脂液と高屈折率の第２の光硬化性樹脂液の混合溶液を用い、
前記第１の光硬化性樹脂液を硬化させるが前記第２の光硬化性樹脂液を硬化させない第１の光照射により、前記第２の光硬化性樹脂液を取り込む形で前記第１の光硬化性樹脂液を硬化させ、光が透過する光路部分を形成する第１の光硬化工程と、
前記光路部分を形成した後、第１の光照射を止めて所定時間静置することで、前記光路部分の表層へ光路部分の外部の混合溶液から未硬化の前記第１の光硬化性樹脂液を拡散させる拡散工程と、
前記第１の光硬化性樹脂液と前記第２の光硬化性樹脂液の両方を硬化させる第２の光照射により、少なくとも前記光路部分の表層へ拡散した未硬化の前記第１の光硬化性樹脂液及び前記光路部分の前記第２の光硬化性樹脂液を硬化させる第２の光硬化工程とから成り、
屈折率の高い光路部分と、その表層の低屈折率部分とを有する光導波路を製造する方法。 Using a mixed solution of a low refractive index first photocurable resin liquid and a high refractive index second photocurable resin liquid having different curing mechanisms,
The first light in a form of taking in the second photocurable resin liquid by first light irradiation that cures the first photocurable resin liquid but does not cure the second photocurable resin liquid. A first photocuring step of curing the curable resin liquid and forming an optical path portion through which light passes;
After forming the optical path portion, the first photo-curing resin liquid is uncured from the mixed solution outside the optical path portion to the surface layer of the optical path portion by stopping the first light irradiation and allowing to stand for a predetermined time. A diffusion step of diffusing
The uncured first photocurable resin diffused to at least the surface layer of the optical path portion by the second light irradiation that cures both the first photocurable resin solution and the second photocurable resin solution. A second photocuring step of curing the resin liquid and the second photocurable resin liquid of the optical path portion,
A method of manufacturing an optical waveguide having an optical path portion having a high refractive index and a low refractive index portion on the surface layer thereof. 前記第１の光照射は、光ファイバにより供給されることを特徴とする請求項１に記載の光導波路を製造する方法。 The method of manufacturing an optical waveguide according to claim 1, wherein the first light irradiation is supplied by an optical fiber.
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