JP2004341065A - Light branching element and optical waveguide element equipped with same, and methods for manufacturing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light branching element in which absorption and loss of light are little. <P>SOLUTION: The light branching element is equipped with a substrate 3 and a translucent resin layer formed on the substrate 3. The resin layer has an inclined plane 5 which is formed so that it goes down from the surface of the resin layer at a prescribed angle toward the surface of the substrate 3 and the inclined plane 5 has reflective areas 5a each of which has a reflective film 6 for reflecting light and a light receiving area 5b for receiving light. As a result, the element can transmits the light which is to be transmitted by making it reach directly to the light receiving area 5b of the element and can suppress the absorption and the loss of the light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２９】
ただし、Ｒ^１、Ｒ^２、Ｒ^３はそれぞれ１価の炭化水素基、アルコキシ基、水素原子を、ｎ、ｍはそれぞれ０以上で、かつ、ｎ＋ｍは５以上の整数を表わす。
このようなポリシランは、一般に２５０ｎｍ以上の紫外領域に吸収を有し、酸素存在下で紫外光を照射するとそのケイ素−ケイ素（Ｓｉ−Ｓｉ）結合が一部切断され、シロキサン（Ｓｉ−Ｏ−Ｓｉ）結合やシラノール（Ｓｉ−ＯＨ）基に変換される。
これにより、ポリシランの紫外吸収が減少するとともに、親水性とアルカリ溶液に対する可溶性が発現される。
また、上記ポリシランは、紫外光を照射することにより、屈折率が低下するという特性もあり、光導波路を形成する上でも有用である。
以下にこの発明の実施例について図面に基づいて詳細に説明する。なお、以下に示す複数の実施例において、共通する部材には同じ符号を用いて説明する。
【００３０】
実施例１
図１は実施例１による光分岐素子の構成を概略的に示す断面図、図２は図１に示される光分岐素子の平面図、図３は図１および図２に示される光分岐素子の要部の斜視図である。
図１〜３に示されるように、実施例１による第１光分岐素子１と第２光分岐素子２は、基板３と、基板３上に形成された透光性の樹脂層４とを備え、樹脂層４は樹脂層４の表面から基板３の表面へ向かって所定の角度で下るように形成された傾斜面５を有し、傾斜面５は光を反射させるための反射膜６を有する反射領域５ａと、光を受け入れるための受光領域５ｂとをそれぞれ有している。
【００３１】
ここで、樹脂層４は、下部クラッド層７、コア層８および上部クラッド層９とから構成されている。コア層８には、コア層８の一部の屈折率を他の部分よりも相対的に高めることにより形成され光導波路として機能するコア８ａ，８ｂ，８ｃが形成されている。傾斜面５はコア８ｂ，８ｃの一端にそれぞれ形成されている。上部クラッド層９は傾斜面５を埋めるようにコア層８上に積層されている。また、反射膜６は金からなる金属薄膜である。
【００３２】
図１中のＡ地点からコア８ａに入射し、コア８ａ中を伝播して第１光分岐素子１に到達した光のうち、反射領域５ａ（図２および図３参照）に到達した光は図１中のＢの方向へ反射され、受光領域５ｂに到達した光は図１中のＥの方向へ向かってそのまま受光領域５ｂ（図２および図３参照）を透過する。
また、第１光分岐素子１の受光領域５ｂを透過した光は、コア８ｂ中を伝播して第２光分岐素子２に到達し、第１光分岐素子１と同様にして図１中のＣの方向とＥの方向に分岐される。
【００３３】
このようにして、第１および第２光分岐素子１，２に到達した光が、第１および第２光分岐素子１，２によってそれぞれ分岐される際の分岐比は、反射膜６が形成されている反射領域５ａと、反射膜６が形成されていない受光領域５ｂとの面積比でほぼ一義的に決定される。
このため、反射膜６の表面での反射率は、伝播する光のモードにかかわりなく略一定となり、光導波路としてのコア８ａ，８ｂ，８ｃがいわゆるマルチモード導波路であってもその分岐比は安定した値が得られる。
【００３４】
例えば、反射膜６が形成された反射領域５ａの反射率を９０％、反射膜６が形成されていない受光領域５ｂの透過率を１００％とすると、１：１の分岐比を実現するには、傾斜面５の面積のうち反射領域５ｂの形成範囲を５２．６％、受光領域５ａの形成範囲を４７．４％とすればよい。このとき、１つの光分岐素子あたりの吸収損失は５％であるので、実施例１のように第１および第２光分岐素子１，２を縦列に配置した場合の全体的な光利用効率は９０．３％となり、従来の金属膜によるハーフミラーに対して大幅に改善される。
なお、コア８ａ，８ｂ，８ｃは、第１および第２光分岐素子１，２が形成されている領域でそれぞれ途切れた状態となっているが、途切れた距離がコアの幅Ｗの２倍以内であれば、光の回折（広がり）による損失は問題とならない。
【００３５】
また、図２に示される第１および第２光分岐素子の間の距離Ｌは、次式に示す条件を満たすように設定するとよい。
Ｌ＞Ｄ×Ｗ／（２λ）
ここで、Ｗは受光領域５ｂの幅、Ｄはコア８ｂの幅、λはコア８ｂ内を伝播する光のうち、最小の波長を有する光の波長である。
上記の式による条件が満たされるように、第１および第２光分岐素子１，２間の距離Ｌを設定すると、第１光分岐素子１の受光領域５ｂを透過しコア８ｂに入射した光は、入射直後にはコア８ｂの中心付近にしか広がっていないが、次の第２光分岐素子２に到達するまでに回折効果によりコア８ｂの幅一杯に広がった状態となる。
【００３６】
例えば、受光領域５ｂの幅Ｗを１０μｍ、コア８ｂの幅Ｄを２０μｍ、コア８ｂを伝播する光のうち、最小の波長を有する光の波長λを０．８５μｍとすると、第１および第２光分岐素子１，２間の距離Ｌは、約１１８μｍより大きければよいこととなる。
これにより、第２光分岐素子２の本来の性能が発揮され、例えば、分岐比が変動しなくなるなどの効果が得られる。
なお、コア８ｂに入射した光は、前述の通り、その中に閉じ込められながら伝播されるので、光がコア８ｂの幅Ｄを超えて分布することはない。
【００３７】
実施例２
図４はこの発明による光導波路素子の概略的な構成を示す断面図である。
図４に示されるように、実施例２による光導波路素子２０は、基板３と、基板３上に形成された透光性の樹脂層４と、樹脂層４中に互いに間隔を空けて形成された第１光分岐素子１および第２光分岐素子２と、第１および第２光分岐素子１，２間で光を伝播するように樹脂層４中に形成された細長い光導波路としてのコア８ｂを備え、第１および第２光分岐素子１，２は上述の実施例１による第１および第２光分岐素子１，２と同じ構成を有している。
【００３８】
ここで、樹脂層４は上述の実施例１と同様に下部クラッド層７、コア層８および上部クラッド層９から構成され、コア層８にはコア８ａ，８ｂ，８ｃが形成され、コア８ａの端部近傍にはコア層８の一部に形成された傾斜面５と、この傾斜面５上に形成された反射膜６からなるミラー２１が形成されている。
また、上部クラッド層９には、ミラー２１、第１光分岐素子１および第２光分岐素子２から上部クラッド層９の表面へそれぞれ立ち上がる垂直コア９ａ，９ｂ，９ｃが形成されている。
【００３９】
垂直コア９ａ，９ｂ，９ｃの上方には、樹脂層４上に形成された電極２２と、電極２２上に塗布されたはんだ２３を介して面発光レーザ２４、第１光検出器２５および第２光検出器２６がそれぞれ実装されている。
面発光レーザ２４から放射された光は、垂直コア９ａの端部から入射し垂直コア９ａ内を伝播してミラー２１に到達する。ミラー２１に到達した光は反射されることによりその光路が９０度変更されてコア８ａに入射し、コア８ａ内を伝播して第１光分岐素子１に到達する。第１光分岐素子１に到達した光は、第１光分岐素子１の分岐作用により垂直コア９ｂへ向かう方向とコア８ｂへ向かう方向との２つの方向に分岐される。
【００４０】
第１光分岐素子１によって分岐された光のうち、垂直コア９ｂへ向かう方向へ分岐された光は、垂直コア９ｂ内を伝播して垂直コア９ｂの端部から放射され、第１光検出器２５に受光されて電気信号に変換される。
一方、コア８ｂへ向かう方向へ分岐された光はコア８ｂ内を伝播して第２光分岐素子２に到達し、第２光分岐素子２の分岐作用により垂直コア９ｃへ向かう方向とコア８ｃへ向かう方向との２つの方向に分岐される。
【００４１】
第２光分岐素子２によって分岐された光のうち、垂直コア９ｃへ向かう方向へ分岐された光は、垂直コア９ｃ内を伝播して垂直コア９ｃの端部から放射され、第２光検出器２６に受光されて電気信号に変換される。
一方、コア８ｃへ向かう方向へ分岐された光は図示しない他の光分岐素子又はミラーへ向かってコア８ｃ内をさらに伝播する。
ここで、光分岐素子１，２の分岐比は、上述の通り、コアを伝播する光のモードに影響され難いので、コア８ａ，８ｂ，８ｃを、幅と厚さが共に２０μｍ程度ある大きなマルチモード導波路として形成することができる。
この結果、発光部の直径が約１０μｍ以上ある面発光レーザ２４からの光も効率よくコア８ａ，８ｂ，８ｃに導くことができる。
【００４２】
また、上部クラッド層９内に垂直コア９ａ，９ｂ，９ｃが形成されているので、垂直コア９ａの端部と面発光レーザ２４との間の距離、並びに、垂直コア９ｂ，９ｃの端部と第１および第２光検出器２５，２６の受光部との間の距離が短くなる。
このため、面発光レーザから放射された光を、広がりが小さい状態で垂直コア９ａへ入射させることができ、また、垂直コア９ｂ，９ｃの端部から放射された光を、広がりが小さい状態で第１および第２光検出器２５，２６に受光させることができ、結果として光の結合効率が向上する。
【００４３】
次に、実施例２による光導波路素子の製造方法について図５〜１８に基づいて説明する。図５〜７および図９〜１８は、図４に示される光導波路素子の製造工程を示す工程図であり、図８は光導波路素子の製造工程で用いられるグレーマスクの構成を示す説明図である。
【００４４】
まず、図５に示されるように、基板３上に下部クラッド層７を形成する。基板３には平滑性に優れるガラス基板、あるいは可撓性と耐熱性に優れるポリイミドフィルムを用いる。
下部クラッド層７は後で形成するコア層８より屈折率の低いものであればよいが、耐熱性（ガラス転移点約３５０℃以上）とスピンコートが可能な点からポリシラン（日本ペイント株式会社製、品名：グラシアＷＧ、品番：ＷＧ−００５）を用いる。耐熱性が約３００℃以上であれば、電子部品を実装する際のはんだ付け工程で変性可能性が小さくなり実装で有利である。
下部クラッド層７は、上記ポリシランを基板３上にスピンコートで塗布し、約３５０℃で焼成して化学的に安定な膜とすることにより形成される。
【００４５】
次に、図６に示されるように、下部クラッド層７の上にコア層８を形成する。コア層８には紫外光を照射することにより親水性と可溶性と屈折率変化とを示すポリシラン（日本ペイント株式会社製、品名：グラシアＷＧ、品番：ＷＧ−００４）を用いる。
ポリシランは、紫外光の照射により分子の一部が切断されて親水性を示すようになるのと同時に、アルカリ溶液に可溶となり、さらに屈折率が低下する。また、耐熱性の点からも好ましい。
但し、下部クラッド層７との屈折率差を確保するため、下部クラッド層７を構成するポリシランとは組成の異なるものを用いている。
コア層８は、上記ポリシランを下部クラッド層７上にスピンコートで塗布し、約２５０℃に加熱して膜中の溶剤を揮発させることにより形成される。
【００４６】
次に、図７に示されるように、グレーマスク３０を介してコア層８に紫外光を照射する。グレーマスク３０は、図８に示されるように透明基体３０ａと遮光膜３０ｂとからなり、遮光膜３０ｂは傾斜面５と対応する箇所において光透過率を漸減させるために膜厚が徐々に変化する光透過部３０ｃと、光透過部３０ｃと隣接する開口部３０ｄとを有している。
紫外光を照射することによるポリシランの化学変化（親水性と可溶性と屈折率変化の発現）は、照射される紫外光の強度に応じてコア層８の表面より厚み方向に向かって進行する。
このため、光透過部３０ｃを介して紫外光が照射された部分では、光透過部３０ｃの膜厚の変化に応じて化学変化が進行し、結果としてコア層８に傾斜面５の立体的な潜像を有する露光領域３１が形成される。
【００４７】
次に、図９に示されるように、得られた基板３をアルカリ溶液に浸漬し、紫外光の照射により親水性と可溶性と屈折率変化とが発現した露光領域３１（図７参照）を除去し傾斜面５を有する凹部３２を形成する。
【００４８】
次に、図１０（ａ）および図１０（ｂ）に示されるように、得られた基板３を無電解めっき法でめっき浴する。この際、凹部３２の内面には先の工程での紫外線照射により生じた親水基が残存するので、凹部３２の内面にのみ金属めっきが施され、反射膜６が形成される。
この工程では、傾斜面５と対向する凹部の内面にも反射膜６が形成されるが、これは光の伝播の妨げとなるので、この部分の反射膜６を次以降の工程で除去する。
【００４９】
すなわち、図１１（ａ）および図１１（ｂ）に示されるように、コア層４上にレジスト３３を塗布し、フォトリソグラフィーにより開口３４ａ，３４ｂ，３４ｃをそれぞれ形成して除去すべき反射膜６を露出させる。
開口３４ａは、傾斜面５を覆いつつ傾斜面５との対向面に形成された反射膜６を露出させるように形成され、開口３４ｂ，３４ｃは傾斜面５との対向面に形成された反射膜６と、傾斜面５に形成された反射膜６の中央部とを露出させるようにＴ字形に形成される。
【００５０】
次に、図１２（ａ）および図１２（ｂ）に示されるように、得られた基板３をエッチング液に浸漬し、不要な反射膜６（図１１（ａ）および図１１（ｂ）参照）を除去する。
次に、図１３（ａ）および図１３（ｂ）に示されるように、コア層８上に残るレジスト３３（図１２（ａ）および図１２（ｃ）参照）を有機溶剤で溶解除去する。
【００５１】
次に、図１４（ａ）および図１４（ｂ）に示されるように、コア層８に光導波路としてのコア８ａ，８ｂ，８ｃを形成するため、コア８ａ，８ｂ，８ｃに対応するパターンの遮光膜３５ｂを備えたマスク３５を介して紫外光を照射する。
すなわち、コア層８を構成するポリシランは、紫外光を照射することにより屈折率が低下するので、コア層８のうち、コア８ａ，８ｂ，８ｃとしない部分に紫外光を照射して屈折率を低下させ、コア８ａ，８ｂ，８ｃとすべき部分の屈折率を相対的に高め、コア８ａ，８ｂ，８ｃを形成するのである。
【００５２】
次に、図１５に示されるように、コア層８を約３５０℃で焼成して化学的に安定させる。
この際、コア層８の屈折率は全体的に低下するが、先の工程での紫外光照射によって生じた屈折率差はほぼそのまま維持され、また、コア層８全体の屈折率はいずれの部分についても下部クラッド層７より高く維持される。
次に、図１６に示されるように、コア層８上に上部クラッド層９を形成する。上部クラッド層９は、コア層８を構成するポリシランと同じポリシランをスピンコートで塗布し、約２５０℃に加熱して膜中の溶剤を揮発させることにより形成される。
【００５３】
次に、図１７（ａ）および図１７（ｂ）に示されるように、傾斜面５の上方と対応する箇所にのみ遮光膜３６ｂを備えたマスク３６を介して紫外光を上部クラッド層９に照射し、照射部分の屈折率を低下させて垂直コア９ａ，９ｂ，９ｃとすべき部分の屈折率を相対的に高めることにより上部クラッド層９内に垂直コア９ａ，９ｂ，９ｃを形成する。
次に、図１８（ａ）および図１８（ｂ）に示されるように、上部クラッド層９を約３５０℃で焼成して化学的に安定させる。
その後、面発光レーザ２４や第１および第２光検出器２５，２６を搭載するための電極２２を上部クラッド層９上に形成し、面発光レーザ２４や第１および第２光検出器２５，２６をそれぞれ電極にはんだ付けすることにより図４に示される光導波路素子２０が完成する。
【００５４】
【発明の効果】
この発明によれば、傾斜面が光を反射させるための反射膜を有する反射領域と、光を受け入れるための受光領域とを有するので、透過させるべき光を光分岐素子の受光領域に直接到達させて透過させることができ、光の吸収損失を極力抑えることができる。
【図面の簡単な説明】
【図１】この発明の実施例１による光分岐素子の構成を概略的に示す断面図である。
【図２】図１に示される光分岐素子の平面図である。
【図３】図１に示される光分岐素子の要部の斜視図である。
【図４】この発明の実施例２による光導波路素子の構成を概略的に示す断面図である。
【図５】図４に示される光導波路素子の製造工程を示す工程図である。
【図６】図４に示される光導波路素子の製造工程を示す工程図である。
【図７】図４に示される光導波路素子の製造工程を示す工程図である。
【図８】図４に示される光導波路素子の製造工程で用いられるグレーマスクの構成を概略的に示す説明図である。
【図９】図４に示される光導波路素子の製造工程を示す工程図である。
【図１０】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１１】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１２】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１３】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１４】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１５】図４に示される光導波路素子の製造工程を示す工程図である。
【図１６】図４に示される光導波路素子の製造工程を示す工程図である。
【図１７】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１８】図４に示される光導波路素子の製造工程を示す工程図であり、同図において（ａ）と（ｂ）は同工程における断面と平面をそれぞれ示している。
【図１９】従来の光信号伝送システムの構成を概略的に示す説明図である。
【符号の説明】
１・・・第１光分岐素子
２・・・第２光分岐素子
３・・・基板
４・・・樹脂層
５・・・傾斜面
５ａ・・・反射領域
５ｂ・・・受光領域
６・・・反射膜
７・・・下部クラッド層
８・・・コア層
８ａ，８ｂ，８ｃ・・・コア
９・・・上部クラッド層
９ａ，９ｂ，９ｃ・・・垂直コア
２０・・・光導波路素子
２１・・・ミラー
２２・・・電極
２３・・・はんだ
２４・・・面発光レーザ
２５・・・第１光検出器
２６・・・第２光検出器
３０・・・グレーマスク
３０ａ・・・透明基体
３０ｂ，３５ｂ，３６ｂ・・・遮光膜
３０ｃ・・・光透過部
３０ｄ・・・開口部
３１・・・露光領域
３２・・・凹部
３３・・・レジスト
３４ａ，３４ｂ，３４ｃ・・・開口
３５，３６・・・マスク
Ｄ・・・コアの幅
Ｌ・・・第１および第２光分岐素子間の距離
Ｗ・・・受光領域の幅[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical branching element, an optical waveguide element including the optical branching element, and a method of manufacturing the same, and more particularly, to an optical branching element for splitting light transmitted from an optical waveguide and a method of manufacturing the same.
[0002]
[Prior art]
In order to realize a computer that performs faster arithmetic processing, the number of clocks of the CPU tends to increase year by year, and a frequency of about GHz is now appearing.
As a result, there is a portion where a high-frequency signal flows in electrical wiring made of copper on a printed circuit board in a computer, and a malfunction occurs due to generation of noise. In addition, it emits electromagnetic waves and affects surroundings.
[0003]
In order to solve such a problem, a method of replacing a part of the electric wiring made of copper on the printed circuit board with an optical wiring made of an optical waveguide and using an optical signal instead of an electric signal has been actively tried. . Since the optical signal does not cause so-called electromagnetic induction, there is little malfunction due to noise as described above.
[0004]
As an optical wiring using a conventional optical waveguide, for example, an optical signal transmission system in which light emitted from a light emitting element is received by a plurality of light receiving elements as shown in FIG. 19 is known (for example, see Patent Document 1). ).
As shown in FIG. 19, the conventional optical signal transmission system is configured by laminating two optical waveguides in the thickness direction of the substrate. The first layer components in contact with the substrate 101 are a first layer clad 102, a first layer core 103, and a first layer mirror layer 104, and the second layer components thereon are a second layer core 106, A second-layer mirror layer 107 and a second-layer clad 108. On the second cladding 108, two light receiving elements 109 are arranged.
[0005]
The first-layer mirror layer 104 and the second-layer mirror layer 107 are formed in a ridge shape similarly to the first-layer core 103 and the second-layer core 106, and thus themselves function as the core of the optical waveguide. The end faces of the first-layer mirror layer 104 and the second-layer mirror layer 107 are reflection surfaces 105 having a 45-degree inclination angle with respect to the substrate 101. These reflection surfaces 105 are half mirrors, and divide half of the incident light in the straight direction and half in the orthogonal direction by reflection. By generating such beam splitting action and waveguide by the mirror layer in various parts in the optical signal transmission system, optical coupling between different layers and light reception by a plurality of light receiving elements 109 are enabled.
[0006]
Another related art related to the present invention is a method for manufacturing an electric circuit board, which comprises forming a polysilane film on a surface of a substrate, and forming a mask having an opening corresponding to a circuit pattern on the polysilane film. The exposed portion is made hydrophilic by irradiating ultraviolet light through, a palladium salt solution is attached to the exposed portion that has been hydrophilized to form a pattern made of palladium salt on the exposed portion, and this pattern is subjected to metal plating. 2. Description of the Related Art A method for manufacturing an electric circuit board serving as a conductive pattern is known (for example, see Patent Document 2).
[0007]
Further, as still another related art related to the present invention, there is known a method of irradiating a polysilane compound with ultraviolet light to lower the refractive index of an irradiation portion in accordance with the irradiation amount (for example, Non-Patent Documents) 1).
[0008]
[Patent Document 1]
JP 2000-47044 A
[Patent Document 2]
JP-A-10-326957
[Non-patent document 1]
Akihiro Hori and one other, "Study of Optical Waveguide Technology Using Photobleaching Polymer Material", Proceedings of the 12th Microelectronics Symposium, October 2002, pp. 223-226.
[0009]
[Problems to be solved by the invention]
Generally, the half mirror is formed of a very thin metal thin film (thickness of 100 ° or less) or a multilayer dielectric film. However, when a metal thin film is used, light use efficiency is reduced due to absorption loss generated when light passes through the half mirror.
As the metal thin film, a titanium thin film is often used. In this case, when the transmittance and the reflectance are set to be the same, an absorption loss occurs about 40%, and the transmittance and the reflectance are each about 30%.
Therefore, when two half mirrors using a titanium thin film are arranged in tandem, the light use efficiency is 36% or less.
[0010]
On the other hand, the multilayer dielectric film has an absorption loss of almost 0%. However, since the multilayer dielectric film is formed by laminating about 4 to 10 thin films having different refractive indices, it is necessary to repeat vacuum deposition many times in the manufacturing process, resulting in poor workability.
In addition, since the multilayer dielectric film exhibits different transmittance and reflectance depending on the mode of light propagating through the optical waveguide, when this is used in a multi-mode waveguide, the branching ratio is dynamically changed due to optical power transfer between modes. There is a problem that changes.
[0011]
In addition, regardless of whether the half mirror is formed of a metal film or a multilayer dielectric film, it is necessary to change the thickness and configuration of the film in order to change the branching ratio. Therefore, in order to form a plurality of optical branching elements having different branching ratios in one optical waveguide element, it is necessary to repeat the process of forming the optical branching element a plurality of times, and the productivity is poor.
[0012]
The present invention has been made in view of the above circumstances, and provides an optical branching element having a small light absorption loss, an optical waveguide element including the optical branching element, and a method of manufacturing the same. .
[0013]
[Means for Solving the Problems]
The present invention includes a substrate and a light-transmitting resin layer formed on the substrate, and the resin layer has an inclined surface formed so as to descend at a predetermined angle from the surface of the resin layer toward the surface of the substrate. The inclined surface is to provide a light branching element having a reflection area having a reflection film for reflecting light and a light receiving area for receiving light.
That is, the light branching element according to the present invention has a reflection area in which the inclined surface has a reflection film for reflecting light, and a light receiving area for receiving light.
For this reason, the light to be transmitted can be directly transmitted to the light receiving area of the light branching element, and the light absorption loss can be minimized.
In addition, since the branching ratio of the light branching element is substantially uniquely determined by the area ratio between the reflection region and the light receiving region, the branching ratio is hardly affected by a change in the propagation mode of light, and the invention can be applied to a multimode waveguide.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An optical branching device according to the present invention includes a substrate and a translucent resin layer formed on the substrate, and the resin layer is formed so as to descend at a predetermined angle from the surface of the resin layer toward the surface of the substrate. Characterized in that the inclined surface has a reflective area having a reflective film for reflecting light and a light receiving area for receiving light.
[0015]
Here, as the substrate, for example, a glass substrate having excellent smoothness or a polyimide film having excellent flexibility and heat resistance can be used.
In addition, as described in the method of manufacturing a light branching element described below, the light-transmitting resin layer exhibits solubility and hydrophilicity by light irradiation, for example, from the viewpoint of facilitating formation of an inclined surface and a reflective film. Resin can be used.
Further, the inclined surface may be formed so as to descend at a predetermined angle from the surface of the resin layer to the surface of the substrate, and the shape, size, and the like are not particularly limited.
[0016]
Further, as the reflection film, for example, a metal film having a thickness of about 0.01 to 1 μm can be used, and as a material of the metal film, for example, gold can be used.
In the light branching device according to the present invention, the reflection region means a region of the inclined surface where a reflection film for reflecting light is formed, and its shape, size, and the like are not particularly limited.
Further, in the light branching device according to the present invention, the light receiving region means a region of the inclined surface where the reflective film is not formed, and its shape, size, and the like are not particularly limited.
[0017]
Further, from another viewpoint, the present invention provides a substrate, a light-transmitting resin layer formed on the substrate, a first optical branching element and a second light-emitting element formed in the resin layer at an interval from each other. A branching element; and an elongated optical waveguide formed in the resin layer so as to propagate light between the first and second optical branching elements. The present invention also provides an optical waveguide device including the device.
[0018]
Here, the same substrate as the above-described light branching element can be used as the substrate, and as the light-transmitting resin, from the viewpoint of facilitating the production of the light branching element and the optical waveguide, it becomes soluble and hydrophilic by light irradiation. A resin that exhibits a change in the refractive index can be used.
In the optical waveguide device according to the present invention, the optical waveguide means a path of an optical signal for confining and propagating the optical signal, and can be constituted by, for example, a portion having a high refractive index formed in a resin layer.
If a portion having a higher refractive index than other portions is formed in the resin layer, an optical signal incident on the portion having a higher refractive index propagates through the interface while being totally reflected at an interface with a portion having a lower refractive index. .
[0019]
Further, in the optical waveguide device according to the present invention, the optical waveguide has a rectangular cross section and a constant width in a direction parallel to the substrate, and the inclined surfaces of the first and second optical branching elements are in contact with both end surfaces of the optical waveguide. They may each have a matching shape and size and may be optically connected to the optical waveguide.
[0020]
In such a configuration, the light receiving region of the first light branching element is formed in the center of the inclined surface in a slit shape having a width W, and the width of the optical waveguide is D, and the wavelength of light propagating in the optical waveguide is λ. At this time, the distance L between the first and second optical branch elements is
L = D × W / (2λ)
May be longer than the distance L represented by
[0021]
That is, when the slit-shaped light receiving region is provided so as to cross the center of the inclined surface in a direction perpendicular to the substrate, light that has just passed through the light receiving region and is in proximity to the first optical waveguide will be transmitted through the light guide. In a part of the wave path, it extends only near the center of the part.
However, if the distance between the first and second optical branching elements is set as described above, the light that has spread only near the center of the optical waveguide will reach the next second optical branching element due to the diffraction effect. The optical waveguide is in a state of being spread to the full width.
Thereby, the original performance of the second optical branching element is exhibited, and for example, an effect that the branching ratio does not change can be obtained.
As described above, since the light is confined and propagated in the optical waveguide, the light does not distribute beyond the width D of the optical waveguide even if the light transmitted through the first optical branching element propagates more than the distance L.
[0022]
Another aspect of the present invention is a method for manufacturing the above-described light branching element according to the present invention, which comprises applying a light-transmitting resin that exhibits hydrophilicity and solubility to light to a substrate. A step of forming a resin layer, and a step of irradiating the resin layer with light through a mask having a region where light transmittance changes continuously to express hydrophilicity and solubility in a part of the resin layer, A step of forming a slope by dissolving and removing a part of the resin layer in which solubility has been developed, a step of forming a reflection film by electroless plating on the surface of the slope having a hydrophilic property, and etching a part of the reflection film And forming a light receiving region and a reflection region by removing the light branching region.
[0023]
According to such a manufacturing method, in forming the inclined surface, a step of irradiating a part of the resin layer on which the inclined surface is to be formed with light to exhibit hydrophilicity and solubility (exposure step); The inclined surface can be easily formed in two steps of a step of dissolving and removing the removed portion (developing step).
Further, since the formed inclined surface exhibits hydrophilicity, a reflection film can be easily formed on the inclined surface by performing electroless plating (plating step).
[0024]
That is, in the above-described manufacturing method, the light branching element can be formed in only three steps of the exposure step, the development step, and the plating step, and all these steps can be processed in the air and are chemical reaction processing. Production can be easily expanded, which is advantageous from the viewpoint of manufacturing cost.
Further, as described above, since the branching ratio of the light branching element manufactured by such a manufacturing method is almost uniquely determined by the area ratio between the reflection region and the light receiving region, a part of the reflection film is removed. The branching ratio can be arbitrarily set depending on the design of the mask used in the process, and depending on the design of the mask, it is also possible to simultaneously form a plurality of optical branching elements having different branching ratios.
[0025]
Further, from another viewpoint, the present invention is a method for manufacturing the above-described optical waveguide element according to the present invention, which is a translucent resin which exhibits hydrophilicity, solubility, and a change in refractive index by light irradiation. Forming a first and second optical branching element in the resin layer by forming a first optical branching element, a second optical branching element, and an optical waveguide in the resin layer. The step of irradiating the resin layer with light through a mask having a region in which the light transmittance changes continuously to cause a part of the resin layer to exhibit hydrophilicity and solubility; Forming a slope by dissolving and removing a part of the light-receiving region; forming a reflective film on the surface of the hydrophilic slope by electroless plating; and removing a part of the reflective film by etching. And forming a reflection region, and forming an optical waveguide. To process also provides a method of manufacturing the optical waveguide device comprising the step of expressing the refractive index change in the resin layer is irradiated with light in the resin layer through a mask corresponding to the pattern of the optical waveguide.
[0026]
According to such a manufacturing method, in forming the optical waveguide, the resin layer is irradiated with light through a mask corresponding to the pattern of the optical waveguide, and a change in the refractive index is caused in the portion irradiated with the light. Thus, an optical waveguide can be easily formed.
[0027]
Here, as a resin used in the method for manufacturing the optical branch element or the method for manufacturing the optical waveguide element, for example, a resin generally called a photobleaching polymer material can be used.
Specific examples of the photobleaching polymer material include, for example, photobleachable polysilane (hereinafter, simply referred to as “polysilane”).
Polysilane is an organosilicon polymer having a structure in which five or more silicon atoms are continuously connected, and specifically, a polymer having a structure as shown in the following Chemical Formula 1.
[0028]
Embedded image

[0029]
Where R¹, R², R³Represents a monovalent hydrocarbon group, an alkoxy group and a hydrogen atom, n and m each represent an integer of 0 or more, and n + m represents an integer of 5 or more.
Such a polysilane generally has an absorption in an ultraviolet region of 250 nm or more, and when irradiated with ultraviolet light in the presence of oxygen, its silicon-silicon (Si-Si) bond is partially broken to form a siloxane (Si-O-Si). ) It is converted into a bond or a silanol (Si-OH) group.
As a result, ultraviolet absorption of polysilane is reduced, and hydrophilicity and solubility in an alkaline solution are exhibited.
In addition, the above polysilane has a property that the refractive index is reduced by irradiating ultraviolet light, and thus is useful for forming an optical waveguide.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in a plurality of embodiments described below, common members will be described using the same reference numerals.
[0030]
Example 1
FIG. 1 is a cross-sectional view schematically showing the configuration of the optical branching device according to the first embodiment, FIG. 2 is a plan view of the optical branching device shown in FIG. 1, and FIG. It is a perspective view of a principal part.
As shown in FIGS. 1 to 3, the first light branching element 1 and the second light branching element 2 according to the first embodiment include a substrate 3 and a translucent resin layer 4 formed on the substrate 3. The resin layer 4 has an inclined surface 5 formed so as to go down from the surface of the resin layer 4 toward the surface of the substrate 3 at a predetermined angle, and the inclined surface 5 has a reflective film 6 for reflecting light. Each has a reflection area 5a and a light receiving area 5b for receiving light.
[0031]
Here, the resin layer 4 includes a lower clad layer 7, a core layer 8, and an upper clad layer 9. The core layer 8 is provided with cores 8a, 8b, and 8c that are formed by increasing the refractive index of a part of the core layer 8 relative to other parts and that function as optical waveguides. The inclined surface 5 is formed at one end of each of the cores 8b and 8c. The upper cladding layer 9 is laminated on the core layer 8 so as to fill the inclined surface 5. The reflection film 6 is a metal thin film made of gold.
[0032]
Of the light that enters the core 8a from the point A in FIG. 1 and propagates through the core 8a and reaches the first optical branch element 1, the light that reaches the reflection region 5a (see FIGS. 2 and 3) is shown in FIG. The light reflected in the direction B in FIG. 1 and reaching the light receiving region 5b passes through the light receiving region 5b (see FIGS. 2 and 3) as it is in the direction E in FIG.
Further, the light transmitted through the light receiving region 5b of the first optical branching element 1 propagates through the core 8b and reaches the second optical branching element 2, and similarly to the first optical branching element 1, C in FIG. And the direction of E.
[0033]
In this manner, when the light reaching the first and second optical branching elements 1 and 2 is branched by the first and second optical branching elements 1 and 2 respectively, the branching ratio is such that the reflection film 6 is formed. The area ratio between the reflecting region 5a having the reflection film 6 and the light receiving region 5b having no reflection film 6 is almost uniquely determined.
For this reason, the reflectivity on the surface of the reflective film 6 becomes substantially constant irrespective of the mode of the propagating light, and even if the cores 8a, 8b, 8c as the optical waveguides are so-called multi-mode waveguides, the branching ratio is high. A stable value is obtained.
[0034]
For example, assuming that the reflectance of the reflection region 5a where the reflection film 6 is formed is 90% and the transmittance of the light receiving region 5b where the reflection film 6 is not formed is 100%, a 1: 1 branching ratio is realized. The formation range of the reflection region 5b and the formation range of the light receiving region 5a may be set to 52.6% and 47.4%, respectively, of the area of the inclined surface 5. At this time, since the absorption loss per optical splitting element is 5%, the overall light utilization efficiency when the first and second optical splitting elements 1 and 2 are arranged in cascade as in the first embodiment is: 90.3%, which is a large improvement over the conventional half mirror made of a metal film.
The cores 8a, 8b, and 8c are interrupted in the areas where the first and second optical branching elements 1 and 2 are formed, but the interrupted distance is within twice the width W of the core. Then, the loss due to light diffraction (spreading) does not matter.
[0035]
The distance L between the first and second optical branching elements shown in FIG. 2 may be set so as to satisfy the following condition.
L> D × W / (2λ)
Here, W is the width of the light receiving region 5b, D is the width of the core 8b, and λ is the wavelength of the light having the minimum wavelength among the light propagating in the core 8b.
When the distance L between the first and second optical branching elements 1 and 2 is set such that the condition according to the above equation is satisfied, light that has passed through the light receiving region 5b of the first optical branching element 1 and has entered the core 8b is Immediately after the incidence, the light spreads only near the center of the core 8b, but spreads to the full width of the core 8b by the diffraction effect before reaching the next second light branching element 2.
[0036]
For example, if the width W of the light receiving region 5b is 10 μm, the width D of the core 8b is 20 μm, and the wavelength λ of the light having the minimum wavelength among the light propagating through the core 8b is 0.85 μm, the first and second light The distance L between the branch elements 1 and 2 only needs to be larger than about 118 μm.
Thereby, the original performance of the second optical branching element 2 is exhibited, and for example, an effect such that the branching ratio does not change can be obtained.
As described above, the light that has entered the core 8b is propagated while being confined therein, so that the light does not distribute beyond the width D of the core 8b.
[0037]
Example 2
FIG. 4 is a sectional view showing a schematic configuration of an optical waveguide device according to the present invention.
As shown in FIG. 4, the optical waveguide device 20 according to the second embodiment is formed with the substrate 3, the light-transmitting resin layer 4 formed on the substrate 3, and the resin layer 4 spaced apart from each other. Core 8b as an elongated optical waveguide formed in the resin layer 4 so that light propagates between the first and second optical branching elements 1 and 2 and the first and second optical branching elements 1 and 2 And the first and second optical splitters 1 and 2 have the same configuration as the first and second optical splitters 1 and 2 according to the first embodiment.
[0038]
Here, the resin layer 4 is composed of a lower clad layer 7, a core layer 8 and an upper clad layer 9 in the same manner as in the first embodiment. The core layer 8 has cores 8a, 8b and 8c formed thereon. Near the end, there is formed a mirror 21 composed of an inclined surface 5 formed on a part of the core layer 8 and a reflection film 6 formed on the inclined surface 5.
In the upper cladding layer 9, vertical cores 9 a, 9 b, 9 c rising from the mirror 21, the first light branching element 1 and the second light branching element 2 to the surface of the upper cladding layer 9 are formed.
[0039]
Above the vertical cores 9a, 9b, 9c, a surface emitting laser 24, a first photodetector 25 and a second electrode 22 are formed via an electrode 22 formed on the resin layer 4 and solder 23 applied on the electrode 22. Each of the photodetectors 26 is mounted.
Light emitted from the surface emitting laser 24 enters from the end of the vertical core 9a, propagates in the vertical core 9a, and reaches the mirror 21. The light that has reached the mirror 21 is reflected so that its optical path is changed by 90 degrees, enters the core 8a, propagates inside the core 8a, and reaches the first optical branching element 1. The light that has reached the first optical branching element 1 is branched by the branching action of the first optical branching element 1 into two directions, a direction toward the vertical core 9b and a direction toward the core 8b.
[0040]
Of the light split by the first optical splitter 1, the light split in the direction toward the vertical core 9b propagates through the vertical core 9b and is radiated from the end of the vertical core 9b, and the first light detector The light is received by 25 and converted into an electric signal.
On the other hand, the light branched in the direction toward the core 8b propagates through the core 8b and reaches the second optical branching element 2, and the direction toward the vertical core 9c and the core 8c due to the branching action of the second optical branching element 2. It is branched into two directions, a heading direction.
[0041]
Of the light split by the second light splitting element 2, the light split in the direction toward the vertical core 9c propagates in the vertical core 9c and is emitted from the end of the vertical core 9c, and the second light detector The light is received by 26 and converted into an electric signal.
On the other hand, the light branched in the direction toward the core 8c further propagates in the core 8c toward another optical branching element or a mirror (not shown).
Here, as described above, the branching ratio of the optical branching elements 1 and 2 is hardly influenced by the mode of light propagating through the core. It can be formed as a mode waveguide.
As a result, light from the surface emitting laser 24 having a light emitting portion having a diameter of about 10 μm or more can be efficiently guided to the cores 8a, 8b, 8c.
[0042]
Also, since the vertical cores 9a, 9b, 9c are formed in the upper cladding layer 9, the distance between the end of the vertical core 9a and the surface emitting laser 24, and the distance between the ends of the vertical cores 9b, 9c. The distance between the first and second photodetectors 25 and 26 and the light receiving section is reduced.
For this reason, the light emitted from the surface emitting laser can be made to enter the vertical core 9a with a small spread, and the light emitted from the ends of the vertical cores 9b and 9c can be converted into a small spread. The light can be received by the first and second photodetectors 25 and 26, and as a result, the light coupling efficiency is improved.
[0043]
Next, a method for manufacturing the optical waveguide device according to the second embodiment will be described with reference to FIGS. 5 to 7 and FIGS. 9 to 18 are process diagrams showing the manufacturing steps of the optical waveguide device shown in FIG. 4, and FIG. 8 is an explanatory view showing the configuration of a gray mask used in the manufacturing process of the optical waveguide device. is there.
[0044]
First, as shown in FIG. 5, the lower cladding layer 7 is formed on the substrate 3. As the substrate 3, a glass substrate excellent in smoothness or a polyimide film excellent in flexibility and heat resistance is used.
The lower clad layer 7 may have a lower refractive index than the core layer 8 to be formed later. However, polysilane (manufactured by Nippon Paint Co., Ltd.) , Product name: Gracia WG, product number: WG-005). If the heat resistance is about 300 ° C. or higher, the possibility of modification in the soldering step when mounting electronic components is reduced, which is advantageous for mounting.
The lower cladding layer 7 is formed by applying the above-mentioned polysilane on the substrate 3 by spin coating and baking it at about 350 ° C. to form a chemically stable film.
[0045]
Next, as shown in FIG. 6, a core layer 8 is formed on the lower cladding layer 7. Polysilane (manufactured by Nippon Paint Co., Ltd., product name: Gracia WG, product number: WG-004) that exhibits hydrophilicity, solubility, and a change in refractive index when irradiated with ultraviolet light is used for the core layer 8.
At the same time as the polysilane is partially hydrophilic and is rendered hydrophilic by irradiation with ultraviolet light, the polysilane becomes soluble in an alkali solution and further has a lower refractive index. It is also preferable from the viewpoint of heat resistance.
However, in order to ensure a difference in refractive index from the lower cladding layer 7, a material having a different composition from polysilane constituting the lower cladding layer 7 is used.
The core layer 8 is formed by applying the above-mentioned polysilane on the lower cladding layer 7 by spin coating and heating it to about 250 ° C. to volatilize the solvent in the film.
[0046]
Next, as shown in FIG. 7, the core layer 8 is irradiated with ultraviolet light via the gray mask 30. As shown in FIG. 8, the gray mask 30 includes a transparent substrate 30a and a light-shielding film 30b. The light-shielding film 30b gradually changes in thickness to gradually reduce the light transmittance at a position corresponding to the inclined surface 5. It has a light transmitting portion 30c and an opening 30d adjacent to the light transmitting portion 30c.
The chemical change of the polysilane due to the irradiation of ultraviolet light (the development of hydrophilicity, solubility, and change in the refractive index) proceeds from the surface of the core layer 8 in the thickness direction according to the intensity of the irradiated ultraviolet light.
For this reason, in the portion irradiated with the ultraviolet light through the light transmitting portion 30c, a chemical change proceeds in accordance with the change in the thickness of the light transmitting portion 30c, and as a result, the three-dimensional surface of the inclined surface 5 is formed on the core layer 8. An exposure area 31 having a latent image is formed.
[0047]
Next, as shown in FIG. 9, the obtained substrate 3 is immersed in an alkaline solution, and the exposed region 31 (see FIG. 7) in which hydrophilicity, solubility, and change in refractive index are developed by irradiation with ultraviolet light is removed. Then, a recess 32 having the inclined surface 5 is formed.
[0048]
Next, as shown in FIGS. 10A and 10B, the obtained substrate 3 is subjected to a plating bath by an electroless plating method. At this time, since the hydrophilic group generated by the ultraviolet irradiation in the previous step remains on the inner surface of the concave portion 32, metal plating is applied only to the inner surface of the concave portion 32, and the reflective film 6 is formed.
In this step, the reflection film 6 is also formed on the inner surface of the concave portion facing the inclined surface 5, but this hinders the propagation of light. Therefore, this portion of the reflection film 6 is removed in the subsequent steps.
[0049]
That is, as shown in FIGS. 11A and 11B, a resist 33 is applied on the core layer 4 and openings 34a, 34b, and 34c are formed by photolithography, and the reflection film 6 to be removed is formed. To expose.
The opening 34a is formed so as to expose the reflecting film 6 formed on the surface facing the inclined surface 5 while covering the inclined surface 5, and the openings 34b and 34c are formed on the reflecting surface formed on the surface facing the inclined surface 5. 6 and a central portion of the reflection film 6 formed on the inclined surface 5 are formed in a T-shape so as to be exposed.
[0050]
Next, as shown in FIGS. 12 (a) and 12 (b), the obtained substrate 3 is immersed in an etching solution, and unnecessary reflection film 6 (see FIGS. 11 (a) and 11 (b)). ).
Next, as shown in FIGS. 13A and 13B, the resist 33 remaining on the core layer 8 (see FIGS. 12A and 12C) is dissolved and removed with an organic solvent.
[0051]
Next, as shown in FIGS. 14A and 14B, in order to form cores 8a, 8b, 8c as optical waveguides in the core layer 8, the patterns corresponding to the cores 8a, 8b, 8c are formed. Ultraviolet light is irradiated through a mask 35 having a light shielding film 35b.
That is, since the refractive index of the polysilane constituting the core layer 8 is reduced by irradiating the ultraviolet light, the portion of the core layer 8 which is not used as the cores 8a, 8b and 8c is irradiated with the ultraviolet light to reduce the refractive index. The cores 8a, 8b, and 8c are formed by lowering the refractive index and increasing the refractive index of the portions to be the cores 8a, 8b, and 8c.
[0052]
Next, as shown in FIG. 15, the core layer 8 is fired at about 350 ° C. to be chemically stabilized.
At this time, the refractive index of the core layer 8 is reduced as a whole, but the refractive index difference caused by the ultraviolet light irradiation in the previous step is maintained almost as it is. Is also maintained higher than the lower cladding layer 7.
Next, as shown in FIG. 16, an upper clad layer 9 is formed on the core layer 8. The upper cladding layer 9 is formed by applying the same polysilane as the core layer 8 by spin coating and heating it to about 250 ° C. to volatilize the solvent in the film.
[0053]
Next, as shown in FIGS. 17A and 17B, ultraviolet light is applied to the upper cladding layer 9 only through a mask 36 having a light shielding film 36b only at a position corresponding to the upper side of the inclined surface 5. The vertical cores 9a, 9b, and 9c are formed in the upper clad layer 9 by irradiating and lowering the refractive index of the irradiated portion to relatively increase the refractive index of the portions to be the vertical cores 9a, 9b, and 9c.
Next, as shown in FIGS. 18A and 18B, the upper cladding layer 9 is fired at about 350 ° C. to be chemically stabilized.
Thereafter, an electrode 22 for mounting the surface emitting laser 24 and the first and second photodetectors 25 and 26 is formed on the upper cladding layer 9, and the surface emitting laser 24 and the first and second photodetectors 25 and 26 are formed. By soldering the electrodes 26 to the respective electrodes, the optical waveguide element 20 shown in FIG. 4 is completed.
[0054]
【The invention's effect】
According to the present invention, since the inclined surface has the reflection area having the reflection film for reflecting the light and the light receiving area for receiving the light, the light to be transmitted directly reaches the light receiving area of the light branching element. And light absorption loss can be minimized.
[Brief description of the drawings]
FIG. 1 is a sectional view schematically showing a configuration of an optical branching device according to a first embodiment of the present invention.
FIG. 2 is a plan view of the optical branching element shown in FIG.
FIG. 3 is a perspective view of a main part of the optical branching element shown in FIG.
FIG. 4 is a sectional view schematically showing a configuration of an optical waveguide device according to a second embodiment of the present invention.
FIG. 5 is a process chart showing a manufacturing process of the optical waveguide device shown in FIG. 4;
FIG. 6 is a process chart showing a manufacturing process of the optical waveguide element shown in FIG. 4;
FIG. 7 is a process chart showing a manufacturing process of the optical waveguide element shown in FIG.
8 is an explanatory view schematically showing a configuration of a gray mask used in a manufacturing process of the optical waveguide element shown in FIG.
FIG. 9 is a process chart showing a manufacturing process of the optical waveguide element shown in FIG.
10 is a process diagram showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the process, respectively.
11 is a process diagram showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the process, respectively.
12 is a process chart showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the same process, respectively.
13 is a process chart showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the same process, respectively.
14 is a process diagram showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the process, respectively.
FIG. 15 is a process chart showing a manufacturing process of the optical waveguide element shown in FIG. 4;
FIG. 16 is a process chart showing a manufacturing process of the optical waveguide element shown in FIG. 4;
17 is a process chart showing a manufacturing process of the optical waveguide device shown in FIG. 4, wherein (a) and (b) show a cross section and a plane in the process, respectively.
18 is a process diagram showing a manufacturing process of the optical waveguide device shown in FIG. 4, in which (a) and (b) respectively show a cross section and a plane in the process.
FIG. 19 is an explanatory diagram schematically showing a configuration of a conventional optical signal transmission system.
[Explanation of symbols]
1 .... first optical branching element
2 ... second optical branching element
3 ... substrate
4 ... Resin layer
5 ... Slope
5a: Reflection area
5b ... light receiving area
6 ... Reflection film
7 ... Lower cladding layer
8 core layer
8a, 8b, 8c ... core
9 Upper clad layer
9a, 9b, 9c ... vertical core
20 ... Optical waveguide element
21 ・ ・ ・ Mirror
22 ... electrode
23 ・ ・ ・ Solder
24 ・ ・ ・ Surface emitting laser
25 first photodetector
26 ... second photodetector
30 gray mask
30a: transparent substrate
30b, 35b, 36b ... light shielding film
30c ... light transmitting part
30d ... opening
31 ... Exposure area
32 ... recess
33 ... resist
34a, 34b, 34c ... opening
35, 36 ... mask
D: Core width
L: distance between the first and second optical branching elements
W: width of light receiving area

Claims (6)

A substrate, comprising a light-transmitting resin layer formed on the substrate, the resin layer having an inclined surface formed so as to descend at a predetermined angle from the surface of the resin layer toward the surface of the substrate; A light splitting element having a reflective area having a reflective film for reflecting light and a light receiving area for receiving light. A substrate, a light-transmitting resin layer formed on the substrate, first and second light-branching elements formed in the resin layer at intervals, and first and second light-branching elements And an elongated optical waveguide formed in the resin layer so as to propagate light between the first and second optical splitters, wherein the first and second optical splitters comprise the optical splitter according to claim 1. The optical waveguide has a rectangular cross section and a constant width in a direction parallel to the substrate, and the inclined surfaces of the first and second optical branching elements have shapes and sizes corresponding to both end surfaces of the optical waveguide, respectively. 3. The optical waveguide device according to claim 2, wherein the optical waveguide device is optically connected to a wave path. The light receiving region of the first light branching element is formed in the center of the inclined surface in a slit shape having a width W, and when the width of the optical waveguide is D and the wavelength of light propagating in the optical waveguide is λ, the first and second light receiving regions are formed. The distance L between the second optical branching elements is
L = D × W / (2λ)
The optical waveguide device according to claim 3, wherein the optical waveguide device is longer than a distance L represented by: A method for manufacturing the optical branching element according to claim 1, wherein a step of applying a light-transmissive resin that exhibits hydrophilicity and solubility by light irradiation to a substrate to form a resin layer, A step of irradiating the resin layer with light through a mask having a region where the transmittance changes continuously to develop hydrophilicity and solubility in a part of the resin layer, and dissolving a part of the resin layer in which the solubility is developed Removing the inclined surface, forming a reflective film on the surface of the hydrophilic inclined surface by electroless plating, and removing a portion of the reflective film by etching to form a light receiving region and a reflective region And a method of manufacturing an optical branching element. 3. A method for manufacturing an optical waveguide device according to claim 2, wherein a light-transmissive resin that exhibits hydrophilicity, solubility, and a change in refractive index by light irradiation is applied to the substrate to form a resin layer. And a step of forming a first optical branching element, a second optical branching element, and an optical waveguide in a resin layer, wherein the step of forming the first and second optical branching elements has a continuous light transmittance. A step of irradiating the resin layer with light through a mask having a changing region to develop hydrophilicity and solubility in a part of the resin layer, and dissolving and removing a part of the resin layer in which the solubility is developed to form a slope. Forming a reflective film by electroless plating on the surface of the inclined surface having hydrophilicity, and forming a light receiving region and a reflective region by removing a part of the reflective film by etching. The step of forming the waveguide corresponds to the pattern of the optical waveguide. Method for manufacturing an optical waveguide element comprising the step of expressing the refractive index change in the irradiation resin layer light to the resin layer through a mask.

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