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JP4524748B2 - Optical monitor and optical monitor array and optical system using the same - Google Patents

Optical monitor and optical monitor array and optical system using the same Download PDF

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JP4524748B2
JP4524748B2 JP2004281740A JP2004281740A JP4524748B2 JP 4524748 B2 JP4524748 B2 JP 4524748B2 JP 2004281740 A JP2004281740 A JP 2004281740A JP 2004281740 A JP2004281740 A JP 2004281740A JP 4524748 B2 JP4524748 B2 JP 4524748B2
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optical fiber
light receiving
refractive index
core
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康博 濱口
諭 牧尾
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Proterial Ltd
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Description

本発明は、光通信システムや光パワー伝送システムにおいて、光信号若しくは光パワーの監視に用いられる光モニタに関する。 The present invention relates to an optical monitor used for monitoring an optical signal or optical power in an optical communication system or an optical power transmission system.

光通信システムや光パワー伝送システムにおいては、それらのシステムの動作状況を監視する必要がある。より具体的には、光アンプ(増幅器)、光アッテネータ(減衰器)、光ゲインイコライザ(増幅・減衰器)等の光信号処理機における光パワーの大きさの監視や、光切替装置における切替経路を確認する必要がある。 In optical communication systems and optical power transmission systems, it is necessary to monitor the operating status of these systems. More specifically, the monitoring of the optical power level in an optical signal processor such as an optical amplifier (amplifier), optical attenuator (attenuator), optical gain equalizer (amplifier / attenuator), and switching path in an optical switching device It is necessary to confirm.

このような要求を実現する単純な構成は、入射通信光を光ファイバカプラ等の光合分波器で出射通信光とモニタ光に分岐した後、モニタ光を伝搬する光ファイバの先に受光素子を配置することで通信光をモニタする構成である。しかしながら、このような構成では、光モニタの小型集積化への要求に答えることが難しい。 A simple configuration that realizes such a requirement is that after the incident communication light is branched into the outgoing communication light and the monitor light by an optical multiplexer / demultiplexer such as an optical fiber coupler, a light receiving element is placed at the end of the optical fiber that propagates the monitor light. It is the structure which monitors communication light by arrange | positioning. However, with such a configuration, it is difficult to answer the demand for miniaturization of the optical monitor.

小型集積化への要求に対しては、例えば特許文献1には以下のような光導波路デバイスが開示されている。光導波路が形成された光導波路プラットフォームの上部に、光導波路方向と直角方向に切り欠き(溝)等による不連続部分を設け、前記溝を覆うように光検出器を実装する。光導波路の光不連続部分から取り出される信号光の一部が光検出器の受光素子で検出される。光導波路の光不連続部分から信号光を取り出す方法の一例として、クラッド層に溝を形成しコア層を露出したり、その溝に高屈折率の誘電体を装荷して信号光の一部を漏れ波として取り出す方法が示されている。 In response to the demand for miniaturization, for example, Patent Document 1 discloses the following optical waveguide device. A discontinuous portion such as a notch (groove) is provided in the direction perpendicular to the optical waveguide direction on the upper portion of the optical waveguide platform on which the optical waveguide is formed, and a photodetector is mounted so as to cover the groove. A part of the signal light extracted from the light discontinuous portion of the optical waveguide is detected by the light receiving element of the photodetector. As an example of a method for extracting signal light from the optical discontinuous portion of the optical waveguide, a groove is formed in the cladding layer to expose the core layer, or a dielectric material having a high refractive index is loaded in the groove so that a part of the signal light is extracted. The method of taking out as a leaky wave is shown.

光ファイバデバイスに関しては、特許文献2に以下のような構成が開示されている。基板の一方の面からクラッドの一部がはみ出た状態で、湾曲保持した光ファイバのクラッドはみ出し部分を削り、除去し、光学的結合平面を形成する。この光学的結合平面上に、高屈折率層を配置することでコアを伝搬する光信号の一部を光検出器へ漏洩させてモニタする。 Regarding the optical fiber device, Patent Document 2 discloses the following configuration. With a portion of the cladding protruding from one surface of the substrate, the protruding portion of the optical fiber held curved is shaved and removed to form an optical coupling plane. By disposing a high refractive index layer on the optical coupling plane, a part of the optical signal propagating through the core is leaked to the photodetector for monitoring.

特開2001−13339号公報JP 2001-13339 A 米国特許第6744948号明細書US Pat. No. 6,744,948

光通信網は光ファイバで構成されているので、光導波路デバイスは、光ファイバデバイスに比べ、光通信網と接続した時の損失が大きくなり易い。また、上記従来例において、取り出された光は必ずしも効率的に受光されているとは言えなかった。例えば、受光素子の手前に空隙層が存在する構成では、コアから取り出された光が伝搬し難いので効率よく受光し難いという問題がある。また、コア層自体に溝を設けた構成では、損失が大きくなる。 Since the optical communication network is composed of optical fibers, the optical waveguide device tends to have a large loss when connected to the optical communication network, as compared to the optical fiber device. In the above conventional example, the extracted light is not necessarily received efficiently. For example, in a configuration in which a gap layer is present in front of the light receiving element, there is a problem in that it is difficult to receive light efficiently because light extracted from the core is difficult to propagate. Further, in the configuration in which the groove is provided in the core layer itself, the loss increases.

また、特許文献2に開示された構成においては、湾曲させた光ファイバの一部を削り除去することで光学的結合平面を形成するので、光信号の取り出し量を決める光学的結合平面の形成自由度は、光ファイバの湾曲のさせ方で制限される。そのため、最適形状の加工が出来ない場合がある。具体的には、光ファイバを深さ方向にはコア近辺まで深く、長さ方向に短く加工する場合、光ファイバの曲げ半径を小さくする必要があり加工が難しい。その結果、光モニタ作製時に低挿入損失化や高受光効率化などが不十分となることが懸念される。さらに光ファイバに一定の湾曲を要求するので、小型化に不利である。また、光ファイバあるいは光ファイバを固定している基板と受光素子が一定の傾きをもった立体的構成は、傾きの制御の困難さが特性を悪化させる可能性があった。 Further, in the configuration disclosed in Patent Document 2, an optical coupling plane is formed by scraping and removing a part of a curved optical fiber, so that the optical coupling plane that determines the amount of optical signal extraction can be freely formed. The degree is limited by how the optical fiber is bent. Therefore, there is a case where the optimum shape cannot be processed. Specifically, when processing the optical fiber deep in the depth direction to the vicinity of the core and shortening in the length direction, it is necessary to reduce the bending radius of the optical fiber, which is difficult to process. As a result, there is a concern that low insertion loss and high light receiving efficiency may become insufficient when manufacturing an optical monitor. Furthermore, since the optical fiber requires a certain curvature, it is disadvantageous for miniaturization. In addition, in the three-dimensional configuration in which the optical fiber or the substrate on which the optical fiber is fixed and the light receiving element have a certain inclination, the difficulty in controlling the inclination may deteriorate the characteristics.

本発明は、上記の課題に鑑み、光ファイバで構成した小型でかつ低挿入損失でかつ高受光効率の光モニタ並びにこれを用いた光モニタアレイ及び光システムを提供することを目的とする。 In view of the above problems, an object of the present invention is to provide a small-sized, low insertion loss and high light-receiving efficiency optical monitor composed of an optical fiber, and an optical monitor array and an optical system using the optical monitor.

[1]本発明は、光ファイバのコアを伝搬する光の一部を光検出器で受光する光モニタにおいて、光ファイバのクラッドの一部がコアの屈折率以上の屈折率を有する置換材料で、光ファイバの中心軸に対し平行な底部と光ファイバの長手方向において当該底部の両端から光ファイバの外周面に向かい伸びた面状の端部とを有する切り欠き状に置換された置換領域を有し、前記光ファイバの中心軸に対し受光面がほぼ平行に配置された前記光検出器の受光素子の中心は、前記置換領域の光ファイバ長手方向の端部よりもコア伝搬光の進行方向前方側に位置するとともに前記光検出器の受光素子と前記光ファイバの外周面との間隙にはクラッドの屈折率以上の屈折率を有する充填材料が充填され、前記置換材料の屈折率n と前記コアの屈折率n に対して、
Δn=(n −n )/n ×100[%]
で定義される屈折率差比Δnが0.65%以上であり、
さらに、前記置換領域はコアと最も近接している部分としてコアとの間隔が1μm以上かつ2μm以下である底部を有し、前記Δn、前記底部の光ファイバ長手方向の長さL0および前記受光素子の光ファイバの長手方向の長さLとが、
0.024×Δn+0.21≦L0/La≦0.081×Δn+0.29
の関係を有し、
加えて、前記光ファイバから前記置換領域へ漏れ、前記置換領域の端部と前記光ファイバのクラッドとの界面を透過し、当該クラッドを伝搬した漏洩光を前記光検出器で受光することを特徴とする光モニタである。かかる構成によって、光ファイバのクラッドの置換領域で漏洩させた光を受光素子で効率よく検出することができるため、光ファイバで構成した小型、低挿入損失かつ高受光効率の光モニタが実現でき、さらに、光ファイバのクラッドの置換領域で漏洩させた光を受光素子で効率よく検出することができるため、光ファイバで構成した小型、低挿入損失かつ高受光効率の光モニタが実現できる。
[1] The present invention provides an optical monitor in which a part of light propagating through an optical fiber core is received by a photodetector, and a replacement material in which a part of the cladding of the optical fiber has a refractive index higher than that of the core. A replacement region replaced with a notch having a bottom parallel to the central axis of the optical fiber and a planar end extending from both ends of the bottom toward the outer peripheral surface of the optical fiber in the longitudinal direction of the optical fiber. And the center of the light receiving element of the photodetector in which the light receiving surface is arranged substantially parallel to the center axis of the optical fiber is the traveling direction of the core propagation light from the end of the replacement region in the longitudinal direction of the optical fiber. filler material having a refractive index of more than the refractive index of the cladding is filled in a gap between the outer peripheral surface of the optical fiber and the light receiving element of the photodetector as well as positioned on the front side, and the refractive index n o of the replacement material Refractive index n of the core with respect to c,
Δn = (n o −n c ) / n c × 100 [%]
The refractive index difference ratio Δn defined by is 0.65% or more,
Furthermore, the replacement region has a bottom portion having a distance of 1 μm or more and 2 μm or less as a portion closest to the core, Δn, a length L 0 of the bottom of the optical fiber in the longitudinal direction, and the light receiving and the longitudinal length L a of the optical fiber element,
0.024 × Δn + 0.21 ≦ L 0 / L a ≦ 0.081 × Δn + 0.29
Have the relationship
In addition, the optical fiber leaks into the replacement region, passes through the interface between the end of the replacement region and the cladding of the optical fiber, and the leaked light propagated through the cladding is received by the photodetector. Is an optical monitor . With this construction, since the light was leaked in the replacement region of the cladding of the optical fiber can be detected efficiently by the light receiving element, a small constituted by an optical fiber, low insertion loss and optical monitor high light receiving efficiency can in realization Furthermore, since the light leaked in the replacement region of the cladding of the optical fiber can be efficiently detected by the light receiving element, it is possible to realize a small-sized, low insertion loss and high light receiving efficiency optical monitor constituted by the optical fiber.

[2]また本発明は、前記底部の光ファイバ長手方向の中心と前記いずれかの光検出器の受光素子の光ファイバ長手方向の中心を結ぶ直線と前記コアの延設方向がなす角度θ[°]が、前記置換材料の屈折率nと前記コアの屈折率nに対して、
Δn=(n−n)/n×100[%]
で定義される屈折率差比Δnに対し
1.13×Δn+5.5≦θ≦1.13×Δn+11
であることを特徴とする前記[1]に記載の光モニタである。かかる構成によって、受光効率に優れた、小型、低挿入損失かつ高受光効率の光モニタが実現できる。
[2 ] Further, in the present invention, an angle θ [] formed by a straight line connecting the center of the bottom optical fiber in the longitudinal direction and the center of the light receiving element of any one of the photodetectors in the optical fiber longitudinal direction and the extending direction of the core. °] it is, with respect to the refractive index n c of the core and the refractive index n o of the replacement material,
Δn = (n o −n c ) / n c × 100 [%]
1.13 × Δn + 5.5 ≦ θ ≦ 1.13 × Δn + 11 with respect to the refractive index difference ratio Δn defined by
The optical monitor according to [1 ], which is characterized in that: With this configuration, it is possible to realize a small, low insertion loss and high light receiving efficiency optical monitor with excellent light receiving efficiency.

[3]また本発明は、前記[1]〜[2]のいずれかに記載の光モニタを2個以上用いたことを特徴とする光モニタアレイである。かかる構成によって、光ファイバで構成した小型、低挿入損失かつ
高受光効率の光モニタアレイを提供することが可能となる。
[3 ] The present invention also provides an optical monitor array using two or more optical monitors according to any one of [1] to [2 ]. With such a configuration, it is possible to provide a small, low insertion loss and high light receiving efficiency optical monitor array composed of optical fibers.

[4]また本発明は、前記[1]〜[3]のいずれかに記載の光モニタを光伝送用の光ファイバに接続し、前記光ファイバで伝搬される光信号の強度を検知することを特徴とする光システムである。かかる構成によって、光システム全体の小型化、低損失化を図ることができる。 [4 ] In the present invention, the optical monitor according to any one of [1] to [3 ] is connected to an optical fiber for optical transmission, and the intensity of an optical signal propagated through the optical fiber is detected. Is an optical system characterized by With this configuration, it is possible to reduce the size and loss of the entire optical system.

本発明によれば、光ファイバで構成した小型でかつ低挿入損失でかつ高受光効率の光モニタ並びにこれを用いた光モニタアレイ及び光システムを実現できる。 According to the present invention, it is possible to realize a small-sized, low insertion loss and high light-receiving efficiency optical monitor composed of an optical fiber, and an optical monitor array and optical system using the optical monitor.

以下、本発明の実施の形態を、図を参照しつつ説明する。なお、これら実施例により本発明が限定されるものではない。 Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited by these Examples.

図1は本発明の光モニタの第1の構成例を示す概略図である。図1(a)は光モニタ側面の断面図に相当する。図1(b)は図1(a)におけるA-A´断面の断面図に相当する。本発明の光モニタ100は光ファイバ101と光検出器102を有する。光ファイバ101は直線配置されている。直線配置することが、光モニタの小型化に有利である。光検出器102は該検出器の受光素子109の受光面の法線が光ファイバ101の軸と直交するように、すなわち受光素子の受光面が光ファイバの軸と平行に配置されている。受光素子の受光面と光ファイバの軸との角度が大きくなると、検出器高が高くなってしまう。例えば長さ1mmの受光素子を用いた場合に、受光素子の傾きによる高さの増加を0.2mm未満に抑えるためには、受光面と光ファイバとの角度は10°未満とすることが好ましい。受光素子の受光面と光ファイバの軸とは平行であることがより好ましい。かかる構成とすることで、光モニタの低背化・小型化が図られるとともに組み立てが簡略化される。ここで光ファイバ101はシングルモード対応の光ファイバでも、マルチモード対応の光ファイバでも良い。あるいはガラス製光ファイバであってもプラスチックファイバであっても良い。光検出器102は裏面、即ち受光素子109が配置されていない面、に受光した光を電気信号として検出するための電気信号用端子を有する。ただしこの端子は図示していない。光ファイバは基板上に配置されていることが望ましい。ただし、該基板の図示は省略した。該基板には光ファイバを整列させる溝が形成されていることが望ましい。該基板と前記光検出器とで、前記光ファイバを挟み込む構成とすることは、光モニタの小型化において望ましい。図示した光モニタを内包するパッケージ部材についても図示を省略した。 FIG. 1 is a schematic diagram showing a first configuration example of an optical monitor according to the present invention. FIG. 1A corresponds to a cross-sectional view of the side surface of the optical monitor. FIG. 1B corresponds to a cross-sectional view taken along the line AA ′ in FIG. The optical monitor 100 of the present invention includes an optical fiber 101 and a photodetector 102. The optical fibers 101 are arranged in a straight line. The linear arrangement is advantageous for downsizing the optical monitor. The photodetector 102 is arranged such that the normal line of the light receiving surface of the light receiving element 109 of the detector is orthogonal to the axis of the optical fiber 101, that is, the light receiving surface of the light receiving element is parallel to the axis of the optical fiber. If the angle between the light receiving surface of the light receiving element and the axis of the optical fiber increases, the detector height increases. For example, when a light receiving element having a length of 1 mm is used, the angle between the light receiving surface and the optical fiber is preferably less than 10 ° in order to suppress an increase in height due to the inclination of the light receiving element to less than 0.2 mm. . More preferably, the light receiving surface of the light receiving element and the axis of the optical fiber are parallel. With this configuration, the optical monitor can be reduced in height and size, and the assembly can be simplified. Here, the optical fiber 101 may be a single-mode compatible optical fiber or a multi-mode compatible optical fiber. Alternatively, it may be a glass optical fiber or a plastic fiber. The photodetector 102 has an electrical signal terminal for detecting received light as an electrical signal on the back surface, that is, the surface where the light receiving element 109 is not disposed. However, this terminal is not shown. The optical fiber is preferably arranged on the substrate. However, illustration of the substrate is omitted. It is desirable that a groove for aligning optical fibers is formed in the substrate. In order to reduce the size of the optical monitor, it is desirable to sandwich the optical fiber between the substrate and the photodetector. The illustration of the package member including the illustrated optical monitor is also omitted.

光ファイバ101のクラッド105の一部を切り欠き状に除去し置換領域106とする。前記切り欠き状とは、光モニタを構成した状態で切り欠き形状を有していることを意味し、置換領域を切り欠き状とすることで、光の漏洩を該部分に集中させ、それ以外の部分からの無駄な漏洩を防ぐことができる。該置換領域106はコア103よりも大きな屈折率を持つ置換材料で充填する。ここで、光ファイバは、クラッドの屈折率がコアの屈折率よりも若干低いので、コア内に光信号を閉じ込め伝搬させることができる。ただし、光信号はコア内だけに閉じ込められているのではなく、一部がコア周辺のクラッドへ、エバネッセント光としてしみ出している。そのためエバネッセント光がしみ出しているコア周辺のクラッドを、コアの屈折率以上の屈折率を有する置換材料で置換することで、光ファイバを伝搬するの伝搬光104を、光ファイバ外部へ漏洩光108として取り出すことができる。前記コアに近接する置換領域の底部の光ファイバ長手方向の中心を、置換領域の光ファイバ長手方向の中心とする。 A part of the clad 105 of the optical fiber 101 is removed in a cutout shape to form a replacement region 106. The notch shape means that the optical monitor is configured to have a notch shape, and the replacement region is notched so that light leakage is concentrated on the portion, and the rest It is possible to prevent useless leakage from the portion. The replacement region 1006 is filled with a replacement material having a higher refractive index than the core 103. Here, since the refractive index of the cladding of the optical fiber is slightly lower than the refractive index of the core, an optical signal can be confined and propagated in the core. However, the optical signal is not confined only in the core, but part of the optical signal oozes out to the cladding around the core as evanescent light. Therefore, by replacing the cladding around the core where the evanescent light has oozed out with a replacement material having a refractive index equal to or higher than the refractive index of the core, the propagation light 104 propagating through the optical fiber is leaked to the outside of the optical fiber 108. Can be taken out as. The center in the optical fiber longitudinal direction at the bottom of the replacement region adjacent to the core is defined as the center in the optical fiber longitudinal direction of the replacement region.

切り欠き状の置換領域106はコア103を伝搬する伝搬光104のエバネッセント光部分と相互作用して、漏洩光108を発生させる。置換材料は、硬化性の材料でも、非硬化性の材料でも良い。例えばガラスや樹脂やオイルなど、あるいはそれらを複合した材料などを用いることが可能である。置換材料を樹脂またはオイルなどの液体とすることは、置換領域106への充填を容易とし、検出部以外への光の漏洩や光の伝搬の妨げの原因となる空隙を生じ難くするので望ましい。また、熱あるいは紫外線等に対し硬化性を持つ樹脂を使用することは、クラッド内の置換領域を該樹脂で置換した後、硬化させることで、所望の形状を維持させることが可能である点で有利である。 The cut-out replacement region 1006 interacts with the evanescent light portion of the propagating light 104 propagating through the core 103 to generate leaked light 108. The replacement material may be a curable material or a non-curable material. For example, it is possible to use glass, resin, oil, or a composite material thereof. It is desirable to use a liquid such as resin or oil as the replacement material because it facilitates filling of the replacement region 1006 and makes it difficult for air gaps that would otherwise interfere with light leakage and light propagation to other than the detection portion. In addition, the use of a resin that is curable with respect to heat, ultraviolet rays, or the like is that a desired shape can be maintained by replacing the replacement region in the cladding with the resin and then curing the resin. It is advantageous.

置換領域106の光ファイバ軸方向の断面形状の例として以下に定義するかまぼこ型、または疑かまぼこ型などがある。かまぼこ型とは、円柱を、円の中心軸に平行かつ円の中心を通らない平面で切断したときの円の中心軸を含まない方の形状と定義した。図1(b)で示した置換領域106はかまぼこ型の一例である。このとき、かまぼこ型の平面部分がコア103に近接する配置となる。また、このとき、かまぼこ型の平面部分の光ファイバ長手方向の中心を、置換領域106の中心とする。また、疑かまぼこ型とは、円柱を円の中心軸に平行かつ円の中心を通らない曲面で切断したときの円の中心軸を含まない方の形状と定義した。このとき、疑かまぼこ状型は、かまぼこ型の平面が曲面である形状となる。図2で示した置換領域106は疑かまぼこ型の一例である。 Examples of the cross-sectional shape of the replacement region 106 in the axial direction of the optical fiber include a kamaboko type defined below and a suspicious kamaboko type. The kamaboko shape was defined as a shape that does not include the center axis of the circle when the cylinder is cut by a plane parallel to the center axis of the circle and not passing through the center of the circle. The replacement region 1006 shown in FIG. 1B is an example of a kamaboko type. At this time, the kamaboko-shaped planar portion is arranged close to the core 103. At this time, the center in the longitudinal direction of the optical fiber of the kamaboko-shaped flat portion is set as the center of the replacement region 106. The suspicious kamaboko type was defined as the shape that does not include the center axis of the circle when the cylinder is cut by a curved surface that is parallel to the center axis of the circle and does not pass through the center of the circle. At this time, the suspicious kamaboko-shaped mold has a shape in which the kamaboko-shaped plane is a curved surface. The replacement region 1006 shown in FIG. 2 is an example of a questionable kamaboko type.

置換領域のクラッドの除去には例えば各種ウェットエッチング工程やドライエッチング工程が利用できる。ウェットエッチングにおけるエッチャントの一例としてはフッ化アンモニウム(NHF)、ドライエッチングにおけるエッチャントの一例としてはCFやSFが考えられる。いずれの場合も、エッチングしたくない部分を保護材料でマスキングして、必要な部分だけをエッチングによって除去加工する。適正な条件下で実施するエッチングにより、優れた寸法精度の加工が実現できる。あるいは、ダイシング等の精密機械加工で置換領域のクラッドを除去しても良い。 For example, various wet etching processes and dry etching processes can be used to remove the cladding in the replacement region. As an example of an etchant in wet etching, ammonium fluoride (NH 4 F) is considered, and as an example of an etchant in dry etching, CF 4 or SF 4 is considered. In either case, a portion that is not desired to be etched is masked with a protective material, and only a necessary portion is removed by etching. By performing etching under appropriate conditions, processing with excellent dimensional accuracy can be realized. Alternatively, the cladding in the replacement region may be removed by precision machining such as dicing.

受光素子109には、できるだけ多くの漏洩光108を受光させることが好ましく、もれなく受光することが望ましい。現実的には、受光素子109の表面積を大きくすることで、受光可能な漏洩光108を増大させることはできる。しかしながら、受光素子109の面積を大きくすると、該受光素子109の暗電流が増加する。暗電流の増大は、受光パワーの測定精度に悪影響を及ぼすので望ましくない。このため、受光素子109の面積はできるだけ小さい方が良い。 It is preferable for the light receiving element 109 to receive as much leakage light 108 as possible, and it is desirable to receive all of the light. Actually, by increasing the surface area of the light receiving element 109, the leaked light 108 that can be received can be increased. However, when the area of the light receiving element 109 is increased, the dark current of the light receiving element 109 increases. An increase in dark current is undesirable because it adversely affects the measurement accuracy of received light power. For this reason, the area of the light receiving element 109 should be as small as possible.

受光素子109を大きくすることなく、受光パワーを増大させるには、漏洩光108の伝搬位置に受光素子109を配置すればよい。検討の結果、漏洩光108は、図1(a)に示すように、コア103から徐々に遠ざかるように伝搬していくことが判った。また、図示していないが、漏洩光108が置換領域106とクラッド105との界面に達した場合、伝搬方向をほとんど変えることなく該界面を透過し、伝搬し続けることが判った。従って、漏洩光108の光ファイバ外部での伝搬位置は、置換領域の光ファイバ長手方向の中心位置よりも前方であり、置換領域106の端部よりも前方に位置する場合もある。これに合わせて、受光素子109の中心は、置換領域の光ファイバ長手方向の中心位置よりも前方、場合によっては、伝搬領域106の端部よりも前方とすることで、効率良く漏洩光108を受光することができる。
In order to increase the light receiving power without increasing the size of the light receiving element 109, the light receiving element 109 may be disposed at the propagation position of the leakage light 108. As a result of the examination, it was found that the leaked light 108 propagates gradually away from the core 103 as shown in FIG. Although not shown, it has been found that when the leaked light 108 reaches the interface between the substitution region 106 and the clad 105, it is transmitted through the interface and hardly propagates with almost no change in the propagation direction. Therefore , the propagation position of the leaked light 108 outside the optical fiber is located in front of the center position of the replacement region in the longitudinal direction of the optical fiber, and may be positioned in front of the end portion of the replacement region 1006. In accordance with this, the center of the light receiving element 109 is located in front of the center position of the replacement region in the longitudinal direction of the optical fiber, and in some cases, in front of the end of the propagation region 1006. It can receive light.

光検出器102の受光素子109はなるべく光ファイバ101に近接して設置することが好ましく、より好ましくは光ファイバ101または置換領域に接して設置する。光検出器102の受光素子109と光ファイバ101との間隙は、クラッド105の屈折率以上の屈折率を有する充填材料114で充填することが好ましい。漏洩光108が屈折率の高い材料から、屈折率の低い材料へと伝搬するとき、大きな反射を伴うので、受光素子で受光される光パワーが低下する。しかしながら、光検出器102の受光素子109と光ファイバ101との間隙をクラッド105の屈折率以上の屈折率を有する充填材料114で充填することで、漏洩光108の伝搬経路には空隙あるいは極端に屈折率が小さい材料が存在せず、受光素子109で高い受光効率が得られる。 The light receiving element 109 of the photodetector 102 is preferably installed as close to the optical fiber 101 as possible, more preferably in contact with the optical fiber 101 or the replacement region. The gap between the light receiving element 109 of the photodetector 102 and the optical fiber 101 is preferably filled with a filling material 114 having a refractive index equal to or higher than the refractive index of the clad 105. When the leakage light 108 propagates from a material having a high refractive index to a material having a low refractive index, a large amount of reflection is caused, so that the optical power received by the light receiving element is reduced. However, by filling the gap between the light receiving element 109 of the photodetector 102 and the optical fiber 101 with the filling material 114 having a refractive index higher than the refractive index of the clad 105, the propagation path of the leaked light 108 has a gap or extremely There is no material having a low refractive index, and the light receiving element 109 can obtain high light receiving efficiency.

充填材料114は前記置換材料と同一の材料を用いることが望ましい。充填材料114と置換材料を同一とすることで、材料数の削減や工程の簡略化が可能となる。別の望ましい形態として、充填材料114を用いて、光ファイバ101と光検出器102を接着固定することは、工程の簡略化に有利である。さらに望ましくは、充填材料114を前記置換材料と同一の材料とし、かつ、該充填材料を用いて光ファイバ101と光検出器102を接着固定することが望ましい。これにより不要な反射や散乱を防止するとともに、材料数の削減や更なる工程の簡略化が可能となる。 The filling material 114 is preferably made of the same material as the replacement material. By making the filling material 114 and the replacement material the same, the number of materials can be reduced and the process can be simplified. As another desirable form, the optical fiber 101 and the photodetector 102 are bonded and fixed using the filling material 114, which is advantageous in simplifying the process. More desirably, the filling material 114 is made of the same material as the replacement material, and the optical fiber 101 and the photodetector 102 are bonded and fixed using the filling material. As a result, unnecessary reflection and scattering can be prevented, and the number of materials can be reduced and further processes can be simplified.

受光効率の向上には、光ファイバ101と光検出器の受光素子109との間隙に充填した材料114の厚さを薄くして、光検出器102をできる限り光ファイバ101に近接させることが望ましい。充填材料114を薄くすれば、充填材料114で吸収・散乱等による漏洩光108の損失を抑制でき、より強い漏洩光を受光素子109で受光できる。このとき、光検出器102と光ファイバ101が接触しても良い。 In order to improve the light receiving efficiency, it is desirable to reduce the thickness of the material 114 filled in the gap between the optical fiber 101 and the light receiving element 109 of the photodetector so that the photodetector 102 is as close to the optical fiber 101 as possible. . If the filling material 114 is made thinner, the filling material 114 can suppress the loss of the leaked light 108 due to absorption / scattering and the like, and the light receiving element 109 can receive stronger leaked light. At this time, the photodetector 102 and the optical fiber 101 may contact each other.

以下、光モニタの好適な寸法について説明する。光モニタはコアを伝搬する信号光にできるだけ影響を与えず、かつ信号光を精度良くモニタすることが要求される。この要求は挿入損失ILと受光効率Rで表現できる。挿入損失ILとは伝搬光104の損失を表すパラメータであり、一般に漏洩光108が大きいほど、挿入損失ILは大きい。受光効率Rは漏洩光がどれだけ効率良く受光素子109で受光できたかを表すパラメータであり、1に近いほど高効率である。デバイスへの入力光パワーをPin、デバイスからの出力光パワーをPout、漏洩光パワーをPleak、受光パワーをPrecとすると、両者はそれぞれ次式で表される。
IL=−10log(Pout/Pin)=−10log((Pin−Pleak)/Pin
R=Prec/Pleak
挿入損失ILが大きいとコア103を伝搬する伝搬光104の損失が大きいので望ましくない。一方で挿入損失ILが小さ過ぎると、漏洩光108も小さくなり受光素子109での受光パワーが低下し、モニタ精度が低下するので望ましくない。受光効率Rは極力大きくすることが望ましい。定量的に表現すると
0.3≦IL≦1.0dB かつ 0.8≦R
とすることが望ましい。
Hereinafter, suitable dimensions of the optical monitor will be described. The optical monitor is required to monitor the signal light with high accuracy without affecting the signal light propagating through the core as much as possible. This requirement can be expressed by the insertion loss IL and the light receiving efficiency R. The insertion loss IL is a parameter representing the loss of the propagation light 104. In general, the larger the leakage light 108, the larger the insertion loss IL. The light receiving efficiency R is a parameter indicating how efficiently the leaked light can be received by the light receiving element 109. The closer to 1, the higher the efficiency. Assuming that the input optical power to the device is P in , the output optical power from the device is P out , the leakage light power is P leak , and the received light power is Prec , both are expressed by the following equations.
IL = −10 log (P out / P in ) = − 10 log ((P in −P leak ) / P in )
R = P rec / P leak
If the insertion loss IL is large, the loss of the propagation light 104 propagating through the core 103 is large, which is not desirable. On the other hand, if the insertion loss IL is too small, the leakage light 108 is also reduced, and the light receiving power at the light receiving element 109 is lowered, which is not desirable because the monitoring accuracy is lowered. It is desirable to increase the light receiving efficiency R as much as possible. Expressed quantitatively, 0.3 ≦ IL ≦ 1.0 dB and 0.8 ≦ R
Is desirable.

置換領域がコアと最も近接している部分を底部とし、底部の光ファイバ長手方向の長さを底部長さLとする。始めに、底部とコアとの間隔gについて説明する。図3に底部とコア103との間隔gをパラメータとしたときの、底部長さLと挿入損失ILとの関係を示す。ここで、底部長さLは50μm未満であると加工精度の確保が困難であり、400μm超であると加工時の強度確保に問題が生じる可能性がある。そこで、底部長さLは50〜400μmとすることが好ましい。この範囲の底部長さLに対し、底部とコアとの間隔gを0μm超かつ3μm以下とすることで、受光能の確保と低挿入損失を実現する条件である0.3≦IL≦1.0[dB]が得られる。さらに望ましくは、底部とコアとの間隔gを1μm以上かつ2μm以下とする。 The partial substitution region is closest to the core and the bottom, and a bottom length L 0 of the optical fiber length in the longitudinal direction of the bottom. First, the gap g between the bottom and the core will be described. 3 to the distance g between the bottom and the core 103 when a parameter, indicating a bottom length L 0 of the relationship between insertion loss IL. Here, if the bottom length L 0 is less than 50 μm, it is difficult to ensure the processing accuracy, and if it exceeds 400 μm, there may be a problem in securing the strength during processing. Therefore, the bottom length L 0 is preferably 50 to 400 μm. With respect to the bottom length L 0 in this range, the distance g between the bottom and the core is set to be more than 0 μm and not more than 3 μm, and 0.3 ≦ IL ≦ 1 which is a condition for ensuring the light receiving ability and realizing the low insertion loss. 0.0 [dB] is obtained. More preferably, the gap g between the bottom and the core is 1 μm or more and 2 μm or less.

次に受光素子109の光ファイバ長手方向の長さLに対する底部長さL0の比L0/Laと、前記置換材料とコアとの屈折率差比Δnについて説明する。ここで屈折率差比Δnは置換領域の屈折率をn、コアの屈折率をnとして次式で定義する。
Δn=(n−n)/n×100[%]
図4に底部とコアとの間隔gが1μmと2μmの場合において、挿入損失ILと受光効率Rについて0.3≦IL≦1.0 dBかつ0.8≦R を実現する受光素子109の長さLに対する底部長さLの比L0/Laと屈折率差比Δnの関係を示す。図中○で示した点においては、底部とコアとの間隔gが1μmと2μmの場合の両方において低挿入損失と高受光効率を両立する。図中×で示した領域においては、底部とコアとの間隔gが1μmと2μmの場合の少なくとも一方において低挿入損失と高受光効率が両立しない。各点の詳細な値は表1に示した。
Then the ratio L 0 / L a bottom length L 0 with respect to the optical fiber longitudinal length L a of the light receiving element 109, the refractive index difference ratio Δn of the replacement material and the core is described. Here the refractive index difference ratio Δn is defined by the following equation refractive index of the replacement region n o, a refractive index of the core as n c.
Δn = (n o −n c ) / n c × 100 [%]
4 shows the length of the light receiving element 109 that realizes 0.3 ≦ IL ≦ 1.0 dB and 0.8 ≦ R with respect to the insertion loss IL and the light receiving efficiency R when the gap g between the bottom and the core is 1 μm and 2 μm. It is showing the relationship between the specific L 0 / La and the refractive index difference ratio Δn of the bottom length L o for L a. In the points indicated by ◯ in the figure, both low insertion loss and high light receiving efficiency are achieved in both cases where the gap g between the bottom and the core is 1 μm and 2 μm. In the region indicated by x in the figure, low insertion loss and high light receiving efficiency are not compatible in at least one of cases where the gap g between the bottom and the core is 1 μm and 2 μm. Detailed values of each point are shown in Table 1.

Figure 0004524748
Figure 0004524748

挿入損失ILと受光効率Rについての望ましい関係である0.3≦IL≦1.0dBかつ0.8≦Rを両立する領域は次式(1)および(2)で表すことができる。
0.024×Δn+0.21≦L0/L≦0.081×Δn+0.29――――(1)
0.65≦Δn ――――――――――――――――――――――――――(2)
従って、ΔnとL0/Laを(1)および(2)式の関係を満たす範囲で選択することで、低挿入損失、高受光効率の光モニタが実現できる。Δnの上限について特に限定しないが、現実的な材料選択をした場合、Δnは17%以下である。
A region in which 0.3 ≦ IL ≦ 1.0 dB and 0.8 ≦ R, which is a desirable relationship between the insertion loss IL and the light receiving efficiency R, can be expressed by the following equations (1) and (2).
0.024 × Δn + 0.21 ≦ L 0 / L a ≦ 0.081 × Δn + 0.29 (1)
0.65 ≦ Δn ―――――――――――――――――――――――――― (2)
Therefore, by selecting Δn and L 0 / La within a range that satisfies the relationship of the expressions (1) and (2), an optical monitor with low insertion loss and high light receiving efficiency can be realized. Although there is no particular limitation on the upper limit of Δn, Δn is 17% or less when a realistic material is selected.

ところでΔnが0%に近い正の値をとるとき、漏洩光108がコア103から遠ざかるときの角度は小さくなる。このため、漏洩光108の伝搬方向と、受光素子109の受光面の法線方向とのずれ角が大きくなる。これは、受光素子109にとっては漏洩光108が拡がったことに相当する。このため、Δnが0%に近い正の値をとるときは、具体的には図4に示した通りΔnが0.65%未満のときは、高受光効率が実現困難となる。このとき、漏洩光108を十分に受光するために、受光素子109を大きくすると、暗電流が増加し受光パワーの測定精度に悪影響を及ぼす。また、高受光効率が実現困難となる別の要因としては、漏洩光108がコア103から遠ざかるときの角度が小さいと、該漏洩光は置換領域106を伝搬後、該置換領域前方のクラッド105を伝搬し、さらにその後充填材料114を通過して受光素子109へと向かう。このとき漏洩光108がクラッド105から充填材料114へと伝搬するときの入射角も小さくなるので、漏洩光108がクラッド105と充填材料114の界面で一部反射されることが挙げられる。 By the way, when Δn takes a positive value close to 0%, the angle when the leaked light 108 moves away from the core 103 becomes small. For this reason, the deviation angle between the propagation direction of the leaked light 108 and the normal direction of the light receiving surface of the light receiving element 109 increases. This corresponds to the spread of the leaked light 108 for the light receiving element 109. Therefore, when Δn takes a positive value close to 0%, specifically, when Δn is less than 0.65% as shown in FIG. 4, it is difficult to achieve high light receiving efficiency. At this time, if the light receiving element 109 is enlarged in order to sufficiently receive the leaked light 108, the dark current increases and adversely affects the measurement accuracy of the received light power. Further, another factor that makes it difficult to achieve high light receiving efficiency is that if the angle at which the leaked light 108 moves away from the core 103 is small, the leaked light propagates through the substitution region 106 and then passes through the cladding 105 in front of the substitution region 106. Propagated, and then passes through the filling material 114 toward the light receiving element 109. At this time, since the incident angle when the leaked light 108 propagates from the clad 105 to the filling material 114 is also reduced, the leaked light 108 is partially reflected at the interface between the clad 105 and the filling material 114.

これに対し、置換領域の形状に変更を加えることで、受光効率を改善することが可能であることを見出した。すなわち、置換領域のコア伝搬光の進行方向前方側に、コア延設方向に対して傾斜した傾斜面設けた構造とし、該傾斜面で漏洩光を反射させることで漏洩光を収束させ、受光効率を改善することができる。図5にかまぼこ型の置換領域の前方に傾斜面を設けた構造の一例を示す。傾斜面216はコア伝搬光の進行方向前方側に行くに従ってコア103との間隔が次第に大きくなっていく。このとき漏洩光108の一部は傾斜面216で反射された後、受光素子109で受光される。図6に傾斜面216とコア103とのなす角度θ2と挿入損失ILおよび受光効率Rとの関係を示す。これはΔn=0.27%、L0/L=1/3、g=1μmとしたときの例である。傾斜面とコア103とのなす角度θ2を適切に選択することで、挿入損失の大きな低下を伴うことなく、受光効率を向上させることができる。傾斜面とコア103とのなす角度θ2を3°以上かつ8°以下の範囲とした場合、傾斜部を設けない場合に比べて1.6倍以上の受光効率を得ることができる。 On the other hand, it has been found that the light receiving efficiency can be improved by changing the shape of the replacement region. That is, an inclined surface inclined with respect to the core extending direction is provided on the front side in the traveling direction of the core propagation light in the replacement region, and the leaked light is converged by reflecting the leaked light on the inclined surface, so that the light receiving efficiency Can be improved. FIG. 5 shows an example of a structure in which an inclined surface is provided in front of the kamaboko type replacement region. The interval between the inclined surface 216 and the core 103 gradually increases as it goes to the front side in the traveling direction of the core propagation light. At this time, a part of the leakage light 108 is reflected by the inclined surface 216 and then received by the light receiving element 109. FIG. 6 shows the relationship between the angle θ2 formed by the inclined surface 216 and the core 103, the insertion loss IL, and the light receiving efficiency R. This is an example when Δn = 0.27%, L 0 / L a = 1/3, and g = 1 μm. By appropriately selecting the angle θ2 formed by the inclined surface and the core 103, it is possible to improve the light receiving efficiency without greatly reducing the insertion loss. When the angle θ2 formed by the inclined surface and the core 103 is in the range of 3 ° or more and 8 ° or less, the light receiving efficiency 1.6 times or more can be obtained as compared with the case where the inclined portion is not provided.

前述の通り、受光素子109の中心は、置換領域の光ファイバ長手方向の中心位置よりも前方とすることで、効率良く漏洩光108を受光することができる。さらに望ましくは、受光効率Rが極大となる位置に受光素子109を配置する。このときの受光素子の位置を最適位置と定義する。図7(a)に屈折率差比Δnと、最適位置に受光素子109を配置したときの、底部の光ファイバ長手方向の中心と該受光素子の中心112とを結ぶ直線とコア103がなす角θ(θはコア延設方向のうち光伝播方向からの角度とする)との関係を示す。同図から屈折率差比Δnと最適受光素子位置の角度θ[°]との間に
θ=1.13×Δn+6.5
の関係があることがわかった。
As described above, the leakage light 108 can be efficiently received by setting the center of the light receiving element 109 forward of the center position of the replacement region in the longitudinal direction of the optical fiber. More desirably, the light receiving element 109 is disposed at a position where the light receiving efficiency R is maximized. The position of the light receiving element at this time is defined as the optimum position. FIG. 7A shows the refractive index difference ratio Δn and the angle formed by the core 103 and the straight line connecting the center of the optical fiber in the longitudinal direction of the bottom and the center 112 of the light receiving element when the light receiving element 109 is disposed at the optimum position. It shows the relationship with θ (θ is an angle from the light propagation direction in the core extending direction). From the figure, θ = 1.13 × Δn + 6.5 between the refractive index difference ratio Δn and the angle θ [°] of the optimum light receiving element position.
It was found that there is a relationship.

図7(b)に最適受光素子位置の角度θからのずれΔθ[°]に対する受光パワーを、最適受光素子位置の角度での受光パワーで規格化して示す。高い受光効率を維持するには、図7(b)に示した規格化受光パワーは0.9以上であることが望ましい。さらに望ましくは0.95以上である。Δθを−1°以上かつ+4.5°以下の範囲の値とすることで、規格化受光パワーについて0.9以上が実現できる。さらに望ましくは、Δθを−1°以上かつ+3°以下の範囲の値とすることで、規格化受光パワーについて0.95以上が実現できる。すなわち図7(a)、(b)から、底部の光ファイバ長手方向の中心と受光素子の中心112とを結ぶ直線とコア103がなす角θ[°]は、屈折率差比Δnに対して
1.13×Δn+5.5≦θ≦1.13×Δn+11
とすることが望ましい。θがこの範囲の値となる位置に受光素子を設置することで、規格化受光パワーについて0.9以上が実現できる。さらに望ましくは、角θ[°]を、屈折率差比Δnに対して
1.13×Δn+5.5≦θ≦1.13×Δn+9.5
の範囲の値とすることで、規格化受光パワーについて0.95以上が実現できる。
FIG. 7B shows the light receiving power with respect to the shift Δθ [°] from the angle θ of the optimum light receiving element position, normalized by the light receiving power at the angle of the optimum light receiving element position. In order to maintain high light receiving efficiency, it is desirable that the normalized light receiving power shown in FIG. More desirably, it is 0.95 or more. By setting Δθ to a value in the range of −1 ° or more and + 4.5 ° or less, the normalized light receiving power of 0.9 or more can be realized. More desirably, by setting Δθ to a value in the range of −1 ° or more and + 3 ° or less, the normalized light receiving power of 0.95 or more can be realized. That is, from FIGS. 7A and 7B, the angle θ [°] formed by the core 103 and the straight line connecting the center in the longitudinal direction of the optical fiber and the center 112 of the light receiving element with respect to the refractive index difference ratio Δn. 1.13 × Δn + 5.5 ≦ θ ≦ 1.13 × Δn + 11
Is desirable. By installing the light receiving element at a position where θ is within this range, 0.9 or more can be realized for the standardized light receiving power. More preferably, the angle θ [°] is set to 1.13 × Δn + 5.5 ≦ θ ≦ 1.13 × Δn + 9.5 with respect to the refractive index difference ratio Δn.
By setting the value in the range, 0.95 or more can be realized for the standardized light receiving power.

図8は本発明の光モニタの第2の構成例を示す概略図である。図8は光モニタ側面の断面図に相当する。本発明の光モニタは、図1に記載した第1の構成例の光モニタに対して、第2の受光素子109Bを設けたことを特徴とする。従って、図8に記載した構成例の光モニタは、一本の光ファイバ101を双方向に伝搬する伝搬光104A、104Bからそれぞれ独立に漏洩光108Aと108Bを発生させ、それぞれ独立に受光素子109A、109Bで受光する構成となっている。図8におけるその他の各記号は、図1と同じ内容を示す。また、図8においては、図1同様に、光検出器102の裏面、即ち受光素子109が配置されていない面、に存在する受光した光を電気信号として検出するための電気信号用端子は図示していない。また図示した光モニタを内包するパッケージ部材等についても図示を省略した。 FIG. 8 is a schematic diagram showing a second configuration example of the optical monitor of the present invention. FIG. 8 corresponds to a cross-sectional view of the side of the optical monitor. The optical monitor of the present invention is characterized in that a second light receiving element 109B is provided for the optical monitor of the first configuration example shown in FIG. Therefore, the optical monitor of the configuration example shown in FIG. 8 generates the leaked lights 108A and 108B independently from the propagation lights 104A and 104B propagating in one optical fiber 101 in both directions, and independently receives the light receiving elements 109A. , 109B. Other symbols in FIG. 8 indicate the same contents as in FIG. Further, in FIG. 8, as in FIG. 1, an electrical signal terminal for detecting received light as an electrical signal on the back surface of the photodetector 102, that is, the surface where the light receiving element 109 is not arranged, is illustrated. Not shown. Also, the illustration of the package member that includes the illustrated optical monitor is omitted.

本構成の光モニタを構成する各要素間、即ち底部とコア103との間隔g、受光素子の長さLに対する底部長さL0の比、置換材料とコア103との屈折率差比Δn、及び受光素子の中心と底部の中心112とを結んだ線とコア103がなす角度θ[°]、の関係は、第1の構成例で説明した関係と同じ関係であることが望ましい。すなわち、底部の光ファイバ長手方向の中心と第2の受光素子109Bの中心とを結ぶ直線とコアとがなす角度は、第1の受光素子の場合とは逆のコア延設方向からの角度である。さらに材料例、作製方法例についても第1の構成例と同様として良い。第2の構成例においては、第1の構成例に対し第2の受光素子を与えた構成とすることで、小型、低挿入損失かつ高受光効率の双方向性光モニタが実現できる。本構成の光モニタは傾斜面216を有する光モニタで構成することも可能である。この場合、置換領域106の前方と後方にそれぞれ傾斜面を構成する。 Between the elements constituting the optical monitor of the configuration, or spacing g between the bottom and the core 103, the ratio of the bottom length L 0 to the length L a of the light receiving element, the refractive index difference ratio Δn of replacement material and the core 103 The angle θ [°] formed by the core 103 and the line connecting the center of the light receiving element and the center 112 of the bottom is preferably the same as the relationship described in the first configuration example. That is, the angle between the core and the straight line connecting the center in the longitudinal direction of the optical fiber at the bottom and the center of the second light receiving element 109B is the angle from the core extending direction opposite to the case of the first light receiving element. is there. Further, a material example and a manufacturing method example may be the same as those of the first structure example. In the second configuration example, a bidirectional light monitor having a small size, a low insertion loss, and a high light receiving efficiency can be realized by providing the second light receiving element to the first configuration example. The optical monitor of this configuration can also be configured with an optical monitor having an inclined surface 216. In this case, inclined surfaces are respectively formed in front and rear of the replacement region 106.

本発明の光モニタアレイは、本発明の光モニタを2個以上用いることで構成される。本発明に使用する光モニタは低損失なので、それを多数個使用しても光の強度を検知することによる損失が少ないことから低損失のモニタアレイを提供することが可能となる。また、構成する光モニタは、光ファイバの湾曲を必要とせず小型化が実現できるので、それを複数用いてアレイ化することによって全体として小型のアレイを構成することができる。例えば、波長多重信号を分波器によって分波し、それぞれの波長の信号に対して光モニタを設ける場合、複数の光モニタをお互いの長手方向がほぼ平行になるように並列配置してパッケージに収めることで複数組の入出力を有する光モニタとしてもよい。また、前記並列配列については、隣合う光モニタの向きが同じ向きとなるように並列させてもよいし、交互に逆向きとなるように並列させることもできる。 The optical monitor array of the present invention is configured by using two or more optical monitors of the present invention. Since the optical monitor used in the present invention has a low loss, even when a large number of optical monitors are used, the loss due to the detection of the light intensity is small, so that a low-loss monitor array can be provided. Further, since the optical monitor to be configured can be downsized without requiring the bending of the optical fiber, a plurality of the optical monitors can be used to form an array, thereby forming a small array as a whole. For example, when wavelength multiplexed signals are demultiplexed by a demultiplexer and an optical monitor is provided for each wavelength signal, a plurality of optical monitors are arranged in parallel so that their longitudinal directions are substantially parallel to each other in the package. It is good also as an optical monitor which has two or more sets of input / output by accommodating. Further, the parallel arrangement may be arranged so that adjacent optical monitors have the same direction, or can be arranged in parallel so that they are alternately reversed.

本発明の光モニタを用いた光システムは、本発明の光モニタを光伝搬用の光ファイバに接続して構成され、前記光ファイバで伝搬される光信号の強度をモニタする。本発明によれば、前記光モニタを用いることによって小型、低挿入損失かつ高受光効率の光システムを提供することができる。例えば、光アンプ(増幅器)、光アッテネータ(減衰器)、光ゲインイコライザ(増幅・減衰器)等の光信号処理機においては、該光信号処理機の出力側に、場合によっては入力側にも、光モニタを設置し、該光信号処理機の動作、例えば増幅率や減衰量を確認し、該信号処理機にフィードバックさせる光システムとして構成する。   An optical system using the optical monitor of the present invention is configured by connecting the optical monitor of the present invention to an optical fiber for light propagation, and monitors the intensity of an optical signal propagated through the optical fiber. According to the present invention, an optical system having a small size, a low insertion loss, and a high light receiving efficiency can be provided by using the optical monitor. For example, in an optical signal processor such as an optical amplifier (amplifier), an optical attenuator (attenuator), an optical gain equalizer (amplifier / attenuator), the output side of the optical signal processor, and in some cases, the input side Then, an optical monitor is installed, and the operation of the optical signal processor, for example, the amplification factor and attenuation amount is confirmed, and the optical system is configured to feed back to the signal processor.

別の光システム例として、例えば、光切替装置においては、該光切替え装置の出力側経路に、場合によっては入力側経路にも、光モニタを設置し、該光切替装置の動作、例えば切替た経路や適正な経路切替状態の維持を確認し、該光切替装置にフィードバックさせる光システムとして構成する。 As another example of an optical system, for example, in an optical switching device, an optical monitor is installed in the output side path of the optical switching device, and in some cases also in the input side path, and the operation of the optical switching device, for example, switching is performed. It is configured as an optical system that confirms the maintenance of a route and an appropriate route switching state and feeds back to the optical switching device.

本発明の光モニタをこれら、あるいはその他の光信号処理機や光切替装置と組み合わせることで、光システムの光モニタ部分を小型化できるので、光システム全体としての小型化が実現できる。同時に、該システムにおいて、低挿入損失でかつ高受光効率の光モニタ機能を付与することができる。 By combining the optical monitor of the present invention with these or other optical signal processors and optical switching devices, the optical monitor portion of the optical system can be reduced in size, so that the overall optical system can be reduced in size. At the same time, the system can be provided with an optical monitoring function with low insertion loss and high light receiving efficiency.

(実施例1)
本発明の具体的な構成例を以下に示す。基本的な構成は前記図1と同様であるので図1を参照しつつ説明する。光ファイバ101は、クラッド105の直径が125μm、コア103の直径が9μmのシングルモード対応の光ファイバである。光検出器102は受光素子109が直径300μmで、受光感度が1000mA/Wのフォトダイオードを用いる。置換領域106はフッ化アンモニウム(NHF)をエッチャントとしたウェットエッチングでクラッドを除去して形成し、その底部長さL0は150μm、即ち受光素子長さLの0.5倍とし、コアと底部との間隔gは2μmである。置換領域106は、コアとの屈折率差比Δnが5.08%の紫外線硬化性樹脂を置換材料として置換する。なお、前記樹脂の屈折率差比Δnは樹脂硬化後の屈折率差比である。前記樹脂の塗布後、受光素子中心110が、底部の中心から233μm前方に位置するように、光検出器102を配置する。このとき底部の中心と受光素子の中心110を結ぶ直線と前記コアがなす角度θは13.5°である。受光素子109と光ファイバ101は、前記樹脂を介して接触させる。このとき、受光素子109と光ファイバ101は幾何学的に線接触するが、図1(b)および図2に示した様に、線接触しない部分にも前記樹脂が行き渡るように、樹脂を塗布し、その後、前記樹脂を硬化させる。本構成例の光モニタ100においては波長1550nmの光に対し、挿入損失0.4dBとなり、受光効率はR=0.85であり、光検出器の出力は69mA/Wであった。
Example 1
A specific configuration example of the present invention is shown below. The basic configuration is the same as that shown in FIG. 1 and will be described with reference to FIG. The optical fiber 101 is a single-mode optical fiber having a clad 105 diameter of 125 μm and a core 103 diameter of 9 μm. The photodetector 102 uses a photodiode having a light receiving element 109 of 300 μm in diameter and a light receiving sensitivity of 1000 mA / W. Replacement area 106 formed by removing the cladding by wet etching using an etchant of ammonium fluoride (NH 4 F), and its bottom length L 0 is 150 [mu] m, i.e. 0.5 times the light receiving element length L a, The gap g between the core and the bottom is 2 μm. In the replacement region 1006, an ultraviolet curable resin having a refractive index difference ratio Δn with respect to the core of 5.08% is replaced as a replacement material. The refractive index difference ratio Δn of the resin is a refractive index difference ratio after the resin is cured. After the application of the resin, the photodetector 102 is arranged so that the light receiving element center 110 is positioned 233 μm ahead of the center of the bottom. At this time, an angle θ between the straight line connecting the center of the bottom and the center 110 of the light receiving element and the core is 13.5 °. The light receiving element 109 and the optical fiber 101 are brought into contact with each other through the resin. At this time, although the light receiving element 109 and the optical fiber 101 are in line contact geometrically, as shown in FIG. 1B and FIG. 2, the resin is applied so that the resin spreads to the portion not in line contact. Then, the resin is cured. In the optical monitor 100 of this configuration example, the insertion loss is 0.4 dB for light having a wavelength of 1550 nm, the light receiving efficiency is R = 0.85, and the output of the photodetector is 69 mA / W.

(実施例2)
本発明の別の具体的な構成例を以下に示す。基本的な構成は前記図8と同様であるので図8を参照しつつ説明する。光ファイバ、受光素子は実施例1のものと同様である。置換領域106はCFをエッチャントとしたドライエッチングでクラッドを除去して形成し、その底部長さL0は170μm、即ち受光素子長さLの0.57倍とし、コアと底部との間隔gは1.5μmである。置換領域106は、コアとの屈折率差比Δnが4.40%の紫外線硬化性樹脂を置換材料として置換する。前記樹脂の塗布後、2つの受光素子の中心110A、110Bが、底部の中心からそれぞれ231μm前方および後方に位置するように、光検出器102を配置する。このとき底部の中心と受光素子の中心110A、110Bとを結ぶそれぞれの直線と前記コアがなす角度θはともに13.7°である。受光素子109と光ファイバ101は、前記樹脂を介して接触させる。このとき、受光素子109と光ファイバ101は幾何学的に線接触するが、実施例1と同様に、線接触しない部分にも前記樹脂が行き渡るように樹脂を塗布し、その後前記樹脂を硬化させる。本構成例の光モニタにおいては波長1550nmの光に対し、挿入損失0.6dBとなり、受光効率はR=0.85であり、光検出器の出力は110mA/Wであった。また、逆方向に伝搬する波長1300nmの光に対しては、挿入損失0.4dBとなり、受光効率はR=0.9であり、光検出器の出力は74mA/Wであった。
(Example 2)
Another specific configuration example of the present invention is shown below. The basic configuration is the same as that shown in FIG. 8 and will be described with reference to FIG. The optical fiber and the light receiving element are the same as those in the first embodiment. Replacement area 106 formed by removing the cladding by dry etching using an etchant of CF 4, and its bottom length L 0 is 170 [mu] m, i.e. 0.57 times the light receiving element length L a, the interval between the core and the bottom g is 1.5 μm. The replacement region 106 is replaced with an ultraviolet curable resin having a refractive index difference ratio Δn with the core of 4.40% as a replacement material. After the application of the resin, the photodetectors 102 are arranged so that the centers 110A and 110B of the two light receiving elements are located 231 μm forward and backward from the center of the bottom, respectively. At this time, the angle θ formed between each straight line connecting the center of the bottom and the centers 110A and 110B of the light receiving element and the core is 13.7 °. The light receiving element 109 and the optical fiber 101 are brought into contact with each other through the resin. At this time, although the light receiving element 109 and the optical fiber 101 are in line contact geometrically, as in the first embodiment, the resin is applied so that the resin spreads over the portion that is not in line contact, and then the resin is cured. . In the optical monitor of this configuration example, the insertion loss was 0.6 dB for light having a wavelength of 1550 nm, the light receiving efficiency was R = 0.85, and the output of the photodetector was 110 mA / W. For light with a wavelength of 1300 nm propagating in the reverse direction, the insertion loss was 0.4 dB, the light receiving efficiency was R = 0.9, and the output of the photodetector was 74 mA / W.

本発明の光モニタの第1の構成例を示す概略図である。It is the schematic which shows the 1st structural example of the optical monitor of this invention. 本発明の光モニタの置換領域の断面形状の第2の例を示す概略図である。It is the schematic which shows the 2nd example of the cross-sectional shape of the replacement area | region of the optical monitor of this invention. 底部とコアとの間隔gをパラメータとしたときの、底部長さLと挿入損失ILとの関係を示した図である。Of the distance g between the bottom and the core when the parameter is a diagram showing the relationship between the bottom length L 0 and the insertion loss IL. 受光素子の長さLaに対する底部長さL0の比L0/Laと屈折率差比Δnの関係を示した図である。FIG. 5 is a diagram showing a relationship between a ratio L 0 / L a of a bottom length L 0 to a length La of a light receiving element and a refractive index difference ratio Δn. 本発明において切り欠き形状を変更した例である。It is the example which changed the notch shape in this invention. 切り欠き形状を変更した本発明において、傾斜部の角度θと挿入損失ILとの関係を示す図である。In this invention which changed notch shape, it is a figure which shows the relationship between angle (theta) 2 of an inclination part, and insertion loss IL. 本発明において、屈折率差比Δnと最適受光素子位置の角度θとの関係(a)、最適受光素子位置からのずれΔθと規格化受光パワーとの関係(b)を示す図である。In this invention, it is a figure which shows the relationship (a) of refractive index difference ratio (DELTA) n and the angle (theta) of an optimal light receiving element position, and the relationship (b) of deviation (DELTA) (theta) from an optimal light receiving element position, and normalized light reception power. 本発明の光モニタの第2の構成例を示す概略図である。It is the schematic which shows the 2nd structural example of the optical monitor of this invention.

符号の説明Explanation of symbols

100,200:光モニタ、
101:光ファイバ、
102:光検出器、
103:コア、
104、104A,104B:伝搬光、
105:クラッド、
106:置換領域、
g:コアと底部との間隔
108,108A,108B:漏洩光、
109,109A,109B:受光素子、
110,110A,110B:受光素子の中心、
0:底部長さ、
112:底部の中心、
,LA,LB:受光素子の長さ、
114:充填材料、
216:傾斜面
100, 200: optical monitor,
101: Optical fiber,
102: photodetector
103: Core,
104, 104A, 104B: propagating light,
105: cladding,
106: replacement region,
g: Space between core and bottom 108, 108A, 108B: leaked light,
109, 109A, 109B: light receiving elements,
110, 110A, 110B: the center of the light receiving element,
L 0 : bottom length,
112: the center of the bottom,
L a , L a A, L a B: length of light receiving element,
114: Filling material,
216: Inclined surface

Claims (4)

光ファイバのコアを伝搬する光の一部を光検出器で受光する光モニタにおいて、光ファイバのクラッドの一部がコアの屈折率以上の屈折率を有する置換材料で、光ファイバの中心軸に対し平行な底部と光ファイバの長手方向において当該底部の両端から光ファイバの外周面に向かい伸びた面状の端部とを有する切り欠き状に置換された置換領域を有し、前記光ファイバの中心軸に対し受光面がほぼ平行に配置された前記光検出器の受光素子の中心は、前記置換領域の光ファイバ長手方向の端部よりもコア伝搬光の進行方向前方側に位置するとともに前記光検出器の受光素子と前記光ファイバの外周面との間隙にはクラッドの屈折率以上の屈折率を有する充填材料が充填され、前記置換材料の屈折率n と前記コアの屈折率n に対して、
Δn=(n −n )/n ×100[%]
で定義される屈折率差比Δnが0.65%以上であり、
さらに、前記置換領域はコアと最も近接している部分としてコアとの間隔が1μm以上かつ2μm以下である底部を有し、前記Δn、前記底部の光ファイバ長手方向の長さL0および前記受光素子の光ファイバの長手方向の長さLとが、
0.024×Δn+0.21≦L0/La≦0.081×Δn+0.29
の関係を有し、
加えて、前記光ファイバから前記置換領域へ漏れ、前記置換領域の端部と前記光ファイバのクラッドとの界面を透過し、当該クラッドを伝搬した漏洩光を前記光検出器で受光することを特徴とする光モニタ。
In an optical monitor that receives a part of the light propagating through the core of the optical fiber with a photodetector, a part of the cladding of the optical fiber is a replacement material having a refractive index greater than the refractive index of the core, and is placed on the central axis of the optical fiber. A replacement region replaced with a notch having a parallel bottom portion and a planar end portion extending from both ends of the bottom portion toward the outer peripheral surface of the optical fiber in the longitudinal direction of the optical fiber, The center of the light receiving element of the photodetector in which the light receiving surface is arranged substantially parallel to the central axis is located on the front side in the traveling direction of the core propagation light with respect to the end portion of the replacement region in the longitudinal direction of the optical fiber, and A gap between the light receiving element of the photodetector and the outer peripheral surface of the optical fiber is filled with a filling material having a refractive index equal to or higher than the refractive index of the cladding, and the refractive index n o of the replacement material and the refractive index n c of the core. Against
Δn = (n o −n c ) / n c × 100 [%]
The refractive index difference ratio Δn defined by is 0.65% or more,
Furthermore, the replacement region has a bottom portion having a distance of 1 μm or more and 2 μm or less as a portion closest to the core, Δn, a length L 0 of the bottom of the optical fiber in the longitudinal direction, and the light receiving and the longitudinal length L a of the optical fiber element,
0.024 × Δn + 0.21 ≦ L 0 / L a ≦ 0.081 × Δn + 0.29
Have the relationship
In addition, the optical fiber leaks into the replacement region, passes through the interface between the end of the replacement region and the cladding of the optical fiber, and the leaked light propagated through the cladding is received by the photodetector. And light monitor.
前記底部の光ファイバ長手方向の中心と前記受光素子の光ファイバ長手方向の中心を結ぶ直線と前記コアの延設方向がなす角度θ[°]が、前記置換材料の屈折率nと前記コアの屈折率nに対して、
Δn=(n−n)/n×100[%]
で定義される屈折率差比Δnに対し
1.13×Δn+5.5≦θ≦1.13×Δn+11
であることを特徴とする請求項1に記載の光モニタ。
The bottom portion of the optical fiber longitudinal center a straight line and an angle theta [°] formed by the extending direction of the core connecting the optical fiber longitudinal direction of the center of the light receiving element, the refractive index n o and the core of the replacement material relative refractive index n c,
Δn = (n o −n c ) / n c × 100 [%]
1.13 × Δn + 5.5 ≦ θ ≦ 1.13 × Δn + 11 with respect to the refractive index difference ratio Δn defined by
The optical monitor according to claim 1, wherein:
請求項1または2のいずれかに記載の光モニタを2個以上用いたことを特徴とする光モニタアレイ。 An optical monitor array comprising two or more optical monitors according to claim 1 or 2 . 請求項1乃至3のいずれかに記載の光モニタを光伝送用の光ファイバに接続し、前記光ファイバで伝搬される光信号の強度を検知することを特徴とする光システム。
An optical system comprising: the optical monitor according to claim 1 connected to an optical fiber for optical transmission; and detecting an intensity of an optical signal propagated through the optical fiber.
JP2004281740A 2004-09-28 2004-09-28 Optical monitor and optical monitor array and optical system using the same Expired - Fee Related JP4524748B2 (en)

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