JPH06331850A - Optical filter and diffraction element used therefor - Google Patents
Optical filter and diffraction element used thereforInfo
- Publication number
- JPH06331850A JPH06331850A JP12251493A JP12251493A JPH06331850A JP H06331850 A JPH06331850 A JP H06331850A JP 12251493 A JP12251493 A JP 12251493A JP 12251493 A JP12251493 A JP 12251493A JP H06331850 A JPH06331850 A JP H06331850A
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- optical filter
- light
- grating
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は波長多重光通信システム
の受信端や光増幅回路などに用いる光フィルタ及び光フ
ィルタに用いる回折素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter used in a receiving end of a wavelength division multiplexing optical communication system or an optical amplifier circuit, and a diffraction element used in the optical filter.
【０００２】[0002]
【従来の技術】近年、光フィルタは波長多重光通信シス
テムにおいて多重された光の中から所望の光を選択する
デバイスとして、また光増幅器で構成される伝送路での
雑音除去デバイスとして、様々な形態が提案され検討さ
れている。特に回折格子を用いた光フィルタは広帯域
で、かつ側波帯阻止特性のよい波長選択が可能である。2. Description of the Related Art In recent years, optical filters have been widely used as a device for selecting a desired light from the multiplexed lights in a wavelength division multiplexing optical communication system, and as a noise removing device in a transmission line composed of an optical amplifier. Forms have been proposed and are being considered. In particular, an optical filter using a diffraction grating has a wide band and can select a wavelength with a good sideband blocking characteristic.
【０００３】このような用途の場合には光フィルタは受
動モジュールとして他の光デバイス及び電気デバイスと
ともにユニット内に実装されて使用されることとなり、
ユニット内の温度分布変化によりデバイスの特性に影響
を与える可能性がある。In such an application, the optical filter is used as a passive module mounted in a unit together with other optical devices and electric devices.
Changes in temperature distribution within the unit may affect the characteristics of the device.
【０００４】図１１に従来の光フィルタの構成図を示
す。図１１において１１は入出力ファイバであり、図の
ように１本で入出力を兼ね備えても良いし、紙面に対し
て垂直な方向に入力ファイバと出力ファイバを各々配置
してもよい。その場合でも図面上では２本のファイバが
重なることになり、表現上同等となるので本実施例では
前者の入出力ファイバ１１として説明する。以後の図面
においても同様な扱いとする。FIG. 11 shows a block diagram of a conventional optical filter. In FIG. 11, reference numeral 11 is an input / output fiber, and one input / output fiber may be provided as shown in the figure, or the input fiber and the output fiber may be arranged in the direction perpendicular to the paper surface. Even in that case, the two fibers will overlap in the drawing, and they are equivalent in terms of expression. Therefore, in the present embodiment, the former input / output fiber 11 will be described. The same applies to subsequent drawings.
【０００５】入出力ファイバ１１からの光はレンズ２１
を介して平行光となり回折格子３１へ入射し、波長分散
を受ける。波長分散光のうち所望の波長域の光が再びレ
ンズ２１を介して入出力ファイバ１１へ結合し波長選択
される。図１の構成で選択される波長λoは、回折格子
３１の格子間隔をΛ、回折格子３１への入射角をθLと
すれば、Light from the input / output fiber 11 is reflected by the lens 21.
Is converted into parallel light via and enters the diffraction grating 31 to undergo wavelength dispersion. Light in a desired wavelength region of the wavelength-dispersed light is again coupled to the input / output fiber 11 via the lens 21 and wavelength is selected. The wavelength λo selected in the configuration of FIG. 1 is given by assuming that the grating interval of the diffraction grating 31 is Λ and the incident angle to the diffraction grating 31 is θ L ,
【０００６】[0006]
【数１】 [Equation 1]
【０００７】をみたしている。この構成で送信されてき
た光源の発振波長の温度ドリフトを補償する機構を有し
た光フィルタが提案されており、温度上昇により発振波
長が長波長側へドリフトする量を機械的に補償する機構
を備えているものが提案されている（例えば特開昭５８
−９１１９号公報）。It is satisfying An optical filter having a mechanism for compensating the temperature drift of the oscillation wavelength of the light source transmitted in this configuration has been proposed, and a mechanism for mechanically compensating the amount of the oscillation wavelength drifting to the long wavelength side due to temperature rise is proposed. The one provided is proposed (for example, JP-A-58).
-9119).
【０００８】この場合は発振波長が温度上昇と共に長波
長側へシフトしていく分Δλを補償するため、In this case, Δλ is compensated for as the oscillation wavelength shifts to the long wavelength side as the temperature rises.
【０００９】[0009]
【数２】 [Equation 2]
【００１０】を満たすように角度Δθだけ回転し、入出
力ファイバ１１から回折格子３１への入射角を大きくす
るように働くものである。It is rotated by an angle Δθ so as to satisfy the above condition, and acts so as to increase the incident angle from the input / output fiber 11 to the diffraction grating 31.
【００１１】[0011]
【発明が解決しようとする課題】しかしながら従来例で
は、図１１の構成で固定してモジュール化した際、周囲
雰囲気温度が上昇すると回折格子が熱膨張を起こし、格
子間隔が変化する。温度変動δＴによる格子間隔の変化
量δΛは回折格子の等価熱膨張係数σeを用いて、However, in the conventional example, when the structure shown in FIG. 11 is fixed and modularized, the diffraction grating causes thermal expansion when the ambient atmospheric temperature rises, and the grating spacing changes. The variation δΛ of the lattice spacing due to the temperature variation δT is calculated by using the equivalent thermal expansion coefficient σ e of the diffraction grating,
【００１２】[0012]
【数３】 [Equation 3]
【００１３】と表せ、光フィルタの選択中心波長波長は
波長変動をδλとして、The selected central wavelength of the optical filter has a wavelength variation of δλ,
【００１４】[0014]
【数４】 [Equation 4]
【００１５】と表されるようにフィルタ自体の選択中心
波長が長波長側へシフトしてしまう問題点を有してい
る。図１２に波長シフトの概念図を示す。モジュール構
築時のフィルター特性曲線を２０１とすれば温度上昇に
よって選択中心波長は長波長側へδλだけシフトして特
性曲線２０２となり、その結果波長λoの透過強度は図
でδＩ減少してしまう。これは温度が下降した場合でも
同様の現象となる。例えばガラス基板製の回折格子を用
いた場合、熱膨張係数は９×１０-6程度であることから
１.３μｍ帯で、格子間隔１.３μｍの回折格子を想定す
ると、３０度温度変化すると約０.３５ｎｍ変化してし
まい、通過帯域１ｎｍ以内の狭帯域フィルタにおいては
過剰損失の増大を招くこととなる。There is a problem that the selective center wavelength of the filter itself shifts to the long wavelength side as expressed by FIG. 12 shows a conceptual diagram of wavelength shift. If the filter characteristic curve when constructing the module is 201, the selected center wavelength shifts by δλ toward the long wavelength side due to temperature rise to become the characteristic curve 202, and as a result, the transmission intensity of the wavelength λo decreases by δI in the figure. This is the same phenomenon even when the temperature drops. For example, when a glass substrate-made diffraction grating is used, the coefficient of thermal expansion is approximately 9 × 10 −6, so assuming a diffraction grating with a grating spacing of 1.3 μm in the 1.3 μm band, it is about This causes a change of 0.35 nm, which causes an increase in excess loss in a narrow band filter having a pass band of 1 nm or less.
【００１６】さらに送信光源の発振波長ドリフトを補償
する従来例の光フィルタは、その周囲の温度変動が必ず
しも送信側の温度変動と一致していないために、上述し
たフィルタ自体の持つ温度特性の影響が加算されてしま
うことになる。Further, in the conventional optical filter for compensating for the oscillation wavelength drift of the transmission light source, the temperature variation around it does not necessarily coincide with the temperature variation on the transmission side, and therefore the influence of the temperature characteristic of the filter itself is exerted. Will be added.
【００１７】また最近の技術進歩により光源の発振波長
安定度は発光素子自体を温度制御して発振波長ドリフト
を０.１ｎｍ以内とすることができるため送信される波
長のゆらぎを考慮する必要性が少なくなってきている。Further, due to the recent technological progress, the oscillation wavelength stability of the light source can be controlled within a range of 0.1 nm by controlling the temperature of the light emitting element itself, so that it is necessary to consider the fluctuation of the transmitted wavelength. It is getting less.
【００１８】加えて、光フィルタに用いる回折素子は基
板上に凹凸形状を有した高分子樹脂の格子層で構成され
ており、格子層の温度変動による格子間隔の変動が高分
子樹脂層の持つ大きい線膨張係数（１０-5〜１０-4のオ
ーダー）により、光フィルタを構成した場合に選択中心
波長シフトを大きくさせる要因となっていた。In addition, the diffractive element used for the optical filter is composed of a polymer resin lattice layer having an irregular shape on the substrate, and the polymer resin layer has a lattice spacing variation due to temperature variation of the lattice layer. The large linear expansion coefficient (on the order of 10 −5 to 10 −4 ) has been a factor for increasing the shift of the selective center wavelength when the optical filter is constructed.
【００１９】本発明は上記問題点に鑑み、フィルタ構成
に起因する周囲温度変化に対する選択中心波長のシフト
を相殺あるいは非常に低減する機構及び構成を有する光
フィルタ並びに回折素子を提供するものである。In view of the above problems, the present invention provides an optical filter and a diffractive element having a mechanism and structure for canceling or significantly reducing the shift of the selected center wavelength due to the change in ambient temperature due to the filter structure.
【００２０】[0020]
【課題を解決するための手段】上記問題点を解決するた
めに本発明の光フィルタは、回折格子を用いた光学的な
フィルタ構成において回折格子に温度変動により回転角
度が変化する機構部を配置する。あるいはレンズ及び入
出力ファイバで構成される光入出力部が温度変動により
回折格子への入射角を変化する機構を有するようにす
る。In order to solve the above problems, in the optical filter of the present invention, in the optical filter structure using the diffraction grating, the diffraction grating is provided with a mechanism portion whose rotation angle changes due to temperature fluctuation. To do. Alternatively, the light input / output unit composed of the lens and the input / output fiber has a mechanism for changing the incident angle to the diffraction grating due to temperature fluctuation.
【００２１】そして温度が上昇した場合に上述した機構
が回折格子に光が入射する角度が小さくなる方向に回転
または移動するような構成とする。Then, when the temperature rises, the above-mentioned mechanism is configured to rotate or move in a direction in which the angle of incidence of light on the diffraction grating becomes smaller.
【００２２】また、光フィルタに用いる回折素子として
熱膨張係数の小さい基板上に回折格子を形成したものを
適用する。As the diffractive element used for the optical filter, a diffractive element having a diffraction grating formed on a substrate having a small coefficient of thermal expansion is applied.
【００２３】[0023]
【作用】本発明は上記した構成によって、温度上昇での
選択中心波長の長波長側へのシフト分を回折格子の入射
角をδθだけ小さくするようにして、According to the present invention, the shift angle of the selected central wavelength to the long wavelength side due to the temperature rise is reduced by the incident angle of the diffraction grating by δθ.
【００２４】[0024]
【数５】 [Equation 5]
【００２５】を満たし選択中心波長が一定となる。回折
素子は熱膨張係数が小さいため（数２）のδΛが小さく
なりその結果、この回折素子を光フィルタに用いた場
合、選択中心波長シフト量δλ自体が小さくなる。And the selected central wavelength is constant. Since the diffractive element has a small coefficient of thermal expansion, δΛ in (Equation 2) becomes small. As a result, when this diffractive element is used for an optical filter, the selective center wavelength shift amount δλ itself becomes small.
【００２６】これは従来例での回折格子の設定傾き角度
の補正の方向とはまったく逆の方向での温度補償とな
る。This is temperature compensation in a direction completely opposite to the direction of correcting the set tilt angle of the diffraction grating in the conventional example.
【００２７】[0027]
【実施例】以下本発明の実施例の光フィルタについて、
図面を参照しながら説明する。Embodiments of the optical filter according to the present invention will be described below.
A description will be given with reference to the drawings.
【００２８】図１は本発明の第１の実施例における光フ
ィルタの基本構成図を示すものである。図１において１
は入出力ファイバ、２はレンズ、３は回折格子、４は温
度補償機構部である。FIG. 1 shows the basic configuration of an optical filter according to the first embodiment of the present invention. 1 in FIG.
Is an input / output fiber, 2 is a lens, 3 is a diffraction grating, and 4 is a temperature compensation mechanism.
【００２９】入出力ファイバ１からの光の振舞いは図１
２と同様であるが、周囲の温度の上昇によって回折格子
３に配置されている温度補償機構部４により回折格子３
を矢印の方向に回転する様な動作をする。δＴの温度上
昇により温度補償機構部４での回転角は（数５）をみた
すδθだけ変化し、入出力ファイバ１からレンズ２を介
して回折格子３に入射する角度を小さくして、波長分散
されて再びレンズ２を介して入出力ファイバ１に結合す
る光の選択中心波長は温度上昇によらずλoとなる。周
囲の温度が降下した場合には温度補償機構部４により入
出力ファイバ１から回折格子３への入射角が大きくなる
ように、即ち回折格子３を図１の矢印とは逆の方向に回
転するように作用することとなる。The behavior of light from the input / output fiber 1 is shown in FIG.
2, but with the temperature compensating mechanism 4 arranged in the diffraction grating 3 due to the rise in the ambient temperature.
Operates like rotating in the direction of the arrow. The rotation angle in the temperature compensation mechanism section 4 changes by δθ satisfying (Equation 5) due to the temperature rise of δT, and the angle of incidence on the diffraction grating 3 from the input / output fiber 1 via the lens 2 is reduced, and the wavelength dispersion is reduced. The selected central wavelength of the light that is coupled to the input / output fiber 1 via the lens 2 again becomes λo regardless of the temperature rise. When the ambient temperature drops, the temperature compensating mechanism 4 increases the incident angle from the input / output fiber 1 to the diffraction grating 3, that is, the diffraction grating 3 is rotated in the direction opposite to the arrow in FIG. It will act like.
【００３０】従って、温度補償機構を回折格子側に設け
ることにより、温度変動により生じる選択中心波長のシ
フトを相殺し安定なモジュールとすることができる。Therefore, by providing the temperature compensating mechanism on the side of the diffraction grating, it is possible to cancel the shift of the selective center wavelength caused by the temperature fluctuation and to provide a stable module.
【００３１】図２は本発明の第２の実施例の光フィルタ
の基本構成図を示したものである。図１の実施例と異な
る点は温度補償機構部６が入出力ファイバ１及びレンズ
２で構成される光入出力部５に配置されていることであ
る。FIG. 2 shows the basic configuration of an optical filter according to the second embodiment of the present invention. The difference from the embodiment of FIG. 1 is that the temperature compensation mechanism section 6 is arranged in the light input / output section 5 composed of the input / output fiber 1 and the lens 2.
【００３２】入出力ファイバ１からの光の振舞いは図１
と同様であるが、周囲の温度の上昇によって光入出力部
５１に配置されている温度補償機構部６により光入出力
部５を矢印の方向に回転する様な移動動作をする。移動
動作により光入出力部６から回折格子３への光の入射角
はδＴの温度上昇により（数５）をみたすδθだけ変化
し、入射する角度を小さくして選択中心波長は温度上昇
によらずλoとなる。周囲の温度が降下した場合には温
度補償機構部６により入出力部５から回折格子３への入
射角が大きくなるように、即ち回折格子３を図２の矢印
とは逆の方向に回転するように作用することとなる。The behavior of light from the input / output fiber 1 is shown in FIG.
However, the temperature compensating mechanism 6 disposed in the light input / output unit 51 performs a moving operation to rotate the light input / output unit 5 in the direction of the arrow as the ambient temperature rises. Due to the moving operation, the incident angle of the light from the light input / output unit 6 to the diffraction grating 3 changes by δθ satisfying (Equation 5) due to the temperature increase of δT, and the incident angle is reduced so that the selected center wavelength varies depending on the temperature rise. Without λo. When the ambient temperature drops, the temperature compensating mechanism 6 increases the incident angle from the input / output unit 5 to the diffraction grating 3, that is, the diffraction grating 3 is rotated in the direction opposite to the arrow in FIG. It will act like.
【００３３】従って、温度補償機構を光入出力部側に設
けることにより、温度変動により生じる選択中心波長の
シフトを相殺し安定なモジュールとすることができる。Therefore, by providing the temperature compensating mechanism on the side of the light input / output unit, it is possible to cancel the shift of the selective center wavelength caused by the temperature fluctuation and to provide a stable module.
【００３４】図３は第１の実施例の光フィルタの温度補
償機構部４の具体的な一構成例を示したものである。図
３で８１，８２は固定部、７１，７２は支持部、９は基
台であり、その他の構成部品は図１と同様である。支持
部７１，７２の材質は同じであり線膨張係数σを有して
いる。なお基台９による熱膨張は光軸方向にのみ作用す
るために選択中心波長に影響を与えることはない。FIG. 3 shows a concrete example of the structure of the temperature compensation mechanism section 4 of the optical filter of the first embodiment. In FIG. 3, 81 and 82 are fixed parts, 71 and 72 are support parts, 9 is a base, and other components are the same as in FIG. The materials of the supporting portions 71 and 72 are the same and have a linear expansion coefficient σ. Since the thermal expansion by the base 9 acts only in the optical axis direction, it does not affect the selective center wavelength.
【００３５】支持部７１，７２は一端を固定部８１，８
２により基台９に固定されており、他端は回折格子３の
裏面より回折格子３を回折格子３の裏面上でＸの間隔を
隔てて支持している。固定部８１および８２から回折格
子３を支持する長尺方向の長さは支持部７１の方が支持
部７２よりも長くその差をδＬとすれば、周囲温度がδ
Ｔ上昇すると回折格子３は相対的にThe support portions 71 and 72 have fixed ends 81 and 8 at one end.
It is fixed to the base 9 by means of 2 and the other end supports the diffraction grating 3 from the back surface of the diffraction grating 3 on the back surface of the diffraction grating 3 with a space of X. As for the length in the lengthwise direction for supporting the diffraction grating 3 from the fixed portions 81 and 82, if the supporting portion 71 is longer than the supporting portion 72 and the difference is δL, the ambient temperature is δ.
When T rises, the diffraction grating 3 becomes relatively
【００３６】[0036]
【数６】 [Equation 6]
【００３７】をみたすδφの角度だけ図３で時計回りに
回転する。このδφが（数５）のδθと等しくすること
により温度変動に対する選択中心波長のシフトを相殺す
ることができる。It rotates clockwise in FIG. 3 by an angle of δφ which satisfies By making δφ equal to δθ in (Equation 5), it is possible to cancel the shift of the selected central wavelength with respect to the temperature fluctuation.
【００３８】例えばガラス基板製の回折格子を用い、
１.３μｍ帯で、格子間隔１.３μｍの回折格子を想定す
ると、支持部にアルミニウムを用いた場合にはＸを５ｍ
ｍ、長さの差δＬを１.１ｍｍ程度とすれば波長シフト
を相殺することができる。For example, using a diffraction grating made of a glass substrate,
Assuming a diffraction grating with a 1.3 μm band and a grating spacing of 1.3 μm, X is 5 m when aluminum is used for the support.
The wavelength shift can be canceled by setting the difference δL between m and length to about 1.1 mm.
【００３９】本実施例では２つの支持部を設けたが、図
４に示すように支持部７１のみとし、回折格子３を図１
の支持部７２で支持される部位を固定部８３により基台
９に固定し、支持部７１により回折格子３を相対的に時
計回りに回転させるようにすることができ、この場合は
支持部の長さ自体をδＬと考えることによって同様の効
果が得られ、かつ支持部自体を小型化できる。Although two supporting portions are provided in this embodiment, only the supporting portion 71 is provided as shown in FIG.
It is possible to fix the portion supported by the supporting portion 72 of the above to the base 9 by the fixing portion 83, and rotate the diffraction grating 3 relatively clockwise by the supporting portion 71. In this case, The same effect can be obtained by considering the length itself as δL, and the supporting portion itself can be downsized.
【００４０】また図３では支持部に同一素材の支持部を
設けたが図５に示すように異なる素材を用いて一端を固
定部８４で基台９に固定された支持部７３（線膨張係数
σ1，長さＬ1）及び固定部８５で一端を固定された支持
部７４（線膨張係数σ2，長さＬ2）を配置することによ
って（数６）は、Further, in FIG. 3, the supporting portion is made of the same material as the supporting portion, but as shown in FIG. 5, the supporting portion 73 (linear expansion coefficient) whose one end is fixed to the base 9 by the fixing portion 84 is made of different materials. (Equation 6) is obtained by arranging σ1, length L1) and the support portion 74 (linear expansion coefficient σ2, length L2) whose one end is fixed by the fixing portion 85.
【００４１】[0041]
【数７】 [Equation 7]
【００４２】と表され、温度補償の設計の自由度が増す
こととなる。次に図６は第２の実施例の光フィルタの温
度補償機構部６の具体的な一構成例を示したものであ
る。図６で２２はレンズ、５１は光入出力部、８６，８
７は固定部、７５，７６は支持部、９は基台であり、そ
の他の構成部品は図２と同様である。支持部７５，７６
の材質は同じであり線膨張係数σを有している。また支
持部７５，７６は一端を固定部８６，８７により基台９
に固定されている。支持部７５の他端は光入出力部５１
の図面で上側の側面より支持し、支持部７６の他端は光
入出力部５１の支持部７５の支持点と対向し、Ｘだけ離
れた位置で支持している。固定部８６および８７から光
入出力部５１を支持する長尺方向の長さをそれぞれＬ
1，Ｌ2とすれば、周囲温度がδＴ上昇すると光入出力部
６は相対的にAs described above, the degree of freedom in designing the temperature compensation increases. Next, FIG. 6 shows a specific configuration example of the temperature compensation mechanism section 6 of the optical filter of the second embodiment. In FIG. 6, 22 is a lens, 51 is a light input / output unit, 86, 8
Reference numeral 7 is a fixed portion, 75 and 76 are support portions, 9 is a base, and other components are the same as those in FIG. Supports 75, 76
Are made of the same material and have a linear expansion coefficient σ. In addition, one end of each of the supporting portions 75 and 76 is fixed by the fixing portions 86 and 87 to the base 9.
It is fixed to. The other end of the support portion 75 has the optical input / output portion 51.
In the drawing, it is supported from the upper side surface, and the other end of the support part 76 faces the support point of the support part 75 of the light input / output part 51 and is supported at a position separated by X. The length in the lengthwise direction for supporting the light input / output unit 51 from the fixed portions 86 and 87 is L, respectively.
If 1 and L2, the optical input / output unit 6 is relatively
【００４３】[0043]
【数８】 [Equation 8]
【００４４】をみたすδφの角度だけ図６で時計回りに
回転する様な移動が生じる。このδφが（数５）のδθ
と等しくすることにより温度変動に対する選択中心波長
のシフトを相殺することができる。A movement is caused to rotate clockwise in FIG. 6 by an angle of δφ that satisfies the above condition. This δφ is δθ of (Equation 5)
The shift of the selected central wavelength with respect to the temperature fluctuation can be offset by setting the same as.
【００４５】例えばガラス基板製の回折格子を用い、
１.３μｍ帯で、格子間隔１.３μｍの回折格子を想定す
ると、支持部にアルミニウムを用いた場合にはＸを１０
ｍｍ、２つの支持部の長さの和を２.２ｍｍ程度とすれ
ば波長シフトを相殺することができる。For example, using a diffraction grating made of a glass substrate,
Assuming a diffraction grating with a grating spacing of 1.3 μm in the 1.3 μm band, X is 10 when aluminum is used for the support.
mm, the wavelength shift can be canceled by setting the sum of the lengths of the two support portions to about 2.2 mm.
【００４６】本実施例では２つの支持部を設けたが、図
７に示すように支持部７５のみとし、光入出力部６を図
６の支持部７６で支持される部位を固定部８８により基
台９に固定し、支持部７５により光入出力部６を相対的
に時計回りに回転させるようにすることができ、この場
合は支持部の長さ自体をＬ1のみと考えることによって
同様の効果が得られ、かつ支持部自体を小型化できる。In this embodiment, two supporting portions are provided. However, as shown in FIG. 7, only the supporting portion 75 is provided, and the portion where the light input / output portion 6 is supported by the supporting portion 76 in FIG. The optical input / output unit 6 can be fixed to the base 9 and the light input / output unit 6 can be relatively rotated clockwise by the supporting unit 75. In this case, the length of the supporting unit is considered to be L1 only. The effect can be obtained, and the supporting portion itself can be downsized.
【００４７】また図６では支持部に同一素材の支持部を
設けたが図８に示すように異なる素材を用いて一端を固
定部８６で基台９に固定された支持部７５（線膨張係数
σ1，長さＬ1）及び固定部８９で一端を固定された支持
部７７（線膨張係数σ2，長さＬ2）を光入出力部６の同
じ側面上に配置することによって（数７）で表される角
度δφで相対的に時計回りに回転し、温度補償の設計の
自由度が増すこととなる。Further, in FIG. 6, a supporting portion made of the same material is provided in the supporting portion, but as shown in FIG. 8, a supporting portion 75 (a linear expansion coefficient) whose one end is fixed to the base 9 by a fixing portion 86 using different materials is used. σ1, length L1) and the support portion 77 (linear expansion coefficient σ2, length L2) whose one end is fixed by the fixing portion 89 are arranged on the same side surface of the light input / output portion 6 and expressed by (Equation 7). The angle of rotation is relatively clockwise, and the degree of freedom in designing the temperature compensation is increased.
【００４８】次に光フィルタに用いる回折素子について
図９に構成図を示してその一実施例について説明する。
回折素子１０４は基板１０１に凹凸形状を有する格子層
１０２及び凹凸形状面上に設けた反射膜１０３で構成さ
れている。格子層１０２は基板１０１の厚さに比べ十分
に薄い膜厚（１／５００以下）で密着配置されている。
基板の材質には線膨張係数の小さいものを用いている。Next, one embodiment of the diffractive element used for the optical filter will be described with reference to the block diagram of FIG.
The diffractive element 104 includes a grating layer 102 having an uneven shape on a substrate 101 and a reflective film 103 provided on the uneven surface. The lattice layer 102 is arranged in close contact with the film thickness (1/500 or less) sufficiently smaller than the thickness of the substrate 101.
As the material of the substrate, a material having a small linear expansion coefficient is used.
【００４９】このような構成により周囲の温度変動に対
する格子間隔の変動が、格子層１０２の厚さが薄いため
に基板の線膨張係数に起因する変動に抑えられる。例え
ば厚さ２ｍｍ程度の耐熱ガラス（線膨張係数２.８×１
０-6）を基板とし、格子層として露光して凹凸形状を有
した２μｍ程度の膜厚のフォトレジスト層で構成し反射
膜は０.２μｍ以内の金属膜とすれば回折素子自体の等
価線膨張係数はほぼ基板の線膨張係数と同じとなる。With such a structure, the variation of the lattice spacing with respect to the ambient temperature variation can be suppressed to the variation due to the linear expansion coefficient of the substrate because the thickness of the lattice layer 102 is thin. For example, heat-resistant glass with a thickness of about 2 mm (coefficient of linear expansion 2.8 x 1
Equivalent line of the diffractive element itself if it is composed of a photoresist layer having a thickness of about 2 μm and having a concavo-convex shape by exposure as a grating layer with a substrate of 0 −6 ) and the reflection film is a metal film within 0.2 μm. The expansion coefficient is almost the same as the linear expansion coefficient of the substrate.
【００５０】図１０に上述した回折素子１０４を用いた
光フィルタの一実施例を示す。この場合温度変動に対す
る中心波長変動は、１.３μｍ帯で、格子間隔１.３μｍ
の回折格子を想定すると、３０度温度変化すると約０.
１ｎｍ以内となり、温度補償を行わなくとも通過帯域１
ｎｍ以内の狭帯域フィルタを構築して十分使用可能なも
のとすることができる。FIG. 10 shows an embodiment of an optical filter using the above-mentioned diffraction element 104. In this case, the central wavelength fluctuation with respect to temperature fluctuation is 1.3 μm band, and the lattice spacing is 1.3 μm.
Assuming a diffraction grating of, if the temperature changes by 30 degrees, it will be about 0.
Within 1 nm, pass band 1 without temperature compensation
A narrow band filter within nm can be constructed to be sufficiently usable.
【００５１】なおこれまでの実施例では単に回折格子と
したが、フーリエ回折格子を用いることによりモジュー
ルとして低損失で、偏光依存性の小さくすことができ
る。In the above-mentioned embodiments, the diffraction grating is simply used, but by using the Fourier diffraction grating, the module can have a low loss and a small polarization dependency.
【００５２】[0052]
【発明の効果】以上のように本発明は回折格子型の光フ
ィルタ自体の持つ温度特性、即ち周囲温度の変動に対す
る選択中心波長の変動を低減あるいは相殺して安定な受
動モジュール構成とすることができるAs described above, according to the present invention, the temperature characteristic of the diffraction grating type optical filter itself, that is, the fluctuation of the selected center wavelength with respect to the fluctuation of the ambient temperature can be reduced or offset to form a stable passive module structure. it can
【図１】本発明の第１の実施例における光フィルタの基
本構成図FIG. 1 is a basic configuration diagram of an optical filter according to a first embodiment of the present invention.
【図２】本発明の第２の実施例における光フィルタの基
本構成図FIG. 2 is a basic configuration diagram of an optical filter according to a second embodiment of the present invention.
【図３】本発明の第１の実施例における光フィルタの温
度補償機構の第１の構成例を示す図FIG. 3 is a diagram showing a first configuration example of a temperature compensation mechanism for an optical filter according to the first embodiment of the present invention.
【図４】本発明の第１の実施例における光フィルタの温
度補償機構の第２の構成例を示す図FIG. 4 is a diagram showing a second configuration example of the temperature compensating mechanism for the optical filter according to the first embodiment of the present invention.
【図５】本発明の第１の実施例における光フィルタの温
度補償機構の第３の構成例を示す図FIG. 5 is a diagram showing a third configuration example of the temperature compensation mechanism for the optical filter according to the first embodiment of the present invention.
【図６】本発明の第２の実施例における光フィルタの温
度補償機構の第１の構成例を示す図FIG. 6 is a diagram showing a first configuration example of a temperature compensation mechanism for an optical filter according to a second embodiment of the present invention.
【図７】本発明の第２の実施例における光フィルタの温
度補償機構の第２の構成例を示す図FIG. 7 is a diagram showing a second configuration example of the temperature compensating mechanism for the optical filter according to the second embodiment of the present invention.
【図８】本発明の第２の実施例における光フィルタの温
度補償機構の第３の構成例を示す図FIG. 8 is a diagram showing a third configuration example of the temperature compensating mechanism for the optical filter according to the second embodiment of the present invention.
【図９】本発明の一実施例における光フィルタに用いる
回折素子の構成図FIG. 9 is a configuration diagram of a diffractive element used in an optical filter according to an embodiment of the present invention.
【図１０】本発明の一実施例における図９の回折素子を
用いた光フィルタの構成図FIG. 10 is a configuration diagram of an optical filter using the diffraction element of FIG. 9 in an example of the present invention.
【図１１】従来の光フィルタの基本構成図FIG. 11 is a basic configuration diagram of a conventional optical filter.
【図１２】従来の光フィルタの選択中心波長の温度変動
を表す概念図FIG. 12 is a conceptual diagram showing the temperature fluctuation of the selected center wavelength of a conventional optical filter.
１ 入出力ファイバ ２ 受光ファイバ ３ 回折格子 ４，６ 温度補償機構部 ５，５１ 光入出力部 ７１〜７７ 支持部 ８１〜８９ 固定部 ９ 基台 １０１ 基板 １０２ 格子層 １０３ 反射膜 １０４ 回折素子 DESCRIPTION OF SYMBOLS 1 Input / output fiber 2 Light receiving fiber 3 Diffraction grating 4,6 Temperature compensation mechanism part 5,51 Light input / output part 71-77 Support part 81-89 Fixed part 9 Base 101 Substrate 102 Lattice layer 103 Reflective film 104 Diffraction element
Claims (16)
１本の受光ファイバで構成され、前記１本の入力ファイ
バからの光が前記レンズを介して前記回折格子で波長分
散を受け、再び前記レンズを介して前記１本の受光ファ
イバに所望の波長域の光が結合するような系において、
前記回折格子に温度変動により回転角度が変化する機構
部を配置し、前記機構部は温度が上昇した場合に前記回
折格子を光の入射する角度が小さくする方向に相対的に
回転することを特徴とする光フィルタ。1. A diffraction grating, a lens, one input fiber, and one light receiving fiber, wherein light from the one input fiber undergoes wavelength dispersion in the diffraction grating via the lens, and again. In a system in which light in a desired wavelength range is coupled to the one light receiving fiber via the lens,
A mechanism unit whose rotation angle is changed by temperature fluctuation is arranged in the diffraction grating, and the mechanism unit relatively rotates the diffraction grating in a direction in which an incident angle of light decreases when the temperature rises. And an optical filter.
を特徴とする請求項１記載の光フィルタ。2. The optical filter according to claim 1, wherein a Fourier diffraction grating is used as the diffraction grating.
と１本の受光ファイバで構成される光入出力部とで成
り、前記１本の入力ファイバからの光が前記レンズを介
して前記回折格子に所定の入射角で入射し、前記回折格
子で波長分散を受け、再び前記レンズを介して前記１本
の受光ファイバに所望の波長域の光が結合するような系
において、前記光入出力部に温度変動により前記回折格
子への入射角を変化する機構を配置し、前記機構部は温
度が上昇した場合に前記回折格子に光の入射する角度が
小さくなる方向に光入出力部を移動させることを特徴と
する光フィルタ。3. A diffraction grating, a lens, a light input / output unit composed of one input fiber and one light receiving fiber, and light from the one input fiber is passed through the lens to obtain the light. In a system in which light enters the diffraction grating at a predetermined incident angle, undergoes wavelength dispersion at the diffraction grating, and is again coupled with light in a desired wavelength range through the lens to the one light receiving fiber, A mechanism for changing the angle of incidence on the diffraction grating due to temperature fluctuations is arranged in the output section, and the mechanism section places the light input / output section in a direction in which the angle of incidence of light on the diffraction grating decreases when the temperature rises. Optical filter characterized by moving.
を特徴とする請求項３記載の光フィルタ。4. The optical filter according to claim 3, wherein a Fourier diffraction grating is used as the diffraction grating.
として、回折格子の裏面ないしは表面の格子溝方向に垂
直な面上に、前記回折格子を支持する少なくとも２つ以
上の素材が同じで長さが異なる支持部分を設けることを
特徴とする光フィルタ。5. The mechanism for changing the rotation angle according to claim 1, wherein at least two or more materials for supporting the diffraction grating are the same on the back surface or the surface of the diffraction grating perpendicular to the grating groove direction. An optical filter comprising support portions having different lengths.
として、回折格子の一端を固定し、他端の前記回折格子
の格子溝方向に垂直な面上に、前記回折格子を支持する
支持部分を設けることを特徴とする光フィルタ。6. A mechanism for changing the rotation angle according to claim 1, wherein one end of the diffraction grating is fixed and the other end is supported on a surface perpendicular to the grating groove direction of the diffraction grating. An optical filter having a portion.
として、回折格子の裏面ないしは表面の格子溝方向に垂
直な面上に、前記回折格子を支持する線膨張係数が異な
る少なくとも２つ以上の支持部分を設けることを特徴と
する光フィルタ。7. The mechanism for changing the rotation angle according to claim 1, wherein at least two or more different linear expansion coefficients for supporting the diffraction grating are provided on the back surface or the surface of the diffraction grating perpendicular to the grating groove direction. An optical filter, characterized in that it is provided with a supporting portion of the.
構として、回折格子の格子溝方向に垂直な面上に光入出
力部を支持する２つ以上の素材の等しい支持部分を離し
て対向させることを特徴とする光フィルタ。8. A mechanism for moving the light input / output unit according to claim 3, wherein two or more equal supporting parts of materials for supporting the light input / output unit are separated on a plane perpendicular to the grating groove direction of the diffraction grating. The optical filter is characterized by facing each other.
として、光入出力部の光入出力端から離れた一端を固定
し、前記光入出力部の前記光入出力端側の回折格子の格
子溝方向に垂直な面上に、前記光入出力部を支持する支
持部分を設けることを特徴とする光フィルタ。9. The mechanism for changing the rotation angle according to claim 3, wherein one end of the light input / output unit separated from the light input / output end is fixed, and the diffraction grating on the light input / output end side of the light input / output unit is fixed. An optical filter, wherein a supporting portion for supporting the light input / output portion is provided on a surface perpendicular to the grating groove direction.
機構として、回折格子の格子溝方向に垂直な面上に光入
出力部を支持する線膨張係数が異なる２つの支持部分を
設けることを特徴とする光フィルタ。10. A mechanism for moving the light input / output unit according to claim 3, wherein two supporting portions having different linear expansion coefficients for supporting the light input / output unit are provided on a surface of the diffraction grating perpendicular to the grating groove direction. An optical filter characterized in that
基板の上に周期的な凹凸形状を有する格子層を設けたこ
とを特徴とする光フィルタに用いる回折素子。11. A diffractive element used for an optical filter, wherein a grating layer having a periodic concavo-convex shape is provided on a substrate having a linear expansion coefficient of 3.0 × 10 −6 ° C. −1 or less.
厚さの１／５００以下であることを特徴とする光フィル
タに用いる回折素子。12. A diffractive element used in an optical filter, wherein the thickness of the grating layer according to claim 11 is 1/500 or less of the thickness of the substrate.
有した面に反射膜を設けることを特徴とする光フィルタ
に用いる回折素子。13. A diffractive element used for an optical filter, wherein a reflective film is provided on the surface of the grating layer having an uneven surface shape according to claim 11.
であることを特徴とする光フィルタに用いる回折素子。14. A diffraction element used in an optical filter, wherein the grating layer according to claim 11 is a photosensitive resin layer.
凸形状がフーリエ形状であることを特徴とする光フィル
タに用いる回折素子。15. A diffractive element used in an optical filter, characterized in that the uneven shape imprinted on the grating layer according to claim 11 is a Fourier shape.
と１本の受光ファイバで構成され、前記１本の入力ファ
イバからの光が前記レンズを介して前記回折格子で波長
分散を受け、再び前記レンズを介して前記１本の受光フ
ァイバに所望の波長域の光が結合するような系におい
て、前記回折格子に請求項１１記載の光フィルタに用い
る回折素子を用いることを特徴とする光フィルタ。16. A diffraction grating, a lens, one input fiber and one light receiving fiber, wherein light from the one input fiber is wavelength-dispersed by the diffraction grating via the lens, and again. An optical filter using the diffraction element used in the optical filter according to claim 11 in the diffraction grating in a system in which light in a desired wavelength range is coupled to the one light receiving fiber via the lens. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12251493A JPH06331850A (en) | 1993-05-25 | 1993-05-25 | Optical filter and diffraction element used therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12251493A JPH06331850A (en) | 1993-05-25 | 1993-05-25 | Optical filter and diffraction element used therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06331850A true JPH06331850A (en) | 1994-12-02 |
Family
ID=14837740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12251493A Pending JPH06331850A (en) | 1993-05-25 | 1993-05-25 | Optical filter and diffraction element used therefor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06331850A (en) |
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