JPH04264516A - Optical isolator - Google Patents
Optical isolatorInfo
- Publication number
- JPH04264516A JPH04264516A JP2623391A JP2623391A JPH04264516A JP H04264516 A JPH04264516 A JP H04264516A JP 2623391 A JP2623391 A JP 2623391A JP 2623391 A JP2623391 A JP 2623391A JP H04264516 A JPH04264516 A JP H04264516A
- Authority
- JP
- Japan
- Prior art keywords
- optical isolator
- optical
- parallel plate
- birefringent
- crystal
- 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
- 230000003287 optical effect Effects 0.000 title claims abstract description 102
- 239000013078 crystal Substances 0.000 claims abstract description 66
- 239000000463 material Substances 0.000 claims abstract description 20
- 239000000126 substance Substances 0.000 claims description 9
- 239000013307 optical fiber Substances 0.000 abstract description 19
- 230000010287 polarization Effects 0.000 description 16
- 238000010586 diagram Methods 0.000 description 10
- 238000006073 displacement reaction Methods 0.000 description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 10
- 239000002223 garnet Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 229910021532 Calcite Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- MTRJKZUDDJZTLA-UHFFFAOYSA-N iron yttrium Chemical compound [Fe].[Y] MTRJKZUDDJZTLA-UHFFFAOYSA-N 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000382 optic material Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、半導体レーザを用いた
光ファイバ通信や光ディスクの入出力等における光学系
の反射戻り光を阻止するための光アイソレータに関し、
特に入射光の偏光方向に影響を受けない偏光無依存型の
光アイソレータに関する。[Field of Industrial Application] The present invention relates to an optical isolator for preventing reflected light from an optical system in optical fiber communication using a semiconductor laser, input/output of an optical disk, etc.
In particular, it relates to a polarization-independent optical isolator that is not affected by the polarization direction of incident light.
【０００２】0002
【従来の技術】光ファイバ通信や光ディスクの入出等の
主要な光源である半導体レーザでは、それに結合される
光ファイバの端面や、光ファイバ同士の接続点、あるい
は結合レンズ，光コネクタ等の光学系からの反射戻り光
を受けると発振が不安定になり、雑音の増加や出力変動
等、動作特性が大幅に劣化することが知られている。こ
の反射光による半導体レーザの動作不安定性を解消し、
安定な光通信用光源を実現するために、これまでに各種
の光アイソレータが開発されている。[Prior Art] Semiconductor lasers, which are the main light source for optical fiber communications and optical disk loading/unloading, are used at the end faces of optical fibers coupled to them, at the connection points between optical fibers, or at optical systems such as coupling lenses and optical connectors. It is known that oscillation becomes unstable when the device receives reflected light from the device, resulting in significant deterioration of operating characteristics such as increased noise and output fluctuations. Eliminating the instability of semiconductor laser operation caused by this reflected light,
Various types of optical isolators have been developed to realize stable light sources for optical communications.
【０００３】偏光子，検光子としてローション・プリズ
ムを用い、ＹＩＧ（イットリウム鉄ガーネット）単結晶
やＢｉ置換ガーネット等のファラデー回転子、このファ
ラデー回転子を順方向に磁化するためのＳｍＣｏなどの
孔あき永久磁石を用いて構成した光アイソレータが一般
に広く知られているが、このような構成の光アイソレー
タはある偏光面しか有効でなく、光アイソレータの偏光
方向に合致しない光が入射した場合には通過光が大幅に
損失するという欠点があった。これに対して、例えば、
光アイソレータを光ファイバ間に挿入して使用する場合
には、光ファイバ中を伝搬する光ビームは一般に直線偏
光が保たれていないので、偏光依存性のない光アイソレ
ータが望ましい。[0003] A Rochon prism is used as a polarizer or an analyzer, and a Faraday rotator such as YIG (yttrium iron garnet) single crystal or Bi-substituted garnet is used, and a perforated material such as SmCo is used to magnetize the Faraday rotator in the forward direction. Optical isolators constructed using permanent magnets are generally widely known, but optical isolators with such a construction are effective only in a certain polarization plane, and if light is incident that does not match the polarization direction of the optical isolator, it will not pass through. The disadvantage was that there was a significant loss of light. On the other hand, for example,
When an optical isolator is used by being inserted between optical fibers, an optical isolator without polarization dependence is desirable because the light beam propagating through the optical fiber generally does not maintain linear polarization.
【０００４】そこで、偏光方向に依存せずに全ての偏光
面に対してアイソレーション効果を示す構成として、ロ
ーションプリズムの代わりに方解石のような平板状複屈
折結晶による常光，異常光の分離／合成を利用した偏光
無依存型の光アイソレータが提案されている。例えば、
松本氏が提案した特開昭５５−２２７２９号公報には、
レンズ，第１の平板状複屈折結晶，１個の磁気光学材料
（ファラデー回転子），旋光性結晶（または異方性結晶
）、および第２の平板状複屈折結晶を入射側から順次配
置し、磁気光学材料を磁化するための永久磁石を有する
光アイソレータが示されている。また、例えば、今野氏
等が提案した特開平２−４６４１９号公報には、結晶光
軸が表面に対して傾いた第１の平板状複屈折結晶，偏光
面を４５°回転するための第１のファラデー回転子，第
１の平板状複屈折結晶に対し√２倍の厚さを有し、また
Ｘ軸を中心として１８０°回転した後、入射光線方向を
回転軸とし４５°回転して配置された第２の平板状複屈
折結晶，上記第１のファラデー回転子と同じ向きに磁化
された第２のファラデー回転子，第１の平板状複屈折結
晶と同一厚さを有し、かつ第２の平板状複屈折結晶に対
し入射光線方向を回転軸として４５°回転し第１の平板
状複屈折結晶の光軸と互いに９０°回転して配置した第
３の平板状複屈折結晶、およびファラデー回転子を磁化
するための永久磁石により構成された光アイソレータが
示されている。[0004] Therefore, as a configuration that exhibits an isolation effect for all polarization planes without depending on the polarization direction, a tabular birefringent crystal such as calcite is used instead of the Rochon prism to separate and combine ordinary and extraordinary light. A polarization-independent optical isolator has been proposed. for example,
In Japanese Patent Application Laid-open No. 55-22729 proposed by Mr. Matsumoto,
A lens, a first plate-shaped birefringent crystal, one magneto-optical material (Faraday rotator), an optically active crystal (or anisotropic crystal), and a second plate-shaped birefringent crystal are arranged in order from the incident side. , an optical isolator with a permanent magnet for magnetizing magneto-optic material is shown. Furthermore, for example, Japanese Patent Application Laid-open No. 2-46419 proposed by Mr. Konno et al. describes a first tabular birefringent crystal whose crystal optical axis is tilted with respect to the surface, and a first plate-shaped birefringent crystal whose crystal optical axis is tilted with respect to the surface. The Faraday rotator has a thickness √2 times that of the first plate-shaped birefringent crystal, and is rotated 180° around the X axis, and then rotated 45° with the direction of the incident light as the rotation axis. a second tabular birefringent crystal, a second Faraday rotator magnetized in the same direction as the first Faraday rotator, the same thickness as the first tabular birefringent crystal, and a second Faraday rotator magnetized in the same direction as the first Faraday rotator; a third tabular birefringent crystal rotated by 45° with respect to the second tabular birefringent crystal with the direction of the incident light as a rotation axis, and arranged to be rotated by 90° with respect to the optical axis of the first tabular birefringent crystal, and An optical isolator constructed of permanent magnets for magnetizing a Faraday rotator is shown.
【０００５】さらにまた、Ｋｏｋ Ｗａｉ Ｃｈａ
ｎｇ氏等が提案した「高性能シングルモード光ファイバ
用偏光無依存型の光アイソレータ」ＯＰＴＩＣＳ Ｌ
ＥＴＴＥＲＳ Ａｐｒｉｌ １５，１９９０，ｖｏ
ｌ．１５，Ｎｏ．８ ｐ．４４９−ｐ．４５１の論文
には、４個の平板状複屈折結晶と３個のファラデー回転
子とを有し、２個の隣接する複屈折結晶間に１個のファ
ラデー回転子を挿入配置するようにして構成された光ア
イソレータが示されている。これら４個の平板状複屈折
結晶の厚みは１：√２：１：√２の割合でそれぞれ設定
され、その結像光軸方向は０°：１３５°：１８０°：
２２５°に順次設定されており、３個のファラデー回転
子は偏光面を全て同一方向の４５°回転するように設け
られている。[0005] Furthermore, Kok Wai Cha
OPTICS L, a “polarization-independent optical isolator for high-performance single-mode optical fibers” proposed by Mr. ng et al.
ETTERS April 15, 1990, vo
l. 15, No. 8 p. 449-p. The article No. 451 describes a structure having four plate-shaped birefringent crystals and three Faraday rotators, with one Faraday rotator inserted between two adjacent birefringent crystals. An optical isolator is shown. The thicknesses of these four tabular birefringent crystals are set at a ratio of 1:√2:1:√2, and the imaging optical axis directions are: 0°:135°:180°:
225°, and the three Faraday rotators are provided to rotate the polarization planes by 45° in the same direction.
【０００６】通常、これらの光アイソレータ本体は、そ
の本体からの反射戻り光を防止するため、図７に示され
るように、光線方向に対して垂直に配置せずに、ほぼ２
°〜６°程度、全体に傾斜して配置している。一例とし
て、図８は上記の特開昭２−４６４１９号公報に記載さ
れた光アイソレータの場合を示し、図９はＯＰＴＩＣＳ
ＬＥＴＴＥＲＳの上記論文に記載された光アイソレ
ータの場合を示す。ここで、２は入射側光ファイバ、４
は入射側コリメートレンズ、６は光アイソレータ本体、
８は出射側コリメートレンズおよび１０は出射側光ファ
イバである。また、１２，１４，１６，１８はそれぞれ
平行平板状複屈折結晶（複屈折性物質）、２０，２２，
２４はそれぞれファラデー回転子である。また、図１０
は図９の光アイソレータの詳細な構成と入射光線の伝搬
状態を示している。Usually, these optical isolator bodies are not disposed perpendicular to the light beam direction, but rather are arranged approximately 2 times perpendicularly to the direction of the light beam, as shown in FIG.
The entire structure is arranged at an angle of about 6 degrees. As an example, FIG. 8 shows the case of the optical isolator described in the above-mentioned Japanese Patent Application Laid-Open No. 2-46419, and FIG.
The case of the optical isolator described in the above-mentioned paper of LETTERS will be shown. Here, 2 is the input side optical fiber, 4
is the input side collimating lens, 6 is the optical isolator body,
8 is a collimating lens on the output side, and 10 is an optical fiber on the output side. In addition, 12, 14, 16, 18 are parallel plate birefringent crystals (birefringent substance), 20, 22,
24 are Faraday rotators, respectively. Also, Figure 10
9 shows the detailed configuration of the optical isolator of FIG. 9 and the propagation state of the incident light beam.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、このよ
うな従来の光アイソレータの構成においては、図８およ
び図９に示すように、光アイソレータ本体を傾斜させて
配置した場合は、光アイソレータを出射後の光線は入射
光線の延長直線上にはなく、そのため光アイソレータの
前後に配置するコリメータレンズ４，８および光ファイ
バ２，１０の軸調整が煩雑で困難となり、そのため光ア
イソレータの組立に相当の時間や熟練を要するという解
決すべき課題があった。[Problems to be Solved by the Invention] However, in the configuration of such a conventional optical isolator, as shown in FIGS. 8 and 9, when the optical isolator main body is arranged at an angle, The rays of light are not on the straight line of extension of the incident rays, which makes it complicated and difficult to adjust the axes of the collimator lenses 4 and 8 and the optical fibers 2 and 10, which are placed before and after the optical isolator, and it takes a considerable amount of time to assemble the optical isolator. There were issues that needed to be solved, such as the need for skill and skill.
【０００８】[0008]
【課題を解決するための手段】本発明の目的は、上述の
点に鑑みて、光アイソレータを入射光線方向に垂直な線
に傾斜させて配置させた場合に、光アイソレータを出射
後の光線を入射光線の延長線上に近づけることができ、
これによりコリメータレンズ，光ファイバの軸調整範囲
を狭めることができる光アイソレータを提供することに
ある。[Means for Solving the Problems] In view of the above-mentioned points, an object of the present invention is to provide an optical isolator that, when the optical isolator is arranged inclined in a line perpendicular to the direction of the incident light beam, the light beam after exiting the optical isolator is It can be brought close to the extension line of the incident ray,
The object of the present invention is to provide an optical isolator that can narrow the axial adjustment range of a collimator lens and an optical fiber.
【０００９】上記目的を達成するため、本発明の第１は
、同一の結晶光軸方向で互いに向きが逆となるように配
置された平行平板状複屈折性物質が２個以上ある複数の
複屈折性物質，ファラデー回転子および磁石から構成さ
れる光アイソレータにおいて、光アイソレータ出射後の
光線軌道をΔｄだけ入射光線軸方向に変位させるように
、前記同一の結晶光軸方向で互いに向きが逆となるよう
に配置された平行平板状複屈折性物質の内の任意の２個
の平行平板状複屈折性物質の厚みを各々Δａ，−Δａだ
け変化させて設定したことを特徴とする。In order to achieve the above object, the first aspect of the present invention is to provide a plurality of birefringent materials having two or more parallel plate-like birefringent substances arranged in opposite directions in the same crystal optical axis direction. In an optical isolator composed of a refractive material, a Faraday rotator, and a magnet, the directions are opposite to each other in the optical axis direction of the same crystal so that the ray trajectory after exiting the optical isolator is displaced by Δd in the axial direction of the incident ray. The present invention is characterized in that the thicknesses of any two of the parallel plate-like birefringent substances arranged so as to be set are changed by Δa and −Δa, respectively.
【００１０】また、本発明の第２は、複数の平行平板状
複屈折性物質，ファラデー回転子および磁石から構成さ
れる光アイソレータにおいて、前記平行平板状複屈折性
物質の内の１個の厚みを−Δａだけ変化させて設定する
と同時に、厚さΔａの平行平板状複屈折性物質を前記−
Δａだけ変化させた前記平行平板状複屈折性物質と同一
の結晶光軸方向で互いに向きが逆となるように追加配置
したことを特徴とした。A second aspect of the present invention is an optical isolator composed of a plurality of parallel plate-shaped birefringent substances, a Faraday rotator, and a magnet, in which the thickness of one of the parallel plate-shaped birefringent substances is is set by changing by -Δa, and at the same time, the parallel plate-shaped birefringent material with thickness Δa is set by changing -Δa.
It is characterized in that the parallel plate-like birefringent material changed by Δa is additionally arranged so that the directions are opposite to each other in the same crystal optical axis direction.
【００１１】[0011]
【作用】本発明では、同一の結晶光軸方向で互いに向き
が逆となるように配置された２個の平行平板状複屈折性
物質の厚みをΔａ，−Δａだけ変化させて設定するか、
あるいは平行平板状複屈折性物質の内の１個の厚みを−
Δａだけ変化させて設定すると同時に、厚さΔａの平行
平板状複屈折性物質を同一の結晶光軸方向で互いに向き
が逆となるように追加配置するように構成しているので
、光アイソレータ出射後の光線軌道をΔｄだけ入射光線
軸方向に変化させることができる。従って、上記Δａ，
−Δａを光アイソレータの設置傾斜角に応じて適切な値
に設定することで、入射光線軸方向に光アイソレータ出
射後の光線軌道をできるだけ近づけ、ほぼ一致させるこ
とができる。[Operation] In the present invention, the thicknesses of two parallel plate-shaped birefringent substances arranged in opposite directions in the same crystal optical axis direction are set by changing by Δa, -Δa, or
Alternatively, the thickness of one of the parallel plate-like birefringent substances is −
At the same time, parallel plate-shaped birefringent materials with a thickness of Δa are additionally arranged in opposite directions in the same crystal optical axis direction, so that the optical isolator output The subsequent ray trajectory can be changed by Δd in the direction of the incident ray axis. Therefore, the above Δa,
By setting -Δa to an appropriate value according to the installation inclination angle of the optical isolator, the ray trajectories after exiting from the optical isolator can be brought as close as possible in the axial direction of the incident ray, so that they almost coincide.
【００１２】0012
【実施例】以下、図面を参照して本発明の実施例を詳細
に説明する。Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
【００１３】図１は本発明の第１の実施例の光アイソレ
ータの概略構成を示す。この光アイソレータ３０は４個
の平行平板状複屈折結晶３２，３６，４０，４２と、２
個のファラデー回転子３４，３８と、これらのファラデ
ー回転子を磁化するための永久磁石（図５の符号４４参
照）とから構成されている。第１のファラデー回転子３
４は第１と第２の平行平板状複屈折結晶３２，３６の間
に挿入設置され、第２のファラデー回転子３８は第２と
第３の平行平板状複屈折結晶３６，４０の間に挿入設置
されており、これらファラデー回転子３４，３８は偏光
面を同一の反時計方向に４５°回転する。平行平板状複
屈折結晶３２，３６，４０，４２としては方解石板の他
にルチルなどの各種の複屈折性結晶物質が利用できる。
ファラデー回転子３４，３８としてはＹＩＧ（イットリ
ウム鉄ガーネット）単結晶，Ｂｉ置換ガーネット，ＲＩ
Ｇ（希土類鉄ガーネット）などの各種の磁気光学材料が
利用できる。また、後述の永久磁石としては例えばＳｍ
Ｃｏなどの環状の孔あき永久磁石等が利用できる。FIG. 1 shows a schematic configuration of an optical isolator according to a first embodiment of the present invention. This optical isolator 30 includes four parallel plate-shaped birefringent crystals 32, 36, 40, 42, and 2
It consists of two Faraday rotators 34, 38 and a permanent magnet (see reference numeral 44 in FIG. 5) for magnetizing these Faraday rotators. First Faraday rotator 3
4 is inserted between the first and second parallel plate birefringent crystals 32 and 36, and the second Faraday rotator 38 is inserted between the second and third parallel plate birefringent crystals 36 and 40. These Faraday rotators 34 and 38 rotate the plane of polarization by 45 degrees in the same counterclockwise direction. As the parallel plate-shaped birefringent crystals 32, 36, 40, and 42, various birefringent crystal materials such as rutile can be used in addition to calcite plates. Faraday rotators 34 and 38 are YIG (yttrium iron garnet) single crystal, Bi-substituted garnet, RI
Various magneto-optical materials such as G (rare earth iron garnet) can be used. In addition, as a permanent magnet to be described later, for example, Sm
An annular perforated permanent magnet made of Co or the like can be used.
【００１４】図２の（Ａ）に示されるように、第１〜第
４の平行平板状複屈折結晶３２，３６，４０，４２の厚
みｔはそれぞれAs shown in FIG. 2A, the thicknesses t of the first to fourth parallel plate-shaped birefringent crystals 32, 36, 40, and 42 are respectively
【００１５】[0015]
【外１】[Outside 1]
【００１６】の大きさであり、それらの結晶の結晶光軸
方向の向きは、０°，１３５°，１８０°，２７０°に
設けられている。このように、光線の入射側端部にある
第１の平行平板状複屈折結晶３２の厚みを所定の厚さ−
Δａだけ減少させるのと同時に、この第１の平行平板状
複屈折結晶３２と同一の結晶光軸方向で向きが反対であ
る厚さΔａの第３の平行平板状複屈折結晶４０を追加配
置して構成している。The crystal optical axes of these crystals are oriented at 0°, 135°, 180°, and 270°. In this way, the thickness of the first parallel plate birefringent crystal 32 at the end on the light incident side is set to a predetermined thickness -
At the same time as decreasing by Δa, a third parallel plate birefringent crystal 40 having a thickness Δa and having the same crystal optical axis direction and opposite direction as the first parallel plate birefringent crystal 32 is additionally arranged. It is composed of
【００１７】図３は本発明の第２の実施例の光アイソレ
ータの概略構成を示す。この光アイソレータ５０は４個
の平行平板状複屈折結晶５２，５６，６０，６４と、３
個のファラデー回転子５４，５８，６２と、これらのフ
ァラデー回転子を磁化するための永久磁石（図６の符号
６６参照）とから構成されている。これらのファラデー
回転子５４，５８，６２はそれぞれ隣り合う２つの平行
平板状複屈折結晶毎に１個づつ挿入配置され、偏光面を
同一方向に４５°回転する。さらに、図４の（Ａ）に示
されるように、第１〜第４の平行平板状複屈折結晶５２
，５６，６０，６４の厚みｔはそれぞれFIG. 3 shows a schematic configuration of an optical isolator according to a second embodiment of the present invention. This optical isolator 50 includes four parallel plate-shaped birefringent crystals 52, 56, 60, 64, and 3
It consists of Faraday rotators 54, 58, and 62, and a permanent magnet (see reference numeral 66 in FIG. 6) for magnetizing these Faraday rotators. These Faraday rotators 54, 58, and 62 are inserted into each of two adjacent parallel plate-shaped birefringent crystals, and rotate the plane of polarization by 45 degrees in the same direction. Furthermore, as shown in FIG. 4A, first to fourth parallel plate-shaped birefringent crystals 52
, 56, 60, and 64 are respectively
【００１８】[0018]
【外２】[Outside 2]
【００１９】の大きさであり、これらの結晶の結晶光軸
方向の向きは０°，１３５°，１８０°，２２５°に設
けられている。このように、本例では、同一の結晶光軸
方向で向きが反対である第１と第３の平行平板状複屈折
結晶５２，５８の厚みをａからΔａ，−Δａだけ変化さ
せている。The crystal optical axes of these crystals are oriented at 0°, 135°, 180°, and 225°. In this way, in this example, the thicknesses of the first and third parallel plate-shaped birefringent crystals 52 and 58, which are in the same crystal optical axis direction but opposite in direction, are changed from a by Δa and -Δa.
【００２０】次に、上述した構成の第１および第２実施
例の光アイソレータ３０，５０の動作について説明する
。Next, the operation of the optical isolators 30 and 50 of the first and second embodiments having the above-described configuration will be explained.
【００２１】光アイソレータにおいて、入射光線の軌道
を変位させる要因は、平行平板状複屈折結晶およびファ
ラデー回転子を光線方向に垂直な線に対して傾斜させて
配置したための屈折と、複屈折結晶自体に基因する屈折
とが挙げられる。前者の屈折による変位は図８および図
９に示されるように、Ｄ，Ｄ′で表わされ、後者の屈折
による変位は、図１０に示されるようにｄで表わされる
。従って、光アイソレータから出射後の光線が入射光線
の延長線上の近傍にあるための条件は数１となる。In an optical isolator, the factors that displace the trajectory of an incident light ray are refraction due to the parallel plate birefringent crystal and Faraday rotator being arranged at an angle with respect to a line perpendicular to the direction of the light beam, and the birefringent crystal itself. and refraction due to. The former displacement due to refraction is represented by D and D' as shown in FIGS. 8 and 9, and the latter displacement due to refraction is represented by d as shown in FIG. 10. Therefore, the condition for the light ray emitted from the optical isolator to be in the vicinity of the extension of the incident light ray is given by Equation 1.
【００２２】[0022]
【数１】Ｄ＋ｄ≒０
ここで、Ｄは入射光線の方向に垂直な線に対する傾斜角
から決められ、ｄは所望するアイソレーションの達成が
得られるように決められるので、従来構成の光アイソレ
ータでは前述したように一般に上記数１が満たされない
のが通例である。[Equation 1]D+d≒0 Here, D is determined from the inclination angle with respect to a line perpendicular to the direction of the incident light beam, and d is determined so as to achieve the desired isolation, so in an optical isolator with a conventional configuration, As mentioned above, it is common that the above equation 1 is not satisfied.
【００２３】しかしながら、図１〜図４に示すような構
成の本発明実施例の光アイソレータにおいては、調整用
の厚みΔａを適切な値に変えれば数１のｄをほぼ−Ｄの
大きさに変えることができる。従って、数１を満たすよ
うに平行平板状複屈折結晶３２，４０（または５２，６
０）のΔａの厚み寸法をあらかじめ所定の値に調整すれ
ば、光アイソレータ３０（または５０）を出射後の光線
を入射光線の延長線上の近傍におくことができる。However, in the optical isolator of the embodiment of the present invention having the configuration shown in FIGS. 1 to 4, if the adjustment thickness Δa is changed to an appropriate value, d in Equation 1 can be reduced to approximately -D. It can be changed. Therefore, parallel plate birefringent crystals 32, 40 (or 52, 6
If the thickness dimension of Δa of 0) is adjusted to a predetermined value in advance, the light beam emitted from the optical isolator 30 (or 50) can be placed near the extension line of the incident light beam.
【００２４】このとき、図２の（Ｃ）および図４の（Ｃ
）から分るように、逆方向における光線分離幅は、Δａ
＝０の時とほぼ変化はなく、従来通りの好ましいアイソ
レーションが得られる。At this time, (C) in FIG. 2 and (C) in FIG.
), the beam separation width in the opposite direction is Δa
There is almost no change from when = 0, and preferable isolation as before can be obtained.
【００２５】次に、本発明に従う具体的な実験例につい
て、図５および図６を用いて説明する。Next, a specific experimental example according to the present invention will be explained using FIGS. 5 and 6.
【００２６】図５は図１および図２に示した第１実施例
の構成の光アイソレータ３０を光アイソレータ本体とし
て用いた実験例の配置構成を示す。本実験例ではａ＝２
ｍｍ，Δａ＝１ｍｍとし、複屈折結晶としてルチル結晶
を用いた。すなわち、ルチル平行平板３２，３６，４０
，４２の厚さはそれぞれ１ｍｍ，２．８２８ｍｍ，２ｍ
ｍ，１ｍｍとした。ファラデー回転子３４，３８として
はＹＩＧファラデー回転子を用い、これらの回転子の周
囲を覆うように円筒状永久磁石４４を取付けた。このよ
うな構成の光アイソレータ３０を光ファイバ４５，４８
間に２°傾斜させて配置し、コリメータレンズとして屈
折率分布型ロッドレンズであるセルフォックマイクロレ
ンズ（商標名）４６，４７を光ファイバ４５，４８と光
アイソレータ間に挿入配置した。FIG. 5 shows the arrangement of an experimental example in which the optical isolator 30 having the structure of the first embodiment shown in FIGS. 1 and 2 was used as the optical isolator main body. In this experimental example, a=2
mm, Δa=1 mm, and a rutile crystal was used as the birefringent crystal. That is, rutile parallel flat plates 32, 36, 40
, 42 have a thickness of 1 mm, 2.828 mm, and 2 m, respectively.
m, 1 mm. YIG Faraday rotators were used as the Faraday rotators 34 and 38, and a cylindrical permanent magnet 44 was attached to cover the periphery of these rotors. The optical isolator 30 having such a configuration is connected to the optical fibers 45 and 48.
SELFOC Microlens (trade name) 46, 47, which is a gradient index rod lens, is inserted between the optical fibers 45, 48 and the optical isolator as collimator lenses.
【００２７】ルチル結晶の屈折率は２．６であるから、
ルチル平行平板３２，３６，４０，４２を２°傾斜させ
た場合の光線軌道の変位Ｄは次の数２によりおおよそ９
０μｍであると推定される。Since the refractive index of rutile crystal is 2.6,
When the rutile parallel plates 32, 36, 40, and 42 are tilted by 2 degrees, the displacement D of the ray trajectory is approximately 9 according to the following equation 2.
It is estimated to be 0 μm.
【００２８】[0028]
【数２】
Ｄ＝６．４ｔａｎ（ｓｉｎ２°／
２．６）＝０．０８６ｍｍそこで、図５の構成における
Δａの値として１ｍｍを採用した場合は、図２（Ｂ）に
示される順方向の変位Δｄ＝−７６μｍ程度となる。よ
って、光アイソレータ３０を変位方向に注意して配置し
て、
Ｄ＋ｄ≒１０μｍ
にすることができた。[Equation 2] D=6.4tan (sin2°/
2.6)=0.086 mm Therefore, when 1 mm is adopted as the value of Δa in the configuration of FIG. 5, the displacement in the forward direction Δd shown in FIG. 2(B) becomes approximately −76 μm. Therefore, by carefully arranging the optical isolator 30 in the displacement direction, it was possible to set D+d≈10 μm.
【００２９】図６は図３および図４に示した第２実施例
の構成の光アイソレータ５０を光アイソレータ本体とし
て用いた実験例の配置構成を示す。本実験例ではFIG. 6 shows the arrangement of an experimental example in which the optical isolator 50 having the configuration of the second embodiment shown in FIGS. 3 and 4 was used as the optical isolator main body. In this experimental example
【００
３０】00
30]
【外３】[Outer 3]
【００３１】とし、複屈折結晶としてルチル結晶を用い
た。すなわち、ルチル平行平板５２，５６，６０，６４
の厚さはそれぞれ０．４１４ｍｍ，２ｍｍ，２．４１４
ｍｍ，２ｍｍとした。ファラデー回転子５４，５８，６
２としてはＹＩＧファラデー回転子を用い、これらの回
転子の周囲を覆うように円筒状永久磁石４４を取付けた
。このような構成の光アイソレータ５０を光ファイバ４
５，４８間に６°傾斜させて配置し、コリメートレンズ
として屈折率分布型ロッドレンズであるセルフォックマ
イクロレンズ（商標名）４６，４７を光ファイバ４５，
４８と光アイソレータ間に挿入配置した。A rutile crystal was used as the birefringent crystal. That is, rutile parallel plates 52, 56, 60, 64
The thickness of is 0.414mm, 2mm, 2.414 respectively.
mm, 2 mm. Faraday rotator 54, 58, 6
2, YIG Faraday rotators were used, and cylindrical permanent magnets 44 were attached so as to cover the periphery of these rotors. The optical isolator 50 having such a configuration is connected to the optical fiber 4.
Selfoc micro lenses (trade name) 46 and 47, which are graded index rod lenses, are arranged between the optical fibers 45 and 48 at an angle of 6 degrees, and serve as collimating lenses.
48 and an optical isolator.
【００３２】上述したようにルチル結晶の屈折率は２．
６である。ルチル平行平板３２，３６，４０，４２の厚
みから考えて、光アイソレータ出射後の光線変位量ｄ−
Δｄは３０３μｍ−７６μｍ＝ほぼ２２７μｍ程度とな
る（図４の（Ｂ）参照）。また、ルチル平行平板３２，
３６，４０，４２を６°傾斜させた場合の屈折による光
線軌道の変位Ｄは次の数３により約２６０μｍ程度とな
る。As mentioned above, the refractive index of rutile crystal is 2.
It is 6. Considering the thickness of the rutile parallel plates 32, 36, 40, 42, the amount of ray displacement d- after exiting the optical isolator
Δd is approximately 303 μm−76 μm=approximately 227 μm (see (B) in FIG. 4). In addition, rutile parallel plate 32,
When 36, 40, and 42 are tilted by 6 degrees, the displacement D of the ray trajectory due to refraction is about 260 μm according to the following equation 3.
【００３３】[0033]
【数３】
Ｄ＝９．１ｔａｎ（ｓｉｎ６°／
２．６）＝０．２５７ｍｍこのように、光アイソレータ
出射後の光線の変位量ｄ−Δｄと上記光線軌道の変位Ｄ
とが同程度の値になるので、光アイソレータからの出射
光を入射光の延長線上に近づけることができた。[Equation 3] D=9.1tan (sin6°/
2.6)=0.257mm In this way, the amount of displacement d-Δd of the light ray after exiting the optical isolator and the displacement D of the above-mentioned ray trajectory
Since the values are approximately the same, it was possible to bring the light emitted from the optical isolator close to the extension of the incident light.
【００３４】[0034]
【発明の効果】以上説明したように、本発明によれば、
光アイソレータ出射後の光線軌道をΔｄだけ変位させる
ように、一対の平行平板状複屈折結晶の厚みをΔａ，−
Δａだけ変化させて設定する、あるいは一個の平行平板
状複屈折結晶を−Δａだけ厚みを変えると同時にΔａの
厚みの平行平板状複屈折結晶を追加配置するようにした
ので、光アイソレータ出射後の光線を入射光線の延長線
上に近づけることができる。従って、本発明によれば、
コリメートレンズ，光ファイバの軸調整範囲を狭めるこ
とができ、これにより調整組立時間の短縮が可能となり
、製品の低廉化に寄与できる効果が得られる。[Effects of the Invention] As explained above, according to the present invention,
The thickness of the pair of parallel plate-shaped birefringent crystals is set to Δa,− so that the ray trajectory after exiting the optical isolator is displaced by Δd.
By changing the thickness by Δa, or by changing the thickness of one parallel plate birefringent crystal by -Δa and simultaneously placing an additional parallel plate birefringent crystal with a thickness of Δa, the It is possible to bring the light ray closer to the extension of the incident light ray. Therefore, according to the invention:
The axis adjustment range of the collimating lens and the optical fiber can be narrowed, thereby making it possible to shorten the adjustment and assembly time, which has the effect of contributing to lower product costs.
【図１】本発明の第１の実施例の光アイソレータを示す
概略構成図である。FIG. 1 is a schematic configuration diagram showing an optical isolator according to a first embodiment of the present invention.
【図２】図１の光アイソレータにおける結晶光軸方向と
偏光面回転方向（Ａ）、および順方向と逆方向の入射光
線の伝搬状態を光線方向から見た光線の軌道（Ｂ），（
Ｃ）を示す概念図である。[Fig. 2] The crystal optical axis direction and polarization plane rotation direction (A) in the optical isolator in Fig. 1, and the propagation states of the incident rays in the forward and reverse directions as viewed from the ray direction (B), (
It is a conceptual diagram showing C).
【図３】本発明の第２実施例の光アイソレータを示す概
略構成図である。FIG. 3 is a schematic configuration diagram showing an optical isolator according to a second embodiment of the present invention.
【図４】図３の光アイソレータにおける結晶光軸方向と
偏光面回転方向（Ａ）、および順方向と逆方向の入射光
線の伝搬状態を光線方向から見た光線の軌道（Ｂ），（
Ｃ）を示す概念図である。FIG. 4 shows the crystal optical axis direction and polarization plane rotation direction (A) in the optical isolator in FIG.
It is a conceptual diagram showing C).
【図５】本発明の第１の実験例の配置構成を示す概略構
成図である。FIG. 5 is a schematic configuration diagram showing the arrangement of a first experimental example of the present invention.
【図６】本発明の第２の実験例の配置構成を示す概略構
成図である。FIG. 6 is a schematic configuration diagram showing the arrangement of a second experimental example of the present invention.
【図７】光アイソレータと光ファイバとの一般的な配置
関係を示す概略構成図である。FIG. 7 is a schematic configuration diagram showing a general arrangement relationship between an optical isolator and an optical fiber.
【図８】従来の光アイソレータの順方向での入射光に対
する出射光の変位の一例を示す光路図である。FIG. 8 is an optical path diagram showing an example of displacement of output light with respect to incident light in the forward direction of a conventional optical isolator.
【図９】従来の光アイソレータの順方向での入射光に対
する出射度の変化の他の例を示す光路図である。FIG. 9 is an optical path diagram showing another example of a change in output power of a conventional optical isolator with respect to incident light in the forward direction.
【図１０】図９の従来の光アイソレータの詳細な構成（
Ａ），結晶光軸方向と偏光面回転方向（Ｂ）、および順
方向と逆方向の入射光線の伝搬状態を光線方向から見た
光線の軌道（Ｃ），（Ｄ）を示す概念図である。[Fig. 10] Detailed configuration of the conventional optical isolator shown in Fig. 9 (
A) is a conceptual diagram showing the crystal optical axis direction and polarization plane rotation direction (B), and the propagation state of the incident ray in the forward direction and the reverse direction as seen from the ray direction (C) and (D). .
３０，５０ 光アイソレータ
３２，３６，４０，４２ 平行平板状複屈折結晶（複
屈折性物質）
３４，３８ ファラデー回転子
５２，５６，６０，６４ 平行平板状複屈折結晶５４
，５８，６２ ファラデー回転子４４，６６ 永久
磁石
４５，４８ 光ファイバ30, 50 Optical isolator 32, 36, 40, 42 Parallel plate birefringent crystal (birefringent material) 34, 38 Faraday rotator 52, 56, 60, 64 Parallel plate birefringent crystal 54
, 58, 62 Faraday rotator 44, 66 Permanent magnet 45, 48 Optical fiber
Claims (2)
となるように配置された平行平板状複屈折性物質が２個
以上ある複数の複屈折性物質，ファラデー回転子および
磁石から構成される光アイソレータにおいて、光アイソ
レータ出射後の光線軌道をΔｄだけ入射光線軸方向に変
位させるように、前記同一の結晶光軸方向で互いに向き
が逆となるように配置された平行平板状複屈折性物質の
内の任意の２個の平行平板状複屈折性物質の厚みを各々
Δａ，−Δａだけ変化させて設定したことを特徴とする
光アイソレータ。[Claim 1] Consisting of a plurality of birefringent materials, a Faraday rotator, and a magnet, including two or more parallel plate-shaped birefringent materials arranged in opposite directions in the same crystal optical axis direction. In the optical isolator, the parallel plate-like birefringence is arranged so that the directions are opposite to each other in the optical axis direction of the same crystal so as to displace the ray trajectory after exiting the optical isolator by Δd in the direction of the axis of the incident ray. An optical isolator characterized in that the thicknesses of any two parallel plate-like birefringent materials among the materials are set to vary by Δa and −Δa, respectively.
ラデー回転子および磁石から構成される光アイソレータ
において、前記平行平板状複屈折性物質の内の１個の厚
みを−Δａだけ変化させて設定すると同時に、厚さΔａ
の平行平板状複屈折性物質を前記−Δａだけ変化させた
前記平行平板状複屈折性物質と同一の結晶光軸方向で互
いに向きが逆となるように追加配置したことを特徴とし
た光アイソレータ。2. An optical isolator comprising a plurality of parallel plate-shaped birefringent substances, a Faraday rotator, and a magnet, wherein the thickness of one of the parallel plate-shaped birefringent substances is changed by −Δa. At the same time as setting the thickness Δa
An optical isolator characterized in that a parallel plate-shaped birefringent material is additionally arranged so that the directions are opposite to each other in the same crystal optical axis direction as the parallel plate-shaped birefringent material changed by -Δa. .
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2623391A JPH04264516A (en) | 1991-02-20 | 1991-02-20 | Optical isolator |
| AU12091/92A AU644044B2 (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
| EP92905098A EP0525208B1 (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
| DE69219526T DE69219526D1 (en) | 1991-02-20 | 1992-02-19 | OPTICAL ISOLATOR |
| US07/937,896 US5381261A (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
| PCT/JP1992/000171 WO1992015040A1 (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
| EP95114378A EP0691563A3 (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
| CA002080904A CA2080904A1 (en) | 1991-02-20 | 1992-02-19 | Optical isolator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2623391A JPH04264516A (en) | 1991-02-20 | 1991-02-20 | Optical isolator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04264516A true JPH04264516A (en) | 1992-09-21 |
Family
ID=12187614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2623391A Pending JPH04264516A (en) | 1991-02-20 | 1991-02-20 | Optical isolator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04264516A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5428477A (en) * | 1991-06-14 | 1995-06-27 | Tokin Corporation | Optical isolator operating independent of polarization of an incident beam |
| US5880875A (en) * | 1995-08-04 | 1999-03-09 | Samsung Electronics Co., Ltd. | Light amplifier having a multi-stage optical isolator |
-
1991
- 1991-02-20 JP JP2623391A patent/JPH04264516A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5428477A (en) * | 1991-06-14 | 1995-06-27 | Tokin Corporation | Optical isolator operating independent of polarization of an incident beam |
| US5880875A (en) * | 1995-08-04 | 1999-03-09 | Samsung Electronics Co., Ltd. | Light amplifier having a multi-stage optical isolator |
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