JP2777262B2 - Optical isolator device - Google Patents
Optical isolator deviceInfo
- Publication number
- JP2777262B2 JP2777262B2 JP9351890A JP9351890A JP2777262B2 JP 2777262 B2 JP2777262 B2 JP 2777262B2 JP 9351890 A JP9351890 A JP 9351890A JP 9351890 A JP9351890 A JP 9351890A JP 2777262 B2 JP2777262 B2 JP 2777262B2
- Authority
- JP
- Japan
- Prior art keywords
- wedge
- birefringent crystal
- shaped birefringent
- optical isolator
- shaped
- 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.)
- Expired - Fee Related
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Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、光通信等に用いられる光アイソレータ装置
の構成に関するものである。Description: TECHNICAL FIELD The present invention relates to a configuration of an optical isolator device used for optical communication and the like.
（従来の技術） 第２図は、くさび形複屈折結晶と45度ファラデー回転
子からなる従来の光アイソレータ装置の構成図であっ
て、同図の（ａ）は１段構成の場合を、同図の（ｂ）は
２段構成の場合をそれぞれ示している（特公昭61−5881
1号公報 参照）。また、第３図の（ａ）および（ｂ）
は、１段構成の光アイソレータ装置の動作を、第４図の
（ａ）および（ｂ）は２段構成の光アイソレータ装置の
動作を説明するための図である。(Prior Art) FIG. 2 is a diagram showing the configuration of a conventional optical isolator device comprising a wedge-shaped birefringent crystal and a 45-degree Faraday rotator. (B) of the figure shows the case of a two-stage configuration, respectively (Japanese Patent Publication No. 61-5881).
No. 1). Also, FIGS. 3 (a) and (b)
FIGS. 4A and 4B are diagrams for explaining the operation of an optical isolator device having a one-stage configuration, and FIGS. 4A and 4B are diagrams for explaining the operation of an optical isolator device having a two-stage configuration.
第２図乃至第４図において、F1,F2は光ファイバ、L1,
L2は光学レンズ、B1,B2,B3,B4はくさび形複屈折結晶、R
1,R2は45度ファラデー回転子である。さらに、第３図お
よび第４図中（ア），（イ），（ウ），（エ），（オ）
は光軸に対して垂直な面での通過点における光線の分布
状態を、CB1〜CB4はくさび形複屈折結晶B1〜B4の光学軸
をそれぞれ示している。2 to 4, F1 and F2 are optical fibers, L1 and L2.
L2 is an optical lens, B1, B2, B3, B4 are wedge-shaped birefringent crystals, R
1, R2 is a 45 degree Faraday rotator. 3 (a), (b), (c), (d), and (e) in FIGS.
Is the distribution of light rays at the passing point of a plane perpendicular to the optical axis, C B1 -C B4 indicates the optical axis of the wedge-shaped birefringent crystal B1~B4 respectively.
従来の光アイソレータ装置において、１段構成の場合
は、くさび形複屈折結晶B1およびB2間に45度ファラデー
回転子R1を配置し、かつ、くさび形複屈折結晶B2の光学
軸をくさび形複屈折結晶B1の光学軸に対して偏光の回転
と同じ方向に45度回転させて構成されている。In the conventional optical isolator device, in the case of a one-stage configuration, a 45-degree Faraday rotator R1 is arranged between the wedge-shaped birefringent crystals B1 and B2, and the wedge-shaped birefringent crystal B2 has a wedge-shaped birefringent optical axis. The crystal B1 is rotated 45 degrees in the same direction as the polarization rotation with respect to the optical axis of the crystal B1.
また、同じく２段構成の場合は、くさび形複屈折結晶
B1およびB2間に45度ファラデー回転子R1を配置した１段
目の光アイソレータと、くさび形複屈折結晶B3およびB4
間に45度ファラデー回転子R2を配置した２段目の光アイ
ソレータとを直列に配置し、かつ、１段目の光アイソレ
ータのくさび形複屈折結晶の傾斜方向と２段目の光アイ
ソレータとくさび形複屈折結晶の傾斜方向とを90度ずら
して構成されている。In the case of a two-stage structure, a wedge-shaped birefringent crystal
First-stage optical isolator with 45-degree Faraday rotator R1 placed between B1 and B2, wedge-shaped birefringent crystals B3 and B4
A second-stage optical isolator having a 45-degree Faraday rotator R2 between them is arranged in series, and the inclination direction of the wedge-shaped birefringent crystal of the first-stage optical isolator and the second-stage optical isolator and wedge It is configured such that the inclination direction of the form birefringent crystal is shifted by 90 degrees.
次に、上記構成による動作を第３図および第４図を用
いて説明する。Next, the operation of the above configuration will be described with reference to FIGS.
まず、第３図に基づいて１段構成の光アイソレータ装
置の動作を説明する。First, the operation of the one-stage optical isolator device will be described with reference to FIG.
光線の伝搬方向が光ファイバF1からF2の方向（以下、
順方向という）の場合、第３図の（ａ）に示すように、
光ファイバF1からレンズL1を経由してくさび形複屈折結
晶B1に入射した光線が、くさび形複屈折結晶B1を通過す
るとき常光線ｏと異常光線ｅとに分離され、異なる角度
で屈折する。The propagation direction of the light beam is from the direction of the optical fiber F1 to F2 (hereinafter, referred to as
In the case of the forward direction), as shown in FIG.
When the light beam incident on the wedge-shaped birefringent crystal B1 from the optical fiber F1 via the lens L1 passes through the wedge-shaped birefringent crystal B1, it is separated into an ordinary ray o and an extraordinary ray e and refracted at different angles.
次いで、45度ファラデー回転子R1により常光線、異常
光線とも偏光方向が45度回転させられた後、くさび形複
屈折結晶B2に入射する。このとき、くさび形複屈折結晶
B2の光学軸は、くさび形複屈折結晶B1の光学軸に対して
偏光の回転と同じ方向に45度回転しているので、常光
線、異常光線はくさび形複屈折結晶B2に対しても常光
線、異常光線となっている。従って、くさび形複屈折結
晶B2を通過した常光線、異常光線は、２本の平行光線と
なる。Next, the polarization direction of both the ordinary ray and the extraordinary ray is rotated by 45 degrees by the 45-degree Faraday rotator R1, and then enters the wedge-shaped birefringent crystal B2. At this time, a wedge-shaped birefringent crystal
Since the optical axis of B2 is rotated by 45 degrees in the same direction as the rotation of the polarization with respect to the optical axis of wedge-shaped birefringent crystal B1, ordinary rays and extraordinary rays are always reflected on wedge-shaped birefringent crystal B2. Light rays, extraordinary rays. Therefore, the ordinary ray and the extraordinary ray that have passed through the wedge-shaped birefringent crystal B2 become two parallel rays.
次に、これら２本の平行光線は、レンズL2によって集
光され、光ファイバF2に結合される。Next, these two parallel rays are condensed by the lens L2 and coupled to the optical fiber F2.
また、順方向とは逆方向に光線が進行する場合は、第
３図の（ｂ）に示すように、光ファイバF2からレンズL2
を経由してくさび形複屈折結晶B2に入射した光は、常光
線ｏと異常光線ｅとに分離され、異なる角度で屈折す
る。When the light beam travels in a direction opposite to the forward direction, as shown in FIG.
The light incident on the wedge-shaped birefringent crystal B2 via the light source is separated into an ordinary ray o and an extraordinary ray e, and refracted at different angles.
次いで、45度ファラデー回転子R1により常光線、異常
光線とも偏光方向が45度回転させられるが、上記した順
方向の動作の場合と逆の方向に回転するため、くさび形
複屈折結晶B1の光学軸に対して常光線、異常光線が入れ
替わることになる。Next, the polarization direction of the ordinary ray and the extraordinary ray is rotated by 45 degrees by the 45-degree Faraday rotator R1, but since the polarization direction is rotated in the opposite direction to the case of the above-described forward operation, the wedge-shaped birefringent crystal B1 The ordinary ray and the extraordinary ray are interchanged with respect to the axis.
従って、これら２光線は、くさび形複屈折結晶B1にて
さらに分離するように屈折するため、レンズL1を通して
も光ファイバF1には結合しない。Therefore, these two rays are refracted so as to be further separated by the wedge-shaped birefringent crystal B1, and are not coupled to the optical fiber F1 even through the lens L1.
次に、第４図に基づいて２段構成の光アイソレータ装
置の動作を説明する。Next, the operation of the two-stage optical isolator device will be described with reference to FIG.
順方向に光線が進行する場合は、第４図の（ａ）に示
すように、光ファイバF1からレンズL1を経由してくさび
形複屈折結晶B1に入射した光線は、くさび形複屈折結晶
B1、45度ファラデー回転子R1およびくさび形複屈折結晶
B2を透過する間に２光線に分離され、さらに２段目の光
アイソレータを通過する間にそれぞれが２光線に分離さ
れる。When the light beam travels in the forward direction, as shown in FIG. 4A, the light beam incident on the wedge-shaped birefringent crystal B1 from the optical fiber F1 via the lens L1 is converted into a wedge-shaped birefringent crystal.
B1, 45 degree Faraday rotator R1 and wedge-shaped birefringent crystal
The light is separated into two light beams while passing through B2, and further separated into two light beams while passing through the second-stage optical isolator.
分離された４光線は平行であり、これらがレンズL2に
よって集光され、光ファイバF2に結合される。The four separated light beams are parallel, are collected by the lens L2, and are coupled to the optical fiber F2.
また、逆方向に光線が進行する場合は、第４図の
（ｂ）に示すように、２段目の光アイソレータを逆に通
過する間に２光線に分離され、さらに１段目の光アイソ
レータを通過する間にそれぞれが２光線に分離される。
これにより得られた４光線は、いずれも位置ずれ、角度
ずれを生じるため、光ファイバF1には結合しない。In the case where the light beam travels in the opposite direction, as shown in FIG. 4 (b), the light beam is split into two light beams while passing through the second-stage optical isolator in reverse, and is further separated into the first-stage optical isolator. Are separated into two rays while passing through.
All of the four light beams thus obtained are not coupled to the optical fiber F1 because they cause positional deviation and angular deviation.
（発明が解決しようとする課題） しかしながら、従来の装置では、順方向に光線が進行
すると、１段構成の光アイソレータ装置の場合、レンズ
L2に入射するまえの光線は平行な２光線に分離されてい
るため、第３図中（ウ）に示すように、光ファイバへ集
光するときに角度ずれが生じ、光ファイバL2への結合効
率が劣化する。従って、順方向の挿入損失が低くなった
り、偏波方向による損失の差が生じてしまうという欠点
があった。(Problems to be Solved by the Invention) However, in the conventional device, when the light beam travels in the forward direction, in the case of a single-stage optical isolator device, a lens
Since the light beam before being incident on L2 is split into two parallel light beams, as shown in (c) in FIG. 3, an angle shift occurs when the light beam is condensed on the optical fiber, and the light beam is coupled to the optical fiber L2. Efficiency deteriorates. Therefore, there are drawbacks in that the insertion loss in the forward direction is reduced, and a difference in loss occurs depending on the polarization direction.
第５図は、平行光線をレンズＬを用いて光ファイバＦ
へ結合する様子を示したものである。第５図に示すよう
に、角度ずれをθ、光ファイバのコア半径をω０、光の
波長をλとすると、結合効率ηは次式で表される。FIG. 5 shows that an optical fiber F
FIG. As shown in FIG. 5, when the angle shift is θ, the core radius of the optical fiber is ω 0 , and the wavelength of light is λ, the coupling efficiency η is expressed by the following equation.
η＝exp（−ω0 2π２θ2/λ２）……（１） ここで、例えば、角度ずれθを３度、光ファイバのコア
半径ω０を５μｍとし、光の波長λを1.55μｍとした
時、結合効率ηは上記（１）式により76％（−1.2dB）
となる。η = exp (−ω 0 2 π 2 θ 2 / λ 2 ) (1) Here, for example, the angle shift θ is 3 degrees, the core radius ω 0 of the optical fiber is 5 μm, and the light wavelength λ is 1.55. μm, the coupling efficiency η is 76% (-1.2 dB) according to the above equation (1).
Becomes
２段構成の光アイソレータの場合も同様に、第４図中
（エ）に示すように、４つの平行線に分離されるため、
さらに結合効率が劣化し、順方向の挿入損失や偏波無依
存性が劣化してしまうという欠点があった。Similarly, in the case of an optical isolator having a two-stage configuration, it is separated into four parallel lines as shown in FIG.
Further, there is a disadvantage that the coupling efficiency is deteriorated, and the insertion loss in the forward direction and the polarization independence are deteriorated.
逆に、１段構成、２段構成のいずれの場合も、高い結
合効率を得るため、くさび形複屈折結晶の傾斜を緩くす
ることも考えられるが、これでは逆方向での角度ずれを
大きくとれないため、高いアイソレーションを得ること
が困難であるという欠点があった。Conversely, in both the one-stage configuration and the two-stage configuration, in order to obtain high coupling efficiency, it is conceivable to make the inclination of the wedge-shaped birefringent crystal gentle. Therefore, there is a disadvantage that it is difficult to obtain high isolation.
本発明は、かかる事情に鑑みてなされたものであり、
その目的は、順方向挿入損失および偏波依存存在が低
く、アイソレーションが高い光アイソレータ装置を提供
することにある。The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an optical isolator device having low insertion loss in the forward direction and low polarization dependence and high isolation.
（課題を解決するための手段） 上記目的を達成するため、請求項（１）では、くさび
形複屈折結晶およびプリズム形複屈折結晶および45度フ
ァラデー回転子よりなる光アイソレータ装置において、
第１のくさび形複屈折結晶、第１の45度ファラデー回転
子、第２のくさび形複屈折結晶を表記した順に配置して
なる第１の光アイソレータユニットと第３のくさび形複
屈折結晶、第２の45度ファラデー回転子、第４のくさび
形複屈折結晶を表記した順に配置してなる第２の光アイ
ソレータユニットとを備え、第２のくさび形複屈折結晶
と第３のくさび形複屈折結晶とが相対するように、第１
の光アイソレータユニットと第２の光アイソレータユニ
ットとを直列に配置し、かつ、第１のくさび形複屈折結
晶と第２のくさび形複屈折結晶の対向面およびその背面
の傾斜方向を等しくなるように配置するとともに、第３
のくさび形複屈折結晶と第４のくさび形複屈折結晶の対
向面およびその背面の傾斜方向を等しくなるように配置
し、さらに、第２のくさび形複屈折結晶と第３のくさび
形複屈折結晶との対向面同士が、互いに光学軸に垂直な
面に対して逆方向に傾くように配置した。(Means for Solving the Problems) In order to achieve the above object, according to claim (1), in an optical isolator device comprising a wedge-shaped birefringent crystal, a prism-shaped birefringent crystal, and a 45-degree Faraday rotator,
A first wedge-shaped birefringent crystal, a first 45-degree Faraday rotator, and a second wedge-shaped birefringent crystal in which a first optical isolator unit and a third wedge-shaped birefringent crystal are arranged in the stated order; A second 45 degree Faraday rotator, a second optical isolator unit in which a fourth wedge-shaped birefringent crystal is arranged in the order described, and a second wedge-shaped birefringent crystal and a third wedge-shaped birefringent crystal. So that the refraction crystal faces
And the second optical isolator unit are arranged in series, and the first wedge-shaped birefringent crystal and the second wedge-shaped birefringent crystal have the same facing surface and the same inclination direction on the back surface. And the third
The wedge-shaped birefringent crystal and the fourth wedge-shaped birefringent crystal are arranged so that the opposing surface and the inclined direction of the back surface thereof are equal, and the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are further arranged. The surfaces facing the crystal were arranged so as to be inclined in opposite directions with respect to a plane perpendicular to the optical axis.
また、請求項（２）では、請求項（１）の構成におい
て、第２のくさび形複屈折結晶と第３のくさび形複屈折
結晶との光学軸を一致させた。Further, in claim (2), in the structure of claim (1), the optical axes of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are matched.
また、請求項（３）では、第２のくさび形複屈折結晶
と第３のくさび形複屈折結晶との対向面同士を、請求項
（１）の構成に代えて、互いに光学軸に垂直な面に対し
て同一方向に傾くように配置した。In claim (3), the opposing surfaces of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are perpendicular to the optical axis, instead of the structure of claim (1). They were arranged so as to be inclined in the same direction with respect to the plane.
また、請求項（４）では、請求項（３）の構成におい
て、第２のくさび形複屈折結晶と第３のくさび形複屈折
結晶の光学軸とを互いに直交させた。Further, in claim (4), in the configuration of claim (3), the optical axes of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are orthogonal to each other.
（作 用） 請求項（１）によれば、第１のくさび形複屈折結晶に
入射した順方向の光線が、第１のくさび形複屈折結晶を
通過するとき、常光線と異常光線とに分離され、異なる
角度で屈折する。(Operation) According to claim (1), when a forward light ray incident on the first wedge-shaped birefringent crystal passes through the first wedge-shaped birefringent crystal, it is converted into an ordinary ray and an extraordinary ray. Separated and refracted at different angles.
次いで、第１の45度ファラデー回転子により常光線、
異常光線とも偏光方向が45度回転させられた後、第２の
くさび形複屈折結晶に入射する。このとき、常光線、異
常光線は第２のくさび形複屈折結晶に対しても常光線、
異常光線となっている。Then, the first 45-degree Faraday rotator ordinary ray,
After the polarization direction of the extraordinary ray is rotated by 45 degrees, the extraordinary ray is incident on the second wedge-shaped birefringent crystal. At this time, the ordinary ray and the extraordinary ray are also the ordinary ray for the second wedge-shaped birefringent crystal.
It is an extraordinary ray.
従って、第１の光アイソレータユニットの第２のくさ
び形複屈折結晶を透過した常光線、異常光線は、２本の
平行光線に分離され、第２の光アイソレータユニットの
第３のくさび形複屈折結晶に入射する。また、第２のく
さびく形複屈折結晶と第３のくさび形複屈折結晶との対
向面同士は、光学軸に垂直な面に対して互いに逆方向に
傾斜しているので、常光線、異常光線は合波する方向に
屈折する。Therefore, the ordinary ray and the extraordinary ray that have passed through the second wedge-shaped birefringent crystal of the first optical isolator unit are separated into two parallel rays, and the third wedge-shaped birefringence of the second optical isolator unit. It is incident on the crystal. In addition, the opposing surfaces of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are inclined in directions opposite to each other with respect to a plane perpendicular to the optical axis. Light rays are refracted in the direction of combining.
次に、これら２光線は、第２の45度ファラデー回転子
により45度回転させられた後、第４のくさび形複屈折結
晶に入射する。このとき、常光線、異常光線は、第４の
くさび形複屈折結晶に対しても常光線、異常光線であ
る。Next, these two light rays are rotated by 45 degrees by the second 45-degree Faraday rotator, and then enter the fourth wedge-shaped birefringent crystal. At this time, the ordinary ray and the extraordinary ray are also the ordinary ray and the extraordinary ray for the fourth wedge-shaped birefringent crystal.
従って、常光線、異常光線は、第２の光アイソレータ
ユニットの出射時に同一軸上で合波される。Therefore, the ordinary ray and the extraordinary ray are combined on the same axis when the second optical isolator unit exits.
一方、第４のくさび形複屈折結晶に入射した逆方向に
進行する光線は、常光線と異常光線とに分離され、異な
る角度で屈折する。On the other hand, the light beam traveling in the opposite direction that has entered the fourth wedge-shaped birefringent crystal is separated into an ordinary light beam and an extraordinary light beam and refracted at different angles.
次いで、第２の45度ファラデー回転子により常光線、
異常光線とも偏光方向が45度回転させられるが、上記し
た順方向動作の場合と逆の方向に回転するため、第３の
くさび形複屈折結晶の光学軸に対して常光線、異常光線
が入れ替わることになる。Then, the ordinary ray by the second 45 degree Faraday rotator,
The polarization direction of the extraordinary ray is also rotated by 45 degrees, but the ordinary ray and the extraordinary ray are switched with respect to the optical axis of the third wedge-shaped birefringent crystal because the extraordinary ray is rotated in the opposite direction to the case of the forward operation described above. Will be.
従って、２つの光線は、第３のくさび形複屈折結晶に
より、さらに分離するように屈折するため、順方向に進
行する光線を出射する光ファイバ端面等には結合しな
い。Therefore, the two light beams are refracted by the third wedge-shaped birefringent crystal so as to be further separated from each other, and are not coupled to the end face of the optical fiber that emits the light beam traveling in the forward direction.
また、請求項（２）によれば、第２のくさび形複屈折
結晶を出射した２光線は、第２のくさび形複屈折結晶と
第３のくさび形複屈折結晶の光学軸方向が一致している
ため、常光線、異常光線は第３のくさび形複屈折結晶に
対しても確実に常光線、異常光線になっている。According to claim (2), the two light beams emitted from the second wedge-shaped birefringent crystal have the same optical axis direction of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal. Therefore, the ordinary ray and the extraordinary ray surely become the ordinary ray and the extraordinary ray even for the third wedge-shaped birefringent crystal.
従って、常光線、異常光線は、第２の光アイソレータ
ユニットの出射時、同一軸上で良好に合波される。Therefore, the ordinary ray and the extraordinary ray are well combined on the same axis when the second optical isolator unit exits.
また、請求項（３）によれば、第１のくさび形複屈折
結晶に入射した順方向の光線が、第１のくさび形複屈折
結晶を通過するとき、常光線と異常光線とに分離され、
異なる角度で屈折する。Further, according to claim (3), when a forward ray incident on the first wedge-shaped birefringent crystal passes through the first wedge-shaped birefringent crystal, it is separated into an ordinary ray and an extraordinary ray. ,
Refract at different angles.
次いで、これら２光線は、第１の45度ファラデー回転
子、さらには第２のくさび形複屈折結晶を通過する間に
２本の平行光線に分離され、第１の光アイソレータユニ
ットを出射した後、第２の光アイソレータユニットの第
３のくさび形複屈折結晶に入射する。このとき、常光
線、異常光線は、第３のくさび形複屈折結晶に対して、
異常光線、常光線に入れ替わる。These two rays are then split into two parallel rays while passing through the first 45 degree Faraday rotator and further through the second wedge-shaped birefringent crystal, after exiting the first optical isolator unit. , Into the third wedge-shaped birefringent crystal of the second optical isolator unit. At this time, the ordinary ray and the extraordinary ray are directed to the third wedge-shaped birefringent crystal.
Extraordinary rays and ordinary rays are replaced.
その後、第１の光アイソレータユニットの場合と同様
に、常光線、異常光線は、第４のくさび形複屈折結晶に
対しても常光線、異常光線として屈折する。Thereafter, similarly to the case of the first optical isolator unit, the ordinary ray and the extraordinary ray are refracted as the ordinary ray and the extraordinary ray with respect to the fourth wedge-shaped birefringent crystal.
従って、第１の光アイソレータユニットで分離された
２本の光線は、それぞれ他方の光線が第１の光アイソレ
ータユニットで経た過程を第２の光アイソレータユニッ
トで経るため、第２の光アイソレータユニットを出射後
は１光線に合波される。Accordingly, the two light beams separated by the first optical isolator unit pass through the process in which the other light beam passes through the first optical isolator unit in the second optical isolator unit. After emission, they are combined into one light beam.
一方、光線が逆方向に進行する場合、第２の光アイソ
レータユニットを上記とは逆方向に通過する間に、異な
る角度で２光線に分離され、さらに、第１の光アイソレ
ータユニットを通過する間に、それぞれが異なる角度で
２光線に分離される。On the other hand, when the light beam travels in the opposite direction, the light beam is split into two light beams at different angles while passing through the second optical isolator unit in a direction opposite to the above, and is further separated while passing through the first optical isolator unit. Each is separated into two rays at different angles.
また、請求項（４）によれば、第２のくさび形複屈折
結晶と第３のくさび形複屈折結晶の光学軸は、互いに直
交しているので、常光線、異常光線は、第３のくさび形
複屈折結晶B3に対して、異常光線、常光線に確実に入れ
替わる。Further, according to claim (4), the optical axes of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are orthogonal to each other. The extraordinary ray and ordinary ray are surely replaced for the wedge-shaped birefringent crystal B3.
従って、常光線、異常光線は、第２の光アイソレータ
ユニットの出射時、同一軸上で良好に合波される。Therefore, the ordinary ray and the extraordinary ray are well combined on the same axis when the second optical isolator unit exits.
（実施例１） 第1A図は、本発明に係る光アイソレータ装置の第１の
実施例を示す構成図、第1B図は第1A図の動作を説明する
ための図であって、第1B図の（ａ）は順方向に進行する
光線に対する動作を、第1B図の（ｂ）は逆方向に進行す
る光線に対する動作を説明するための図である。Embodiment 1 FIG. 1A is a block diagram showing a first embodiment of the optical isolator device according to the present invention, and FIG. 1B is a diagram for explaining the operation of FIG. 1A. FIG. 1A is a diagram for explaining the operation with respect to the light beam traveling in the forward direction, and FIG. 1B is a diagram for explaining the operation with respect to the light beam traveling in the reverse direction.
なお、第1A図および第1B図においては、従来例を示す
第２図と同一構成部分は同一符号をもって表している。
即ち、F1,F2は光ファイバ、L1,L2は光学レンズ、B1は第
１のくさび形複屈折結晶、B2は第２のくさび形複屈折結
晶、B3は第３のくさび形複屈折結晶、B4は第４のくさび
形複屈折結晶、R1は第１の45度ファラデー回転子、R2は
第２の45度ファラデー回転子である。また、第1B図中、
（ア），（イ）、（ウ），（エ），（オ）は通過点にお
ける光線の断面分布図、CB1〜CB4は第１乃至第４のくさ
び形複屈折結晶B1〜B4の光学軸をそれぞれを示してい
る。1A and 1B, the same components as those in FIG. 2 showing the conventional example are denoted by the same reference numerals.
That is, F1 and F2 are optical fibers, L1 and L2 are optical lenses, B1 is a first wedge birefringent crystal, B2 is a second wedge birefringent crystal, B3 is a third wedge birefringent crystal, B4 Is a fourth wedge-shaped birefringent crystal, R1 is a first 45 degree Faraday rotator, and R2 is a second 45 degree Faraday rotator. Also, in FIG. 1B,
(A), (b), (c), (d), (e) is a cross-sectional distribution diagram of the light rays at the passing point, C B1 -C B4 is the first to fourth wedge-shaped birefringent crystal B1~B4 The optical axes are shown respectively.
第1A図の光アイソレータ装置は、第１のくさび形複屈
折結晶B1、第１の45度ファラデー回転子R1、第２のくさ
び形複屈折結晶B2を表記した順に配置して第１の光アイ
ソレータユニットIS1を構成するとともに、第３のくさ
び形複屈折結晶B3、第２の45度ファラデー回転子R2、第
４のくさび形複屈折結晶B4を表記した順に配置して第２
の光アイソレータユニットIS2を構成し、さらに、第２
のくさび形複屈折結晶B2と第３のくさび形複屈折結晶B3
とが相対するように、第１の光アイソレータユニットIS
1と第２の光アイソレータユニットIS2とを光線の順方向
進行に対して表記した順に直列に配置することによって
構成されている。この場合、第２のくさび形複屈折結晶
B2と第３のくさび形複屈折結晶B3との光学軸は一致させ
てある。The optical isolator device shown in FIG. 1A includes a first wedge-shaped birefringent crystal B1, a first 45-degree Faraday rotator R1, and a second wedge-shaped birefringent crystal B2, which are arranged in the stated order in a first optical isolator. A unit IS1 is formed, and a third wedge-shaped birefringent crystal B3, a second 45-degree Faraday rotator R2, and a fourth wedge-shaped birefringent crystal B4 are arranged in the stated order to form a second wedge-shaped birefringent crystal B4.
Optical isolator unit IS2, and the second
Wedge-shaped birefringent crystal B2 and third wedge-shaped birefringent crystal B3
And the first optical isolator unit IS
The first and second optical isolator units IS2 are arranged in series in the order described with respect to the forward travel of light rays. In this case, a second wedge-shaped birefringent crystal
The optical axes of B2 and the third wedge-shaped birefringent crystal B3 are matched.
この構成における各素子の配置関係は、第１のくさび
形複屈折結晶B1と第２のくさび形複屈折結晶B2と対向面
およびその背面の傾斜方向が等しくなるように配置され
るとともに、第３のくさび形複屈折結晶B3と第４のくさ
び形複屈折結晶B4の対向面およびその背面の傾斜方向を
等しくなるように配置され、かつ、第２のくさび形複屈
折結晶B2と第３のくさび形複屈折結晶B3との対向面同士
が、互いに光学軸に垂直な面に対して逆方向に傾くよう
に配置されている。The arrangement relationship of the elements in this configuration is such that the first wedge-shaped birefringent crystal B1 and the second wedge-shaped birefringent crystal B2 are arranged so that the facing surface and the inclined direction of the back surface thereof are equal to each other, and The wedge-shaped birefringent crystal B3 and the fourth wedge-shaped birefringent crystal B4 are arranged so that the opposing surface and the inclined direction of the back surface thereof are equal, and the second wedge-shaped birefringent crystal B2 and the third wedge The surfaces facing the birefringent crystal B3 are arranged so as to be inclined in opposite directions to each other with respect to a plane perpendicular to the optical axis.
次に、上記構成による動作を第1B図を用いて説明す
る。Next, the operation of the above configuration will be described with reference to FIG. 1B.
まず、第1B図の（ａ）に基づいて光線が順方向に進行
する場合の動作を説明する。First, the operation in the case where the light beam travels in the forward direction will be described based on FIG. 1A.
光ファイバF1からレンズL1を経由して第１のくさび形
複屈折結晶B1に入射した順方向の光線が、第１のくさび
形複屈折結晶B1を通過するとき、常光線ｏと異常光線ｅ
とに分離され、異なる角度で屈折する。When a forward ray incident on the first wedge-shaped birefringent crystal B1 from the optical fiber F1 via the lens L1 passes through the first wedge-shaped birefringent crystal B1, an ordinary ray o and an extraordinary ray e
And refracted at different angles.
次いで、第１の45度ファラデー回転子R1により常光
線、異常光線とも偏光方向が45度回転させられた後、第
２のくさび形複屈折結晶B2に入射する。このとき、第２
のくさび形複屈折結晶B2と光学軸は、第１のくさび形複
屈折結晶B1の光学軸に対して偏光が回転した同一の方向
に45度回転しているので、常光線、異常光線は第２のく
さび形複屈折結晶B2に対しても常光線、異常光線となっ
ている。Next, after the polarization direction of both the ordinary ray and the extraordinary ray is rotated by 45 degrees by the first 45-degree Faraday rotator R1, they are incident on the second wedge-shaped birefringent crystal B2. At this time, the second
Since the wedge-shaped birefringent crystal B2 and the optical axis are rotated by 45 degrees in the same direction in which the polarization is rotated with respect to the optical axis of the first wedge-shaped birefringent crystal B1, the ordinary ray and the extraordinary ray are The wedge-shaped birefringent crystal B2 also has an ordinary ray and an extraordinary ray.
従って、第２のくさび形複屈折結晶B2を透過した常光
線、異常光線は、２本の平行線に分離する。このとき、
第２のくさび形複屈折結晶B2と第３のくさび形複屈折結
晶B3の光学軸方向は一致しているため、常光線、異常光
線は第３のくさび形複屈折結晶B3に対しても常光線、異
常光線になっている。また、第２のくさび形複屈折結晶
B2と第３のくさび形複屈折結晶B3との対向面同士は、光
学軸に垂直な面に対して互いに逆方向に傾斜しているの
で、常光線、異常光線は合波する方向に屈折する。Therefore, the ordinary ray and the extraordinary ray transmitted through the second wedge-shaped birefringent crystal B2 are separated into two parallel lines. At this time,
Since the optical axis directions of the second wedge-shaped birefringent crystal B2 and the third wedge-shaped birefringent crystal B3 are coincident, the ordinary ray and the extraordinary ray are always applied to the third wedge-shaped birefringent crystal B3. Light rays, extraordinary rays. Also, a second wedge-shaped birefringent crystal
The opposing surfaces of B2 and the third wedge-shaped birefringent crystal B3 are inclined in opposite directions to the plane perpendicular to the optical axis, so that ordinary rays and extraordinary rays are refracted in the direction of multiplexing. .
次に、これら２光線は、第２の45度ファラデー回転子
R2により45度回転させられた後、第４のくさび形複屈折
結晶B4に入射する。このとき、第４のくさび形複屈折結
晶B4の光学軸は、第３のくさび形複屈折結晶B3の光学軸
に対して偏光の回転方向と同じ方向に45度回転している
ので、常光線、異常光線は、第４のくさび形複屈折結晶
B4に対しても常光線、異常光線である。Next, these two rays are passed through a second 45 degree Faraday rotator.
After being rotated 45 degrees by R2, it is incident on the fourth wedge-shaped birefringent crystal B4. At this time, the optical axis of the fourth wedge-shaped birefringent crystal B4 is rotated by 45 degrees in the same direction as the polarization rotation direction with respect to the optical axis of the third wedge-shaped birefringent crystal B3. The extraordinary ray is the fourth wedge-shaped birefringent crystal
B4 is an ordinary ray and an extraordinary ray.
従って、常光線、異常光線は、同一軸上で合波され、
光学レンズL2により光ファイバF2に結合される。Therefore, the ordinary ray and the extraordinary ray are combined on the same axis,
The light is coupled to the optical fiber F2 by the optical lens L2.
このように上記構成における順方向動作では、光線の
分離による角度ずれが起きないため、結合効率の偏波依
存性がなく、かつ、光ファイバへの結合効率が高い。As described above, in the forward operation in the above configuration, since there is no angle shift due to the separation of the light beams, there is no polarization dependence of the coupling efficiency, and the coupling efficiency to the optical fiber is high.
次に、第1B図の（ｂ）に基づいて光線が逆方向に進行
する場合の動作を説明する。Next, the operation when the light beam travels in the reverse direction will be described based on FIG. 1B (b).
光ファイバF2からレンズL2を経由して第４のくさび形
複屈折結晶B4に入射した光線は、常光線ｏと異常光線ｅ
とに分離され、異なる角度で屈折する。Light rays incident on the fourth wedge-shaped birefringent crystal B4 from the optical fiber F2 via the lens L2 are an ordinary ray o and an extraordinary ray e.
And refracted at different angles.
次いで、第２の45度ファラデー回転子R2により常光
線、異常光線とも偏光方向が45度回転させられるが、上
記した順方向動作の場合と逆の方向に回転するため、第
３のくさび形複屈折結晶B3の光学軸に対して常光線、異
常光線が入れ替わることになる。Next, the polarization direction of both the ordinary ray and the extraordinary ray is rotated by 45 degrees by the second 45-degree Faraday rotator R2. However, since the polarization direction is rotated in a direction opposite to that in the above-described forward operation, the third wedge-shaped composite is rotated. The ordinary ray and the extraordinary ray are switched with respect to the optical axis of the refraction crystal B3.
従って、２つの光線は、第３のくさび形複屈折結晶B3
により、さらに分離するように屈折するため、光ファイ
バF1には結合しない。Therefore, the two light beams are divided into a third wedge-shaped birefringent crystal B3
Therefore, the light is refracted so as to be further separated, and is not coupled to the optical fiber F1.
また、第２の45度ファラデー回転子R2の不完全性によ
り生じた漏れ光も、第１の45度ファラデー回転子R1およ
び第１のくさび形複屈折結晶B1によって角度ずれが起き
るため、光ファイバF1には結合しない。Also, the leakage light generated due to the imperfection of the second 45-degree Faraday rotator R2 also causes an angle shift due to the first 45-degree Faraday rotator R1 and the first wedge-shaped birefringent crystal B1, so that the optical fiber Does not bind to F1.
以上説明したように、本実施例によれば、順方向での
光線の分離による角度ずれが起きないため、くさび形複
屈折結晶の傾斜を従来よりかなり大きくとることが可能
である。従って、逆方向の場合の角度ずれが大きくな
り、従来より高いアイソレーションと良好な偏波無依存
性を持つ光アイソレータ装置を実現できる。As described above, according to this embodiment, since the angle shift does not occur due to the separation of the light beam in the forward direction, it is possible to make the inclination of the wedge-shaped birefringent crystal considerably larger than in the past. Accordingly, the angle shift in the reverse direction becomes large, and an optical isolator having higher isolation and better polarization independence than the conventional one can be realized.
（実施例２） 第6A図は、本発明に係る光アイソレータ装置の第２の
実施例を示す構成図、第6B図は第6A図の動作を説明する
ための図であって、第6B図の（ａ）は順方向に進行する
光線に対する動作を、第6B図の（ｂ）は逆方向に進行す
る光線に対する動作を説明するための図である。(Embodiment 2) FIG. 6A is a configuration diagram showing a second embodiment of the optical isolator device according to the present invention, and FIG. 6B is a diagram for explaining the operation of FIG. 6A. FIG. 6A is a diagram for explaining an operation with respect to a light beam traveling in a forward direction, and FIG. 6B is a diagram for explaining an operation with respect to a light beam traveling in a backward direction.
本第２の実施例が前記第１に実施例と異なる点は、第
２のくさび形複屈折結晶B2と第３のくさび形複屈折結晶
B3との対向面同士を、互いに光学軸に垂直な面に対して
同一方向に傾くように配置し、かつ、第２のくさび形複
屈折結晶B2と第３のくさび形複屈折結晶B3の光学軸とを
互いに直交させたことにある。The second embodiment differs from the first embodiment in that the second wedge-shaped birefringent crystal B2 and the third wedge-shaped birefringent crystal are different.
The two wedge-shaped birefringent crystals B2 and the third wedge-shaped birefringent crystal B3 are arranged so that their surfaces facing B3 are inclined in the same direction with respect to the plane perpendicular to the optical axis. The axes are orthogonal to each other.
次に、上記構成による動作を第6B図を用いて説明す
る。Next, the operation of the above configuration will be described with reference to FIG. 6B.
光線が順方向に進行する場合、第6B図の（ａ）に示す
ように、光ファイバF1からレンズL1を経由して第１のく
さび形複屈折結晶B1に入射した順方向の光線が、第１の
くさび形複屈折結晶B1を通過するとき、常光線ｏと異常
光線ｅとに分離され、異なる角度で屈折する。When the light beam travels in the forward direction, as shown in (a) of FIG. 6B, the forward light beam incident on the first wedge-shaped birefringent crystal B1 from the optical fiber F1 via the lens L1, When passing through one wedge-shaped birefringent crystal B1, it is separated into an ordinary ray o and an extraordinary ray e and refracted at different angles.
次いで、これら２光線は、第１の45度ファラデー回転
子R1、さらには第２のくさび形複屈折結晶B2を通過する
間に２本の平行光線に分離され、第３のくさび形複屈折
結晶B3に入射する。このとき、第２のくさび形複屈折結
晶B2と第３のくさび形複屈折結晶B3の光学軸は、互いに
直交しているので、常光線、異常光線は、第３のくさび
形複屈折結晶B3に対して、異常光線、常光線に入れ替わ
る。These two rays are then split into two parallel rays while passing through a first 45-degree Faraday rotator R1 and further through a second wedge-shaped birefringent crystal B2 to form a third wedge-shaped birefringent crystal. It is incident on B3. At this time, since the optical axes of the second wedge-shaped birefringent crystal B2 and the third wedge-shaped birefringent crystal B3 are orthogonal to each other, the ordinary ray and the extraordinary ray are reflected by the third wedge-shaped birefringent crystal B3. In contrast, extraordinary rays and ordinary rays are replaced.
その後、第１の光アイソレータユニットIS1の場合と
同様に、常光線、異常光線は、第４のくさび形複屈折結
晶B4に対しても常光線、異常光線として屈折する。Thereafter, similarly to the case of the first optical isolator unit IS1, the ordinary ray and the extraordinary ray are refracted as the ordinary ray and the extraordinary ray also to the fourth wedge-shaped birefringent crystal B4.
従って、第１の光アイソレータユニットIS1で分離さ
れた２本の光線は、それぞれ他方の光線が第１の光アイ
ソレータユニットIS1で経た過程を第２の光アイソレー
タユニットIS2で経るため、第２の光アイソレータユニ
ットIS2を出射後は１光線に合波され、レンズL2によい
光ファイバF2の結合される。Accordingly, the two light beams separated by the first optical isolator unit IS1 pass through the second optical isolator unit IS2 after the other light beam passes through the first optical isolator unit IS1. After the light exits the isolator unit IS2, the light is combined into one light beam, and the optical fiber F2 is coupled to the lens L2.
このように本第２の実施例における順方向動作におい
ても、光線の分離による角度ずれが起きないため、結合
効率の偏波依存性がなく、かつ、光ファイバへの結合効
率が高い。As described above, even in the forward operation in the second embodiment, since there is no angle shift due to the separation of the light beam, there is no polarization dependence of the coupling efficiency, and the coupling efficiency to the optical fiber is high.
一方、光線が逆方向に進行する場合、第２の光アイソ
レータユニットIS2を上記とは逆方向に通過する間に、
異なる角度で２光線に分離され、さらに、第１の光アイ
ソレータユニットIS1を通過する間に、それぞれが異な
る角度で２光線に分離される。On the other hand, when the light beam travels in the opposite direction, while passing through the second optical isolator unit IS2 in the opposite direction,
The light is split into two light beams at different angles, and further split into two light beams at different angles while passing through the first optical isolator unit IS1.
従って、本第２の実施例においても、逆方向の場合の
角度ずれが大きくなり、従来装置に比べて、高いアイソ
レーションと良好な偏波無依存性を持つ光アイソレータ
装置を実現できる。Therefore, also in the second embodiment, the angle shift in the reverse direction becomes large, and an optical isolator device having higher isolation and better polarization independence than the conventional device can be realized.
（発明の効果） 以上説明したように、請求項（１），（２），（３）
または（４）によれば、順方向の光線の位置ずれおよび
角度ずれを起こさないため、順方向の挿入損失が低くて
偏波依存性を持たず、高いアイソレーションを有する光
アイソレータ装置を提供することができる。(Effects of the Invention) As described above, claims (1), (2), and (3)
According to (4), there is provided an optical isolator device which has low forward insertion loss, does not have polarization dependency, and has high isolation because the forward light beam does not shift in position and does not shift in angle. be able to.
第1A図は本発明に係る光アイソレータ装置の第１の実施
例を示す構成図、第1B図は第1A図の動作を説明するため
の図、第２図は従来の光アイソレータ装置の構成図、第
３図は第２図の（ａ）の動作を説明するための図、第４
図は第２図の（ｂ）の動作を説明するための図、第５図
はレンズによる平行光線の光ファイバへの結合の様子を
示す図、第6A図は本発明に係る光アイソレータ装置の第
２の実施例を示す構成図、第6B図は第6A図の動作を説明
するための図である。 図中、F1,F2……光ファイバ、L1,L2……光学レンズ、B1
……第１のくさび形複屈折結晶、B2……第２のくさび形
複屈折結晶、B3……第３のくさび形複屈折結晶、B4……
第４のくさび形複屈折結晶、R1……第１の45度ファラデ
ー回転子、R2……第２の45度ファラデー回転子。1A is a block diagram showing a first embodiment of the optical isolator device according to the present invention, FIG. 1B is a diagram for explaining the operation of FIG. 1A, and FIG. 2 is a block diagram of a conventional optical isolator device. FIG. 3 is a diagram for explaining the operation of FIG.
FIG. 5 is a diagram for explaining the operation of FIG. 2 (b), FIG. 5 is a diagram showing the manner in which parallel rays are coupled to an optical fiber by a lens, and FIG. 6A is a diagram of an optical isolator device according to the present invention. FIG. 6B is a configuration diagram showing the second embodiment, and FIG. 6B is a diagram for explaining the operation of FIG. 6A. In the figure, F1, F2 ... optical fiber, L1, L2 ... optical lens, B1
... first wedge-shaped birefringent crystal, B2 ... second wedge-shaped birefringent crystal, B3 ... third wedge-shaped birefringent crystal, B4 ...
Fourth wedge-shaped birefringent crystal, R1 ... first 45 degree Faraday rotator, R2 ... second 45 degree Faraday rotator.
Claims (4)
折結晶および45度ファラデー回転子よりなる光アイソレ
ータ装置において、 第１のくさび形複屈折結晶、第１の45度ファラデー回転
子、第２のくさび形複屈折結晶を表記した順に配置して
なる第１の光アイソレータユニットと、 第３のくさび形複屈折結晶、第２の45度ファラデー回転
子、第４のくさび形複屈折結晶を表記した順に配置して
なる第２の光アイソレータユニットとを備え、 第２のくさび形複屈折結晶と第３のくさび形複屈折結晶
とが相対するように、第１の光アイソレータユニットと
第２の光アイソレータユニットとを直列に配置し、 かつ、第１のくさび形複屈折結晶と第２のくさび形複屈
折結晶の対向面およびその背面の傾斜方向を等しくなる
ように配置するとともに、第３のくさび形複屈折結晶と
第４のくさび形複屈折結晶の対向面およびその背面の傾
斜方向を等しくなるように配置し、 さらに、第２のくさび形複屈折結晶と第３のくさび形複
屈折結晶との対向面同士が、互いに光学軸に垂直な面に
対して逆方向に傾くように配置した ことを特徴とする光アイソレータ装置。1. An optical isolator device comprising a wedge-shaped birefringent crystal, a prism-shaped birefringent crystal, and a 45-degree Faraday rotator, comprising: a first wedge-shaped birefringent crystal, a first 45-degree Faraday rotator; A first optical isolator unit in which wedge-shaped birefringent crystals are arranged in the indicated order, a third wedge-shaped birefringent crystal, a second 45-degree Faraday rotator, and a fourth wedge-shaped birefringent crystal are shown. A first optical isolator unit and a second optical isolator so that the second wedge-type birefringent crystal and the third wedge-type birefringent crystal face each other. An isolator unit is arranged in series, and the first wedge-shaped birefringent crystal and the second wedge-shaped birefringent crystal are arranged so that the opposing surface and the inclination direction of the back surface thereof are equal to each other. The third wedge-shaped birefringent crystal and the fourth wedge-shaped birefringent crystal are arranged so that the opposing surface and the inclined direction of the back surface thereof are equal, and the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are further arranged. An optical isolator device, wherein opposing surfaces of a birefringent crystal are arranged so as to be inclined in opposite directions with respect to a plane perpendicular to the optical axis.
形複屈折結晶との光学軸を一致させた請求項（１）記載
の光アイソレータ装置。2. The optical isolator device according to claim 1, wherein the optical axes of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are matched.
形複屈折結晶との対向面同士を、請求項（１）の構成に
代えて、互いに光学軸に垂直な面に対して同一方向に傾
くように配置した請求項（１）記載の光アイソレータ装
置。3. The opposing surfaces of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal may be replaced with respect to surfaces perpendicular to the optical axis, instead of the structure of claim (1). The optical isolator device according to claim 1, wherein the optical isolator devices are arranged to be inclined in the same direction.
形複屈折結晶の光学軸とを互いに直交させた請求項
（３）記載の光アイソレータ装置。4. The optical isolator device according to claim 3, wherein the optical axes of the second wedge-shaped birefringent crystal and the third wedge-shaped birefringent crystal are orthogonal to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9351890A JP2777262B2 (en) | 1990-04-09 | 1990-04-09 | Optical isolator device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9351890A JP2777262B2 (en) | 1990-04-09 | 1990-04-09 | Optical isolator device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03290612A JPH03290612A (en) | 1991-12-20 |
| JP2777262B2 true JP2777262B2 (en) | 1998-07-16 |
Family
ID=14084556
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9351890A Expired - Fee Related JP2777262B2 (en) | 1990-04-09 | 1990-04-09 | Optical isolator device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2777262B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05224150A (en) * | 1992-02-10 | 1993-09-03 | Nippon Telegr & Teleph Corp <Ntt> | Optical isolator device |
| JP4956004B2 (en) * | 2006-01-06 | 2012-06-20 | 古河電気工業株式会社 | Optical isolator |
| JP4968210B2 (en) * | 2008-08-19 | 2012-07-04 | 住友金属鉱山株式会社 | Polarization-independent optical isolator |
-
1990
- 1990-04-09 JP JP9351890A patent/JP2777262B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03290612A (en) | 1991-12-20 |
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