JPH04360118A - Optical isolator - Google Patents
Optical isolatorInfo
- Publication number
- JPH04360118A JPH04360118A JP13664791A JP13664791A JPH04360118A JP H04360118 A JPH04360118 A JP H04360118A JP 13664791 A JP13664791 A JP 13664791A JP 13664791 A JP13664791 A JP 13664791A JP H04360118 A JPH04360118 A JP H04360118A
- Authority
- JP
- Japan
- Prior art keywords
- optical
- polarization
- optical system
- polarized light
- plane
- 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 131
- 230000010287 polarization Effects 0.000 claims abstract description 88
- 238000000926 separation method Methods 0.000 claims description 19
- 230000002194 synthesizing effect Effects 0.000 abstract description 8
- 230000015572 biosynthetic process Effects 0.000 description 9
- 238000003786 synthesis reaction Methods 0.000 description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、光アイソレータ、特に
入射光の偏波面を考慮することなく作動し得るようにし
た偏波無依存型光アイソレータに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator, and more particularly to a polarization-independent optical isolator that can operate without considering the plane of polarization of incident light.
【０００２】0002
【従来の技術】図２は、この種従来の光アイソレータの
構造例を示しているが、この光アイソレータでは入射光
が第１の偏光子１を通過した後にファラデー回転子２に
よってその偏波面が４５度回転し、更に該第１の偏光子
１に対して４５度傾いた偏光面を有する第２の偏光子３
を通過する。一方、上記入射光とは逆方向の反射戻り光
は第２の偏光子３に対して偏波面が一致した成分のみが
該第２の偏光子３を通過し、この後上記ファラデー回転
子２によってその偏波面が更に４５度回転する。従って
、該ファラデー回転子２を通過したかかる反射戻り光は
第１の偏光子１に対してその偏波面が９０度回転してい
ることになり、このため上記入射光の入射側にまでは到
達することができなくなる。このような従来の光アイソ
レータによれば上記逆方向の反射戻り光が遮断され、こ
の種光アイソレータの機能が発揮される。尚、図２に示
した構造の光アイソレータを複数段に構成することによ
り更に大きなアイソレーション効果を得ることができる
。2. Description of the Related Art FIG. 2 shows an example of the structure of a conventional optical isolator of this kind. In this optical isolator, after incident light passes through a first polarizer 1, its plane of polarization is changed by a Faraday rotator 2. a second polarizer 3 having a polarization plane rotated by 45 degrees and further tilted by 45 degrees with respect to the first polarizer 1;
pass through. On the other hand, of the reflected return light in the opposite direction to the above-mentioned incident light, only the component whose polarization plane matches the second polarizer 3 passes through the second polarizer 3, and is then processed by the Faraday rotator 2. The plane of polarization is further rotated by 45 degrees. Therefore, the reflected return light that has passed through the Faraday rotator 2 has its plane of polarization rotated by 90 degrees with respect to the first polarizer 1, and therefore does not reach the incident side of the incident light. be unable to do so. According to such a conventional optical isolator, the above-mentioned reflected return light in the opposite direction is blocked, and the function of this type of optical isolator is exhibited. Note that an even greater isolation effect can be obtained by configuring the optical isolator having the structure shown in FIG. 2 in multiple stages.
【０００３】0003
【発明が解決しようとする課題】しかしながら、上述し
た構造の光アイソレータは入射光の偏波面の傾きに依存
する特性を有しており、入射光の偏波面に第１の偏光子
１の偏光面を一致させておく必要があるため、特に入射
光の偏波面が予め特定することができない光伝送系にお
いては光アイソレータとしての機能を十分有効に発揮す
ることができないという問題があった。[Problems to be Solved by the Invention] However, the optical isolator having the above structure has a characteristic that depends on the inclination of the polarization plane of the incident light, and the polarization plane of the first polarizer 1 is different from the polarization plane of the incident light. Since it is necessary to match the polarization plane of the incident light, there is a problem that the function as an optical isolator cannot be sufficiently effectively exhibited, especially in an optical transmission system where the plane of polarization of incident light cannot be specified in advance.
【０００４】本発明はかかる実情に鑑み、入射光の偏波
面を全く考慮しないで済み、且つその適正機能を発揮す
ることができる偏波無依存型の光アイソレータを提供す
ることを目的とする。In view of the above circumstances, it is an object of the present invention to provide a polarization-independent optical isolator that does not require any consideration of the plane of polarization of incident light and is capable of exhibiting its proper function.
【０００５】[0005]
【課題を解決するための手段】本発明による光アイソレ
ータは、入射光の偏波面に依存する構造を有する光アイ
ソレータユニットの入射側に２枚の偏光分離・合成素子
と偏光回転子とから成る第１の光学系を、又上記光アイ
ソレータユニットの出射側には偏光回転子と２枚の偏光
分離・合成素子とから成る第２の光学系をそれぞれ配設
し、上記第１の光学系において分離された光路の偏光成
分の一方の偏波面を回転させることにより、分離された
双方の光路の偏光成分の偏波面が上記光アイソレータユ
ニットの入射側の偏光子の偏波面と一致するように該光
アイソレータユニットに入射させると共に、上記光アイ
ソレータユニットの出射側において上記分離されている
光路の偏光成分を上記第２の光学系によって再び結合さ
せ、上記第１の光学系の入射側と上記第２の光学系の出
射側において光軸が一致するようになっている。[Means for Solving the Problems] An optical isolator according to the present invention comprises an optical isolator unit having a structure that depends on the plane of polarization of incident light, and which includes two polarization separation/synthesizing elements and a polarization rotator on the incident side of the optical isolator unit. 1 optical system, and a second optical system consisting of a polarization rotator and two polarization separation/synthesis elements are disposed on the output side of the optical isolator unit, and the first optical system separates and combines the polarization elements. By rotating the polarization plane of one of the polarization components of the separated optical paths, the light is At the same time, the polarized light components of the separated optical paths are recombined by the second optical system on the output side of the optical isolator unit, and the polarization components of the optical paths separated on the output side of the optical isolator unit are recombined. The optical axes are made to coincide on the output side of the optical system.
【０００６】[0006]
【作用】本発明によれば、入射光は先ず第１の光学系の
２枚の偏光分離・合成素子によって互いに９０度の角度
をなす偏光成分を有する２つの光路に分離される。そし
て、分離された光路の一方の光路にのみ配置された偏光
回転子により上記２つの光路の偏光成分の偏波面を一致
させた後にこれらの光路の偏光成分に偏光面を合わせた
光アイソレータユニットの偏光子へ入射する。更に該光
アイソレータユニットを通過した上記２つの偏光成分を
第２の光学系の一方にのみ配置された偏光回転子により
互いに直交させた後に２枚の偏光分離・合成素子により
再び結合させる。このとき、第１の光学系に入射する以
前の光軸と第２の光学系から出射される光軸は一致して
いる。一方、逆方向の光は第２の光学系の２枚の偏光分
離・合成素子により互いに９０度の角度をなす偏光成分
を有する２つの光路に分離され、このうち一方の光路に
のみ配置された偏光回転子により偏波面が一致した後に
上記とは逆方向から光アイソレータユニットに入射する
。従って、該光アイソレータユニットの作用により逆方
向の光は上記第１の光学系の入射側へは戻ることができ
ない。According to the present invention, incident light is first separated into two optical paths having polarization components that are at an angle of 90 degrees to each other by the two polarization separation/synthesis elements of the first optical system. Then, the polarization planes of the polarization components of the two optical paths are matched by a polarization rotator disposed only on one of the separated optical paths, and then an optical isolator unit whose polarization plane is matched with the polarization components of these optical paths is formed. incident on the polarizer. Further, the two polarized light components that have passed through the optical isolator unit are made orthogonal to each other by a polarization rotator disposed only on one side of the second optical system, and then recombined by two polarization separation/synthesis elements. At this time, the optical axis before entering the first optical system and the optical axis emitted from the second optical system coincide. On the other hand, the light in the opposite direction is separated by the two polarization separation/synthesizing elements of the second optical system into two optical paths having polarization components that are at an angle of 90 degrees to each other. After the planes of polarization are matched by the polarization rotator, the light enters the optical isolator unit from a direction opposite to that described above. Therefore, due to the action of the optical isolator unit, the light in the opposite direction cannot return to the incident side of the first optical system.
【０００７】[0007]
【実施例】以下、図１に基づき図２を参照して本発明に
よる光アイソレータの第一実施例を説明する。先ず図１
において、４は従来例の光アイソレータ（図２）を偶数
個直列に接続して構成されて成る光アイソレータユニッ
トである。この光アイソレータユニット４を構成する各
光アイソレータは、従来例の場合と同様に第１の偏光子
，ファラデー回転子及び第２の偏光子から構成されてい
るが、光アイソレータユニット４の入射側と出射側の偏
光面は一致もしくは互いに９０度の角度をなしている。
そして、光アイソレータユニット４の両側には後述する
第１の光学系及び第２の光学系が配置されるようになっ
ているが、ここでは上記第１の光学系の側を入射側とす
る。更に図中、５及び６は第１の光学系に配置されてい
て例えばＴｉＯ２ （ルチル）によって形成されたそれ
ぞれ複屈折板でなる偏光分離・合成素子、７は第１の光
学系に配置されていて例えば１／２波長板で成る偏光回
転子、８は第２の光学系に配置されていて上記偏光回転
子７と同様に構成されて成る偏光回転子、９及び１０は
第２の光学系に配置された偏光分離・合成素子である。DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the optical isolator according to the present invention will be described below with reference to FIG. 1 and FIG. 2. First, Figure 1
4, an optical isolator unit is constructed by connecting an even number of conventional optical isolators (FIG. 2) in series. Each optical isolator constituting this optical isolator unit 4 is composed of a first polarizer, a Faraday rotator, and a second polarizer as in the conventional example, but the incident side of the optical isolator unit 4 The planes of polarization on the output side coincide or form an angle of 90 degrees with each other. A first optical system and a second optical system, which will be described later, are arranged on both sides of the optical isolator unit 4, but here, the side of the first optical system is assumed to be the incident side. Further, in the figure, numerals 5 and 6 are arranged in the first optical system, and are polarization separation/combining elements each made of a birefringent plate made of TiO2 (rutile), for example, and 7 is arranged in the first optical system. 8 is a polarization rotator arranged in the second optical system and configured in the same manner as the polarization rotator 7, and 9 and 10 are the second optical system. This is a polarization separation/synthesis element placed in the
【０００８】上記の場合、先ず第１の光学系において、
入射光は２枚の偏光分離・合成素子５，６を通過して互
いに直交する偏光成分を有する光路ａ及び光路ｂに分離
されるが、上記偏光回転子７は、これらの分離された光
路の偏光成分のうちの光路ａの偏光成分のみが通過し且
つ偏波面が９０度回転して光路ｂの偏光成分の偏波面と
一致するように配置されている。又、上記光アイソレー
タユニット４は、その入射側の偏光子１（図２、符号１
参照）の偏光面が該偏光子１に入射すべき上記光路ａ及
び光路ｂの偏光成分の偏波面と一致するように配置され
ている。更に、第２の光学系において、かかる光アイソ
レータユニット４を通過した光路ａ及び光路ｂの偏光成
分が結合されるように、上記偏光回転子８及び偏光分離
・合成素子９，１０が配置される。In the above case, first, in the first optical system,
The incident light passes through two polarization separation/synthesizing elements 5 and 6 and is separated into optical path a and optical path b, which have mutually orthogonal polarization components. The polarization rotator 7 separates these separated optical paths. Of the polarized light components, only the polarized light component of the optical path a passes through, and the polarization plane is rotated by 90 degrees to match the polarization plane of the polarized light component of the optical path b. Further, the optical isolator unit 4 has a polarizer 1 (FIG. 2, reference numeral 1) on its incident side.
(see) such that the plane of polarization of the polarizer 1 coincides with the plane of polarization of the polarization components of the optical path a and optical path b that are to be incident on the polarizer 1. Furthermore, in the second optical system, the polarization rotator 8 and the polarization separation/combining elements 9 and 10 are arranged so that the polarization components of the optical path a and the optical path b that have passed through the optical isolator unit 4 are combined. .
【０００９】本発明による光アイソレータは上記のよう
に構成されているから、入射光は先ず、２枚の偏光分離
・合成素子５，６へ入射し、これらにより互いに９０度
の角度をなす偏光成分を有する光路ａ及び光路ｂに分離
される。従って、これら２枚の偏光分離・合成素子５，
６を通過した直後の光路ａ，ｂの偏波面は直交している
が、これらの光路ａ，ｂのうち偏光回転子７が配置され
ている光路ａの偏光成分の偏波面だけが９０度回転し、
両光路ａ，ｂの偏光成分の偏波面は一致する。そして更
に各偏光成分は上記光アイソレータユニット４へ入射す
る。次に第２の光学系において、偏光回転子８が配置さ
れている光路ｂの偏光成分の偏波面だけが９０度回転し
て光路ａの偏光成分の偏波面と直交する。このように互
いに直交した両偏光成分は、２枚の偏光分離・合成素子
９及び１０によって再び結合されるが、この時入射光と
出射光の光軸は一致している。Since the optical isolator according to the present invention is constructed as described above, the incident light first enters the two polarization separation/synthesizing elements 5 and 6, which separate the polarization components forming an angle of 90 degrees with each other. The beam is separated into an optical path a and an optical path b. Therefore, these two polarization separation/synthesis elements 5,
Immediately after passing through 6, the polarization planes of optical paths a and b are orthogonal, but among these optical paths a and b, only the polarization plane of the polarization component of optical path a, where polarization rotator 7 is arranged, is rotated by 90 degrees. death,
The planes of polarization of the polarized light components of both optical paths a and b match. Further, each polarized light component is incident on the optical isolator unit 4. Next, in the second optical system, only the polarization plane of the polarization component of the optical path b, in which the polarization rotator 8 is arranged, is rotated by 90 degrees to be orthogonal to the polarization plane of the polarization component of the optical path a. The two polarized light components, which are orthogonal to each other, are combined again by the two polarized light separation/synthesizing elements 9 and 10, but at this time, the optical axes of the incident light and the outgoing light coincide.
【００１０】一方、第２の光学系側から入射する逆方向
の光は、先ず、２枚の偏光分離・合成素子１０及び９に
よって互いに９０度の角度をなす偏光成分を有する光路
ａ及び光路ｂに分離される。そして、これらの光路ａ，
ｂのうち光路ｂの偏光成分のみが偏光回転子８により９
０度回転した後に上記とは逆方向から光アイソレータユ
ニット４へ入射する。従って、該光アイソレータユニッ
ト４の作用によりかかる逆方向の光はもはや第１の光学
系の入射側へは戻ることができない。尚、上記の場合、
２つの光路ａ及び光路ｂを入れ換えて行っても同様な作
用効果を得ることができる。On the other hand, the light in the opposite direction that enters from the second optical system side is first divided into optical paths a and b, which have polarized components making an angle of 90 degrees to each other, by the two polarization separation/synthesizing elements 10 and 9. separated into And these optical paths a,
Of b, only the polarized component of optical path b is polarized by polarization rotator 8.
After rotating by 0 degrees, the light enters the optical isolator unit 4 from the opposite direction to that described above. Therefore, due to the action of the optical isolator unit 4, such light in the opposite direction can no longer return to the incident side of the first optical system. In addition, in the above case,
Similar effects can be obtained even if the two optical paths a and b are switched.
【００１１】[0011]
【発明の効果】上述したように本発明によれば、特に入
射光の偏波面を予め特定し得ない光伝送系に対して偏波
面を光アイソレータユニットの入射側の偏光子の偏光面
と一致させることができ、これにより偏波面の状態を考
慮することなく従来用いられている光アイソレータユニ
ットを利用して光アイソレータの機能を有効且つ十分に
発揮させることができる。更に、入射光と出射光の光軸
が一致しているので優れた実用的効果がある等の利点が
ある。そして又、空間ビーム光や光ファイバー用として
利用することができるのは勿論であるが、その場合に既
存の光アイソレータと簡単に置換することができる等の
利点がある。As described above, according to the present invention, the plane of polarization can be made to match the plane of polarization of the polarizer on the incident side of the optical isolator unit, especially for optical transmission systems where the plane of polarization of incident light cannot be specified in advance. As a result, the function of the optical isolator can be effectively and fully demonstrated using a conventionally used optical isolator unit without considering the state of the polarization plane. Furthermore, since the optical axes of the incident light and the outgoing light coincide, there are advantages such as excellent practical effects. Of course, it can also be used for spatial beam light and optical fibers, and in that case it has the advantage of being able to easily replace existing optical isolators.
【図１】本発明の光アイソレータの第一実施例による全
体構成図である。FIG. 1 is an overall configuration diagram of a first embodiment of an optical isolator of the present invention.
【図２】従来の光アイソレータの全体構成図である。FIG. 2 is an overall configuration diagram of a conventional optical isolator.
１ 第１の偏光子 ２ ファラデー回転子 ３ 第２の偏光子 ４ 光アイソレータユニット ５ 偏光分離・合成素子 ６ 偏光分離・合成素子 ７ 偏光回転子 ８ 偏光回転子 ９ 偏光分離・合成素子 １０ 偏光分離・合成素子 1 First polarizer 2 Faraday rotator 3 Second polarizer 4 Optical isolator unit 5 Polarization separation/synthesis element 6 Polarization separation/synthesis element 7 Polarization rotator 8 Polarization rotator 9 Polarization separation/synthesis element 10 Polarization separation/synthesis element
Claims (1)
る光アイソレータユニットの入射側に２枚の偏光分離・
合成素子と偏光回転子とから成る第１の光学系を、又上
記光アイソレータユニットの出射側には偏光回転子と２
枚の偏光分離・合成素子とから成る第２の光学系をそれ
ぞれ配設し、上記第１の光学系において分離された光路
の偏光成分の一方の偏波面を回転させることにより、分
離された双方の光路の偏光成分の偏波面が上記光アイソ
レータユニットの入射側の偏光子の偏波面と一致するよ
うに該光アイソレータユニットに入射させると共に、上
記光アイソレータユニットの出射側において上記分離さ
れている光路の偏光成分を上記第２の光学系によって再
び結合させ、上記第１の光学系の入射側と上記第２の光
学系の出射側において光軸が一致するようにしたことを
特徴とする光アイソレータ。Claim 1: An optical isolator unit having a structure that depends on the polarization plane of incident light has two polarization separation plates on the incident side.
A first optical system consisting of a combining element and a polarization rotator, and a polarization rotator and a second optical system on the output side of the optical isolator unit.
A second optical system consisting of two polarized light separation/combining elements is respectively provided, and by rotating one plane of polarization of the polarized light components of the optical path separated in the first optical system, the two polarized light components are separated. The optical path is made to enter the optical isolator unit such that the plane of polarization of the polarized light component of the optical path coincides with the plane of polarization of the polarizer on the input side of the optical isolator unit, and the optical path is separated on the output side of the optical isolator unit. An optical isolator characterized in that the polarized light components of are recombined by the second optical system so that the optical axes thereof coincide on the input side of the first optical system and the output side of the second optical system. .
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13664791A JPH04360118A (en) | 1991-06-07 | 1991-06-07 | Optical isolator |
| CA 2058036 CA2058036C (en) | 1990-12-20 | 1991-12-18 | Optical isolator |
| DE1991624955 DE69124955T2 (en) | 1990-12-20 | 1991-12-19 | Polarization-independent optical isolator |
| EP19910121786 EP0492437B1 (en) | 1990-12-20 | 1991-12-19 | Polarization independent optical isolator |
| US07/931,566 US5267078A (en) | 1990-12-20 | 1992-08-18 | Optical isolator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13664791A JPH04360118A (en) | 1991-06-07 | 1991-06-07 | Optical isolator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04360118A true JPH04360118A (en) | 1992-12-14 |
Family
ID=15180215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13664791A Pending JPH04360118A (en) | 1990-12-20 | 1991-06-07 | Optical isolator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04360118A (en) |
-
1991
- 1991-06-07 JP JP13664791A patent/JPH04360118A/en active Pending
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