JPS6012610B2 - Optical path switching device - Google Patents

Description

【発明の詳細な説明】 本発明は光ファイバーを使用せる光伝送路の切替装置に
関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical transmission line switching device that uses optical fibers.

近年光ファイバーを用いた光通信システムが実用性の段
階を迎え、基本的な構成部品即ち光源、伝送路及び受光
器から成る光システムの開発が進んでいる。In recent years, optical communication systems using optical fibers have reached the stage of practical use, and the development of optical systems consisting of basic components, ie, light sources, transmission lines, and optical receivers, is progressing.

前記の基本的構成部品に次いで光スイッチ、光交換機等
の光路切換装置の開発はより高度の光システムの実現の
ために強く望まれている。しかしながら研究開発の現状
では将釆の光集積回路を目標として機能的薄膜導電素子
が重点的に検討されており、これらは主としてレーザ光
源を用いたもので薄膜回路中の光伝送モードも単一又は
数種モードに限定されたものである。現用のファイバー
システムが多重モード、半導体レーザ、発光ダイオード
ＬＥＤ光源を用いたものが多くを占めているが、光路功
替装置としても、単一モードのレーザ光に対してのみな
らず多重モードレーザ又は半導体レーザ光源に対しても
有用な特性を発揮するものが望まれている。従釆の光フ
アィバ・システムに於けるスイッチングは伝送光を先づ
電気信号に変換し、この電気信号を電子交換装置によっ
て切替え、出力側の各端末に取付けられた発光源を駆動
させる方法が主として用いられている。本発明はこれを
改良して光路を直接電気光学効果によって切替えて光信
号をそのまま出力側に導出する光路切替装置である。In addition to the above-mentioned basic components, the development of optical path switching devices such as optical switches and optical exchangers is strongly desired in order to realize more advanced optical systems. However, in the current state of research and development, functional thin film conductive elements are being studied with emphasis on the future of optical integrated circuits, and these mainly use laser light sources, and the optical transmission mode in the thin film circuit is either single or It is limited to several modes. Most current fiber systems use multimode lasers, semiconductor lasers, and light emitting diode LED light sources, but optical path switching devices can also be used not only for single mode laser light but also for multimode laser or light emitting diode light sources. There is a desire for something that exhibits useful characteristics also for semiconductor laser light sources. The main method of switching in conventional optical fiber systems is to first convert transmitted light into an electrical signal, and then switch this electrical signal using an electronic switching device to drive a light emitting source attached to each terminal on the output side. It is used. The present invention is an optical path switching device that improves this and directly switches the optical path using the electro-optic effect and directs the optical signal to the output side as it is.

これを図面により詳細に説明すると、第１図はそのブロ
ックダイアグラムであって、１，２は２本の離隔せる入
力側光ファイバー、３，４は２本の離隔せる出力側光フ
アイバ、５，６は偏光素子例えば偏光板、偏光フィルム
、複屈折結晶を用いたプリズムで５は紙面に垂直な成分
の偏光のみを通し、６は紙面に平行な成分の偏光のみを
通過させる。To explain this in detail with reference to drawings, FIG. 1 is a block diagram thereof, in which 1 and 2 are two separated input side optical fibers, 3 and 4 are two separated output side optical fibers, and 5 and 6 are two separated input side optical fibers. numeral 5 is a prism using a polarizing element such as a polarizing plate, a polarizing film, or a birefringent crystal; numeral 5 passes only the polarized light component perpendicular to the plane of the paper; and 6 passes only the polarized light component parallel to the plane of the paper.

７及び８は自然後屈折を有する水晶又は方解石の単結晶
プリズム、９は偏波面変更素子であつて電気光学単結晶
であるＫＤＰ（燐酸＝水素カリウム）、ＡＤＰ（燐酸＝
水素アンモニウム）、Ｂｊ，２Ｓｉｏ数又は既２戊０沙
から成り両側に電圧印加用電源１０‘こ接続せる透明電
極１１，１２を備え前記単結晶体７，８の中間に配置さ
れ、電極１１，１２に印加される電圧により偏波面を９
０ｏ回転変更する。7 and 8 are quartz or calcite single crystal prisms with natural retrorefraction, 9 is a polarization plane changing element and is an electro-optical single crystal KDP (phosphoric acid = potassium hydrogen), ADP (phosphoric acid =
Transparent electrodes 11 and 12 are made of ammonium hydrogen (ammonium hydrogen), Bj, 2Sio number or 2Sio, and are connected to a voltage applying power source 10' on both sides, and are arranged between the single crystal bodies 7 and 8, and the electrodes 11, The plane of polarization is changed to 9 by the voltage applied to 12.
Change 0o rotation.

次に本発明の光路切替装置の動作を説明する。Next, the operation of the optical path switching device of the present invention will be explained.

第１図に於いて入力側光ファイバーー，２の出射端では
光は通常橋円偏波状態に偏っており、これを紙面に垂直
に偏つている状態を・、紙面に水平又は平行に偏ってい
る状態を一で示す二つの偏波から合成されているものと
する。上記のような光が入力ファイバー，２の出射端か
らそれぞれ偏光板５，６を通って華直偏波のみ及び水平
偏波のみで単結晶プリズム７まで進む。前記プリズム７
の入射面に直角に入射して入射点Ｐまで直進せる光は、
前記プリズム７内ではそのまま直進するものと第２図に
示す如くプリズム７に方解石を使用せる場合、その光学
軸をａ軸及びｂ軸とすると紙面に垂直及び水平な偏波成
分の光に対する屈折率楕円体の紙面への投影楕円図Ｅと
結晶面に平行な接線ＡＢとの接点Ｆと前記Ｐとを結ぶ線
の延長線上の他端Ｒを結ぶＰＲに直進する光とに分離す
る。前者は紙面と水平な偏波に対し生じ、後者は紙面に
垂直な偏波光に対し生ずる。従って偏光板５を通った光
は紙面に垂直な偏波成分のみであるからＰＲに沿って進
み、プリズム他端Ｒで再び面に垂直に出射される。また
偏光波６を通った光は紙面に水平に偏っているのでＱＲ
に沿い進み、出射点ＲでＰから来た光と合体し出射端面
に垂直に出る。前記の出射光は次いで偏波面変換素子９
に入り、電極１１，１２に印加される電圧が０の時は前
記素子９への入射時点での偏波状態を保持したまま素子
９を通過する。In Figure 1, at the output end of the input optical fiber 2, the light is normally polarized into a circularly polarized state. It is assumed that the polarized waves are synthesized from two polarized waves whose state is one. The light described above travels from the output end of the input fiber 2 through polarizing plates 5 and 6, respectively, to the single-crystal prism 7 with only the Chinese polarization and only the horizontal polarization. Said prism 7
The light that enters the plane of incidence at right angles and travels straight to the point of incidence P is:
If calcite is used for the prism 7 as shown in FIG. 2, the refractive index for light with polarized components perpendicular and horizontal to the plane of the paper is as follows: Projection of the ellipsoid onto the paper surface The light is separated into light that travels straight to PR, which connects the other end R on the extension of the line connecting P and the contact point F between the ellipsoid diagram E projected on the plane of the ellipsoid and the tangent AB parallel to the crystal plane. The former occurs for polarized light horizontal to the plane of the paper, and the latter occurs for polarized light perpendicular to the plane of the paper. Therefore, since the light that has passed through the polarizing plate 5 is only a polarized component perpendicular to the plane of the drawing, it travels along PR and is again emitted perpendicularly to the plane at the other end R of the prism. Also, since the light that has passed through polarized wave 6 is polarized horizontally to the paper surface, the QR
The light travels along the emission point R, combines with the light coming from P, and exits perpendicularly to the emission end face. The emitted light then passes through the polarization conversion element 9
When the voltage applied to the electrodes 11 and 12 is 0, the light passes through the element 9 while maintaining the polarization state at the time of incidence on the element 9.

前記素子９の印加電圧がＶ打の時は紙面に垂直に偏波し
た光に対しては偏波方向を９０ｏ回転せしめ、紙面と平
行な偏波光に、またこれと逆に紙面に対し平行な偏光波
に対しては紙面に垂直な方向に偏波した光に変換される
。偏波面変換素子９を通過した光は再び後屈折プリズム
８を通る。When the voltage applied to the element 9 is V, the direction of polarization is rotated by 90 degrees for light polarized perpendicular to the plane of the paper, and vice versa, the direction of polarization is rotated by 90 degrees, and vice versa. Polarized waves are converted into light polarized in a direction perpendicular to the plane of the paper. The light that has passed through the polarization plane conversion element 9 passes through the back-refraction prism 8 again.

このときプリズム入射光の偏波状態によって光はＳ→Ｔ
又はＳ→Ｕのいづれかの光路をたどることになる。例え
ば複屈折プリズムとして方解石を用いその光学軸を第２
図の光軸に対して紙面内で９０ｏ回転した方位をもつよ
うにしておくと、第３図に示す如く紙面に垂直な偏波成
分を有する光はＳ→Ｔへ、紙面に平行な偏波成分を有す
る光はＳ→Ｕに伝播する。前記の複屈折プリズム８を出
射した光は出力側光フアィバ３，４に結合される。上記
の光路功替装置の動作をまとめると第１表に示す如く、
偏波面変換素子９の電極１１，１２に印加される電圧Ｖ
が０の時は光フアイバ１→３，２→４、Ｖ＝Ｖｍの時は
１→４，２→３となるので、偏波面変換素子９に印加さ
れる電圧の切替えにより光路の切替えを行うことができ
るのである。第１表 光路切替えは上記の例のほかにＶ＝０の時に１→４，２
→３、Ｖ＝Ｖ竹の時に１→３，２→４とすることも可能
である。At this time, depending on the polarization state of the light incident on the prism, the light changes from S to T.
Alternatively, the light path will be followed from S to U. For example, using calcite as a birefringent prism, its optical axis is
If the direction is rotated by 90 degrees in the plane of the paper with respect to the optical axis in the figure, the light with a polarization component perpendicular to the plane of the paper will go from S to T, as shown in Figure 3, and the polarization parallel to the plane of the paper will go from S to T. The light having the component propagates from S to U. The light emitted from the birefringent prism 8 is coupled to the output optical fibers 3 and 4. The operation of the above optical path switching device is summarized as shown in Table 1.
Voltage V applied to electrodes 11 and 12 of polarization conversion element 9
When is 0, the optical fibers are 1→3, 2→4, and when V=Vm, they are 1→4, 2→3, so the optical path is switched by switching the voltage applied to the polarization plane conversion element 9. It is possible. Table 1: In addition to the above example, optical path switching is performed from 1 to 4, 2 when V=0.
→3, it is also possible to set it as 1→3, 2→4 when V=V bamboo.

次に実験例を示すと、入出力光フアィバ１，２，３，４
にはコア径１６０仏、偏光板５，６には厚さ５００〃の
偏光フィルム、複屈折プリズム７，８には光路長２４側
、開口寸法８仰角の方解石プリズムで異常光との開き角
は約６ｏのもの、偏波面変換素子９には厚さ５００山の
Ｂｉ．２Ｓｉ○沙単結晶用を用いその両側面に透明電極
を蒸着したものを使用した。Next, to show an experimental example, input and output optical fibers 1, 2, 3, 4
The core diameter is 160 mm, the polarizing plates 5 and 6 are polarizing films with a thickness of 500 mm, and the birefringent prisms 7 and 8 are calcite prisms with an optical path length of 24 mm and an aperture size of 8 elevation angles, and the aperture angle with the extraordinary light is The polarization conversion element 9 has a Bi. A 2Si○sha single crystal was used and transparent electrodes were deposited on both sides thereof.

前記のＢｉ，ぶｉＱｏ単結晶は旋光性があるため入射す
る直線偏波光はＢｉ，２Ｓｉ０２。単結晶を出射する時
に一定角度回転した方向の直線偏波となって出射される
。旋光度は波長６３３肋の光に対し２０ｏ／柳であるた
め、５００ムの結晶では１００回転するため特にプリズ
ム８の光学軸を１ｏｏ光進行から見て左向きに回転補正
した。この結果光ファイバー，２から入射する光東は変
換素子９の印加電圧が０の時それぞれ光ファイバー３，
４から出射することが確認された。何となれば光が光フ
ァィバ１のみに入射した時に光フアィバ３，４の光量を
測定した結果３の光量と４の光量との比は１０００：１
の強度比である。同様に光が光フアィバ２のみに入射し
た時の４の光量と３の光量との比は１０００：１の強度
比である。このことから光が光フアィバ１，２に同時に
入射した場合にも同等の分離が生じているものと推定さ
れた。次に変換素子９の印放電圧を４７００ボルトとし
た時光ファィバ１に入射した光は光ファイバー４から出
射され、光ファイバー３から出射されなかった。Since the Bi, 2SiQo single crystal mentioned above has optical rotation, the incident linearly polarized light is Bi, 2Si02. When emitted from the single crystal, it is emitted as a linearly polarized wave in a direction rotated by a certain angle. Since the optical rotation is 20°/yanagi for light with a wavelength of 633 ribs, a crystal of 500 μm rotates 100 times, so the optical axis of the prism 8 was specifically rotated to the left when viewed from the 10 μm light progression. As a result, when the voltage applied to the conversion element 9 is 0, the light beams entering from the optical fibers 3 and 2 are respectively
It was confirmed that it was emitted from 4. The reason is that when light enters only optical fiber 1, the light intensity of optical fibers 3 and 4 is measured, and the ratio of the light intensity of 3 and 4 is 1000:1.
is the intensity ratio of Similarly, when the light enters only the optical fiber 2, the ratio of the light amount of 4 to the light amount of 3 is an intensity ratio of 1000:1. From this, it was presumed that a similar separation occurs even when the light is incident on the optical fibers 1 and 2 at the same time. Next, when the voltage applied to the conversion element 9 was set to 4,700 volts, the light incident on the optical fiber 1 was emitted from the optical fiber 4 but not from the optical fiber 3.

光フアィバ２に入射した光は光フアィバ３に出射され光
ファイバー４には出射されなかった。以上の実験により
偏光面変換素子９の印加電圧の切替えにより確実に光路
の切替えを行うことができることを確認した。本発明の
光路切替装置は偏波方向を異にする二つの光をそれぞれ
分離して入射端に入射させ、その出射端から一とまとめ
にして出射する複屈折効果を有する第１単結晶と、偏波
方向を異にする二つの光を入射端に一とまとめにして入
射せしめ、その出射端にて二つの光に分離する複屈折効
果を有する第２単結晶との中間に、偏波面変換用電気光
学素子を配置し、前記変換素子の制御電極に印加する電
圧を制御することにより前記第１単結晶の入射端に連結
する２光路と第２単綾の出射端に連結する２光路とを相
互に切替えるものであるから簡単な装置により入射光信
号をそのまま切替えて出射側に出射させることができる
。The light that entered the optical fiber 2 was emitted to the optical fiber 3 and not to the optical fiber 4. Through the above experiment, it was confirmed that the optical path could be reliably switched by switching the voltage applied to the polarization plane conversion element 9. The optical path switching device of the present invention includes a first single crystal having a birefringence effect that separates two lights having different polarization directions and makes them enter an input end, and outputs them together from an output end; A polarization plane converter is installed between the second single crystal, which has a birefringence effect, which allows two lights with different polarization directions to enter the input end as one and separate them into two lights at the output end. By arranging an electro-optical element for the conversion element and controlling the voltage applied to the control electrode of the conversion element, two optical paths are connected to the input end of the first single crystal and two optical paths are connected to the output end of the second single crystal. Since the signals are mutually switched, it is possible to switch the incident optical signal as it is and output it to the output side using a simple device.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の光路切替装置のブロックダイアグラム
、第２図及び第３図はそれぞれ複屈折効果を有する単結
晶内の光路を示す。 １，２は入力光フアィバ、３，４は出力光フアィバ、５
，６は偏光素子、７，８は第１及び第２複屈折効果を有
する単結晶、９は電気光学単結晶、１１，１２は制御電
極、ａｂは光学軸。 次’図才２図 オ３図FIG. 1 is a block diagram of the optical path switching device of the present invention, and FIGS. 2 and 3 each show an optical path within a single crystal having a birefringence effect. 1 and 2 are input optical fibers, 3 and 4 are output optical fibers, and 5
, 6 are polarizing elements, 7 and 8 are single crystals having first and second birefringence effects, 9 is an electro-optic single crystal, 11 and 12 are control electrodes, and ab is an optical axis. Next 'Figure 2, Figure 3

Claims (1)

【特許請求の範囲】 １ 偏波方向を異にする二つの光をそれぞれ分離して入
射端から入射させ、その出射端から一とまとめにして出
射する複屈折効果を有する第１単結晶と、偏波方向を異
にする二つの光を入射端にて一まとめにして入射せしめ
その出射端にて二つの光に分離する複屈折効果を有する
第２単結晶との中間に偏波面変換用電気光学単結晶素子
を配置し、前記変換素子の制御電極の印加電圧を制御す
ることにより前記第１単結晶入射端に連結する二光路と
第２単結晶出射端に連続する二光線とを相互に切替える
ことを特徴とする光路切替装置。 ２ 偏波面変換用電気光学単結晶素子としてＢＳＯ又は
ＢＧＯを使用することを特徴とする前記第１項記載の光
路切替装置。[Scope of Claims] 1. A first single crystal having a birefringence effect that separates two lights having different polarization directions and causes them to enter from an input end and output them together from an output end; Electricity for polarization conversion is installed between the second single crystal, which has a birefringence effect, which allows two lights with different polarization directions to enter at the input end and separate into two lights at the output end. By arranging an optical single crystal element and controlling the voltage applied to the control electrode of the conversion element, two optical paths connected to the first single crystal input end and two light beams continuous to the second single crystal output end are mutually connected. An optical path switching device characterized by switching. 2. The optical path switching device according to item 1, wherein a BSO or BGO is used as the electro-optic single crystal element for polarization plane conversion.