JPH0915545A - Polarization independent optical control element - Google Patents
Polarization independent optical control elementInfo
- Publication number
- JPH0915545A JPH0915545A JP15949995A JP15949995A JPH0915545A JP H0915545 A JPH0915545 A JP H0915545A JP 15949995 A JP15949995 A JP 15949995A JP 15949995 A JP15949995 A JP 15949995A JP H0915545 A JPH0915545 A JP H0915545A
- Authority
- JP
- Japan
- Prior art keywords
- optical
- optical waveguide
- traveling
- light
- polarization
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference
- G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference in an optical waveguide structure
- G02F1/2255—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference in an optical waveguide structure controlled by a high-frequency electromagnetic component in an electric waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/17—Multi-pass arrangements, i.e. arrangements to pass light a plurality of times through the same element, e.g. by using an enhancement cavity
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光変調器や光スイッチ
などの光制御素子の中で、小型で駆動電圧が小さく高速
動作が可能で、かつ入力光の偏波状態に依存しない偏波
無依存光制御素子に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical control element such as an optical modulator or an optical switch, which is small in size, has a small driving voltage, can operate at high speed, and is independent of the polarization state of input light. The present invention relates to an independent light control element.
【０００２】[0002]
【従来の技術】高速かつ大容量の光伝送システムや、光
交換システムにおいては、高速で駆動するために、駆動
電圧が小さい光制御素子が有用である。この種の光制御
素子の一例としては、光スイッチや位相変調器や、光強
度変調器等があり、基本技術として、プリズムや光ファ
イバを機械的に移動させるメカニカル型、石英系ガラス
導波路等で用いられる熱光学効果型、Ｔｉ拡散ＬｉＮｂ
Ｏ3 導波路等で用いられる電気光学効果型、等に大別さ
れる。この中でメカニカル型や熱光学効果型の光制御素
子は偏波依存性はないが、その応答速度は１ｍｓｅｃ程
度以上と遅いという問題がある。2. Description of the Related Art In a high-speed and large-capacity optical transmission system or an optical switching system, an optical control element having a low driving voltage is useful for driving at a high speed. Examples of this type of light control element include an optical switch, a phase modulator, a light intensity modulator, and the like. As a basic technique, a mechanical type that mechanically moves a prism or an optical fiber, a silica-based glass waveguide, or the like. Optical effect type, Ti diffusion LiNb used in
It is roughly classified into an electro-optical effect type used in O 3 waveguides and the like. Among them, the mechanical type and thermo-optical effect type optical control elements do not have polarization dependence, but there is a problem that their response speed is as slow as about 1 msec or more.
【０００３】一方、電気光学効果型光制御素子は、応答
速度が極めて速いという特徴を持っている。しかしなが
ら、同じ電圧あるいは電界を印加しても、屈折率変化が
光の偏波方向によって異なり、その動作が偏波方向に依
存したものになってしまうという問題があった。On the other hand, the electro-optical effect type light control element is characterized by an extremely fast response speed. However, even if the same voltage or electric field is applied, there is a problem that the change in the refractive index differs depending on the polarization direction of light, and the operation becomes dependent on the polarization direction.
【０００４】従来の光制御素子としてマッハツェンダ型
光強度変調器の例を、図１５および１６に示す。図１５
は該光強度変調器の透視的に見た平面図であり、図１６
は図１５のＡ−Ａ’線に沿う断面図である。An example of a Mach-Zehnder type light intensity modulator as a conventional light control element is shown in FIGS. FIG.
FIG. 16 is a perspective plan view of the light intensity modulator.
FIG. 16 is a sectional view taken along the line AA ′ of FIG. 15.
【０００５】この光強度変調器では、例えば、電気光学
効果を有するｚ板ＬｉＮｂＯ3 基板１に、Ｔｉ熱拡散に
より光導波路２が形成されている。この基板１の上には
ＳｉＯ2 バッファ層８が０．３〜１μｍ程度形成され、
バッファ層８の上には進行波型電極３が形成されてい
る。進行波型電極３間に給電線１１からマイクロ波電圧
Ｖが供給される。In this light intensity modulator, for example, an optical waveguide 2 is formed on a z-plate LiNbO 3 substrate 1 having an electro-optic effect by Ti thermal diffusion. A SiO 2 buffer layer 8 having a thickness of about 0.3 to 1 μm is formed on the substrate 1.
The traveling wave electrode 3 is formed on the buffer layer 8. A microwave voltage V is supplied from the power supply line 11 between the traveling wave electrodes 3.
【０００６】ここで、強度が一定の入射光６を光導波路
２に入射させると、光はマッハツェンダ干渉計を構成す
るＹ分岐部９ａで二つの光導波路にパワーを分配する。
光導波路２、２と、電極３に印加した電圧とが相互作用
する領域で、その入力電圧に応じて光の屈折率あるいは
位相が変化し、Ｙ分岐部９ｂで光が干渉し合い出射光７
の強度が変化する。Here, when the incident light 6 having a constant intensity is incident on the optical waveguide 2, the light is distributed to the two optical waveguides at the Y branch portion 9a which constitutes the Mach-Zehnder interferometer.
In the region where the optical waveguides 2 and 2 interact with the voltage applied to the electrode 3, the refractive index or the phase of the light changes according to the input voltage, and the light beams interfere with each other at the Y branch portion 9b and the emitted light 7
Intensity changes.
【０００７】このような光導波路２内では、基板面に垂
直な電界成分を有するＴＭモードと水平方向に電界成分
を有するＴＥモードと呼ばれる直交する二つの偏波モー
ドが伝搬する。光導波路２と、電極３に印加した電圧と
が相互作用する領域（領域の長さをＬとする）では、光
の伝搬方向をＬｉＮｂＯ3 結晶のｘ軸方向とし、光導波
路２内における実効的な電界をＥｚとした場合、ＴＭモ
ードに対する屈折率変化Δｎ（ＴＭ）はＴＥモードに対
する屈折率変化Δｎ（ＴＥ）の約３倍である。ここで、
駆動電圧Ｖｐと相互作用長Ｌとは、In such an optical waveguide 2, two orthogonal polarization modes called a TM mode having an electric field component perpendicular to the substrate surface and a TE mode having an electric field component in the horizontal direction propagate. In the region where the optical waveguide 2 interacts with the voltage applied to the electrode 3 (the length of the region is L), the light propagation direction is set to the x-axis direction of the LiNbO 3 crystal, and the effective optical waveguide 2 When the electric field is Ez, the refractive index change Δn (TM) for the TM mode is about three times the refractive index change Δn (TE) for the TE mode. here,
The drive voltage Vp and the interaction length L are
【０００８】[0008]
【数１】 Ｖｐ・Ｌ＝Γ …（１） Γ：光変調器の材質、構造等により決まる定数 で示される関係があるため、従来例においては、ＴＭモ
ードに対する定数ΓをΓ（ＴＭ）とし、ＴＥモードに対
する定数ΓをΓ（ＴＥ）とすると、## EQU00001 ## Vp.L = .GAMMA .... (1) .GAMMA .: Since there is a relationship represented by a constant determined by the material and structure of the optical modulator, in the conventional example, the constant .GAMMA. For the TM mode is .GAMMA. , And the constant Γ for the TE mode is Γ (TE),
【０００９】[0009]
【数２】 Γ（ＴＥ）〜３Γ（ＴＭ） …（２） と表記できる。[Expression 2] Γ (TE) to 3Γ (TM) (2)
【００１０】この光強度変調器の場合、進行波型電極３
は分布定数回路として構成されているので、理想的には
電気回路的な帯域制限はない。しかし、実際にはマイク
ロ波と光には位相速度差があり、これによって動作周波
数の上限が制限される。In the case of this light intensity modulator, the traveling wave type electrode 3
Is configured as a distributed constant circuit, so ideally there is no electric circuit band limitation. However, in reality, there is a phase velocity difference between the microwave and light, which limits the upper limit of the operating frequency.
【００１１】マイクロ波に対する基板の実効的な屈折率
をｎm 、光に対する光導波路の実効的な屈折率をｎ0 と
表すと、この位相速度によって生じる上限周波数ｆv
は、次式で与えられる［参考文献：信学論（Ｃ），Ｊ６
４−Ｃ，ｐ２６４−２７１，１９８１］。When the effective refractive index of the substrate for microwaves is n m and the effective refractive index of the optical waveguide for light is n 0 , the upper limit frequency f v generated by this phase velocity is shown.
Is given by the following formula [Reference: Theological theory (C), J6
4-C, p264-271, 1981].
【００１２】[0012]
【数３】 ｆv ＝１．４ｃ／（πＬ｜ｎm −ｎ0 ｜） …（３） ただし、ｃは真空中における光速である。上記屈折率ｎ
m は基板の実効的な比誘電率εeff に対して、F v = 1.4c / (πL | n m −n 0 |) (3) where c is the speed of light in vacuum. The refractive index n
m is the effective relative permittivity ε eff of the substrate,
【００１３】[0013]
【数４】 ｎm ＝εeff １／２ …（４） で与えられる。## EQU4 ## given by n m = ε eff 1/2 (4).
【００１４】電気光学効果を持つ基板材料では、一般に
マイクロ波に対する屈折率ｎm は、光に対する屈折率ｎ
0 とは必ずしも一致しない。基板の実効的な比誘電率ε
effは、構造や材質によって異なるが、従来例において
はｎm が３．２程度の値となる。In a substrate material having an electro-optical effect, the refractive index n m for microwaves is generally the refractive index n for light.
Does not necessarily match 0 . Effective relative permittivity of substrate ε
eff varies depending on the structure and the material, but in the conventional example, nm has a value of about 3.2.
【００１５】図１７は、図１５、図１６の光強度変調器
において、電極の長さ（相互作用長）を２０ｍｍとした
場合に、波長１．３μｍにおいて得られた特性の一例で
ある。光がＯＮ／ＯＦＦするのに要する電圧（駆動電
圧）はＶｐ（ＴＭ）が５Ｖであるのに対し、Ｖｐ（Ｔ
Ｅ）は１５Ｖであった。これは、上述した（１）式およ
び（２）式の関係から推定される値と一致している。な
お、周波数帯域としては、ＴＭモードの屈折率ｎ0 （Ｔ
Ｍ）＝２．１５、ＴＥモードの屈折率ｎ0 （ＴＥ）＝
２．２２で、屈折率ｎm は屈折率ｎ0 の約１．５倍の大
きさになるので、式（３）から７ＧＨｚ程度になる。FIG. 17 shows an example of characteristics obtained at a wavelength of 1.3 μm in the light intensity modulator shown in FIGS. 15 and 16 when the electrode length (interaction length) is 20 mm. The voltage (driving voltage) required to turn on / off the light is Vp (TM) of 5V, while Vp (TM) is 5V.
E) was 15V. This agrees with the value estimated from the relationships of the above-described expressions (1) and (2). As the frequency band, the TM mode refractive index n 0 (T
M) = 2.15, TE mode refractive index n 0 (TE) =
At 2.22, the refractive index n m is about 1.5 times as large as the refractive index n 0 , so that it is about 7 GHz from the formula (3).
【００１６】[0016]
【発明が解決しようとする課題】しかしながら、上記従
来例によれば、ＴＭおよびＴＥモードとも同時にＯＮ／
ＯＦＦする場合には、電圧がそれぞれ０Ｖおよび１５Ｖ
において達成されるため、駆動電圧として最低１５Ｖ必
要であり、高速で動作させる場合に駆動電源にとって大
きな負担となる。However, according to the above conventional example, both the TM and TE modes are simultaneously turned on / off.
When turned off, the voltage is 0V and 15V respectively
In order to achieve this, a minimum drive voltage of 15 V is required, which imposes a heavy burden on the drive power supply when operating at high speed.
【００１７】また、光強度変調器の高速動作化は、上記
（３）式から明らかなように、動作周波数に応じて、相
互作用長Ｌを短くすることにより達成できるものの、相
互作用長Ｌを短くすると、上記（１）式で示されるよう
に、駆動電圧が大きくなるという欠点があった。Further, as is apparent from the above equation (3), the high speed operation of the optical intensity modulator can be achieved by shortening the interaction length L according to the operating frequency, but the interaction length L is reduced. When the length is shortened, there is a drawback that the driving voltage becomes large as shown in the above formula (1).
【００１８】さらに、両モードのＯＦＦ電圧がずれる
と、消光比劣化が生じてしまい、システム上許容される
消光比を確保できなくなることが予想される。Further, if the OFF voltages of both modes are deviated, the extinction ratio is deteriorated, and it is expected that the extinction ratio allowed in the system cannot be secured.
【００１９】本発明の課題は、上述した従来の問題点を
解消し、低駆動電圧で高速動作が可能な、小型で入力光
の偏波状態に依存しない偏波無依存光制御素子を提供す
ることにある。An object of the present invention is to solve the above-mentioned conventional problems and to provide a small polarization independent optical control element which can operate at high speed with a low driving voltage and which does not depend on the polarization state of input light. Especially.
【００２０】[0020]
【課題を解決するための手段】上記課題を達成するた
め、本発明の請求項１の偏波無依存光制御素子は、電気
光学効果を有する光学基板と、該光学基板の表面付近に
形成された光導波路と、該光導波路が形成された前記光
学基板面上に配置された進行波型電極とを備え、前記電
極にマイクロ波を印加して誘起される電圧により前記光
導波路と前記電極との相互作用領域が形成される偏波無
依存光制御素子であって、波長板および反射層を有する
とともに光偏波面を実質的に９０°前後回転して折り返
す折り返し部を前記光導波路の少なくとも一ケ所に具備
し、かつ前記光導波路、前記折り返し光導波路および前
記進行波型電極の長さを、前記相互作用部におけるマイ
クロ波と光との実効的な走行時間がほぼ一致する長さ
に、設定したことを特徴とする。In order to achieve the above object, the polarization-independent light control element according to claim 1 of the present invention is formed on an optical substrate having an electro-optical effect and near the surface of the optical substrate. Optical waveguide and a traveling wave type electrode arranged on the surface of the optical substrate on which the optical waveguide is formed, and the optical waveguide and the electrode are formed by a voltage induced by applying a microwave to the electrode. Is a polarization-independent light control element in which an interaction region of the optical waveguide is formed. The optical waveguide, the folded optical waveguide, and the traveling-wave electrode, which are provided at a certain position, are set to have a length at which the effective traveling time of the microwave and the light in the interaction portion is substantially the same. Special feature To.
【００２１】また、本発明の請求項２の偏波無依存光制
御素子は、電気光学効果を有する光学基板と、該光学基
板の表面付近に形成された光導波路と、該光導波路が形
成された前記光学基板面上に配置された進行波型電極と
を備え、前記電極にマイクロ波を印加して誘起される電
圧により前記光導波路と前記電極との相互作用領域が形
成される偏波無依存光制御素子であって、波長板および
反射層を有するとともに光偏波面を実質的に９０°前後
回転して折り返す折り返し部を前記光導波路の少なくと
も一ケ所に具備し、かつ前記光導波路、前記折り返し光
導波路および前記進行波型電極の長さを、直交する伝搬
光モードの前記相互作用部におけるマイクロ波の実効的
な電圧の総和がほぼ一致する長さに、設定したことを特
徴とする。According to a second aspect of the polarization independent light control element of the present invention, an optical substrate having an electro-optical effect, an optical waveguide formed near the surface of the optical substrate, and the optical waveguide are formed. And a traveling wave type electrode disposed on the surface of the optical substrate, and a non-polarized wave in which an interaction region between the optical waveguide and the electrode is formed by a voltage induced by applying a microwave to the electrode. A dependent light control element, which comprises a turnback portion having a wave plate and a reflection layer and turning back and forth a light polarization plane substantially at 90 ° back and forth in at least one position of the light guide, and the light guide, It is characterized in that the lengths of the folded optical waveguide and the traveling wave type electrode are set to such a length that the total sum of the effective voltages of the microwaves in the interaction portion of the orthogonal propagating light modes substantially coincides with each other.
【００２２】本発明の請求項３の偏波無依存性光制御素
子は、前記請求項２の光制御素子において、進行波型電
極を二つ以上に分割したことを特徴とする。A polarization-independent light control element according to a third aspect of the present invention is characterized in that, in the light control element according to the second aspect, the traveling wave type electrode is divided into two or more.
【００２３】本発明の請求項４の偏波無依存光制御素子
は、前記請求項２または３に記載の光制御素子におい
て、光導波路の折り返し部を二つ以上具備したことを特
徴とする。A polarization-independent light control element according to a fourth aspect of the present invention is characterized in that, in the light control element according to the second or third aspect, two or more folded portions of the optical waveguide are provided.
【００２４】本発明の請求項５の偏波無依存光制御素子
は、前記請求項２ないし４のいずれかに記載の光制御素
子において、光導波路、折り返し光導波路および進行波
型電極の長さを、相互作用部におけるマイクロ波と光と
の実効的な走行時間がほぼ一致する長さに、設定したこ
とを特徴とする。A polarization-independent light control element according to a fifth aspect of the present invention is the light control element according to any one of the second to fourth aspects, wherein the lengths of the optical waveguide, the folded optical waveguide and the traveling wave type electrode are the same. Is set to a length at which the effective traveling times of the microwave and the light in the interaction section are substantially equal to each other.
【００２５】[0025]
【作用】本発明によれば、光導波路の折り返し部におい
て、波長板により偏波方向を９０°回転させて反射させ
ることでＴＥモードとＴＭモードが変換されるので、入
射時にＴＥおよびＴＭモードであった入射光が、分岐後
再び合波するまでに受ける位相変化は同じになり、偏波
依存性がなくなる。また、電気光学効果を有する光学基
板の大きさには制限があるが、本発明のように光導波路
を折り返すと相互作用長を長くすることができ、駆動電
圧を非常に低減することができる。また、折り返し部で
電極と光導波路の長さに差を設けることができるので、
マイクロ波と光の位相速度差を補償することができ、従
来より高速動作を行うことが可能となる。また、同じ駆
動電圧に対して全素子長を短くすることができるため、
小型化も図ることができる。According to the present invention, in the folded portion of the optical waveguide, the TE mode and the TM mode are converted by rotating the polarization direction by 90 ° and reflecting by the wave plate. The existing incident light undergoes the same phase change until it is recombined after being split, and the polarization dependence disappears. Further, although the size of the optical substrate having the electro-optical effect is limited, when the optical waveguide is folded back as in the present invention, the interaction length can be increased and the driving voltage can be greatly reduced. Also, since it is possible to provide a difference in length between the electrode and the optical waveguide at the folded portion,
The phase velocity difference between the microwave and the light can be compensated, and the high speed operation can be performed as compared with the conventional case. Also, since the total element length can be shortened for the same drive voltage,
It can be downsized.
【００２６】さらに、ＴＥモードとＴＭモードを２回以
上入れ変えられるので、マイクロ波の伝搬損失によって
生じる各偏波モードの実効的な電圧の不均衡を解消する
ことができ、従って、高速動作においても偏波依存性の
無い特性が得られる。Further, since the TE mode and the TM mode can be exchanged twice or more, it is possible to eliminate the effective voltage imbalance of each polarization mode caused by the propagation loss of microwaves, and therefore, in high speed operation. Also, the characteristics without polarization dependence can be obtained.
【００２７】これらの動作原理は、次の実施例の中で実
際のデバイスに沿ってより具体的に説明する。These operating principles will be described more specifically along with actual devices in the following embodiments.
【００２８】[0028]
【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 of the present invention will be described below in detail with reference to the drawings.
【００２９】（実施例１）図１は、本発明による偏波無
依存光制御素子として、マッハツェンダ型光強度変調器
の第１の実施例を説明するための平面図であり、図２は
図１のＡ−Ａ′線に沿う拡大断面図である。(Embodiment 1) FIG. 1 is a plan view for explaining a first embodiment of a Mach-Zehnder type optical intensity modulator as a polarization independent light control element according to the present invention, and FIG. It is an expanded sectional view which follows the AA 'line of FIG.
【００３０】本実施例では、図１５および１６に示した
従来例と同様に電気光学効果を有するｚ板ＬｉＮｂＯ3
基板１上にＴｉ熱拡散法により光導波路２を形成してい
る。この光導波路２には、光度変換型折り返し光導波路
部１０が形成されている。光導波路２上に進行波型電極
３を配置している。光導波路２を伝搬する光が電極３に
よる吸収損失を少なくするために、例えばＳｉＯ2 でバ
ッファ層８を基板１と電極３との間に１μｍ程度形成し
ている。進行波型電極３に給電線１１からマイクロ波電
圧Ｖが供給される。In this example, a z-plate LiNbO 3 having an electro-optical effect similar to the conventional example shown in FIGS. 15 and 16 was used.
The optical waveguide 2 is formed on the substrate 1 by the Ti thermal diffusion method. In this optical waveguide 2, a light intensity conversion type folded optical waveguide portion 10 is formed. A traveling wave electrode 3 is arranged on the optical waveguide 2. In order to reduce the absorption loss of the light propagating through the optical waveguide 2 due to the electrode 3, the buffer layer 8 is formed of, for example, SiO 2 between the substrate 1 and the electrode 3 by about 1 μm. The microwave voltage V is supplied to the traveling wave electrode 3 from the power supply line 11.
【００３１】図３に、第１の実施例の光路変換型折り返
し光導波路部１０の端部近傍の拡大一部断面視した平面
図の一例を示す。研磨等で形成した光路変換型光導波路
の折り返し部１０の端部に、片側に高反射膜５を形成し
た１／４波長板４を、その主軸が基板面と４５°となる
ように傾けて接合した。ここで、波長板４は、（２ｎ＋
１）／４波長板（ｎは０以上の整数）でもよい。また、
光導波路端部と波長板４との屈折率不整合による不要な
反射光を除去するため、光導波路端部と波長板４との間
に反射防止膜を形成している。なお、波長板４の厚さ
は、厚い程損失が大きくなるため、薄い方が望ましい。FIG. 3 shows an example of a plan view of an enlarged partial cross-sectional view of the vicinity of the end of the optical path conversion type folded optical waveguide portion 10 of the first embodiment. At the end of the folded portion 10 of the optical path conversion type optical waveguide formed by polishing or the like, a quarter wavelength plate 4 having a high reflection film 5 formed on one side is tilted so that its main axis is at 45 ° to the substrate surface. Joined. Here, the wave plate 4 is (2n +
1) / 4 wavelength plate (n is an integer of 0 or more) may be used. Also,
An antireflection film is formed between the end portion of the optical waveguide and the wavelength plate 4 in order to remove unnecessary reflected light due to the refractive index mismatch between the end portion of the optical waveguide and the wavelength plate 4. It should be noted that the thickness of the wave plate 4 is preferably thin because the loss increases as the thickness increases.
【００３２】次に、上記構成による光強度変調器の動作
について説明する。Next, the operation of the light intensity modulator having the above structure will be described.
【００３３】強度が一定の入射光を光導波路２に入射さ
せると、光はマッハツェンダ干渉計を構成するＹ分岐部
９ａで二つの光導波路にパワーを分配する。光導波路２
と電極３とが第１の相互作用領域（ＰＱ間：長さＬ1 ）
１３でその入力信号に応じて光の屈折率あるいは位相が
変化する。折り返し部１０において、光が４５°傾いた
１／４波長板４を往復するため、実効的に１／２波長板
を通過したことと同じになり、ＴＭモードがＴＥモード
へ、ＴＥモードがＴＭモードへ変換される。第２の相互
作用領域（ＲＳ間：長さＬ2 ）１４を経てＹ分岐部９ｂ
で光が合波する。ここで、Ｌ1 とＬ2 が等しい場合（Ｌ
＝Ｌ1 ＝Ｌ2 ）、分岐してから合波するまでの間に、異
なる入射光モードが受ける位相変化が等しくなり、各モ
ードとも二つの光導波路間の屈折率変化を同じように受
ける。従って、各入射モードとも同じ電圧において合波
部（Ｙ分岐部９ｂ）で干渉し合い出射光７の強度が変化
する。When incident light having a constant intensity is incident on the optical waveguide 2, the light is distributed to the two optical waveguides at the Y branch portion 9a which constitutes the Mach-Zehnder interferometer. Optical waveguide 2
And the electrode 3 are the first interaction area (between PQ: length L1)
At 13, the refractive index or phase of light changes according to the input signal. In the folding part 10, the light reciprocates the quarter-wave plate 4 inclined by 45 °, which is the same as effectively passing through the half-wave plate, and the TM mode is changed to the TE mode and the TE mode is changed to the TM mode. Converted to mode. The second branching region 9b via the second interaction region (RS: length L 2 ) 14
The light is combined at. Here, if L1 and L 2 is equal to (L
= L1 = L 2), until multiplexing from the branch, different incident light mode the phase change is equal to undergo, undergoing a change in refractive index between the two optical waveguides in the same way in each mode. Therefore, in each incident mode, the same voltage causes interference at the combining portion (Y branch portion 9b) and the intensity of the emitted light 7 changes.
【００３４】ここで、図１５、図１６で示した従来構造
におけるＴＭモード（ＴＥモード）における駆動電圧を
Ｖｐ（ＴＭ）（Ｖｐ（ＴＥ））とすると、駆動電圧Ｖｐ
（ＴＭ＋ＴＥ）は、Here, assuming that the driving voltage in the TM mode (TE mode) in the conventional structure shown in FIGS. 15 and 16 is Vp (TM) (Vp (TE)), the driving voltage Vp
(TM + TE) is
【００３５】[0035]
【数５】 Vp（TM＋TE）＝(2/(1/Vp(TM)＋1/Vp(TE)) ＝2Vp(TM)Vp(TE)/(Vp(TM＋Vp(TE)) …（５） で与えられる。この時、相互作用長ＬとＴＭモード（Ｔ
Ｅモード）に対するΓ（ＴＭ）（Γ（ＴＥ））は、従来
構造の値とほぼ同じとする。[Equation 5] Vp (TM + TE) ＝ (2 / (1 / Vp (TM) ＋ 1 / Vp (TE)) ＝ 2Vp (TM) Vp (TE) / (Vp (TM + Vp (TE))… (5) At this time, the interaction length L and the TM mode (T
Γ (TM) (Γ (TE)) for E mode) is almost the same as that of the conventional structure.
【００３６】一方、ＴＭモードとＴＥモード光の平均的
な実効屈折率をｎ0 、マイクロ波の実効的な屈折率をｎ
m 、ＱＲ間に実効的な光導波路の長さをＬ3 、ＱＲ間の
実効的な電極の長さをＬ3 ′とした時に、On the other hand, the average effective refractive index of TM mode and TE mode light is n 0 , and the effective refractive index of microwaves is n.
When the effective optical waveguide length between m and QR is L 3 and the effective electrode length between QR is L 3 ′,
【００３７】[0037]
【数６】 ｎm （Ｌ1 ＋Ｌ3 ′）＝ｎ0 （Ｌ1 ＋Ｌ3 ） …（６） の関係が成り立つように設定すると、Ｐ点におけるマイ
クロ波と光の各位相面が、Ｒ点においても一致する。つ
まり、相互作用部における実効的な走行時間を一致させ
ることができる。従って、上限周波数は前記（３）式の
ＬをＬ1 とした値となる。図１５、図１６の光制御素子
の相互作用長Ｌと図１の光制御素子の相互作用長Ｌ1 を
等しくすると、周波数帯域は同じとなり、かつ上記で示
したように入射光の偏波モードに依存せずに駆動電圧を
低減することができる。[Equation 6] If the relationship of n m (L1 + L 3 ′) = n 0 (L1 + L 3 ) ... (6) is established, each phase plane of the microwave and light at the point P is also at the R point. Match. That is, it is possible to match the effective travel times in the interaction units. Therefore, the upper limit frequency is a value where L in the equation (3) is L1. If the interaction length L of the light control element of FIGS. 15 and 16 and the interaction length L1 of the light control element of FIG. 1 are made equal, the frequency bands become the same, and as described above, the polarization mode of the incident light is changed. The drive voltage can be reduced without depending on it.
【００３８】なお、上記（６）式から僅かにずれた場合
でも、低電圧化、高速動作化等に大きな影響は与えな
い。Even if the equation (6) is slightly deviated, it does not have a great influence on the reduction of the voltage and the increase of the operation speed.
【００３９】図４は、全相互作用長を４０ｍｍとして、
波長１．３μｍの光を用いたときの印加電圧に対する光
出力特性である。ここで、横軸は電極に印加した電圧を
縦軸に出射光強度を示す。駆動電圧は３．８Ｖであり、
入射光の偏波によらず同じ特性を示すことがわかる。図
１５、図１６で示した従来例におけるＶｐ（ＴＭ）＝５
Ｖ、Ｖｐ（ＴＥ）＝１５Ｖの値から、上記（５）式を用
いて駆動電圧Ｖｐ（ＴＭ＋ＴＥ）を推定した値と良く一
致していることがわかる。よって、本発明による構成に
よって偏波無依存光強度変調器は、従来の構成によるも
のと比較して１／４程度の駆動電圧ですむことになる。
また、周波数帯域は図１５、図１６の従来例と同程度で
あった。さらに、入射光の偏波に対してＯＮ／ＯＦＦ電
圧が一致しているため、消光比劣化はほとんとない。FIG. 4 shows that the total interaction length is 40 mm,
It is a light output characteristic with respect to an applied voltage when light having a wavelength of 1.3 μm is used. Here, the horizontal axis represents the voltage applied to the electrodes and the vertical axis represents the intensity of emitted light. The drive voltage is 3.8V,
It can be seen that the same characteristics are exhibited regardless of the polarization of the incident light. Vp (TM) = 5 in the conventional example shown in FIGS.
From the values of V and Vp (TE) = 15V, it can be seen that the values are in good agreement with the values obtained by estimating the drive voltage Vp (TM + TE) using the above equation (5). Therefore, with the configuration according to the present invention, the polarization-independent optical intensity modulator requires a driving voltage of about 1/4 as compared with the conventional configuration.
Further, the frequency band was about the same as that of the conventional example shown in FIGS. Further, since the ON / OFF voltage matches the polarized wave of the incident light, the extinction ratio is hardly deteriorated.
【００４０】このように、本発明の光強度変調器は、偏
波依存性を無くし、かつその駆動電圧を従来より大幅に
低減することができ、またマイクロ波と光の位相速度差
を補償することができるため高速動作を実現することが
できる。As described above, the optical intensity modulator of the present invention can eliminate the polarization dependence, can drastically reduce the drive voltage thereof, and can compensate the phase velocity difference between the microwave and the light. Therefore, high-speed operation can be realized.
【００４１】（実施例２）図５は、２×２光スイッチと
した本発明の第２の実施例である。図１と同一構成要素
には同一符号を付して説明を簡略化した。図１の第１の
実施例のＹ分岐部９ａ，９ｂを２×２カプラ部１５に置
き換えた２×２光スイッチの構成となっている。２×２
カプラは部１５、方向性結合器やＸ分岐等で構成し、各
偏波に対してそれぞれ３ｄＢとなるように設定してあ
る。(Embodiment 2) FIG. 5 shows a second embodiment of the present invention in which a 2 × 2 optical switch is used. The same components as those in FIG. 1 are designated by the same reference numerals to simplify the description. The configuration is a 2 × 2 optical switch in which the Y branch units 9a and 9b of the first embodiment of FIG. 1 are replaced with a 2 × 2 coupler unit 15. 2x2
The coupler is composed of the unit 15, the directional coupler, the X branch, and the like, and is set to be 3 dB for each polarized wave.
【００４２】以上の実施例では、マイクロ波と光の速度
不整合による帯域制限が主要因で、マイクロ波の伝搬に
伴う損失が無視できるような場合を示した。In the above-mentioned embodiments, the case where the loss due to the propagation of microwaves can be neglected is mainly due to the band limitation due to the speed mismatch between microwaves and light.
【００４３】一方、マイクロ波と光の速度不整合によ
り、マイクロ波の伝搬に伴う損失が帯域制限の主要因と
なる場合は、ＴＭモードとＴＥモードの全相互作用領域
で受ける実効的な電圧の総和が異なり、偏波依存性が生
じてしまう問題がある。On the other hand, when the loss due to the propagation of microwaves is the main factor of band limitation due to the speed mismatch between microwaves and light, the effective voltage received in the entire interaction region of TM mode and TE mode is There is a problem that the total sum is different and polarization dependence occurs.
【００４４】（実施例３）図６は、マイクロ波の伝搬損
失が無視できない場合の本発明の第３の実施例である。
図中、図１および図５と同一構成要素には同一符号を付
して説明を簡略化した。第１のマイクロ波給電線１６と
第２のマイクロ波給電線１７からの入力は、Ｐ点におけ
るマイクロ波と光の各位相面が、Ｒ点においても一致す
るように、Ｐ点からＲ点までの光の到達時間Δｔだけ遅
延時間を有する。図７は、マイクロ波と光速度が一致し
た場合におけるマイクロ波の伝搬距離に対する実効的な
電圧（パワー）を示している。電圧は伝搬距離に対して
指数関数的に減衰する。特に周波数が高い場合、図１に
示す第１の実施例では、図８で示すように光が受ける実
効的な電圧の総和が入射偏波モードによって異なってく
る。図９は、図６において、第１，第２のマイクロ波の
パワーを同じ値に設定した場合の光が受ける実効的な電
圧の距離依存性を示している。これにより、マイクロ波
の伝搬損失による高周波領域におけるＰＱ間の実効的な
電圧とＲＳ間の実効的な電圧を一致させることができる
ため、ＤＣあるいは低周波動作だけでなく高周波動作に
おいても偏波依存性をなくすことができる。(Embodiment 3) FIG. 6 shows a third embodiment of the present invention when the propagation loss of microwaves cannot be ignored.
In the figure, the same components as those in FIGS. 1 and 5 are designated by the same reference numerals to simplify the description. The inputs from the first microwave feed line 16 and the second microwave feed line 17 are from the P point to the R point so that the microwave and light phase planes at the P point also match at the R point. The light has a delay time of Δt. FIG. 7 shows the effective voltage (power) with respect to the propagation distance of the microwave when the light velocity matches the microwave. The voltage decays exponentially with propagation distance. Particularly when the frequency is high, in the first embodiment shown in FIG. 1, the total effective voltage received by the light varies depending on the incident polarization mode, as shown in FIG. FIG. 9 shows the distance dependence of the effective voltage received by the light when the powers of the first and second microwaves are set to the same value in FIG. As a result, the effective voltage between the PQ and the effective voltage between the RS in the high frequency region due to the propagation loss of the microwave can be made to coincide with each other, so that the polarization dependence is achieved not only in the DC or low frequency operation but also in the high frequency operation. You can eliminate the sex.
【００４５】（実施例４）図１０は、マイクロ波の伝搬
損失が無視できない場合の光路変換型折り返し光導波路
部１０を２ケ所用いて相互作用部を２回折り返しとした
本発明の第４の実施例を示す図である。本実施例では第
１の相互作用領域（ＰＱ間）１３＋第３の相互作用領域
（ＴＵ間）１８の長さと第２の相互作用領域（ＲＳ間）
１４の長さを等しくしている。図１１は、入射偏波モー
ド光が受ける実効的な電圧の距離依存性を示している。
ＰＱ間およびＴＵ間の電圧の総和とＲＳ間の電圧の総和
を等しくするように各領域の長さを設定すれば、入射の
各モード光が受ける実効的な電圧をほぼ等しくすること
ができるため、ＤＣあるいは低周波領域だけでなく、高
周波領域においても偏波依存性をなくすことができる。
なお、繰り返し回数を３回以上行ってもよい。また、速
度不整合が問題とならない場合には、上記相互作用領域
の長さは限定されない。(Embodiment 4) FIG. 10 shows a fourth embodiment of the present invention in which the optical path conversion type folded optical waveguide portion 10 is used in two places and the interaction portion is folded back twice when the propagation loss of the microwave cannot be ignored. It is a figure which shows an Example. In this embodiment, the length of the first interaction area (between PQ) 13 + the third interaction area (between TUs) 18 and the second interaction area (between RSs).
The lengths of 14 are made equal. FIG. 11 shows the distance dependence of the effective voltage received by the incident polarization mode light.
By setting the length of each region so that the sum of the voltages between PQ and TU and the sum of the voltages between RS are equal, the effective voltage received by each incident mode light can be made substantially equal. , It is possible to eliminate the polarization dependence not only in the DC or low frequency region but also in the high frequency region.
The number of repetitions may be three or more. Further, the length of the interaction region is not limited if the velocity mismatch does not matter.
【００４６】（変形例）図１２、図１３、図１４は、前
記第１，第２，第３および第４の実施例における光路変
換型折り返し光導波路部の端部近傍の他の構成を示す図
である。図１２、図１３は角度θの光導波路４０２と光
導波路端部４０３で構成され、光導波路端部に取り付け
られた波長板４の周囲にはこの波長板４を取り付けるた
めの溝１９が形成されている。また図１４は光導波路２
が端部近傍で３ｄＢカプラを形成し、カプラ部２０を光
が波長板４を通して往復することにより光路が変換され
る構造である。(Modification) FIGS. 12, 13 and 14 show another structure near the end of the optical path conversion type folded optical waveguide portion in the first, second, third and fourth embodiments. It is a figure. 12 and 13 are composed of an optical waveguide 402 having an angle θ and an optical waveguide end 403, and a groove 19 for attaching the wavelength plate 4 is formed around the wavelength plate 4 attached to the optical waveguide end. ing. FIG. 14 shows the optical waveguide 2
Forms a 3 dB coupler in the vicinity of the end portion, and the optical path is converted by the light traveling back and forth through the coupler portion 20 through the wave plate 4.
【００４７】これら実施例では、Ｔｉ熱拡散法による光
導波路について説明したが、例えばイオン交換法等によ
り形成してもよい。また、リッジ型光導波路としてもよ
い。さらに、光導波路として直線導波路を用いることに
よって位相変調器を構成することができる。また、バッ
ファ層材料についてもＳｉＯ2 の場合について説明した
が、アルミナやテフロン等の誘電体や半絶縁体を用いて
もよい。進行波型電極としてＣＰＷ電極について説明し
たが、ＡＣＰＳ電極等の電極構造を用いてもよい。Although the optical waveguides by the Ti thermal diffusion method are described in these embodiments, they may be formed by, for example, the ion exchange method. Further, it may be a ridge type optical waveguide. Furthermore, a phase modulator can be constructed by using a linear waveguide as the optical waveguide. Although the case of using SiO 2 as the buffer layer material has been described, a dielectric material such as alumina or Teflon or a semi-insulating material may be used. Although the CPW electrode has been described as the traveling-wave electrode, an electrode structure such as an ACPS electrode may be used.
【００４８】以上では、ｚ板ＬｉＮｂＯ3 基板中の電気
光学効果を用いた光制御素子について実施例を示してき
たが、個の他にｘ板やｙ板のＬｉＮｂＯ3 基板や、他の
強誘電体をはじめ、半導体や有機物などの異方性を有す
る基板の電気光学効果を用いた光制御素子にも本発明の
構成は非常に有効であることは言うまでもない。In the above, the examples of the light control element using the electro-optic effect in the z-plate LiNbO 3 substrate have been shown. However, in addition to the above, an x-plate or y-plate LiNbO 3 substrate or another ferroelectric substance is used. It goes without saying that the configuration of the present invention is very effective not only for the body but also for the light control element using the electro-optical effect of the substrate having anisotropy such as semiconductors and organic substances.
【００４９】[0049]
【発明の効果】以上説明したように、電気光学効果を有
する光学基板と、該光学基板の表面付近に形成された光
導波路と、かつ該光導波路が形成された前記光学基板面
上に配置された進行波型電極とを備え、前記電極にマイ
クロ波を印加して誘起される電圧により前記光導波路と
前記電極との相互作用領域が形成される偏波無依存光制
御素子であって、波長板および反射層を有するとともに
光偏波面を実質的に９０°前後回転して折り返す折り返
し部を前記光導波路の少なくとも一ケ所に具備し、また
相互作用部におけるマイクロ波と光との実効的な走行時
間あるいは電圧がほぼ一致するように、該光導波路や該
折り返し光導波路の長さや繰り返し数、および前記進行
波型電極の長さや分割数を設定することにより、入力光
の偏波状態によらず、相互作用長を長くすることができ
るため、駆動電圧を非常に低減することができる。ま
た、マイクロ波と光の位相速度差を補償することがで
き、従来より高速動作を行うことが可能となる。また、
同じ駆動電圧に対して全素子長を短くすることができる
ため、小型化も図ることができる。また、マイクロ波の
伝搬損失によって生じる各偏波モードの実効的な電圧の
不均衡を解消することができるため、高速動作において
も偏波依存性の無い特性が得られる。As described above, the optical substrate having the electro-optical effect, the optical waveguide formed near the surface of the optical substrate, and the optical substrate provided with the optical waveguide are arranged. A polarization-independent light control element having a traveling wave type electrode, wherein an interaction region between the optical waveguide and the electrode is formed by a voltage induced by applying a microwave to the electrode, At least one portion of the optical waveguide is provided with a folded portion having a plate and a reflective layer and substantially rotating the plane of polarization of light by about 90 ° back and forth, and the microwave and light effectively travel in the interaction portion. By setting the length and the number of repetitions of the optical waveguide and the folded optical waveguide, and the length and the number of divisions of the traveling wave type electrode so that the time or the voltage is substantially the same, the polarization state of the input light is changed. , It is possible to increase the interaction length can be greatly reduced driving voltage. Further, it is possible to compensate for the phase velocity difference between the microwave and the light, and it is possible to perform a higher speed operation than in the past. Also,
Since the total element length can be shortened for the same drive voltage, miniaturization can be achieved. Further, since it is possible to eliminate the effective voltage imbalance in each polarization mode caused by the propagation loss of microwaves, it is possible to obtain the characteristic without polarization dependence even in high-speed operation.
【図１】光制御素子としてマッハツェンダ強度光変調器
とした本発明の第１の実施例の平面図である。FIG. 1 is a plan view of a first embodiment of the present invention in which a Mach-Zehnder intensity optical modulator is used as a light control element.
【図２】図１のＡ−Ａ′線に沿う断面図である。FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG.
【図３】第１の実施例における折り返し光導波路端部近
傍の平面図である。FIG. 3 is a plan view of the vicinity of an end portion of a folded optical waveguide in the first embodiment.
【図４】図１に示すマッハツェンダ強度光変調器の電極
に電圧を印加した場合の光出力特性図である。4 is a light output characteristic diagram when a voltage is applied to the electrodes of the Mach-Zehnder intensity optical modulator shown in FIG.
【図５】２×２光スイッチとした本発明の第２の実施例
の平面図である。FIG. 5 is a plan view of a second embodiment of the present invention which is a 2 × 2 optical switch.
【図６】マイクロ波の伝搬損失が無視できない場合の本
発明の第３の実施例の平面図である。FIG. 6 is a plan view of a third embodiment of the present invention when the propagation loss of microwaves cannot be ignored.
【図７】マイクロ波の伝搬損失がある場合のマイクロ波
電圧（パワー）の伝搬距離依存性を示す図である。FIG. 7 is a diagram showing the propagation distance dependence of microwave voltage (power) when there is microwave propagation loss.
【図８】図１に示す第１の実施例における入射偏波モー
ド光が受ける実効的な電圧の距離依存性を示す図であ
る。8 is a diagram showing the distance dependence of the effective voltage received by the incident polarization mode light in the first example shown in FIG.
【図９】図６に示す実施例における入射偏波モード光が
受ける実効的な電圧の距離依存性を示す図である。9 is a diagram showing the distance dependence of the effective voltage received by the incident polarization mode light in the embodiment shown in FIG.
【図１０】マイクロ波の伝搬損失が無視できない場合の
光路変換型折り返し光導波路を２回用いた本発明の第４
の実施例の平面図である。FIG. 10 is a fourth example of the present invention in which an optical path conversion type folded optical waveguide is used twice when the propagation loss of microwaves cannot be ignored.
It is a top view of an Example of.
【図１１】入射偏波モード光が受ける実効的な電圧の距
離依存性を示す図である。FIG. 11 is a diagram showing distance dependence of an effective voltage received by incident polarization mode light.
【図１２】第１，第２，第３および第４の実施例におけ
る折り返し光導波路端部近傍の変形例を示す平面図であ
る。FIG. 12 is a plan view showing a modified example near the folded optical waveguide end portion in the first, second, third and fourth embodiments.
【図１３】図１２のＡ−Ａ′線に沿う断面図である。13 is a cross-sectional view taken along the line AA ′ of FIG.
【図１４】第１，第２，第３および第４の実施例におけ
る折り返し光導波路端部近傍の他の変形例を示す平面図
である。FIG. 14 is a plan view showing another modified example near the end of the folded optical waveguide in the first, second, third and fourth examples.
【図１５】従来のマッハツェンダ型強度光変調器の一例
を示す平面図である。FIG. 15 is a plan view showing an example of a conventional Mach-Zehnder type intensity optical modulator.
【図１６】図１５のＡ−Ａ′線に沿う断面図である。16 is a sectional view taken along the line AA ′ in FIG.
【図１７】図１５に示す従来のマッハツェンダ強度光変
調器の電極に電圧を印加した場合の光出力特性図であ
る。17 is an optical output characteristic diagram when a voltage is applied to the electrodes of the conventional Mach-Zehnder intensity optical modulator shown in FIG.
１ ＬｉＮｂＯ3 基板 ２ 光導波路 ３ 進行波型電極 ４ 薄膜型１／４波長板 ５ 高反射膜 ６ 入射光 ７ 出射光 ８ ＳｉＯ2 バッファ層 ９ａ、９ｂ マッハツェンダ干渉計を構成する光導波路
のＹ分岐部 １０ 折り返し型光導波路部 １１ マイクロ波給電線 １２ 終端抵抗 １３ 第１の相互作用領域 １４ 第２の相互作用領域 １５ ２×２カプラ部 １６ マイクロ波給電線 １７ マイクロ波給電線 １８ 第３の相互作用領域 １９ 溝 ２０ ３ｄＢカプラ部 ４０２ 光導波路 ４０３ 光導波路端部1 LiNbO 3 Substrate 2 Optical Waveguide 3 Traveling Wave Type Electrode 4 Thin Film Type 1/4 Wave Plate 5 High Reflection Film 6 Incident Light 7 Emitted Light 8 SiO 2 Buffer Layers 9a, 9b Y Branch of Optical Waveguide Constituting Mach-Zehnder Interferometer 10 Folded-type Optical Waveguide Section 11 Microwave Feed Line 12 Terminating Resistor 13 First Interaction Area 14 Second Interaction Area 15 2 × 2 Coupler Section 16 Microwave Feed Line 17 Microwave Feed Line 18 Third Interaction Area 19 Groove 20 3 dB Coupler 402 Optical Waveguide 403 Optical Waveguide End
───────────────────────────────────────────────────── フロントページの続き (72)発明者 井上 靖之 東京都千代田区内幸町１丁目１番６号 日 本電信電話株式会社内 (72)発明者 安藤 慎治 東京都千代田区内幸町１丁目１番６号 日 本電信電話株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Inoue 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Shinji Ando 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation
Claims (5)
学基板の表面付近に形成された光導波路と、該光導波路
が形成された前記光学基板面上に配置された進行波型電
極とを備え、前記電極にマイクロ波を印加して誘起され
る電圧により前記光導波路と前記電極との相互作用領域
が形成される偏波無依存光制御素子であって、 波長板および反射層を有するとともに光偏波面を実質的
に９０°前後回転して折り返す折り返し部を前記光導波
路の少なくとも一ケ所に具備し、かつ前記光導波路、前
記折り返し光導波路および前記進行波型電極の長さを、
前記相互作用部におけるマイクロ波と光との実効的な走
行時間がほぼ一致する長さに、設定したことを特徴とす
る偏波無依存光制御素子。1. An optical substrate having an electro-optical effect, an optical waveguide formed near the surface of the optical substrate, and a traveling wave type electrode arranged on the optical substrate surface on which the optical waveguide is formed. A polarization-independent light control element comprising an interaction region between the optical waveguide and the electrode formed by a voltage induced by applying a microwave to the electrode, which has a wave plate and a reflection layer. The optical waveguide is provided with a folded-back portion which is rotated substantially 90 ° about back and forth at at least one portion of the optical waveguide, and the lengths of the optical waveguide, the folded optical waveguide and the traveling wave type electrode are
A polarization-independent light control element, characterized in that the effective traveling time of the microwave and light in the interaction section is set to substantially match.
学基板の表面付近に形成された光導波路と、該光導波路
が形成された前記光学基板面上に配置された進行波型電
極とを備え、前記電極にマイクロ波を印加して誘起され
る電圧により前記光導波路と前記電極との相互作用領域
が形成される偏波無依存光制御素子であって、 波長板および反射層を有するとともに光偏波面を実質的
に９０°前後回転して折り返す折り返し部を前記光導波
路の少なくとも一ケ所に具備し、かつ前記光導波路、前
記折り返し光導波路および前記進行波型電極の長さを、
直交する伝搬光モードの前記相互作用部におけるマイク
ロ波の実効的な電圧の総和がほぼ一致する長さに、設定
したことを特徴とする偏波無依存光制御素子。2. An optical substrate having an electro-optical effect, an optical waveguide formed near the surface of the optical substrate, and a traveling wave type electrode arranged on the optical substrate surface on which the optical waveguide is formed. A polarization-independent light control element comprising an interaction region between the optical waveguide and the electrode formed by a voltage induced by applying a microwave to the electrode, which has a wave plate and a reflection layer. The optical waveguide is provided with a folded-back portion which is rotated substantially 90 ° about back and forth at at least one portion of the optical waveguide, and the lengths of the optical waveguide, the folded optical waveguide and the traveling wave type electrode are
A polarization-independent light control element, characterized in that the lengths are set so that the total sum of the effective voltages of the microwaves in the interaction portion of the orthogonal propagation light modes is substantially the same.
ことを特徴とする請求項２に記載の偏波無依存光制御素
子。3. The polarization independent light control element according to claim 2, wherein the traveling wave electrode is divided into two or more.
備したことを特徴とする請求項２または３に記載の偏波
無依存光制御素子。4. The polarization independent optical control element according to claim 2, further comprising two or more folded portions of the optical waveguide.
よび前記進行波型電極の長さを、前記相互作用部におけ
るマイクロ波と光との実効的な走行時間がほぼ一致する
長さに、設定したことを特徴とする請求項２ないし４の
いずれかに記載の偏波無依存光制御素子。5. The lengths of the optical waveguide, the folded optical waveguide, and the traveling-wave electrode are set so that the effective traveling times of the microwave and the light in the interaction section are substantially the same. The polarization-independent light control element according to any one of claims 2 to 4, wherein
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15949995A JP3250712B2 (en) | 1995-06-26 | 1995-06-26 | Polarization independent light control element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15949995A JP3250712B2 (en) | 1995-06-26 | 1995-06-26 | Polarization independent light control element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0915545A true JPH0915545A (en) | 1997-01-17 |
| JP3250712B2 JP3250712B2 (en) | 2002-01-28 |
Family
ID=15695109
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15949995A Expired - Fee Related JP3250712B2 (en) | 1995-06-26 | 1995-06-26 | Polarization independent light control element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3250712B2 (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09105894A (en) * | 1995-07-07 | 1997-04-22 | Koninkl Ptt Nederland Nv | Polarization-independent optical device |
| US5886807A (en) * | 1997-01-24 | 1999-03-23 | California Institute Of Technology | Traveling-wave reflective electro-optic modulator |
| JP2005099554A (en) * | 2003-09-26 | 2005-04-14 | Sumitomo Osaka Cement Co Ltd | Reflection type optical modulator |
| WO2006067578A1 (en) * | 2004-12-20 | 2006-06-29 | Schlumberger Technology B.V. | Methods and apparatus for single fiber optical telemetry |
| JP2006259543A (en) * | 2005-03-18 | 2006-09-28 | Fujitsu Ltd | Optical device |
| WO2007013128A1 (en) * | 2005-07-25 | 2007-02-01 | Fujitsu Limited | Semiconductor chip module |
| JP2007094440A (en) * | 2007-01-11 | 2007-04-12 | Fujitsu Ltd | Optical waveguide, optical device, and method for manufacturing the optical waveguide |
| GB2452505A (en) * | 2007-09-05 | 2009-03-11 | Univ Kent Canterbury | Optical external modulator and method of modulating a light beam |
| US7995872B2 (en) | 2007-02-14 | 2011-08-09 | Ngk Insulators, Ltd. | Optical modulator component and optical modulator |
| CN108490649A (en) * | 2018-03-14 | 2018-09-04 | 中国电子科技集团公司第四十四研究所 | It is realized using a quarter slide and polarizes unrelated lithium niobate electro-optic phase modulator |
-
1995
- 1995-06-26 JP JP15949995A patent/JP3250712B2/en not_active Expired - Fee Related
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09105894A (en) * | 1995-07-07 | 1997-04-22 | Koninkl Ptt Nederland Nv | Polarization-independent optical device |
| US5886807A (en) * | 1997-01-24 | 1999-03-23 | California Institute Of Technology | Traveling-wave reflective electro-optic modulator |
| JP2005099554A (en) * | 2003-09-26 | 2005-04-14 | Sumitomo Osaka Cement Co Ltd | Reflection type optical modulator |
| JP4519436B2 (en) * | 2003-09-26 | 2010-08-04 | 住友大阪セメント株式会社 | Reflective light modulator |
| GB2437430A (en) * | 2004-12-20 | 2007-10-24 | Schlumberger Holdings | Methods and apparatus for single fiber optical telemetry |
| WO2006067578A1 (en) * | 2004-12-20 | 2006-06-29 | Schlumberger Technology B.V. | Methods and apparatus for single fiber optical telemetry |
| US7515774B2 (en) | 2004-12-20 | 2009-04-07 | Schlumberger Technology Corporation | Methods and apparatus for single fiber optical telemetry |
| JP2006259543A (en) * | 2005-03-18 | 2006-09-28 | Fujitsu Ltd | Optical device |
| JP4555715B2 (en) * | 2005-03-18 | 2010-10-06 | 富士通株式会社 | Optical device |
| JPWO2007013128A1 (en) * | 2005-07-25 | 2009-02-05 | 富士通株式会社 | Semiconductor chip module |
| US7536066B2 (en) | 2005-07-25 | 2009-05-19 | Fujitsu Limited | Semiconductor chip module |
| WO2007013128A1 (en) * | 2005-07-25 | 2007-02-01 | Fujitsu Limited | Semiconductor chip module |
| JP4603581B2 (en) * | 2005-07-25 | 2010-12-22 | 富士通株式会社 | Semiconductor chip module |
| JP2007094440A (en) * | 2007-01-11 | 2007-04-12 | Fujitsu Ltd | Optical waveguide, optical device, and method for manufacturing the optical waveguide |
| US7995872B2 (en) | 2007-02-14 | 2011-08-09 | Ngk Insulators, Ltd. | Optical modulator component and optical modulator |
| JP5421595B2 (en) * | 2007-02-14 | 2014-02-19 | 日本碍子株式会社 | Traveling wave type optical modulator |
| GB2452505A (en) * | 2007-09-05 | 2009-03-11 | Univ Kent Canterbury | Optical external modulator and method of modulating a light beam |
| CN108490649A (en) * | 2018-03-14 | 2018-09-04 | 中国电子科技集团公司第四十四研究所 | It is realized using a quarter slide and polarizes unrelated lithium niobate electro-optic phase modulator |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3250712B2 (en) | 2002-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2603437B2 (en) | Periodic domain inversion electro-optic modulator | |
| US4157860A (en) | Dual polarization electromagnetic switch and modulator | |
| US4291939A (en) | Polarization-independent optical switches/modulators | |
| US7088875B2 (en) | Optical modulator | |
| US7058241B2 (en) | Optical modulator | |
| KR100472056B1 (en) | Polarization-independent optical polymeric intensity modulator | |
| JP3250712B2 (en) | Polarization independent light control element | |
| Burns et al. | Broad-band reflection traveling-wave LiNbO 3 modulator | |
| WO2007058366A1 (en) | Optical waveguide device | |
| WO1985001123A1 (en) | High switching frequency optical waveguide switch, modulator, and filter devices | |
| JP2000028979A (en) | Optical control element independent of polarization | |
| JPH07325276A (en) | Polarization-independent optical control element | |
| JP4703158B2 (en) | Light control element | |
| US7088874B2 (en) | Electro-optic devices, including modulators and switches | |
| JPH04355714A (en) | Optical control element | |
| US6980706B2 (en) | Waveguide optical modulator | |
| US5530777A (en) | Optical modulation device | |
| JP3020340B2 (en) | Optical waveguide type optical device | |
| JPH05241115A (en) | Waveguide type optical device | |
| JP3031394B2 (en) | Transmission wavelength control method | |
| JPH09185025A (en) | Optical control element | |
| WO2023176055A1 (en) | Optical modulator | |
| JP2848455B2 (en) | Waveguide type optical device | |
| JP2898066B2 (en) | Optical device | |
| KR19980073463A (en) | Integrated Optical Reflective Optical Modulator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071116 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081116 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091116 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101116 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101116 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111116 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111116 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121116 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121116 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131116 Year of fee payment: 12 |
|
| LAPS | Cancellation because of no payment of annual fees |