JPH0894983A - Branch modulation type optical modulator - Google Patents
Branch modulation type optical modulatorInfo
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- JPH0894983A JPH0894983A JP23545094A JP23545094A JPH0894983A JP H0894983 A JPH0894983 A JP H0894983A JP 23545094 A JP23545094 A JP 23545094A JP 23545094 A JP23545094 A JP 23545094A JP H0894983 A JPH0894983 A JP H0894983A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は分岐変調型光変調器（マ
ッハツェンダー型光変調器）の改良に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a branch modulation type optical modulator (Mach-Zehnder type optical modulator).
【０００２】[0002]
【従来の技術】近年のマッハツェンダー型光変調器にお
いては、Ｔｉ熱拡散ＬｉＮｂＯ3 チャンネル型導波路
が、そのＬｉＮｂＯ3 自体の大きな電気光学定数ならび
に駆動電圧が小さくできるという点で、提案されてい
る。2. Description of the Related Art In recent Mach-Zehnder type optical modulators, Ti thermal diffusion LiNbO 3 channel type waveguides have been proposed in that LiNbO 3 itself can have a large electro-optical constant and a driving voltage. .
【０００３】図７はこのマッハツェンダー型光変調器１
であり、２はｚカットニオブ酸リチウム板（ＬｉＮｂＯ
3 ｚ板）から成る基板、３はこの基板２上に設けたＳｉ
Ｏ2バッファ層、４は電気光学効果のある基板表層に設
けられた導波路、５は電極、６は偏光板である。FIG. 7 shows this Mach-Zehnder type optical modulator 1.
And 2 is a z-cut lithium niobate plate (LiNbO
3 z plate) substrate 3 is Si provided on this substrate 2
An O 2 buffer layer, 4 is a waveguide provided on the surface layer of the substrate having an electro-optical effect, 5 is an electrode, and 6 is a polarizing plate.
【０００４】この光変調器１によれば、上記導波路４
は、光入射部４ａと、分波部４ｂと、位相変調部４ｃ
と、合波部４ｄと、光出射部４ｅとから成り、偏光板６
を通して光入射部４ａに入射した光は分波部４ｂにより
分波し、次いで位相変調部４ｃを伝搬し、合波部４ｄを
介して合成されて光出射部４ｅに到る。According to this optical modulator 1, the waveguide 4 is provided.
Is a light incident section 4a, a demultiplexing section 4b, and a phase modulation section 4c.
And a light combining part 4d and a light emitting part 4e.
The light incident on the light incident portion 4a through the light is demultiplexed by the demultiplexing portion 4b, then propagates through the phase modulating portion 4c, is combined via the multiplexing portion 4d, and reaches the light emitting portion 4e.
【０００５】各位相変調部４ｃ上には電極５を形成し
て、この電極５に印加すると非対称電界が発生し、この
電界により各位相変調部４ｃの屈折率を変化させ、更に
この屈折率の変化に応じて、それぞれの光に位相差が生
じる。そして、上記電界強度の大きさにより位相変調部
４ｃの屈折率の変化量が決まるので、かかる位相差によ
り合成後の出射光の強度制御ができる。When an electrode 5 is formed on each phase modulator 4c and applied to the electrode 5, an asymmetric electric field is generated, and the electric field changes the refractive index of each phase modulator 4c. A phase difference occurs in each light according to the change. Then, since the amount of change in the refractive index of the phase modulator 4c is determined by the magnitude of the electric field intensity, the intensity of the emitted light after combination can be controlled by the phase difference.
【０００６】このＬｉＮｂＯ3 結晶には、光学的に異方
性があり、ｚカットＬｉＮｂＯ3 基板表層において、ｘ
方向に光が伝搬するように導波路を作製した場合では、
光の偏光方向により屈折率が異なるので、ＴＥモード光
が常光線、ＴＭモードが異常光となる。そこで、電界を
ｚ軸方向に印加したときの常光線および異常光の屈折率
の変化はそれぞれ、 Δｎo ＝ｒ13ｎ0 3 Ｅz ／２ Δｎe ＝ｒ33ｎe 3 Ｅz ／２ となって、ｒ33がｒ13に比べて数倍程度の大きくなるの
で、ＴＭモードの方がＴＥモードに比べ、電界の影響を
大きく受けることになる。したがって、変調動作に用い
るに際しては、ＴＭモードの方が印加効率が大きい点で
望ましいので、ＴＭモード光のみを導波させるために、
前記のように偏光板６を設けて、その偏光板６の偏光方
向と結晶の光学軸（ｚ軸）を一致させて、偏光板６を介
して光の入射を行っている。This LiNbO 3 crystal has optical anisotropy, and x is present in the surface layer of the z-cut LiNbO 3 substrate.
In the case of making a waveguide so that light propagates in the direction,
Since the refractive index differs depending on the polarization direction of light, TE mode light becomes ordinary light and TM mode becomes extraordinary light. Therefore, when the electric field is applied in the z-axis direction, the changes in the refractive indices of the ordinary ray and the extraordinary ray are Δn o = r 13 n 0 3 E z / 2 Δn e = r 33 n e 3 E z / 2, respectively. Then, r 33 becomes several times larger than r 13 , so that the TM mode is more affected by the electric field than the TE mode. Therefore, when used for the modulation operation, the TM mode is preferable because it has a higher application efficiency. Therefore, in order to guide only the TM mode light,
As described above, the polarizing plate 6 is provided, and the polarization direction of the polarizing plate 6 and the optical axis (z axis) of the crystal are aligned with each other, and light is incident through the polarizing plate 6.
【０００７】[0007]
【従来技術の問題点】しかしながら、上記構成のマッハ
ツェンダー型光変調器１においては、導波路４の作製条
件（Ｔｉ拡散前のＴｉ拡散源の幅、膜厚、拡散時間、拡
散温度等）、並びに導波路４と電極５との配置関係を、
駆動電圧が最小化するとともに、ＴＭ最低次モードがカ
ットオフにならない範囲内で、最適設計しているが、偏
光板６の偏光方向を基板２の結晶軸に対して正確に設定
することが難しく、よって入射した光は、ＴＭモードの
みならず、ＴＥモードが励起される場合があり、これに
より、そのＴＥモードも電界により変調を受け、その結
果、これらＴＭ、ＴＥの両モードの重ね合わせによって
図３の消光比特性図が示す通り、各ピークにおいて消光
比にばらつきが生じるという問題点があった。However, in the Mach-Zehnder interferometer type optical modulator 1 having the above-mentioned structure, the manufacturing conditions of the waveguide 4 (width of Ti diffusion source before Ti diffusion, film thickness, diffusion time, diffusion temperature, etc.), And the arrangement relationship between the waveguide 4 and the electrode 5,
The optimum design is made within a range in which the driving voltage is minimized and the TM lowest order mode is not cut off, but it is difficult to accurately set the polarization direction of the polarizing plate 6 with respect to the crystal axis of the substrate 2. Therefore, the incident light may be excited not only in the TM mode but also in the TE mode. As a result, the TE mode is also modulated by the electric field, and as a result, due to the superposition of both TM and TE modes. As shown in the extinction ratio characteristic diagram of FIG. 3, there is a problem in that the extinction ratio varies at each peak.
【０００８】この問題点を解決するためには、入射光の
偏光方向と結晶の光学軸を精度よく一致させることが重
要であるが、実際上その精度を高めることは難しく、熟
練した技術が要する。In order to solve this problem, it is important to accurately match the polarization direction of the incident light with the optical axis of the crystal, but it is difficult to increase the accuracy in practice, and a skilled technique is required. .
【０００９】しかも、その光変調器１の構成が複雑にな
り、コストの増大を招いていた。Moreover, the structure of the optical modulator 1 is complicated, resulting in an increase in cost.
【００１０】更にＴＭモードのみを励起させ、ＴＥモー
ド成分をカットオフする導波路の条件を選択すると、駆
動電圧を下げるための最適化の設定が難しくなるという
問題点があった。Further, when the condition of the waveguide that excites only the TM mode and cuts off the TE mode component is selected, there is a problem that it is difficult to set optimization for lowering the driving voltage.
【００１１】したがって、本発明の目的は構成が複雑に
ならないようにして、駆動電圧の特性を損なわず、しか
も、消光比特性の良好な分岐変調型光変調器（マッハツ
ェンダー型光変調器）を提供することにある。Therefore, an object of the present invention is to provide a branch modulation type optical modulator (Mach-Zehnder type optical modulator) which does not complicate the structure, does not impair the characteristics of the driving voltage, and has excellent extinction ratio characteristics. To provide.
【００１２】[0012]
【課題を解決するための手段】本発明は、ＬｉＮｂＯ3
成る基板の表層に所定濃度のＴｉ原子を含有させて導波
路を設けるとともに、この導波路に光入射部と、分波部
と、位相変調部と、合波部と、光出射部とを構成した分
岐変調型光変調器において、前記光入射部もしくは光出
射部にＴｉ原子濃度の小さい領域を設けたことを特徴と
する。The present invention is directed to LiNbO 3
The surface layer of the substrate is provided with a waveguide containing a predetermined concentration of Ti atoms, and the waveguide is provided with a light incident portion, a demultiplexing portion, a phase modulating portion, a multiplexing portion, and a light emitting portion. In the above branch modulation type optical modulator, a region having a low Ti atom concentration is provided in the light incident part or the light emitting part.
【００１３】[0013]
【作用】上記構成の分岐変調型光変調器によれば、導波
路のうち光入射部もしくは光出射部にＴｉ原子濃度の小
さい領域を設けているので、ＴＭモードが励起され、か
つＴＥモードをカットオフの状態となるように屈折率分
布を設定することができ、これにより、出射光において
ＴＥモード成分が混在しないか、もしくはその成分を相
当程度にまで減少でき、その結果、偏光板を配置しなく
ても、消光比特性の良好な分岐変調型光変調器が得られ
る。According to the branch modulation type optical modulator having the above structure, since the region having a low Ti atom concentration is provided in the light incident part or the light emitting part of the waveguide, the TM mode is excited and the TE mode is generated. The refractive index distribution can be set so as to be in a cut-off state, whereby the TE mode component is not mixed in the emitted light or the component can be reduced to a considerable extent, and as a result, the polarizing plate is arranged. Even without doing so, a branch modulation type optical modulator having a good extinction ratio characteristic can be obtained.
【００１４】また、上記構成のように導波路のうち光入
射部もしくは光出射部にＴｉ原子濃度の小さい領域を設
けるのであれば、その導波路をＴｉ熱拡散法により作製
する場合に、そのフォトリソ技術において所定のマスク
形状にするだけで容易に形成することができる。したが
って、その製造コストが低減し、低コストな分岐変調型
光変調器を得られる。Further, if a region having a low Ti atom concentration is provided in the light incident part or the light emitting part of the waveguide as in the above structure, when the waveguide is manufactured by the Ti thermal diffusion method, the photolithography is performed. In the technology, it can be easily formed only by forming a predetermined mask shape. Therefore, the manufacturing cost can be reduced, and a low-cost branch modulation type optical modulator can be obtained.
【００１５】[0015]
【実施例】図１は実施例のマッハツェンダー型光変調器
７である。なお、図７と同一箇所には同一符号を付す。
２ａはｚカットニオブ酸リチウム板（ＬｉＮｂＯ3 ｚ
板）から成る基板であり、この基板２ａに幅５μｍ程度
の導波路８をＴｉ熱拡散法により作製した。このＴｉ熱
拡散法は１０００℃もしくはそれよりも僅かに高い温度
でＴｉ熱拡散を行って、Ｔｉ原子をドープした。そのド
ープの際には、フォトリソ技術により所定形状のマスク
を用いて、レジストパターンを形成し、リフトオフ法に
よりＴｉパターンを作製した後、Ｔｉ熱拡散をおこなっ
た。1 shows a Mach-Zehnder type optical modulator 7 according to an embodiment. The same parts as those in FIG. 7 are designated by the same reference numerals.
2a is a z-cut lithium niobate plate (LiNbO 3 z
A waveguide 8 having a width of about 5 μm was formed on the substrate 2a by a Ti thermal diffusion method. In this Ti thermal diffusion method, Ti thermal diffusion was performed at a temperature of 1000 ° C. or slightly higher to dope Ti atoms. At the time of the doping, a resist pattern was formed by a photolithography technique using a mask having a predetermined shape, a Ti pattern was formed by a lift-off method, and then thermal diffusion of Ti was performed.
【００１６】そして、このＴｉ熱拡散法は非常に高温で
おこなうので、基板２ａの＋Ｃ面のＴｉ拡散した領域で
は分極反転が生じる場合があり、このような影響を避け
るために、この導波路８を−Ｃ面表層９に作製した。Since this Ti thermal diffusion method is performed at an extremely high temperature, polarization inversion may occur in the Ti-diffused region of the + C plane of the substrate 2a, and in order to avoid such an influence, this waveguide 8 is used. Was prepared on the surface layer 9 of the -C plane.
【００１７】この導波路８上に設けた電極５について
は、図１に示すようなＣＰＳ構造の他に、ＣＰＷ構造で
あってもよい。The electrode 5 provided on the waveguide 8 may have a CPW structure in addition to the CPS structure shown in FIG.
【００１８】また、この電極５を導波路８上に設ける
と、導波光の伝搬損失が生じ易くなり、特にＴＭモード
光にその現象が顕著である。そこで、この伝搬損失を低
減するために基板２ａ上にＳｉＯ2 バッファ層３を設け
ている。Further, when the electrode 5 is provided on the waveguide 8, a propagation loss of guided light is likely to occur, and the phenomenon is particularly remarkable in TM mode light. Therefore, in order to reduce this propagation loss, the SiO 2 buffer layer 3 is provided on the substrate 2a.
【００１９】この導波路８についても、光入射部８ａ
と、分波部８ｂと、位相変調部８ｃと、合波部８ｄと、
光出射部８ｅとから成り、そして、光入射部８ａに入射
した光は分波部８ｂにより分波し、次いで位相変調部８
ｃを伝搬し、合波部８ｄを介して合成されて光出射部８
ｅに到り、出射する構成であり、この構成によれば、各
位相変調部８ｃ上に形成した両電極５の間に高周波電力
を印加すると電界が発生し、この電界により各位相変調
部８ｃの屈折率が変化し、更にこの屈折率の変化に応じ
て、それぞれの光に位相差が生じ、そして、上記電界強
度の大きさにより位相変調部８ｃの屈折率の程度が決ま
るので、かかる位相差により合成後の出射光の強度制御
ができた。The waveguide 8 is also provided with a light incident portion 8a.
A demultiplexing unit 8b, a phase modulating unit 8c, a multiplexing unit 8d,
The light is incident on the light incident part 8a and is split by the branching part 8b.
c propagates and is combined via the combining unit 8d to form the light emitting unit 8
In this configuration, when high frequency power is applied between both electrodes 5 formed on each phase modulation section 8c, an electric field is generated, and this electric field causes each phase modulation section 8c. Changes in refractive index, and a phase difference occurs in each light according to the change in refractive index, and the magnitude of the electric field strength determines the degree of the refractive index of the phase modulator 8c. The intensity of the emitted light after the combination could be controlled by the phase difference.
【００２０】次に導波路８に設けたＴｉ原子濃度の小さ
い領域を説明する。本実施例においては、この導波路８
を作製するに当たって、光入射部８ａもしくは光出射部
８ｅに、Ｔｉ原子濃度の小さい領域を設けている。以
下、この領域はＴＥモードをカットオフの状態となるよ
うに設定するためのものであるので、ＴＥモードカット
オフ領域１０を称する。Next, the region of the waveguide 8 having a low Ti atom concentration will be described. In this embodiment, the waveguide 8
In manufacturing, the light incident portion 8a or the light emitting portion 8e is provided with a region having a low Ti atom concentration. Hereinafter, since this area is for setting the TE mode to be in the cutoff state, the TE mode cutoff area 10 is referred to.
【００２１】このＴＥモードカットオフ領域１０を図２
〜図５に示す。なお、これらの図中、矢印は光の伝搬方
向である。図２のＴＥモードカットオフ領域１０ａで
は、拡散前のＴｉ幅を導波路８における拡散前のＴｉ幅
に比べて２０〜５０％程度にまで小さくし、そして、そ
の領域１０ａの厚み（深度）が導波路８と同じになるよ
うに設けた。This TE mode cutoff region 10 is shown in FIG.
~ Shown in FIG. In these figures, the arrow indicates the light propagation direction. In the TE mode cutoff region 10a of FIG. 2, the Ti width before diffusion is reduced to about 20 to 50% of the Ti width before diffusion in the waveguide 8, and the thickness (depth) of the region 10a is reduced. It was provided so as to be the same as the waveguide 8.
【００２２】また、図３のＴＥモードカットオフ領域１
０ｂのように、Ｔｉ幅の変化による拡散Ｔｉ原子濃度の
調節をおこなうのと同様な効果を得るために、導波路８
ａもしくは８ｅの内部にＴｉの未ドープ領域を設けた
り、図４のＴＥモードカットオフ領域１０ｃのように、
ドット状に形成してもよい。Further, the TE mode cutoff region 1 shown in FIG.
0b, in order to obtain the same effect as adjusting the diffused Ti atom concentration by changing the Ti width, the waveguide 8
An undoped region of Ti is provided inside a or 8e, or like the TE mode cutoff region 10c of FIG.
You may form in a dot shape.
【００２３】あるいは、上記のようなＴｉ厚みを変えな
い各ＴＥモードカットオフ領域１０ａ、１０ｂ、１０ｃ
以外に、図５に示すように２層構成の導波路８の一部に
１層構成にしたＴＥモードカットオフ領域１０ｄを設け
て、Ｔｉ厚みをその領域で小さくしてもよい。Alternatively, each TE mode cutoff region 10a, 10b, 10c which does not change the Ti thickness as described above.
Alternatively, as shown in FIG. 5, a TE-mode cutoff region 10d having a single-layer structure may be provided in a part of the waveguide 8 having a two-layer structure to reduce the Ti thickness in that region.
【００２４】かくして上記各構成のＴＥモードカットオ
フ領域１０（１０ａ、１０ｂ、１０ｃ、１０ｄ）を設け
たことにより、各領域１０の屈折率の分布が、導波路８
のものと比べて異なり、これにより、ＴＭモードを励起
してＴＥモードをカットオフの状態に設定することがで
き、その結果、図６に示す通りの消光比特性図が得られ
た。同図によれば、横軸が電極５に印加する電圧であ
り、出射光の強弱が理想的に形態となって、各ピークに
おける消光比が一定となった。Thus, by providing the TE mode cutoff regions 10 (10a, 10b, 10c, 10d) having the above-mentioned respective configurations, the distribution of the refractive index of each region 10 is changed to the waveguide 8.
This is different from that of the above, and this allows the TM mode to be excited to set the TE mode to the cutoff state, and as a result, the extinction ratio characteristic diagram as shown in FIG. 6 was obtained. According to the figure, the horizontal axis is the voltage applied to the electrode 5, the intensity of the emitted light has an ideal form, and the extinction ratio at each peak is constant.
【００２５】なお、本発明は上記実施例に限定されるも
のではなく、本発明の要旨を逸脱しない範囲内で種々の
変更や改良等は何ら差し支えない。たとえば、ＴＥモー
ドカットオフ領域１０については実施例の他に各種形状
や構造を採用することができ、ＴＥモードカットオフ領
域１０ｃにおいては、その球状のドットの他に、任意形
状のドット状点源であってもよい。The present invention is not limited to the above embodiments, and various changes and improvements may be made without departing from the scope of the present invention. For example, the TE mode cutoff region 10 can adopt various shapes and structures other than the embodiment. In the TE mode cutoff region 10c, in addition to the spherical dots, a dot-shaped point source of an arbitrary shape can be used. May be
【００２６】[0026]
【発明の効果】以上の通り、本発明によれば、導波路の
うち光入射部もしくは光出射部にＴｉ原子濃度の小さい
領域を設けているので、ＴＭモードが励起され、かつＴ
Ｅモードをカットオフの状態となるように屈折率分布を
設定することができ、これにより、出射光においてＴＥ
モード成分が混在しないか、もしくはその成分を相当程
度にまで減少でき、その結果、偏光板を配置しなくて
も、駆動電圧の特性を損なわず、消光比特性の良好な分
岐変調型光変調器が得られた。As described above, according to the present invention, since the region where the Ti atom concentration is low is provided in the light incident portion or the light emitting portion of the waveguide, the TM mode is excited and the T
It is possible to set the refractive index distribution so that the E mode is in a cutoff state.
A branch modulation type optical modulator in which mode components are not mixed or the components can be reduced to a considerable extent, and as a result, the characteristics of the driving voltage are not impaired and the extinction ratio characteristics are excellent without disposing a polarizing plate. was gotten.
【００２７】また、本発明によれば、導波路をＴｉ熱拡
散法により作製する場合に、そのフォトリソ技術におい
て所定のマスク形状にするだけでＴｉ原子濃度の小さい
領域を容易に形成することができ、これにより、製造コ
ストが低減し、低コストな分岐変調型光変調器を得られ
た。Further, according to the present invention, when the waveguide is manufactured by the Ti thermal diffusion method, a region having a low Ti atom concentration can be easily formed only by forming a predetermined mask shape in the photolithography technique. As a result, the manufacturing cost is reduced, and a low-cost branch modulation type optical modulator is obtained.
【図１】実施例の分岐変調型光変調器の斜視図である。FIG. 1 is a perspective view of a branch modulation type optical modulator of an embodiment.
【図２】実施例の分岐変調型光変調器における導波路の
要部を示す概略図である。FIG. 2 is a schematic diagram showing a main part of a waveguide in a branch modulation type optical modulator of an example.
【図３】実施例の分岐変調型光変調器における導波路の
要部を示す概略図である。FIG. 3 is a schematic view showing a main part of a waveguide in the branch modulation type optical modulator of the embodiment.
【図４】実施例の分岐変調型光変調器における導波路の
要部を示す概略図である。FIG. 4 is a schematic diagram showing a main part of a waveguide in a branch modulation type optical modulator of an example.
【図５】実施例の分岐変調型光変調器における導波路の
要部を示す概略図である。FIG. 5 is a schematic diagram showing a main part of a waveguide in the branch modulation type optical modulator of the embodiment.
【図６】実施例の分岐変調型光変調器の消光比特性を示
す線図である。FIG. 6 is a diagram showing an extinction ratio characteristic of a branch modulation type optical modulator of an example.
【図７】従来の分岐変調型光変調器の斜視図である。FIG. 7 is a perspective view of a conventional branch modulation type optical modulator.
【図８】従来の分岐変調型光変調器のの消光比特性を示
す線図である。FIG. 8 is a diagram showing an extinction ratio characteristic of a conventional branch modulation type optical modulator.
７ マッハツェンダー型光変調器 ２ａ ｚカットニオブ酸リチウム（ＬｉＮｂＯ3
ｚ）基板 ８ 導波路 ５ 電極 ３ ＳｉＯ2 バッファ層 ８ａ 光入射部 ８ｂ 分波部 ８ｃ 位相変調部 ８ｄ 合波部８ｄ ８ｅ 光出射部 １０ ＴＥモードカットオフ領域7 Mach-Zehnder type optical modulator 2a z-cut lithium niobate (LiNbO 3
z) substrate 8 waveguide 5 electrode 3 SiO 2 buffer layer 8a light incident portion 8b demultiplexing portion 8c phase modulation portion 8d multiplexing portion 8d 8e light emitting portion 10 TE mode cutoff region
Claims (1)
Ｔｉ原子を含有させて導波路を設けるとともに、該導波
路に光入射部と、分波部と、位相変調部と、合波部と、
光出射部とを構成した分岐変調型光変調器において、前
記光入射部もしくは光出射部にＴｉ原子濃度の小さい領
域を設けたことを特徴とする分岐変調型光変調器。1. A surface layer of a substrate made of LiNbO 3 is provided with a waveguide containing a predetermined concentration of Ti atoms, and a light incidence portion, a demultiplexing portion, a phase modulation portion, and a multiplexing portion are provided in the waveguide. ,
A branch modulation type optical modulator comprising a light emitting section, wherein a region having a low Ti atom concentration is provided in the light incident section or the light emitting section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23545094A JP3602874B2 (en) | 1994-09-29 | 1994-09-29 | Branch modulation type optical modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23545094A JP3602874B2 (en) | 1994-09-29 | 1994-09-29 | Branch modulation type optical modulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0894983A true JPH0894983A (en) | 1996-04-12 |
| JP3602874B2 JP3602874B2 (en) | 2004-12-15 |
Family
ID=16986294
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23545094A Expired - Fee Related JP3602874B2 (en) | 1994-09-29 | 1994-09-29 | Branch modulation type optical modulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3602874B2 (en) |
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1994
- 1994-09-29 JP JP23545094A patent/JP3602874B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3602874B2 (en) | 2004-12-15 |
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