JPH055334B2 - - Google Patents
Info
- Publication number
- JPH055334B2 JPH055334B2 JP28523687A JP28523687A JPH055334B2 JP H055334 B2 JPH055334 B2 JP H055334B2 JP 28523687 A JP28523687 A JP 28523687A JP 28523687 A JP28523687 A JP 28523687A JP H055334 B2 JPH055334 B2 JP H055334B2
- Authority
- JP
- Japan
- Prior art keywords
- linbo
- conductive film
- optical
- refractive index
- modulator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000003287 optical effect Effects 0.000 claims description 42
- 229910013641 LiNbO 3 Inorganic materials 0.000 claims description 26
- 239000002184 metal Substances 0.000 claims description 21
- 229910052751 metal Inorganic materials 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 4
- 239000012780 transparent material Substances 0.000 description 8
- 239000004020 conductor Substances 0.000 description 3
- 229910006404 SnO 2 Inorganic materials 0.000 description 2
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 2
- -1 Si 3 N 4 Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
Landscapes
- Optical Integrated Circuits (AREA)
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、LiNbO3基板を用いた導波型の光ス
イツチ・変調器に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a waveguide type optical switch/modulator using a LiNbO 3 substrate.
LiNbO3基板を用いた導波型光スイツチ・変調
器は、光交換機および光通信ネツトワークにおけ
る伝送路切替器，外部変調器などへの応用があ
る。また、この光スイツチ・変調器には、方向性
結合器型、反射器型、分岐干渉型などの種類があ
る。
Waveguide optical switches and modulators using LiNbO 3 substrates have applications in optical exchanges, transmission line switches in optical communication networks, external modulators, etc. Further, there are various types of optical switches/modulators, such as a directional coupler type, a reflector type, and a branching interference type.
これらの各種のスイツチ・変調器において、光
路をスイツチするまたは光を変調するため制御信
号が印加される電極として金属を用いたり、導電
性の透明材料を用いたりする。 In these various types of switches/modulators, metal or conductive transparent material is used as the electrode to which a control signal is applied in order to switch the optical path or modulate the light.
宮沢信太郎らによる応用物理学会誌第48巻第９
号（1979）865ページから874ページによれば、電
極として金属膜を用いる光スイツチ・変調器は、
これをTMモードで動作させる場合には、金属膜
による光の吸収を防ぐために、光導波路と金属膜
の間にLiNbO3基板より屈折率が低く、かつ、光
の吸収の少ない光学的なバツフア層を施すことが
記載されている。このバツフア層は通常SiO2，
Si3N4，SiONxなどが用いられる。しかし、方向
性結合器型の光スイツチ・変調器において、この
構造では光スイツチ特性のDCドリフト、すなわ
ちスイツチ電圧のシフトが生じる場合がある。こ
れは、バツフア層がその主要因であると言われて
おり、バツフア層を必要としない導電性の透明材
料を用いれば前記DCドリフトが回避されること
が示されている。 Journal of Applied Physics, Vol. 48, No. 9 by Shintaro Miyazawa et al.
(1979), pages 865 to 874, optical switches and modulators that use metal films as electrodes are
When operating this in TM mode, in order to prevent light absorption by the metal film, an optical buffer layer that has a lower refractive index than the LiNbO 3 substrate and absorbs less light is placed between the optical waveguide and the metal film. It is stated that this should be done. This buffer layer is usually made of SiO 2 ,
Si 3 N 4 , SiON x , etc. are used. However, in a directional coupler type optical switch/modulator, this structure may cause a DC drift in the optical switch characteristics, that is, a shift in the switch voltage. It is said that the buffer layer is the main cause of this, and it has been shown that the DC drift can be avoided by using a conductive transparent material that does not require a buffer layer.
これを第２図および第３図を参照して説明す
る。第２図は、方向性結合器型の光スイツチ・変
調器において、電極として金属膜１６ａ，１６ｂ
を用いた構造の断面図である。図中、１１は
LiNbO3基板を、１４ａ，１４ｂは光導波路、１
７はバツフア層である。第３図は、同じく方向性
結合器型の光スイツチ・変調器において、電極と
して導電性の透明材料（In2O3）１５ａ，１５ｂ
を用いた構造の断面図である。なお、第２図と同
一の要素には、同一の番号を付して示している。 This will be explained with reference to FIGS. 2 and 3. FIG. 2 shows metal films 16a and 16b used as electrodes in a directional coupler type optical switch/modulator.
FIG. In the figure, 11 is
A LiNbO 3 substrate, 14a and 14b are optical waveguides, 1
7 is a buffer layer. Figure 3 shows a similar directional coupler type optical switch/modulator using conductive transparent materials (In 2 O 3 ) 15a, 15b as electrodes.
FIG. Note that the same elements as in FIG. 2 are indicated with the same numbers.
第２図と第３図の比較を行えば明らかなよう
に、導電性の透明材料を用いた電極の構造は金属
膜を用いたものに比べバツフア層１７を必要とせ
ず簡易であり、また、前述したバツフア層１７が
主要因と考えられるスイツチ特性のDCドリフト
が存在しないという利点がある。 As is clear from a comparison between FIG. 2 and FIG. 3, the structure of an electrode using a conductive transparent material is simpler than one using a metal film because it does not require the buffer layer 17, and There is an advantage that there is no DC drift in the switch characteristics, which is thought to be caused mainly by the buffer layer 17 mentioned above.
しかし、前記文献において使用された透明材料
（In2O3）はLiNbO3基板に比べ高い屈折率を有す
るため、光の損失があり、これを防ぐためには、
LiNbO3基板に比べ低い屈折率を有する透明材料
を電極、その引き出し線およびパツドとして利用
する必要がある。このような透明材料としては、
ITO（InO3−SnO2）や有機導電性材料がある。こ
れら材料は、導電性はあるものの体積抵抗率が高
く、例えばITOは約５×10-6Ω・ｍであり、金属
に比べ高い。金属の一例として、Auの体積抵抗
率は約2.4×10-8Ω・ｍである。従つて、同一の電
極構造で同一の厚さでの高速応答特性は金属を用
いた電極の方が約50倍程度速い。つまり、ITOや
有機導電材料を用いた電極では高速スイツチ、高
速変調など高周波での使用は困難となる。
However, since the transparent material (In 2 O 3 ) used in the above literature has a higher refractive index than the LiNbO 3 substrate, there is a loss of light, and in order to prevent this,
It is necessary to use a transparent material with a lower refractive index than the LiNbO 3 substrate for the electrodes, their lead wires, and pads. As such transparent materials,
Examples include ITO (InO 3 −SnO 2 ) and organic conductive materials. Although these materials have electrical conductivity, their volume resistivity is high; for example, ITO has a volume resistivity of approximately 5×10 −6 Ω·m, which is higher than that of metals. As an example of metal, the volume resistivity of Au is approximately 2.4×10 −8 Ω·m. Therefore, with the same electrode structure and the same thickness, the high-speed response characteristics of the metal electrode are about 50 times faster. In other words, electrodes made of ITO or organic conductive materials are difficult to use in high-frequency applications such as high-speed switching and high-speed modulation.
本発明の目的は、上述のような問題点を解決
し、LiNbO3基板より低い屈折率をもつ導電性材
料と金属とを併用することにより、スイツチ特性
のDCドリフトがなく、かつ、光の損失増加も招
くことなく、高速動作を可能とする光スイツチ・
変調器を提供することにある。 The purpose of the present invention is to solve the above-mentioned problems and eliminate DC drift in switch characteristics and reduce optical loss by using a conductive material with a lower refractive index than the LiNbO 3 substrate in combination with metal. An optical switch that enables high-speed operation without increasing
The purpose of the present invention is to provide a modulator.
本発明は、LiNbO3基板を用いた導波型の光ス
イツチ・変調器において、
光路をスイツチするまたは光を変調するための
制御信号が印加される電極，その引き出し線およ
びパツドとしてLiNbO3より屈折率が低い導電膜
を直接にLiNbO3基板上に形成し、かつ、光導波
路上に形成された導電膜領域上に、導電膜より屈
折率が低い物質を設け、この物質上に、および光
導波路上に形成されていない導電膜領域上に直接
に金属膜を設けたことを特徴としている。
The present invention relates to a waveguide type optical switch/modulator using a LiNbO 3 substrate, in which a control signal for switching the optical path or modulating the light is applied as an electrode, its lead line, and a pad that is refracted from LiNbO 3 . A conductive film with a low refractive index is formed directly on the LiNbO 3 substrate, and a material with a lower refractive index than the conductive film is provided on the conductive film region formed on the optical waveguide. It is characterized in that a metal film is provided directly on the conductive film region that is not formed on the road.
次に本発明の実施例について図面を参照して説
明する。
Next, embodiments of the present invention will be described with reference to the drawings.
第１図は本発明の一実施例に係る方向性結合器
型の光スイツチ・変調器の断面図である。 FIG. 1 is a sectional view of a directional coupler type optical switch/modulator according to an embodiment of the present invention.
この光スイツチ・変調器は、光路をスイツチす
るまたは光を変調するための制御信号が印加され
る電極，その引き出し線およびパツドとして
LiNbO3より屈折率が低い導電膜１３ａ，１３ｂ
を直接にLiNbO3基板１１上に形成し、かつ、光
導波路１４ａ，１４ｂ上に形成された導電膜領域
上に、導電膜より屈折率が低い物質１８ａ，１８
ｂを設け、この物質上に、および光導波路上に形
成されていない導電膜領域上に直接に金属膜１９
ａ，１９ｂを設けている。 This optical switch/modulator consists of an electrode, its lead wire, and a pad to which a control signal for switching the optical path or modulating the light is applied.
Conductive films 13a and 13b with a lower refractive index than LiNbO 3
are formed directly on the LiNbO 3 substrate 11, and on the conductive film regions formed on the optical waveguides 14a and 14b, substances 18a and 18 whose refractive index is lower than that of the conductive film are formed.
b, and a metal film 19 is provided directly on this material and on the conductive film region not formed on the optical waveguide.
a and 19b are provided.
光導波路１４ａ，１４ｂは、LiNbO3基板１１
中へのTiの熱拡散で製作される。 The optical waveguides 14a and 14b are formed using a LiNbO 3 substrate 11.
Manufactured by thermal diffusion of Ti inside.
LiNbO3より屈折率が低い導電膜１３ａ，１３
ｂとしては、前述したようにITO（InO3−SnO2）
や有機導電膜などがある。それぞれの屈折率は
ITOが約1.8〜1.9であり、有機導電膜は約1.5〜2.0
であり、LiNbO3の約2.2に比べ屈折率は低い。 Conductive films 13a, 13 with a lower refractive index than LiNbO 3
As mentioned above, b is ITO (InO 3 −SnO 2 )
and organic conductive films. The refractive index of each
ITO is about 1.8 to 1.9, and organic conductive film is about 1.5 to 2.0
The refractive index is lower than that of LiNbO 3 , which is approximately 2.2.
導電膜より更に低屈折率の物質には石英ガラス
系などを用いることができる。 As the material having a refractive index lower than that of the conductive film, quartz glass or the like can be used.
以上のような構造をとれば、すなわち、
LiNbO3より屈折率が低い導電膜１３ａ，１３ｂ
の上に金属膜１９ａ，１９ｂを設ければ、引き出
し線、パツドを含めた電極自体の抵抗値は低くな
り高速動作が可能となる。 If we take the above structure, that is,
Conductive films 13a and 13b with a lower refractive index than LiNbO 3
If metal films 19a and 19b are provided on the electrodes, the resistance value of the electrodes themselves including the lead wires and pads will be lowered and high-speed operation will be possible.
また、光導波路１４ａ，１４ｂ上に形成された
導電膜領域上に導電膜より屈折率が低い物質１８
ａ，１８ｂを設けているのは、その領域上に直接
に金属を設けると金属による光の吸収を受け、光
の損失増加を招くからである。 Further, a substance 18 having a refractive index lower than that of the conductive film is provided on the conductive film region formed on the optical waveguides 14a and 14b.
The reason why portions a and 18b are provided is that if metal is provided directly on these areas, light will be absorbed by the metal, leading to an increase in light loss.
このような本実施例によれば、光の損失増加を
招くことなく、かつ、スイツチ特性のDCドリフ
トなく高速動作が可能となる光スイツチ・変調器
を得ることができる。 According to this embodiment, it is possible to obtain an optical switch/modulator that is capable of high-speed operation without causing an increase in optical loss and without DC drift in the switch characteristics.
第１図に示す構造において、方向性結合器の電
極の形状として幅10μm，ギヤツプ4μm，長さ2.2
mmのものを形成した場合の周波数応答特性は、例
えばLiNbO3より屈折率が低い導電膜としてITO
のみで形成した場合は約1MHzの応答が限界であ
るのに対して、ITOよりなる導電膜と金属の厚み
を同一にした場合、この構造により約50MHz以上
の応答が得られ、高周波の使用が可能となる。 In the structure shown in Figure 1, the shape of the electrode of the directional coupler is 10 μm in width, 4 μm in gap, and 2.2 μm in length.
For example, ITO is used as a conductive film with a lower refractive index than LiNbO 3 .
However, if the conductive film made of ITO and the metal are made of the same thickness, a response of approximately 50 MHz or more can be obtained with this structure, making it possible to use high frequencies. It becomes possible.
以上、本発明の一実施例について説明したが、
本発明による光スイツチ・変調器は方向性結合器
型に限定されるものでなく、反射器型，分岐干渉
型などのあらゆる光スイツチ・変調器にも適用で
きるのは明らかである。 Although one embodiment of the present invention has been described above,
It is clear that the optical switch/modulator according to the present invention is not limited to the directional coupler type, but can be applied to any type of optical switch/modulator such as a reflector type or a branching interference type.
〔発明の効果〕
以上説明したように、本発明によればLiNbO3
基板を用いた導波型の光スイツチ・変調器におい
て、光路をスイツチするまたは光を変調するため
の制御信号が印加される電極、その引き出し線お
よびパツドとしてLiNbO3より屈折率が低い導電
膜を直接にLiNbO3基板上に形成し、かつ、光導
波路上に形成された導電膜領域上に導電膜より屈
折率が低い物質を設け、さらにその上に金属膜を
設け、光導波路上に形成されていない導電膜領域
上に直接に金属膜を設けることにより、光の損失
増加を招くことがなく、かつ、スイツチ特性の
DCドリフトがなく高速動作を可能とする光スイ
ツチ・変調器を実現することができる。[Effect of the invention] As explained above, according to the present invention, LiNbO 3
In a waveguide type optical switch/modulator using a substrate, a conductive film with a refractive index lower than LiNbO 3 is used as the electrode to which a control signal for switching the optical path or modulating the light is applied, its lead wire, and pad. It is formed directly on the LiNbO 3 substrate, and a material with a lower refractive index than the conductive film is provided on the conductive film region formed on the optical waveguide, and a metal film is further provided on top of the conductive film region, which is formed on the optical waveguide. By providing a metal film directly on the conductive film region that is not covered, there is no increase in light loss, and the switch characteristics can be improved.
It is possible to realize an optical switch/modulator that has no DC drift and can operate at high speed.
第１図は本発明の一実施例の光スイツチ・変調
器の断面図、第２図、第３図は従来例の光スイツ
チ・変調器における電極構造の断面図である。
１１……LiNbO3基板、１３ａ，１３ｂ……
LiNbO3より屈折率が低い導電膜、１４ａ，１４
ｂ……光導波路、１５ａ，１５ｂ……導電性の透
明材料（In2O3）、１６ａ，１６ｂ……金属膜、１
７……バツフア層、１８ａ，１８ｂ……LiNbO3
より屈折率が低い導電膜より屈折率が低い物質、
１９ａ，１９ｂ……金属膜。
FIG. 1 is a sectional view of an optical switch/modulator according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views of electrode structures in conventional optical switches/modulators. 11...LiNbO 3 substrate, 13a, 13b...
Conductive film with lower refractive index than LiNbO 3 , 14a, 14
b... Optical waveguide, 15a, 15b... Conductive transparent material (In 2 O 3 ), 16a, 16b... Metal film, 1
7... Buffer layer, 18a, 18b... LiNbO 3
A substance with a lower refractive index than a conductive film with a lower refractive index,
19a, 19b...Metal film.
Claims (1)
変調器において、 光路をスイツチするまたは光を変調するための
制御信号が印加される電極、その引き出し線およ
びパツドとしてLiNbO3より屈折率が低い導電膜
を直接にLiNbO3基板上に形成し、かつ、光導波
路上に形成された導電膜領域上に、導電膜より屈
折率が低い物質を設け、この物質上に、および光
導波路上に形成されていない導電膜領域上に直接
に金属膜を設けたことを特徴とする光スイツチ・
変調器。[Claims] 1. Waveguide type optical switch using LiNbO 3 substrate.
In the modulator, a conductive film with a refractive index lower than that of LiNbO 3 is formed directly on the LiNbO 3 substrate as the electrode, its lead line, and pad to which a control signal for switching the optical path or modulating the light is applied, and , a substance having a lower refractive index than the conductive film is provided on the conductive film region formed on the optical waveguide, and a metal film is provided directly on this material and on the conductive film region not formed on the optical waveguide. A light switch featuring
modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28523687A JPH01128038A (en) | 1987-11-13 | 1987-11-13 | Optical switching and modulating device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28523687A JPH01128038A (en) | 1987-11-13 | 1987-11-13 | Optical switching and modulating device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01128038A JPH01128038A (en) | 1989-05-19 |
| JPH055334B2 true JPH055334B2 (en) | 1993-01-22 |
Family
ID=17688877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28523687A Granted JPH01128038A (en) | 1987-11-13 | 1987-11-13 | Optical switching and modulating device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01128038A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001159442A (en) | 1999-12-01 | 2001-06-12 | Unisia Jecs Corp | Stay damper |
-
1987
- 1987-11-13 JP JP28523687A patent/JPH01128038A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01128038A (en) | 1989-05-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |