JPH0293423A - Optical waveguide device - Google Patents
Optical waveguide deviceInfo
- Publication number
- JPH0293423A JPH0293423A JP24520188A JP24520188A JPH0293423A JP H0293423 A JPH0293423 A JP H0293423A JP 24520188 A JP24520188 A JP 24520188A JP 24520188 A JP24520188 A JP 24520188A JP H0293423 A JPH0293423 A JP H0293423A
- Authority
- JP
- Japan
- Prior art keywords
- traveling wave
- thickness
- electrode
- buffer layer
- wave electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 42
- 239000000758 substrate Substances 0.000 claims abstract description 18
- 239000013078 crystal Substances 0.000 claims description 6
- 230000005684 electric field Effects 0.000 claims description 4
- 230000007423 decrease Effects 0.000 abstract description 7
- 230000008719 thickening Effects 0.000 abstract 2
- 238000010586 diagram Methods 0.000 description 7
- 239000010931 gold Substances 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
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
- G02F1/03—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 based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/035—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 based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect in an optical waveguide structure
- G02F1/0356—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 based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect in an optical waveguide structure controlled by a high-frequency electromagnetic wave component in an electric waveguide structure
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
〔概要］
光導波路デバイスに関し、光変調器の変調帯域の拡大、
動作電圧の低減等を目的とし、バッファ層の厚さを０．
８μｍ〜４μｍ、進行波電極の厚さを６μｍ〜５０μｍ
の構成として、いずれも従来用いられている構造の２倍
以上の厚さとした。[Detailed Description of the Invention] [Summary] Regarding optical waveguide devices, expanding the modulation band of an optical modulator,
For the purpose of reducing operating voltage, etc., the thickness of the buffer layer is set to 0.
8 μm to 4 μm, and the thickness of the traveling wave electrode to 6 μm to 50 μm.
Both structures are more than twice as thick as conventional structures.
本発明は光通信装置における光導波路デバイスに係り、
特に超高速のスイッチングや変調を行う場合の変調帯域
の拡大と動作電圧の低減を図った光導波路デバイスの構
成に関する。The present invention relates to an optical waveguide device in an optical communication device,
In particular, it relates to the structure of an optical waveguide device that aims to expand the modulation band and reduce the operating voltage when performing ultra-high-speed switching and modulation.
一般に光スィッチや光変調器等に使用される光導波路デ
バイスでは、ニオブ酸リチウム（ＬｉＮｂＯ：＋）等の
電気光学結晶基板表面に形成した光導波路に電界を印加
して屈折率を変化させ、該導波路中を進行する光信号の
スイッチングや位相変調を行っている。 しかし該導波
路中を進行する光信号やマイクロ波信号の速度は、該導
波路を取り巻く材料例えば上記結晶基板等の誘電率ひい
ては誘電率の平方根で定義される屈折率によって大きく
変化する。Generally, in optical waveguide devices used in optical switches and optical modulators, an electric field is applied to an optical waveguide formed on the surface of an electro-optic crystal substrate such as lithium niobate (LiNbO:+) to change the refractive index. It performs switching and phase modulation of optical signals traveling in a waveguide. However, the speed of the optical signal or microwave signal traveling through the waveguide varies greatly depending on the dielectric constant of the material surrounding the waveguide, such as the above-mentioned crystal substrate, and the refractive index defined by the square root of the dielectric constant.
例えば、導波路を取り巻く材料の誘電率をε、屈折率を
ｎ、導波路中の速度をＶ、光速度をＣとすると、
ｎ−εＩ／ｚ
ｖ ＝ ｃ ／ ｎ
なる関係がある。For example, if the dielectric constant of the material surrounding the waveguide is ε, the refractive index is n, the velocity in the waveguide is V, and the speed of light is C, then there is the following relationship: n-εI/z v = c/n.
この場合、上記のニオブ酸リチウム（ＬｉＮｂＯ＋）で
は、例えば誘電率εが２８〜４３と大きく、従って光波
の屈折率（約２．１）に対してマイクロ波の屈折率（約
４．０）が大きいことから、特にＧＨｚオーダ等高周波
数のマイクロ波を伝送するときはその伝送速度が光に比
べて遅くなる。In this case, the above-mentioned lithium niobate (LiNbO+) has a large dielectric constant ε of 28 to 43, so the refractive index for microwaves (about 4.0) is lower than the refractive index for light waves (about 2.1). Because of their large size, especially when transmitting high frequency microwaves such as on the order of GHz, the transmission speed is slower than that of light.
このため、従来では効率良く動作させるのに進行波電極
を取り巻く材料の誘電率εを小さくしたり、該進行波電
極の構造を工夫してマイクロ波の速度を大きくして光波
との速度整合をとるようにしている。For this reason, in order to operate efficiently, conventional methods have required reducing the dielectric constant ε of the material surrounding the traveling wave electrode, or devising the structure of the traveling wave electrode to increase the speed of the microwave and matching the speed with the light wave. I try to take it.
第６図は従来の光導波路デバイスの構成例を示した図で
あり、特に高速動作が必要である光スィッチ、光変調器
等における場合を示している。FIG. 6 is a diagram showing an example of the configuration of a conventional optical waveguide device, particularly in the case of an optical switch, an optical modulator, etc., which require high-speed operation.
図で、１は横方向に結晶軸方位のＸ軸を、奥行き方向に
Ｙ軸を、また電気光学係数ｒ３３を用いるために厚さ方
向にＺ軸が来るようカットしたニオブ酸リチウム（Ｌｉ
ＮｂＯａ）よりなる導波路基板でありその表面には結晶
軸図示Ｙ方向にチタン（Ｔｉ）蒸着膜を帯状にパターニ
ング形成した後、該チタンを導波路基板１中に熱拡散し
て該導波路基板１よりも屈折率の大きい７μｍ程度の径
を有する光導波路２を形成している。In the figure, 1 is lithium niobate (Li) cut so that the X-axis of the crystal axis is in the horizontal direction, the Y-axis is in the depth direction, and the Z-axis is in the thickness direction to use the electro-optic coefficient r33.
The waveguide substrate is made of NbOa), on the surface of which a titanium (Ti) vapor deposited film is patterned in a band shape in the Y direction of the crystal axis, and then the titanium is thermally diffused into the waveguide substrate 1 to form the waveguide substrate. An optical waveguide 2 having a diameter of about 7 μm, which has a larger refractive index than 1, is formed.
ついで進行波電極近傍の誘電率を小さくし、それととも
に光学的に該電極への光のしみだしを防ぐため、該導波
路基板ｌの表面全面に通常の化学気相成長法（ＣＶＤ）
技術によって０．３〜０．４μｍの厚さに誘電率εが４
．０、屈折率が１．４５程度の二酸化シリコン（ＳｉＯ
□）を被着させてバッファ層３を形成している。Next, in order to reduce the dielectric constant in the vicinity of the traveling wave electrode and at the same time optically prevent light from seeping into the electrode, the entire surface of the waveguide substrate l is coated with conventional chemical vapor deposition (CVD).
Depending on the technology, the dielectric constant ε is 4 at a thickness of 0.3 to 0.4 μm.
．． 0, silicon dioxide (SiO) with a refractive index of about 1.45
□) is deposited to form the buffer layer 3.
更に上記バッファ層３の表面で該光導波路２に対応する
位置には、帯状に例えば幅が数μｍ、厚さ３μｍ程度の
金（Ａｕ）Ｉ膜からなる信号用電極４と接地用電極５を
蒸着、メツキ等の手段を用いて配置している。Further, on the surface of the buffer layer 3, at a position corresponding to the optical waveguide 2, a signal electrode 4 and a grounding electrode 5 made of a gold (Au) I film having a width of several μm and a thickness of about 3 μm, for example, are formed in a strip shape. They are arranged using methods such as vapor deposition and plating.
かかる構成になる光導波路デバイスでは、画電極４．５
間に電界を与えるとバッファ層３を介して電気力線ａが
形成され、該導波路基板１の屈折率が変化して高速のス
イッチングまたは変調を数ボルトの低電圧で行う場合に
は、前述した導波路基板における光波とマイクロ波の屈
折率の違いによる速度のズレが無視できなくなってきて
いる。In the optical waveguide device having such a configuration, the picture electrode 4.5
When an electric field is applied between them, electric lines of force a are formed through the buffer layer 3, and when the refractive index of the waveguide substrate 1 changes and high-speed switching or modulation is performed at a low voltage of several volts, the above-mentioned The difference in speed between light waves and microwaves due to the difference in refractive index in the waveguide substrate can no longer be ignored.
従来の光導波路制用進行波電極の形成方法では１０ＧＨ
ｚオーダあるいはそれ以上の超高速のスイッチングまた
は変調を数ボルト程度（１０ボルト以下）の低電圧で動
作できないという問題があった。In the conventional method of forming traveling wave electrodes for controlling optical waveguides, 10GH
There has been a problem in that ultrahigh-speed switching or modulation of Z order or higher cannot be performed at a low voltage of about several volts (10 volts or less).
（問題点を解決するための手段〕
上記問題点は、光導波路が設けられた光導波路基板上に
バッファ層と進行波電極を形成する場合、それらの厚さ
を従来の２倍以上の、バッファ層は０．８μｍ〜４μｍ
、進行波電極は６μｍ〜５０μｍの厚さに形成すること
によって解決される。(Means for solving the problem) The above problem is that when forming a buffer layer and a traveling wave electrode on an optical waveguide substrate on which an optical waveguide is provided, the thickness of the buffer layer and the traveling wave electrode is twice or more than that of the conventional buffer layer. The layer is 0.8μm to 4μm
, the traveling wave electrode is formed with a thickness of 6 μm to 50 μm.
光導波路デバイスでマイクロ波の速度を速くして光速に
近づけるには進行波電極を厚くすることが有効であり、
特に６μｍ以上の厚さに該進行波電極を形成した場合に
はその効果が大きい。In order to increase the speed of microwaves in optical waveguide devices and bring them closer to the speed of light, it is effective to make the traveling wave electrode thicker.
The effect is particularly great when the traveling wave electrode is formed to have a thickness of 6 μm or more.
しかしながら、このように進行波電極を厚くすると該進
行波電極を構成する信号用電極と接地用電極間の静電容
量が増し、その結果進行波電極の特性インピーダンスが
減少してしまう。However, if the traveling wave electrode is made thicker in this manner, the capacitance between the signal electrode and the grounding electrode that constitute the traveling wave electrode increases, and as a result, the characteristic impedance of the traveling wave electrode decreases.
この傾向は進行波電極の場合印加電圧が等しいならば特
性インピーダンスが低い程消費電力が増加するので不利
である。This tendency is disadvantageous in the case of traveling wave electrodes because if the applied voltages are the same, the lower the characteristic impedance, the higher the power consumption.
また、現在広く一般に使われている電源、測定機器、コ
ネクタケーブルは５０Ω系で製作されているので、デバ
イスの特性インピーダンスを５０Ωにすることは重要で
ある。Furthermore, since power supplies, measuring instruments, and connector cables that are currently widely used are manufactured in the 50Ω system, it is important to set the characteristic impedance of the device to 50Ω.
以上のような理由により、進行波電極を厚くしたことに
よる特性インピーダンスの減少を何らかの方法で増加さ
せる必要がある。この手段としてバッファ層を厚くする
ことが有効であることを理論計算および実験により見出
した。バッファ層を厚くすると進行波電極の特性インピ
ーダンスが増加するとともにマイクロ波の伝搬速度が増
す。これは、バッファ層に用いる材料が一般に、基板材
料よりも誘電率の小さい材料であることによる。For the reasons mentioned above, it is necessary to somehow increase the decrease in characteristic impedance caused by increasing the thickness of the traveling wave electrode. We have found through theoretical calculations and experiments that increasing the thickness of the buffer layer is an effective means of achieving this. Increasing the thickness of the buffer layer increases the characteristic impedance of the traveling wave electrode and increases the propagation speed of microwaves. This is because the material used for the buffer layer generally has a lower dielectric constant than the substrate material.
尚、バッファ層を厚くすることによって光導波路部分に
印加される電界が弱まり、変調効率が多少低下するが、
この点に関しても理論計算および実験により電極長を充
分に長くすることによって解決できることを見出してい
る。Note that by making the buffer layer thicker, the electric field applied to the optical waveguide becomes weaker, and the modulation efficiency decreases to some extent;
We have found through theoretical calculations and experiments that this problem can be solved by making the electrode length sufficiently long.
すなわち、バッファ層を厚くすると変調帯域も動作電圧
も両方増加するがその割合は前者の方が大きく、また両
者ともに電極長に反比例することを考慮すると、変調帯
域が等しい変調器を製作した場合に、バッファ層を厚べ
すれば電極長は長くなるが動作電圧はむしろ減少するこ
とになるからである。In other words, when the buffer layer is thickened, both the modulation band and the operating voltage increase, but the former is larger, and considering that both are inversely proportional to the electrode length, if a modulator with the same modulation band is manufactured, This is because if the buffer layer is made thicker, the electrode length becomes longer, but the operating voltage actually decreases.
以上のように、進行波電極を厚くすることとバッファ層
を厚くすることを同時に行えば、従来よりも変調帯域が
広く動作電圧が低い、しかも進行波電極の特性インピー
ダンスが５０Ωであるような変調器を製作することがで
きる。As described above, if we simultaneously increase the thickness of the traveling wave electrode and the buffer layer, we can achieve modulation with a wider modulation band and lower operating voltage than before, and in which the characteristic impedance of the traveling wave electrode is 50Ω. You can make utensils.
第１図（Ａ） （Ｂ） （Ｃ）は本発明になる光導波路
デバイスの例を示す工程図である。FIGS. 1A, 1B, and 1C are process diagrams showing an example of an optical waveguide device according to the present invention.
第１図（Ａ）において、６は第６図同様にニオブ酸リチ
ウム（ＬｉＮｂＯｚ）よりなるＺ板としてカットした導
波路基板であり、横方向にＸ軸がくるようにカットしで
ある。In FIG. 1(A), 6 is a waveguide substrate cut as a Z plate made of lithium niobate (LiNbOz) in the same manner as in FIG. 6, and is cut so that the X axis is in the lateral direction.
また該導波路基板６表面には、結晶軸Ｙ方向にチタン（
Ｔｉ）をパターニング形成した後に加熱して上記チタン
を導波路基板６に熱拡散させた径が７μｍ程度の帯状の
光導波路７が相互に１０数μｍの間隔を保って平行に形
成されている。Further, the surface of the waveguide substrate 6 is made of titanium (
Band-shaped optical waveguides 7 having a diameter of about 7 μm are formed in parallel with each other with an interval of 10-odd μm, which is formed by patterning Ti) and thermally diffusing the titanium onto the waveguide substrate 6 by heating.
８は第６図のバッファＮ３に比し厚さだけを０゜８μｍ
〜４μｍと厚くした二酸化シリコン（ＳｉＯｚ）からな
るバッファ層であり、９は通常の蒸着技術で該バッファ
層８の全面に被着形成した厚さ１０００〜２０００人程
度の金（Ａｕ）蒸着膜を示している。8 has a thickness of 0°8 μm compared to buffer N3 in Figure 6.
9 is a buffer layer made of silicon dioxide (SiOz) thickened to ~4 μm, and 9 is a gold (Au) vapor deposited film with a thickness of about 1000 to 2000 layers, which is deposited on the entire surface of the buffer layer 8 using a normal vapor deposition technique. It shows.
次いで各光導波路７に対応した所定位置に信号用電極と
接地用電極を形成するため、レジストｌＯを厚さ３〜４
μｍ程度にパターニングし、第１図（Ｂ）に示す状態に
する。Next, in order to form signal electrodes and ground electrodes at predetermined positions corresponding to each optical waveguide 7, resist lO is deposited to a thickness of 3 to 4 mm.
It is patterned to a size of about .mu.m to form the state shown in FIG. 1(B).
その後、上記レジスＮＯのパターン空間部すなわち電極
形成部分に電界メツキ技術によって金（Ａｕ）メツキを
施し幅５〜２０μｍ程度の信号用電極１１と幅の広い接
地用電極１２を有する進行波電極を、該画電極１１．１
２の間隔がバッファ層８に接する部分で１０μｍ〜３０
μｍｊｌれるように形成する。After that, the pattern space part of the resist NO, that is, the electrode forming part, is plated with gold (Au) by electroplating technology to form a traveling wave electrode having a signal electrode 11 with a width of about 5 to 20 μm and a wide ground electrode 12. The picture electrode 11.1
2 is 10 μm to 30 μm at the part in contact with the buffer layer 8.
It is formed so that μmjl can be formed.
このような方法で製作した変調器の変調帯域、動作電圧
および進行波電極の厚さの関係を第２図に示す。ここで
バッファ層の厚さを０．３μｍと従来の厚さとし、且つ
信号用電極１１の幅は９ｕｍ、画電極１１と１２の間隔
は１５μｍで一定とじである。FIG. 2 shows the relationship among the modulation band, operating voltage, and thickness of the traveling wave electrode of the modulator manufactured by this method. Here, the thickness of the buffer layer is 0.3 μm, which is the conventional thickness, the width of the signal electrode 11 is 9 μm, and the interval between the picture electrodes 11 and 12 is constant at 15 μm.
第２図から、進行波電極を厚くするにしたがって変調帯
域は点線Ａの如く増加するが、動作電圧は実線Ｂに示す
ようにほとんど変化しないことがわかる。From FIG. 2, it can be seen that as the traveling wave electrode becomes thicker, the modulation band increases as shown by the dotted line A, but the operating voltage hardly changes as shown by the solid line B.
また、第３図には進行波電極の特性インピーダンスと該
進行波電極の厚さの関係を示し、特性インピーダンスは
進行波電極が厚くなるにしたがって実線Ｃの通り単調に
減少している。Further, FIG. 3 shows the relationship between the characteristic impedance of the traveling wave electrode and the thickness of the traveling wave electrode, and the characteristic impedance monotonically decreases as shown by the solid line C as the traveling wave electrode becomes thicker.
次に、バッファ層８を厚くした場合の効果について第４
図および第５図により説明する。Next, we will discuss the effect of increasing the thickness of the buffer layer 8 in the fourth section.
This will be explained with reference to the drawings and FIG.
ここで進行波電極の厚さは９μｍ、信号用電極１１の幅
は９μｍ、画電極１１と１２の間隔は１５μｍで一定と
しである。Here, the thickness of the traveling wave electrode is 9 μm, the width of the signal electrode 11 is 9 μm, and the interval between the picture electrodes 11 and 12 is constant at 15 μm.
第４図には変調帯域、動作電圧およびバッファ層厚の関
係が示してあり、特に変調帯域の増加（点線りを参照）
が動作電圧の増加（実線Ｅを参照）よりもかなり顕著で
あることがわかる。Figure 4 shows the relationship between modulation band, operating voltage and buffer layer thickness, especially as the modulation band increases (see dotted line).
is much more pronounced than the increase in operating voltage (see solid line E).
第５図には動作電圧を変調帯域で規格化した値（点ｖＡ
Ｆを参照）、進行波電極の特性インピーダンスおよびバ
ッファ層８の厚さの関係が示しである。Figure 5 shows the value of the operating voltage normalized by the modulation band (point vA
F), the relationship between the characteristic impedance of the traveling wave electrode and the thickness of the buffer layer 8 is shown.
前述のように、変調帯域、動作電圧はともに進行波電極
長に反比例するので、バッファ層８を厚くすると第４図
の点線Ｅの如く動作電圧は増加するが、これは該進行波
電極の長さを長くすることにより対処できる。また、進
行波電極の特性インピーダンスはバッファ層８を厚くす
ることによって増加させることができることも示されて
おり（実線Ｇを参照）、進行波電極を厚くした場合に起
こる特性インピーダンスの減少に対して有効な対処法に
なる。As mentioned above, both the modulation band and the operating voltage are inversely proportional to the length of the traveling wave electrode, so when the buffer layer 8 is made thicker, the operating voltage increases as indicated by the dotted line E in FIG. This can be dealt with by increasing the length. It has also been shown that the characteristic impedance of the traveling wave electrode can be increased by increasing the thickness of the buffer layer 8 (see solid line G), which corresponds to the decrease in characteristic impedance that occurs when the traveling wave electrode is made thicker. It's an effective solution.
実際に、進行波電極の厚さを９μｍ、信号用電極１１の
幅を９μｍ、信号用電極１１と接地用電極１２の間隔を
１５μｍ、バッファ層８の厚さを０．８μｍ、進行波電
極長を２０ｍｍとして変調器を作製したところ、波長１
．５５μｍの光に対して動作電圧８．５■、変調帯域１
０ＧＨｚ、特性インピーダンス５０Ωの特性が得られた
。Actually, the thickness of the traveling wave electrode was 9 μm, the width of the signal electrode 11 was 9 μm, the distance between the signal electrode 11 and the grounding electrode 12 was 15 μm, the thickness of the buffer layer 8 was 0.8 μm, and the traveling wave electrode length was When a modulator was fabricated with a wavelength of 20 mm, the wavelength of 1
．． Operating voltage 8.5■ for 55μm light, modulation band 1
Characteristics of 0 GHz and characteristic impedance of 50 Ω were obtained.
さらに広帯域、低動作電圧の変調器を得ようとする場合
には、進行波電極およびバッファ層８をもっと厚くし電
極長を伸ばすことで実現できる。If it is desired to obtain a modulator with a wider band and a lower operating voltage, it can be achieved by making the traveling wave electrode and the buffer layer 8 thicker and increasing the electrode length.
この際、動作電圧の最小値は電気光学結晶基板のウェハ
ーサイズで制限されることから該進行波電極の長さは２
０ｍｍ〜５０ｍｍの範囲が好ましい。At this time, since the minimum value of the operating voltage is limited by the wafer size of the electro-optic crystal substrate, the length of the traveling wave electrode is 2
A range of 0 mm to 50 mm is preferable.
また、進行波電極を厚くすることはマイクロ波が進行波
電極を伝搬する場合の導体損失の低減に効果があり、バ
ッファ層８を厚くすることは導波路７を伝搬する光波の
進行波電極による吸収損失を低減できる効果も合わせ持
つ。In addition, increasing the thickness of the traveling wave electrode is effective in reducing conductor loss when microwaves propagate through the traveling wave electrode, and increasing the thickness of the buffer layer 8 is effective in reducing conductor loss when the microwave propagates through the traveling wave electrode. It also has the effect of reducing absorption loss.
更に、バッファＮ８の厚さの上限については、４μｍ程
度とすれば光の速度整合が完全にとれて変調帯域が分散
を無視した場合に無限大になることから設定されており
、結局該バッファ層８の厚さは０．８μｍ〜４μｍが好
ましい。また、進行波電極の厚さの上限は厚膜形成のプ
ロセスによって制限されることから、メツキ形成可能な
最大厚さである５０μｍが設定される。Furthermore, the upper limit of the thickness of the buffer N8 is set to about 4 μm because the velocity matching of light will be completely achieved and the modulation band will become infinite if dispersion is ignored. The thickness of No. 8 is preferably 0.8 μm to 4 μm. Further, since the upper limit of the thickness of the traveling wave electrode is limited by the process of forming a thick film, the maximum thickness that can be plated is set at 50 μm.
以上の各種効果を考慮すると、光学的見地から有効な信
号用電極幅５〜２０μｍで信号用電極と接地用電極との
間隔がバッファ層に接する部分で１０〜３０μｍである
進行波電極において、バッファ層厚については０．８μ
ｍ〜４μｍ、進行波型極厚については６μｍ〜５０μｍ
で構成することが有効である。また、動作電圧とウェハ
ーサイズを考慮すると進行波電極長としては２０ｍｍ〜
５０ｍｍがとくに有効と考えられる。Considering the various effects mentioned above, from an optical point of view, in a traveling wave electrode in which the effective signal electrode width is 5 to 20 μm and the distance between the signal electrode and the ground electrode is 10 to 30 μm at the part in contact with the buffer layer, The layer thickness is 0.8μ
m ~ 4μm, 6μm ~ 50μm for traveling wave type extra thick
It is effective to configure the Also, considering the operating voltage and wafer size, the traveling wave electrode length is 20 mm ~
50 mm is considered to be particularly effective.
以上記載した内容は、光スィッチ等の同種の進行波電極
を用いた光導波路デバイスにも適用できる。The content described above can also be applied to optical waveguide devices using the same type of traveling wave electrodes, such as optical switches.
［発明の効果］
上述の如く本発明により、従来の構成のものよりも広帯
域で、且つ動作電圧の低い光変調器や光スィッチを特性
インピーダンス５０Ωで製作できる。[Effects of the Invention] As described above, according to the present invention, it is possible to manufacture an optical modulator or optical switch with a characteristic impedance of 50Ω that has a wider band and lower operating voltage than those with a conventional configuration.
イスを示す図である。FIG.
第２図は変調帯域と動作電圧および電極厚の関係を示す
図である。FIG. 2 is a diagram showing the relationship between modulation band, operating voltage, and electrode thickness.
第３図は特性インピーダンスと電極厚の関係を示す図で
ある。FIG. 3 is a diagram showing the relationship between characteristic impedance and electrode thickness.
第４図は変調帯域と動作電圧およびバッファ層厚の関係
を示す図である。FIG. 4 is a diagram showing the relationship between modulation band, operating voltage, and buffer layer thickness.
第５図は特性インピーダンスと動作電圧を変調帯域で規
格化したものおよびバッファ層厚の関係を示す図である
。FIG. 5 is a diagram showing the relationship between characteristic impedance, operating voltage normalized by modulation band, and buffer layer thickness.
第６図は従来の光導波路デバイスの構成例を示す図であ
る。FIG. 6 is a diagram showing an example of the configuration of a conventional optical waveguide device.
〔符号の説明］
１．６は導波路基板、 ２．７は光導波路、３．８はバ
ッファ層、 ４．１１は信号用電極、５．１２は接地
用電極、９は金蒸着膜、[Explanation of symbols] 1.6 is a waveguide substrate, 2.7 is an optical waveguide, 3.8 is a buffer layer, 4.11 is a signal electrode, 5.12 is a grounding electrode, 9 is a gold vapor deposited film,
第１図（Ａ） （Ｂ） （Ｃ）は本発明に係る光導波路
デバ１？１
／θ
ノＯ
重２＆肖
シへ）
イ
１！
θ”ｇｌ、０
３．０
ノぐ・、λフ１肩
（１党）
岨
）ΣFigure 1 (A) (B) (C) shows the optical waveguide device according to the present invention. θ”gl, 0 3.0 Nog, λfu 1 shoulder (1 party) 岨)Σ
Claims (2)
導波路よりも屈折率が小さいバッファ層が少なくとも１
層以上形成され、この上に電界印加用の進行波電極が形
成された構造を持つ光導波路デバイスに於いて、 前記バッファ層の厚さを０．８μｍ〜４μｍ、前記進行
波電極の厚さを６μｍ〜５０μｍとしたことを特徴とす
る光導波路デバイス。(1) At least one buffer layer having a refractive index lower than that of the optical waveguide is provided on the optical waveguide formed on the electro-optic crystal substrate.
In an optical waveguide device having a structure in which a traveling wave electrode for applying an electric field is formed on the buffer layer, the thickness of the buffer layer is 0.8 μm to 4 μm, and the thickness of the traveling wave electrode is 0.8 μm to 4 μm. An optical waveguide device characterized by having a thickness of 6 μm to 50 μm.
た請求項１に記載の光導波路デバイス。(2) The optical waveguide device according to claim 1, wherein the traveling wave electrode has a length of 20 mm to 50 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24520188A JPH0293423A (en) | 1988-09-29 | 1988-09-29 | Optical waveguide device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24520188A JPH0293423A (en) | 1988-09-29 | 1988-09-29 | Optical waveguide device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0293423A true JPH0293423A (en) | 1990-04-04 |
Family
ID=17130127
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24520188A Pending JPH0293423A (en) | 1988-09-29 | 1988-09-29 | Optical waveguide device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0293423A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0813092A1 (en) * | 1996-06-14 | 1997-12-17 | Sumitomo Osaka Cement Co., Ltd. | Optical waveguide modulator with traveling-wave type electrodes |
| EP1079257A2 (en) * | 1999-08-27 | 2001-02-28 | Ngk Insulators, Ltd. | Travelling wave optical modulator |
-
1988
- 1988-09-29 JP JP24520188A patent/JPH0293423A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0813092A1 (en) * | 1996-06-14 | 1997-12-17 | Sumitomo Osaka Cement Co., Ltd. | Optical waveguide modulator with traveling-wave type electrodes |
| US5748358A (en) * | 1996-06-14 | 1998-05-05 | Sumitomo Osaka Cement Co., Ltd. | Optical modulator with optical waveguide and traveling-wave type electrodes |
| EP1079257A2 (en) * | 1999-08-27 | 2001-02-28 | Ngk Insulators, Ltd. | Travelling wave optical modulator |
| EP1079257A3 (en) * | 1999-08-27 | 2001-09-12 | Ngk Insulators, Ltd. | Travelling wave optical modulator |
| US6400494B1 (en) | 1999-08-27 | 2002-06-04 | Ngk Insulators, Ltd. | Traveling wave optical modulator |
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