JP2011215294A - Optical modulator - Google Patents

Optical modulator Download PDF

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JP2011215294A
JP2011215294A JP2010082232A JP2010082232A JP2011215294A JP 2011215294 A JP2011215294 A JP 2011215294A JP 2010082232 A JP2010082232 A JP 2010082232A JP 2010082232 A JP2010082232 A JP 2010082232A JP 2011215294 A JP2011215294 A JP 2011215294A
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electrode
substrate
optical modulator
signal electrode
signal
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Masayuki Ichioka
雅之 市岡
Takashi Jinriki
孝 神力
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Sumitomo Osaka Cement Co Ltd
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Sumitomo Osaka Cement Co Ltd
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Priority to PCT/JP2011/057939 priority patent/WO2011125692A1/en
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    • 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
    • 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
    • G02F1/0305—Constructional arrangements
    • G02F1/0316—Electrodes

Abstract

PROBLEM TO BE SOLVED: To provide an optical modulator whose frequency response characteristic can be widened in bandwidth while suppressing an increase in a drive voltage, and which is suppressed in an increase in manufacturing time and cost.SOLUTION: In an optical modulator which has a substrate 1 having an electro-optical effect, an optical waveguide 2 formed on the substrate 1, and a modulating electrode modulating light waves propagating through the optical waveguide 2, the modulating electrode is a coplanar electrode comprising a signal electrode S and grounding electrodes G disposed so as to sandwich the signal electrodes S, and gaps (G1 and G2) between the signal electrode and the grounding electrodes are configured so as to gradually become wider in the direction from the portion closest to the substrate to the portion far away from the substrate, and at least the entire signal electrode is configured from a single material.

Description

本発明は、光変調器に関するものであり、特に、電気光学効果を有する基板に光導波路及び変調電極を形成した光変調器に関する。   The present invention relates to an optical modulator, and more particularly to an optical modulator in which an optical waveguide and a modulation electrode are formed on a substrate having an electro-optic effect.

光通信分野や光計測分野において、ニオブ酸リチウムなどの電気光学効果を有する基板に光導波路及び変調電極を形成した光変調器が多用されている。このような光変調器は、数十ＧＨｚ以上の高速変調が可能であり、より一層の高速変調や周波数応答特性の改善が求められている。   In the optical communication field and the optical measurement field, an optical modulator in which an optical waveguide and a modulation electrode are formed on a substrate having an electrooptic effect such as lithium niobate is frequently used. Such an optical modulator can perform high-speed modulation of several tens of GHz or more, and further improvement in high-speed modulation and frequency response characteristics is required.

光変調器の変調電極については、図１に光変調器の断面の一部を示すように、基板１上に信号電極Ｓ及び接地電極Ｇが形成されている。符号２は、基板１に形成された光導波路を示している。   As for the modulation electrode of the optical modulator, a signal electrode S and a ground electrode G are formed on the substrate 1 as shown in a part of a cross section of the optical modulator in FIG. Reference numeral 2 denotes an optical waveguide formed on the substrate 1.

図１のような形状の変調電極では、信号電極の幅が、基板に最も近い部分の幅（Ｗ１）から基板から最も離れた部分の幅（Ｗ２）へと徐々に幅が大きくなるように形成され、信号電極Ｓと接地電極Ｇとの間隔は、逆に、基板に最も近い部分の間隔（Ｇ１）から基板から最も離れた部分の間隔（Ｇ２）へと徐々に狭くなるよう構成されている。   In the modulation electrode having the shape as shown in FIG. 1, the width of the signal electrode is gradually increased from the width (W1) of the portion closest to the substrate to the width (W2) of the portion farthest from the substrate. On the contrary, the interval between the signal electrode S and the ground electrode G is configured to gradually narrow from the interval (G1) closest to the substrate to the interval (G2) farthest from the substrate. .

しかしながら、図１のような形状の変調電極を利用する場合には、周波数応答帯域の広帯域化を図るためには、信号電極と接地電極との間隔Ｇ１を広くする必要があるが、間隔Ｇ１を大きくすると駆動電圧が上昇するという問題を生じる。   However, when the modulation electrode having the shape as shown in FIG. 1 is used, it is necessary to widen the gap G1 between the signal electrode and the ground electrode in order to widen the frequency response band. If it is increased, the drive voltage increases.

他方、特許文献１には、図２に示すような形状の変調電極も提案されている。基板１の上に電極下部（台座）３を形成し、その上に電極上部を形成し、電極の断面形状が連続的な形状とはなっていない。電極上部の幅（Ｗ２）は、電極下部の幅（Ｗ１)より幅の狭い電極であり、また、電極下部の信号電極Ｓと接地電極Ｇとの間隔（Ｇ１）は、電極上部の間隔（Ｇ２）よりも狭くなっている。信号電極や接地電極を形成している。   On the other hand, Patent Document 1 also proposes a modulation electrode having a shape as shown in FIG. An electrode lower part (pedestal) 3 is formed on the substrate 1 and an electrode upper part is formed thereon, and the cross-sectional shape of the electrode is not continuous. The width (W2) of the upper portion of the electrode is narrower than the width (W1) of the lower portion of the electrode, and the interval (G1) between the signal electrode S and the ground electrode G below the electrode is the interval (G2) of the upper portion of the electrode. ) Is narrower than. A signal electrode and a ground electrode are formed.

しかしながら、図２の電極を形成するには、少なくとも２回以上の電極形成プロセスが必要であり、電極形成に掛る時間やコストが増大する原因となる。   However, forming the electrode of FIG. 2 requires at least two electrode formation processes, which increases the time and cost for electrode formation.

特開平９−１８５０２５号公報JP-A-9-185025

本発明が解決しようとする課題は、上述したような問題を解決し、駆動電圧の増加を抑制しながら周波数応答特性の広帯域化が可能な光変調器を提供することであり、さらには、製造に掛る時間やコストの増加を抑制した光変調器を提供することである。   The problem to be solved by the present invention is to provide an optical modulator capable of solving the above-described problems and capable of widening the frequency response characteristic while suppressing an increase in drive voltage, and further, manufacturing. It is an object to provide an optical modulator that suppresses an increase in time and cost.

上記課題を解決するため、請求項１に係る発明は、電気光学効果を有する基板と、該基板に形成された光導波路と、該光導波路を伝搬する光波を変調するための変調電極とを有する光変調器において、該基板はＸカット型の基板であり、該基板の厚みは、２０μｍ以下であり、該変調電極は、信号電極とそれを挟むように配置される接地電極とからなるコプレーナ型電極であり、該信号電極と該接地電極との間隔は、基板に最も近い部分から基板からはなれる方向に向かって徐々に広くなるよう、該信号電極か該接地電極のどちらか一方が該基板の法線方向に対して傾斜するように構成され、少なくとも該信号電極全体は、単一の材料から構成されることを特徴とする。 In order to solve the above problems, an invention according to claim 1 includes a substrate having an electro-optic effect, an optical waveguide formed on the substrate, and a modulation electrode for modulating a light wave propagating through the optical waveguide. In the optical modulator, the substrate is an X-cut substrate, the thickness of the substrate is 20 μm or less, and the modulation electrode is a coplanar type including a signal electrode and a ground electrode arranged so as to sandwich the signal electrode. Either the signal electrode or the ground electrode so that the distance between the signal electrode and the ground electrode gradually increases from the portion closest to the substrate toward the direction away from the substrate. In this case , at least the entire signal electrode is made of a single material.

請求項２に係る発明は、請求項１に記載の光変調器において、該信号電極と該接地電極との間隔は連続的に変化するよう構成されていることを特徴とする。 The invention according to claim 2, in the optical modulator according to claim 1, the distance between the signal electrode and the grounding electrode is it characterized by being configured to change continuously.

請求項１に係る発明により、電気光学効果を有する基板と、該基板に形成された光導波路と、該光導波路を伝搬する光波を変調するための変調電極とを有する光変調器において、該変調電極は、信号電極とそれを挟むように配置される接地電極とからなるコプレーナ型電極であり、該信号電極と該接地電極との間隔は、基板に最も近い部分から基板からはなれる方向に向かって徐々に広くなるよう、該信号電極か該接地電極のどちらか一方が該基板の法線方向に対して傾斜するように構成され、少なくとも該信号電極全体は、単一の材料から構成されるため、駆動電圧の増加を抑制しながら周波数応答特性の広帯域化を実現可能な光変調器を提供することが可能となる。しかも、少なくとも信号電極全体が単一の材料で構成されるため、１度の製造プロセスで信号電極を形成することも可能となる。さらに、基板はＸカット型の基板であり、基板の厚みは、２０μｍ以下であるため、変調電極が形成する電界を効率良く光導波路に印加することが可能となり、周波数応答特性をより改善することも可能となる。 The invention according to 請 Motomeko 1, a substrate having an electro-optic effect, an optical waveguide formed on the substrate, an optical modulator having a modulation electrode for modulating light waves propagating through the optical waveguide, the The modulation electrode is a coplanar electrode composed of a signal electrode and a ground electrode arranged so as to sandwich the signal electrode, and the distance between the signal electrode and the ground electrode is in a direction away from the substrate from the portion closest to the substrate. The signal electrode or the ground electrode is configured to be inclined with respect to the normal direction of the substrate so that the signal electrode gradually becomes wider toward the substrate , and at least the entire signal electrode is formed of a single material. Therefore, it is possible to provide an optical modulator capable of realizing a wide frequency response characteristic while suppressing an increase in drive voltage. In addition, since at least the entire signal electrode is made of a single material, the signal electrode can be formed by a single manufacturing process. Furthermore, since the substrate is an X-cut substrate and the thickness of the substrate is 20 μm or less, the electric field formed by the modulation electrode can be efficiently applied to the optical waveguide, and the frequency response characteristics can be further improved. Is also possible.

請求項２に係る発明により、信号電極と接地電極との間隔は連続的に変化するよう構成されているため、図２に示した従来の光変調器のように、電極の製造工程が複雑化することが抑制され、製造時間や製造コストの増加も抑えられる。 According to the invention of claim 2, since the distance between the signal electrode and the ground electrode is configured to continuously change, the electrode manufacturing process becomes complicated as in the conventional optical modulator shown in FIG. it is suppressed that, even Ru suppresses increase of manufacturing time and manufacturing cost.

従来の光変調器の変調電極の断面を示す図である。It is a figure which shows the cross section of the modulation electrode of the conventional optical modulator. 従来の他の光変調器の変調電極の断面を示す図である。It is a figure which shows the cross section of the modulation | alteration electrode of the other conventional optical modulator. 本発明の光変調器の参考例に係る変調電極の断面を示す図である。It is a figure which shows the cross section of the modulation electrode which concerns on the reference example of the optical modulator of this invention. 本発明の光変調器に係る信号電極と接地電極について、他の実施例を示す図である。 For the signal electrode and the ground electrode according to the optical modulator of the present invention, showing another actual施例. 本発明の光変調器の参考例について、基板が薄板である場合の断面を示す図である。It is a figure which shows the cross section in case the board | substrate is a thin plate about the reference example of the optical modulator of this invention. 本発明の光変調器の参考例の製造プロセス（その１）の一部を示す図である。It is a figure which shows a part of manufacturing process (the 1) of the reference example of the optical modulator of this invention. 本発明の光変調器の参考例の製造プロセス（その２）の一部を示す図である。It is a figure which shows a part of manufacturing process (the 2) of the reference example of the optical modulator of this invention. 本発明の光変調器の参考例の製造プロセス（その３）の一部を示す図である。It is a figure which shows a part of manufacturing process (the 3) of the reference example of the optical modulator of this invention. 本発明の光変調器の参考例と従来例との周波数応答特性の比較結果を示すグラフである。It is a graph which shows the comparison result of the frequency response characteristic of the reference example of the optical modulator of this invention, and a prior art example.

以下、本発明の光変調器について、好適例を用いて詳細に説明する。
図３に示すように、本発明の参考例は、電気光学効果を有する基板１と、該基板に形成された光導波路２と、該光導波路を伝搬する光波を変調するための変調電極とを有する光変調器において、該変調電極は、信号電極Ｓとそれを挟むように配置される接地電極Ｇとからなるコプレーナ型電極であり、該信号電極と該接地電極との間隔（Ｇ１，Ｇ２）は、基板に最も近い部分から基板からはなれる方向に向かって徐々に広くなるよう構成され、少なくとも該信号電極（Ｓ）全体は、単一の材料から構成されることを特徴とする。 Hereinafter, the optical modulator of the present invention will be described in detail using preferred examples.
As shown in FIG. 3, the reference example of the present invention includes a substrate 1 having an electro-optic effect, an optical waveguide 2 formed on the substrate, and a modulation electrode for modulating a light wave propagating through the optical waveguide. In the optical modulator, the modulation electrode is a coplanar electrode composed of a signal electrode S and a ground electrode G arranged so as to sandwich the signal electrode S, and a distance (G1, G2) between the signal electrode and the ground electrode Is configured to gradually widen from the portion closest to the substrate in a direction away from the substrate, and at least the entire signal electrode (S) is formed of a single material.

電気光学効果を有する基板１としては、特に、ＬｉＮｂＯ３，ＬｉＴａＯ３又はＰＬＺＴ（ジルコン酸チタン酸鉛ランタン）のいずれかの単結晶が好適に利用可能である。また、基板に形成する光導波路は、例えば、ＬｉＮｂＯ３基板（ＬＮ基板）上にチタン（Ｔｉ）などの高屈折率物質を熱拡散することにより形成される。また、光導波路となる部分の両側に溝を形成したリブ型光導波路や光導波路部分を凸状としたリッジ型導波路も利用可能である。 As the substrate 1 having an electro-optic effect, any single crystal of LiNbO 3 , LiTaO 3 or PLZT (lead lanthanum zirconate titanate) can be suitably used. The optical waveguide formed on the substrate is formed, for example, by thermally diffusing a high refractive index material such as titanium (Ti) on a LiNbO 3 substrate (LN substrate). Further, a rib-type optical waveguide in which grooves are formed on both sides of a portion that becomes an optical waveguide and a ridge-type waveguide in which the optical waveguide portion is convex can be used.

変調電極は、信号電極Ｓや接地電極Ｇから構成され、基板表面に、Ｔｉ・Ａｕの電極パターンを形成し、金メッキ方法などにより形成することが可能である。さらに、必要に応じて光導波路形成後の基板表面に誘電体ＳｉＯ２等のバッファ層を設けることも可能である。なお、本発明に係る「信号電極全体は、単一の材料で構成される」との意味において、上述のように、基板と電極を構成する材料との接合強度を高めるため、Ｔｉ・Ａｕの電極パターンのような下地を設けることは、排除していない。 The modulation electrode includes a signal electrode S and a ground electrode G, and can be formed by forming a Ti / Au electrode pattern on the surface of the substrate and using a gold plating method or the like. Furthermore, a buffer layer such as a dielectric SiO 2 can be provided on the substrate surface after the formation of the optical waveguide, if necessary. In the sense that “the entire signal electrode is composed of a single material” according to the present invention, as described above, in order to increase the bonding strength between the substrate and the material constituting the electrode, Providing a base such as an electrode pattern is not excluded.

本発明の光変調器の特徴の一つは、変調電極を構成する信号電極Ｓと接地電極Ｇとの間隔を、基板１に最も近い部分から基板からはなれる方向に向かって徐々に広くなるよう構成することである。このため、本発明の参考例では、図３に示すように信号電極と接地電極の両方に傾斜した側面を形成することも可能であるが、本発明の光変調器の特徴は、図４（ａ）に示すように、信号電極Ｓのみに傾斜した側面を設けたり、図４（ｂ）に示すように、接地電極Ｇのみに傾斜した側面を設けることである。 One of the features of the optical modulator of the present invention is that the distance between the signal electrode S and the ground electrode G constituting the modulation electrode is gradually increased from the portion closest to the substrate 1 toward the direction away from the substrate. Is to configure. Therefore, in the reference example of the present invention, as shown in FIG. 3, it is possible to form inclined side surfaces on both the signal electrode and the ground electrode, but the characteristics of the optical modulator of the present invention are shown in FIG. as shown in a), or provided with a side surface inclined only in the signal electrode S, as shown in FIG. 4 (b), is a this providing a side inclined only to the ground electrode G.

少なくとも信号電極全体を単一の材料で構成することで、電極の製造工程が複雑化することが抑制される。しかも、信号電極の部分毎に異なる材料を使用する場合には、電気信号の伝搬にムラが発生し易くなり、信号の伝搬損失が増加したり、光導波路へ印加される電界にムラ、更にはインピーダンスの急激な変化による電気信号の反射によるインピーダンス不整合が生じるなどの不具合も発生する。   By composing at least the entire signal electrode with a single material, it is possible to suppress complication of the electrode manufacturing process. In addition, when different materials are used for each part of the signal electrode, unevenness of electric signal propagation is likely to occur, signal propagation loss increases, electric field applied to the optical waveguide is uneven, Inconveniences such as impedance mismatch due to reflection of electrical signals due to a sudden change in impedance also occur.

また、信号電極と接地電極との間隔は連続的に変化するよう構成することで、１度の製造プロセスで変調電極を形成することも可能となる。また、不連続部分よる電気信号の反射や空気中への放出が減少するため、伝搬損失の増大、インピーダンスの急激な変化による電気信号の反射によるインピーダンス不整合などの不具合が抑制できる。   In addition, by configuring the interval between the signal electrode and the ground electrode to change continuously, the modulation electrode can be formed by a single manufacturing process. In addition, since reflection of the electric signal by the discontinuous portion and emission into the air are reduced, it is possible to suppress problems such as an increase in propagation loss and impedance mismatch due to reflection of the electric signal due to a sudden change in impedance.

ここで、信号電極と接地電極との間隔が「連続的に変化する」とは、電極の高さ方向に向かって該間隔が滑らかに変化することを意味している。なお、信号電極の電気信号の伝播方向に沿って形状が滑らかに変化することで、インピーダンス不整合を抑制できる。   Here, “the distance between the signal electrode and the ground electrode changes continuously” means that the distance changes smoothly in the height direction of the electrode. The impedance mismatch can be suppressed by smoothly changing the shape of the signal electrode along the propagation direction of the electric signal.

また、本発明のような変調電極の形状は、信号電極に沿って、信号入力用パッド部、該パッド部から作用部（変調電極が形成する電界が光導波路に作用する部分）など、基本的には、信号電極の全てに渡って適用することが好ましいが、少なくとも作用部に適用するだけでも十分に周波数応答特性を改善することが可能となる。   Further, the shape of the modulation electrode as in the present invention is basically such as a signal input pad portion along the signal electrode, and an action portion (a portion where the electric field formed by the modulation electrode acts on the optical waveguide) from the pad portion. However, it is preferable to apply to all of the signal electrodes. However, it is possible to sufficiently improve the frequency response characteristic even if it is applied to at least the action part.

図５は、薄板の基板１を、接着剤４などを用いて補強基板５に接合した構成を示している。図５に示すように、本発明の光変調器に使用される基板は、Ｘカット型の基板であり、基板の厚みは、２０μｍ以下であることがより好ましい。Ｘカット型基板を用いた場合には、信号電極Ｓと接地電極Ｇとの間に光導波路２が配置されるため、信号電極Ｓと接地電極Ｇとの基板に最も近い部分の間隔（Ｇ１）を狭くすることで、電界を効率良く光導波路に印加でき、駆動電圧の低減を図ることが可能である。   FIG. 5 shows a configuration in which the thin substrate 1 is bonded to the reinforcing substrate 5 using an adhesive 4 or the like. As shown in FIG. 5, the substrate used in the optical modulator of the present invention is an X-cut substrate, and the thickness of the substrate is more preferably 20 μm or less. When an X-cut substrate is used, the optical waveguide 2 is disposed between the signal electrode S and the ground electrode G, and therefore the distance between the signal electrode S and the ground electrode G closest to the substrate (G1) By narrowing, the electric field can be efficiently applied to the optical waveguide, and the drive voltage can be reduced.

また、２０μｍ以下の厚みを有する薄板を利用することで、変調信号であるマイクロ波の閉じ込めが強くなり、光導波路に効率良く電界を印加できると共に、マイクロ波と光波との速度整合も図ることが可能となる。   In addition, by using a thin plate having a thickness of 20 μm or less, the confinement of the microwave that is the modulation signal is strengthened, an electric field can be efficiently applied to the optical waveguide, and speed matching between the microwave and the light wave can be achieved. It becomes possible.

図６乃至８は、電極の製造プロセスの一部を示す図である。
図６では、基板１上に塗布したフォトレジスト膜１０にフォトマスク２０を用いて、パターン露光を行う様子を示している。フォトマスク２０の透過部２１を透過した光は、フォトレジスト膜１０に所定のパターンを露光する。符号２２はフォトマスクの不透過部であり、符号１１はフォトレジスト膜の露光部分、符号１２は、フォトレジスト膜の非露光部分を各々示している。 6 to 8 are diagrams showing a part of an electrode manufacturing process.
FIG. 6 shows a state in which pattern exposure is performed using the photomask 20 on the photoresist film 10 applied on the substrate 1. The light transmitted through the transmission part 21 of the photomask 20 exposes a predetermined pattern on the photoresist film 10. Reference numeral 22 denotes a non-transparent portion of the photomask, reference numeral 11 denotes an exposed portion of the photoresist film, and reference numeral 12 denotes an unexposed portion of the photoresist film.

図６では、露光の前後において、フォトレジスト膜のベーク時（硬化時）に、温度や時間を調整することで、台形の露光パターン（１１）を形成することが可能である。この露光終了後、現像を行い、露光部１１のレジストを除去し、メッキにより金の電極を符号１１の部分に形成することが可能である。   In FIG. 6, the trapezoidal exposure pattern (11) can be formed by adjusting the temperature and time before and after the exposure, when the photoresist film is baked (cured). After this exposure, development is performed, the resist in the exposed portion 11 is removed, and a gold electrode can be formed on the portion 11 by plating.

図７では、フォトマスク２０を用いてフォトレジスト膜１０を露光する際に、矢印ａ〜ｃのように、光の照射角度を変化させることで、図７のような露光パターン（台形の露光部１１）を形成することが可能となる。   In FIG. 7, when the photoresist film 10 is exposed using the photomask 20, the exposure pattern (trapezoidal exposure portion as shown in FIG. 7) is obtained by changing the light irradiation angle as indicated by arrows a to c. 11) can be formed.

図８では、基板１の上に、形状の異なるレジストパターン（３０〜３２）を積み上げることで、符号４０で示すような基板側から上に向かって徐々に幅が狭くなる空間を形成する。この空間に電極材料を充填することで、基板側の幅（Ｗ１）より上側の幅（Ｗ２）が狭い信号電極を形成することが可能となる。   In FIG. 8, resist patterns (30 to 32) having different shapes are stacked on the substrate 1 to form a space whose width gradually decreases from the substrate side to the top as indicated by reference numeral 40. By filling this space with the electrode material, it is possible to form a signal electrode having a width (W2) narrower than the width (W1) on the substrate side.

本発明の参考例に係る光変調器として、図３の形状において、Ｗ１＝３０μｍ、Ｗ２＝２６μｍ、Ｇ１＝２０μｍ、Ｇ２＝２４μｍとした場合の周波数応答特性をシュミレーションした結果を図９に示す。また、従来例として、図１の形状において、Ｗ１＝３０μｍ、Ｗ２＝３４μｍ、Ｇ１＝２０μｍ、Ｇ２＝１６μｍとした場合についても同様に、図９に示す。 FIG. 9 shows the result of simulating the frequency response characteristics of the optical modulator according to the reference example of the present invention when W1 = 30 μm, W2 = 26 μm, G1 = 20 μm, and G2 = 24 μm in the shape of FIG. Further, as a conventional example, the case of W1 = 30 μm, W2 = 34 μm, G1 = 20 μm, G2 = 16 μm in the shape of FIG. 1 is also shown in FIG.

図９の結果から、本発明の参考例の光変調器の方が、周波数応答特性が格段に改善していることが容易に理解される。 From the result of FIG. 9, it is easily understood that the frequency response characteristic of the optical modulator of the reference example of the present invention is remarkably improved.

以上説明したように、本発明によれば、駆動電圧の増加を抑制しながら周波数応答特性の広帯域化が可能な光変調器を提供することであり、さらには、製造に掛る時間やコストの増加を抑制した光変調器を提供することが可能となる。   As described above, according to the present invention, there is provided an optical modulator capable of widening the frequency response characteristic while suppressing an increase in driving voltage, and further, an increase in manufacturing time and cost. It is possible to provide an optical modulator that suppresses the above.

１ 基板
２ 光導波路
３ 電極下部
４ 接着剤
５ 補強基板
１０ フォトレジスト膜
２０ フォトマスク DESCRIPTION OF SYMBOLS 1 Substrate 2 Optical waveguide 3 Electrode lower part 4 Adhesive 5 Reinforcement substrate 10 Photoresist film 20 Photomask

Claims (3)

電気光学効果を有する基板と、該基板に形成された光導波路と、該光導波路を伝搬する光波を変調するための変調電極とを有する光変調器において、
該変調電極は、信号電極とそれを挟むように配置される接地電極とからなるコプレーナ型電極であり、
該信号電極と該接地電極との間隔は、基板に最も近い部分から基板からはなれる方向に向かって徐々に広くなるよう構成され、
少なくとも該信号電極全体は、単一の材料から構成されることを特徴とする光変調器。 In an optical modulator having a substrate having an electro-optic effect, an optical waveguide formed on the substrate, and a modulation electrode for modulating a light wave propagating through the optical waveguide,
The modulation electrode is a coplanar electrode composed of a signal electrode and a ground electrode arranged so as to sandwich the signal electrode,
The interval between the signal electrode and the ground electrode is configured to gradually widen from the portion closest to the substrate toward the direction away from the substrate,
An optical modulator characterized in that at least the entire signal electrode is made of a single material. 請求項１に記載の光変調器において、該信号電極と該接地電極との間隔は連続的に変化するよう構成されていることを特徴とする光変調器。   2. The optical modulator according to claim 1, wherein a distance between the signal electrode and the ground electrode is continuously changed. 請求項１又は２に記載の光変調器において、該基板はＸカット型の基板であり、該基板の厚みは、２０μｍ以下であることを特徴とする光変調器。   3. The optical modulator according to claim 1, wherein the substrate is an X-cut substrate, and the thickness of the substrate is 20 μm or less. 4.
JP2010082232A 2010-03-31 2010-03-31 Optical modulator Pending JP2011215294A (en)

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Publication number Priority date Publication date Assignee Title
WO2024069952A1 (en) * 2022-09-30 2024-04-04 住友大阪セメント株式会社 Optical waveguide element, optical modulation device using same, and optical transmission device

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JP2009086336A (en) * 2007-09-28 2009-04-23 Sumitomo Osaka Cement Co Ltd Optical waveguide type device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009086336A (en) * 2007-09-28 2009-04-23 Sumitomo Osaka Cement Co Ltd Optical waveguide type device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024069952A1 (en) * 2022-09-30 2024-04-04 住友大阪セメント株式会社 Optical waveguide element, optical modulation device using same, and optical transmission device

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