JPH0517295A - Lithium niobate single crystal thin film subjected to domain inversion treatment - Google Patents
Lithium niobate single crystal thin film subjected to domain inversion treatmentInfo
- Publication number
- JPH0517295A JPH0517295A JP3191221A JP19122191A JPH0517295A JP H0517295 A JPH0517295 A JP H0517295A JP 3191221 A JP3191221 A JP 3191221A JP 19122191 A JP19122191 A JP 19122191A JP H0517295 A JPH0517295 A JP H0517295A
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- Japan
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- thin film
- single crystal
- lithium niobate
- niobate single
- crystal thin
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Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、薄膜導波路型第2高調
波発生素子を始めとして、各種の光学材料に好適なドメ
イン反転処理が施されてなるニオブ酸リチウム単結晶薄
膜に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium niobate single crystal thin film obtained by subjecting various optical materials including a thin film waveguide type second harmonic generating element to a suitable domain inversion process.
【0002】[0002]
【従来の技術】近年、光応用技術の進展に伴ってレ−ザ
光源の短波長化が要求されている。レ−ザ光源の短波長
化により記録密度や感光感度を向上させ、これによって
光ディスク、レ−ザプリンタ等を始めとしてより一層光
機器分野への利用範囲が拡大される。2. Description of the Related Art In recent years, there has been a demand for a laser light source having a shorter wavelength with the progress of optical application technology. By shortening the wavelength of the laser light source, the recording density and the photosensitivity are improved, whereby the range of use in the optical equipment field such as optical discs and laser printers is further expanded.
【0003】このため、入射するレ−ザ光の波長を1/
2に変換できる第2高調波発生(SHG)素子の研究が
行われて来た。かかる第2高調波発生(SHG)素子と
して、非線型光学結晶のバルク単結晶が用いられて来た
が数mW〜数十mWの低い光源出力で高い変換効率を得
る必要から薄膜導波路型のSHG素子が必要となってき
た。Therefore, the wavelength of the incident laser light is 1 /
Research has been conducted on a second harmonic generation (SHG) element that can be converted to 2. A bulk single crystal of a non-linear optical crystal has been used as such a second harmonic generation (SHG) element, but it is necessary to obtain a high conversion efficiency with a low light source output of several mW to several tens of mW, so that a thin film waveguide type is used. SHG elements have become necessary.
【0004】このような薄膜導波路型SHG素子用の非
線形光学材料としては、例えばニオブ酸リチウム単結晶
バルクにTi等の異種元素を拡散させて屈折率を変化さ
せた層を導波路としたものやタンタル酸リチウム基板上
にニオブ酸リチウム単結晶薄膜を導波路としたものなど
が知られている。As such a non-linear optical material for a thin film waveguide type SHG element, for example, a layer in which a different element such as Ti is diffused into a bulk lithium niobate single crystal to change the refractive index is used as a waveguide. Also known are those in which a lithium niobate single crystal thin film is used as a waveguide on a lithium tantalate substrate.
【0005】このような導波路にレ−ザ光を入射させる
とSHGは発生するが、レ−ザ光と高周波との干渉によ
りSHG光は導波路伝播に伴って次式で与えられる干渉
距離(コヒ−レンス長)lcごとに極大極小を繰り返す
こととなる。 lc=(2n+1)λf/4(nf−nSH) 式中、添字f及びSHはそれぞれ基本波及び高調波成分
をλは波長、nは屈折率を示す。When laser light is incident on such a waveguide, SHG is generated. However, due to the interference between the laser light and high frequency, the SHG light causes an interference distance ( Coherence length) The maximum and minimum are repeated for each lc. lc = (2n + 1) λf / 4 (nf-nSH) In the formula, the subscripts f and SH represent the fundamental wave and harmonic components, λ is the wavelength, and n is the refractive index.
【0006】したがって、lc毎に分極波の符号を交互
に反転させることによりSHG光の出力は打消がなくな
り、逆に加合せが生じ、SHGの出力は加算される結果
大きな変換効率を得ることができる。このlc毎に分極
反転させたドメイン反転の理論は1962年頃より提案
され、1988年頃よりSHGの出力強度を高めるため
にドメイン反転処理が利用されるようになった。Therefore, by alternately inverting the sign of the polarization wave for each lc, the output of the SHG light disappears and the addition occurs on the contrary, and the output of the SHG is added, so that a large conversion efficiency can be obtained. it can. The theory of domain inversion in which polarization is inverted for each lc has been proposed since about 1962, and domain inversion processing has been used since 1988 to increase the output intensity of SHG.
【0007】非線形光学材料基板上にドメイン反転構造
部を設け、この上に光導波路を設けてチェレンコフ放射
による第2高周波発生素子が提案されている(例えば特
願平2−93624号公報参考)。しかし、チェレンコ
フ放射型第2高調波発生素子では変換されたビ−ムは、
基板内方向に放射され、ビ−ムスポット形状は例えば三
日月状スポットという特異な形状をしているため、これ
を光ディスやレ−ザプリンタの光源として使用する場合
にはチェレンコフ放射光を回折限界まで絞りこまなけれ
ばならないが、現在この目的に適したレンズが実用化さ
れていないためチェレンコフ放射型のSHG発生素子は
未だ実用的ではない。There has been proposed a second high frequency generating element by Cherenkov radiation by providing a domain inversion structure portion on a non-linear optical material substrate and providing an optical waveguide thereon (see, for example, Japanese Patent Application No. 2-93624). However, the beam converted by the Cherenkov radiation type second harmonic generation element is
The beam spot is radiated in the inward direction of the substrate, and the beam spot has a unique shape, for example, a crescent spot. Therefore, when this beam spot is used as a light source for an optical disc or a laser printer, the Cherenkov radiation is diffraction-limited. However, since a lens suitable for this purpose has not been put into practical use at present, the Cherenkov radiation type SHG generating element is not yet practical.
【0008】これに対して、その導波路にドメイン反転
処理を施すことによって、高効率で円形もしくは楕円形
のビ−ムスポット形状の出力を得るようにした第2高調
波発生素子が提案されている。しかし、導波路にドメイ
ン反転処理を施す手段として、例えばニオブ酸リチウム
単結晶バルクにTiを拡散させたり、プロトン交換を行
って導波路を作成すると、ニオブ酸リチウムの結晶構造
が変化してニオブ酸リチウム結晶構造ではなくなり、し
たがって必然的に非線形光学特性が変化し、非線形分極
テンソルの値が小さくなり、非線形光学特性が低下する
という欠点があった。On the other hand, a second harmonic generating element has been proposed in which a domain inversion process is applied to the waveguide to obtain a circular or elliptical beam spot-shaped output with high efficiency. There is. However, as a means for performing domain inversion processing on the waveguide, for example, when Ti is diffused into a lithium niobate single crystal bulk or a proton exchange is performed to form the waveguide, the crystal structure of lithium niobate is changed to change the niobate. The lithium crystal structure is no longer present, so that the nonlinear optical characteristics inevitably change, the value of the nonlinear polarization tensor becomes small, and the nonlinear optical characteristics deteriorate.
【0009】[0009]
【解決しようとする課題】本発明は、上記の点を改良
し、高調波のビ−ムスポット形状の良好な、かつ、出力
の大きい第2高調波発生素子を提供すべく種々検討した
結果、タンタル酸リチウム基板上に格子整合されたニオ
ブ酸リチウム単結晶薄膜よりなる導波路を分極反転した
ニオブ酸リチウム単結晶薄膜が上記目的を達成すること
を見出し、本発明を完成したもので、本発明の目的は、
薄膜導波路型第2高調波発生素子を始めとして、各種の
光学材料に好適なドメイン反転処理が施されてなるニオ
ブ酸リチウム単結晶薄膜を提供するにある。DISCLOSURE OF THE INVENTION As a result of various studies to improve the above-mentioned points and to provide a second harmonic generating element having a good harmonic beam spot shape and a large output, The inventors have found that a lithium niobate single crystal thin film in which a waveguide made of a lattice-matched lithium niobate single crystal thin film on a lithium tantalate substrate is polarization-inverted achieves the above object, and completed the present invention. The purpose of
Another object of the present invention is to provide a lithium niobate single crystal thin film obtained by subjecting various optical materials including a thin film waveguide type second harmonic generating element to a suitable domain inversion process.
【0010】[0010]
【課題を解決するための手段】本発明の要旨は、タンタ
ル酸リチウム基板上に格子整合され、周期毎に結晶軸方
向に分極が反転されるようにドメイン反転処理が施され
たニオブ酸リチウム単結晶薄膜である。すなわち、タン
タル酸リチウム基板上に格子整合されたニオブ酸リチウ
ム単結晶薄膜は、次の一般式(I)の条件を満足するよ
うに、周期毎に結晶軸方向に分極が反転されている。 (2m+1)λf/4(nf−nSHG) (I) 式中、nfは基本波長光における実効屈折率、nSHG
は第2高調波光における実効屈折率であり、mは整数で
ある。The gist of the present invention is to provide a lithium niobate single crystal which is lattice-matched on a lithium tantalate substrate and which is domain-inverted so that the polarization is inverted in the crystal axis direction at every period. It is a crystal thin film. That is, in the lithium niobate single crystal thin film lattice-matched on the lithium tantalate substrate, the polarization is inverted in the crystal axis direction at every period so as to satisfy the condition of the following general formula (I). (2m + 1) λf / 4 (nf-nSHG) (I) In the formula, nf is an effective refractive index in the fundamental wavelength light, nSHG
Is the effective refractive index of the second harmonic light, and m is an integer.
【0011】本発明においてはニオブ酸リチウム単結晶
薄膜はタンタル酸リチウム基板上に形成されているの
で、従来のニオブ酸リチウム基板にプロトン拡散させて
得た導波路やニオブ酸リチウム基板にTi拡散させて得
た導波路より非線形光学特性に優れており、しかも、ニ
オブ酸リチウム単結晶薄膜はタンタル酸リチウムと格子
整合されているので、ニオブ酸リチウム膜の結晶性、伝
播損失の低減が期待され、更に、良質の膜が厚い膜厚で
形成される。更に、ニオブ酸リチウムの非線形分極テン
ソルの値はニオブ酸リチウムバルクと同じ値であるので
SHG変換効率の向上が期待できる。In the present invention, since the lithium niobate single crystal thin film is formed on the lithium tantalate substrate, it is Ti diffused on the waveguide obtained by proton diffusion on the conventional lithium niobate substrate or on the lithium niobate substrate. It is superior in nonlinear optical characteristics to the obtained waveguide, and since the lithium niobate single crystal thin film is lattice-matched with lithium tantalate, it is expected to reduce the crystallinity and propagation loss of the lithium niobate film. Further, a good quality film is formed with a large film thickness. Further, since the value of the non-linear polarization tensor of lithium niobate is the same as that of the lithium niobate bulk, improvement in SHG conversion efficiency can be expected.
【0012】なお、タンタル酸リチウム基板上のニオブ
酸リチウム単結晶薄膜の非線形分極テンソルの値は、ニ
オブ酸リチウムバルクの値より小さくなるため、格子整
合は実用的なSHG素子を得るためには不可欠である。
格子整合は、ニオブ酸リチウム単結晶薄膜のa軸の格子
定数をタンタル酸リチウム基板のa軸の格子定数の9
9.81〜100.07%、より好ましくは99.92
〜100.03%とすることである。Since the value of the nonlinear polarization tensor of the lithium niobate single crystal thin film on the lithium tantalate substrate is smaller than that of the lithium niobate bulk, lattice matching is indispensable for obtaining a practical SHG element. Is.
Lattice matching is performed by changing the a-axis lattice constant of the lithium niobate single crystal thin film to the a-axis lattice constant of the lithium tantalate substrate.
9.81-100.07%, more preferably 99.92
It is to be set to 100.03%.
【0013】本発明において、ニオブ酸リチウム単結晶
薄膜とタンタル酸リチウム基板を格子整合させる手段は
特に限定されるものではないが、国際出願番号PCT/
JP90/01207に記載の方法が望ましく、1)ナ
トリウムとマグネシウムをニオブ酸リチウム単結晶薄膜
中に含有させること、2)Li/Nbの比率を41/5
9〜56/44の間で変える方法、3)Tiなどのタン
タル酸リチウム基板のa軸の格子定数を小さくする元素
を含有させる方法、などがあるが、1)の方法が有利で
ある。In the present invention, the means for lattice-matching the lithium niobate single crystal thin film and the lithium tantalate substrate is not particularly limited, but international application number PCT /
The method described in JP90 / 01207 is preferable, 1) sodium and magnesium are contained in a lithium niobate single crystal thin film, and 2) the Li / Nb ratio is 41/5.
There is a method of changing between 9 and 56/44, 3) a method of adding an element such as Ti that reduces the a-axis lattice constant of the lithium tantalate substrate, and the method of 1) is advantageous.
【0014】この理由は、ナトリウムとマグネシウムの
イオン又は原子はニオブ酸リチウムの結晶格子に対する
置換、或いはドープにより、ニオブ酸リチウムの格子定
数(a軸)を大きくする効果を有するため、ナトリウムと
マグネシウムの組成を調整することにより、容易に前記
タンタル酸リチウム基板とニオブ酸リチウム単結晶との
格子整合を得ることができ、さらに、ナトリウムやマグ
ネシウムは光学特性を何ら損なうことがないだけでな
く、マグネシウムについては光学損傷を防止するという
重要な効果をも有するからである。The reason for this is that the ions or atoms of sodium and magnesium have the effect of increasing the lattice constant (a axis) of lithium niobate by substitution or doping with respect to the crystal lattice of lithium niobate. By adjusting the composition, it is possible to easily obtain lattice matching between the lithium tantalate substrate and the lithium niobate single crystal, and sodium and magnesium do not impair the optical characteristics at all, and Has an important effect of preventing optical damage.
【0015】また、前記ナトリウム、マグネシウムを含
有させる場合、その含有量は、それぞれニオブ酸リチウ
ム単結晶に対して、ナトリウムの量は0.1〜14.3
モル%、マグネシウムの量は0.8〜10.8モル%で
あることが望ましい。その理由は、ナトリウムの含有量
が、0.1モル%より少ない場合は、マグネシウムの添
加量の如何に関わらず、タンタル酸リチウム基板と格子
整合できる程、格子定数が大きくならず、又、14.3
モル%を越える場合は、逆に格子定数が大きくなりす
ぎ、いずれの場合もタンタル酸リチウム基板とニオブ酸
リチウム単結晶との格子整合が得られないからである。When sodium and magnesium are contained, the content of sodium is 0.1 to 14.3 with respect to lithium niobate single crystal.
The amounts of mol% and magnesium are preferably 0.8 to 10.8 mol%. The reason is that, when the content of sodium is less than 0.1 mol%, the lattice constant does not become large enough to be lattice-matched with the lithium tantalate substrate, regardless of the amount of magnesium added. .3
On the other hand, if it exceeds mol%, the lattice constant becomes too large, and in any case, the lattice matching between the lithium tantalate substrate and the lithium niobate single crystal cannot be obtained.
【0016】又、マグネシウムの含有量が、0.8モル
%より少ない場合は、光損傷を防止する効果が不充分で
あり、10.8モル%を越える場合は、ニオブ酸マグネ
シウム系の結晶が析出してしまうため、含有させること
ができない。If the magnesium content is less than 0.8 mol%, the effect of preventing optical damage is insufficient, and if it exceeds 10.8 mol%, magnesium niobate-based crystals are formed. Since it precipitates, it cannot be contained.
【0017】次に本発明にかかるニオブ酸リチウム単結
晶薄膜の製造方法について説明するが、本発明のニオブ
酸リチウム単結晶薄膜は、その製造方法に限定されるも
のではない。Next, a method of manufacturing the lithium niobate single crystal thin film according to the present invention will be described, but the lithium niobate single crystal thin film of the present invention is not limited to the manufacturing method.
【0018】先ず、本発明においてタンタル酸リチウム
基板にニオブ酸リチウム単結晶薄膜を格子整合させて該
単結晶薄膜を形成する。ニオブ酸リチウム単結晶薄膜の
製造方法としては、液相エピタキシャル成長法、スパッ
タ、蒸着法などが望ましいが、特に液相エピタキシャル
成長法が好適である。First, in the present invention, a lithium niobate single crystal thin film is lattice-matched to a lithium tantalate substrate to form the single crystal thin film. As a method for producing the lithium niobate single crystal thin film, a liquid phase epitaxial growth method, a sputtering method, a vapor deposition method or the like is desirable, but a liquid phase epitaxial growth method is particularly preferable.
【0019】この理由は、結晶性に優れた均質な膜が得
やすく、その結果、光伝搬損失が少なく、光導波路とし
て好適なニオブ酸リチウムのもつ非線形光学効果、音響
光学効果などを十分生かせる優れた特性をもったニオブ
酸リチウム単結晶薄膜が得られ、更に生産性にも優れて
いるからである。The reason for this is that a homogeneous film having excellent crystallinity can be easily obtained, and as a result, light propagation loss is small, and the nonlinear optical effect and acousto-optical effect of lithium niobate suitable as an optical waveguide can be fully utilized. This is because a lithium niobate single crystal thin film having the above characteristics can be obtained and the productivity is also excellent.
【0020】液相エピタキシャル成長法としては、Li
2O,Nb2O5,V2O5,Na2O,MgOなどからなる溶融
体にタンタル酸リチウム基板を接触させ、液相エピタキ
シャル成長によりニオブ酸リチウム単結晶薄膜のa軸の
格子定数をタンタル酸リチウム基板のa軸の格子定数に
整合させる方法を用いるのが、高品質の結晶が得られる
ので望ましい。As the liquid phase epitaxial growth method, Li
The lithium tantalate substrate was brought into contact with a melt composed of 2 O, Nb 2 O 5 , V 2 O 5 , Na 2 O, MgO, etc., and the a-axis lattice constant of the lithium niobate single crystal thin film was measured by liquid phase epitaxial growth. It is preferable to use a method of matching the lattice constant of the a-axis of the lithium oxide substrate because a high quality crystal can be obtained.
【0021】本発明でLi2O,Nb2O5,V2O5,Na2
O,MgOなどからなる溶融体を使用する理由として
は、Li2OとV2O5は、フラックスとして作用してニ
オブ酸リチウム単結晶の液相エピタキシャル成長を実現
できるからである。In the present invention, Li 2 O, Nb 2 O 5 , V 2 O 5 and Na 2
The reason for using the melt composed of O, MgO, etc. is that Li 2 O and V 2 O 5 act as a flux to realize liquid phase epitaxial growth of a lithium niobate single crystal.
【0022】また、Na及びMgをニオブ酸リチウム単
結晶薄膜に含有させることにより、ニオブ酸リチウム単
結晶薄膜のa軸の格子定数を大きくすることができるの
で、形成されるニオブ酸リチウム単結晶薄膜のa軸の格
子定数をタンタル酸リチウム基板のa軸の格子定数に合
わせることができ、これによって厚い膜厚を有するニオ
ブ酸リチウム単結晶薄膜を得ることができるのである。Further, by including Na and Mg in the lithium niobate single crystal thin film, the a-axis lattice constant of the lithium niobate single crystal thin film can be increased, so that the formed lithium niobate single crystal thin film is formed. The lattice constant of the a-axis can be matched with the lattice constant of the a-axis of the lithium tantalate substrate, whereby a lithium niobate single crystal thin film having a large film thickness can be obtained.
【0023】このようにして得られたニオブ酸リチウム
単結晶薄膜に分極反転処理を施す。分極反転処理とし
て、次の2種類の方法がある。 A.ニオブ酸リチウム単結晶導波路にTiを拡散し、キ
ュリ−点を降下させた後、キュリ−点よりやや低い温度
で加熱して冷却することにより分極反転させる方法。 B.ニオブ酸リチウム単結晶導波路にフォトレジストに
より、スパッタレジストを形成し、SiO2をスパッタ
し、ついで、これを加熱することにより、LiがSiO
2に拡散する。ついで、SiO2を除去し、キュリ−点よ
りやや低い温度で加熱して冷却することにより分極反転
させる方法。The lithium niobate single crystal thin film thus obtained is subjected to polarization reversal treatment. There are the following two types of polarization inversion processing. A. A method of diffusing Ti into a lithium niobate single crystal waveguide, lowering the Curie point, and then heating and cooling at a temperature slightly lower than the Curie point to invert the polarization. B. A lithium sputtered resist was formed on the lithium niobate single crystal waveguide with a photoresist, SiO 2 was sputtered, and then this was heated so that Li was changed to SiO 2.
Spread to 2 . Then, SiO 2 is removed, and the polarization is inverted by heating at a temperature slightly lower than the Curie point and cooling.
【0024】これらの方法を図面をもって説明する。A
の方法について、図1を参照しながら説明する。タンタ
ル酸リチウム基板1上に格子整合されたニオブ酸リチウ
ム単結晶薄膜2をエピタキシル法で成長させ、このニオ
ブ酸リチウム単結晶薄膜上にフォトリソグラフィ−によ
ってスプライトパタ−ン3を形成させる(c図)。次い
で、このスプライトパタ−ンを有する表面全体にTiを
真空蒸着によってTi薄膜4を形成し(d図)、スプラ
イトパタ−ンを除去した後(e図)、これを加熱処理し
てTiをニオブ酸単結晶薄膜中に拡散させ(f図)、つ
いで急冷し、ドメイン反転層5を有するニオブ酸リチウ
ム単結晶薄膜を得た。These methods will be described with reference to the drawings. A
The method will be described with reference to FIG. A lattice-matched lithium niobate single crystal thin film 2 is grown on a lithium tantalate substrate 1 by an epitaxy method, and a sprite pattern 3 is formed on the lithium niobate single crystal thin film by photolithography (Fig. C). .. Then, a Ti thin film 4 is formed by vacuum deposition of Ti on the entire surface having the sprite pattern (Fig. D), and after removing the sprite pattern (Fig. E), the Ti thin film 4 is heat treated to niobium Ti. It was diffused in the acid single crystal thin film (Fig. F) and then rapidly cooled to obtain a lithium niobate single crystal thin film having the domain inversion layer 5.
【0025】このドメイン反転層5を有するニオブ酸単
結晶薄膜の一部を切出し(g図)、Tiパタ−ンに対して
垂直方向に一本線のパタ−ン6をフォトリソグラフによ
って画き、Tiを真空蒸着して(h図)、次いでイオンビ
−ムエッチングによりリッジ型の導波路6を形成する
(i図)。A part of the niobate single crystal thin film having the domain inversion layer 5 is cut out (FIG. 3G), and a single-line pattern 6 is drawn in the direction perpendicular to the Ti pattern by photolithography to show Ti. It is vacuum-deposited (Fig. H), and then a ridge type waveguide 6 is formed by ion beam etching.
(Fig. i).
【0026】Bの方法は図2において、Aの方法と同様
にタンタル酸リチウム基板1上に格子整合されたニオブ
酸リチウム単結晶薄膜2を設け(b図)、この上にスプ
ライトパタ−ン3を形成した後(c図)、これにSiO2
を蒸着しSiO2膜7を形成し(d図)、スプライトパ
タンを除去した(e図)。その後、これに加熱処理を施
すことによってLiをSiO2に拡散させ、拡散部7’
を形成したのち急冷する。(f図)。さらにSiO2を研
磨により除去し、これによってドメイン反転層5を有す
るニオブ酸リチウム単結晶薄膜を得た(g図)。その後は
A方法と同様にしてリッヂ型の導波路6を形成する(i
図)。次に実施例をもって本発明を更に具体的に説明す
る。In the method B, as in the method A, a lattice-matched lithium niobate single crystal thin film 2 is provided on the lithium tantalate substrate 1 (FIG. 2B), and the sprite pattern 3 is formed thereon. After forming (Fig. C), SiO 2
Was evaporated to form a SiO 2 film 7 (Fig. D), and the sprite pattern was removed (Fig. E). After that, by subjecting this to a heat treatment, Li is diffused into SiO 2 to form a diffusion portion 7 ′.
After forming, quench rapidly. (Figure f). Further, SiO 2 was removed by polishing, whereby a lithium niobate single crystal thin film having a domain inversion layer 5 was obtained (FIG. 7G). After that, the Ridge type waveguide 6 is formed in the same manner as the method A (i.
(Figure). Next, the present invention will be described more specifically with reference to Examples.
【0027】[0027]
実施例1 (1)Na2CO3 21モル%、Li2CO3 29モル
%、V2O5 40モル%、Nb2O5 10モル%、Mg
Oを前記溶融物組成から析出可能なLiNbO3の理論
量に対して2モル%添加した混合物を白金ルツボに入
れ、エピタキシャル成長育成装置中で空気雰囲気下で、
1100℃まで加熱してルツボの内容物を溶解した。 (2)溶融体を1時間当りに60℃の冷却速度で912℃
まで徐冷した後、タンタル酸リチウム単結晶の(000
1)面を光学研磨した後、化学エッチングしたものを基
板材料として溶融体中に100rpmで回転させながら
12分間浸漬した。Example 1 (1) Na 2 CO 3 21 mol%, Li 2 CO 3 29 mol%, V 2 O 5 40 mol%, Nb 2 O 5 10 mol%, Mg
A mixture in which 2 mol% of O was added to the theoretical amount of LiNbO 3 that can be precipitated from the melt composition was placed in a platinum crucible, and was placed in an epitaxial growth and growth apparatus under an air atmosphere,
The contents of the crucible were melted by heating to 1100 ° C. (2) Melt at 912 ° C at a cooling rate of 60 ° C per hour
After slowly cooling down to (000) of lithium tantalate single crystal
1) After optically polishing the surface, the chemically etched product was used as a substrate material and immersed in a melt for 12 minutes while rotating at 100 rpm.
【0028】(3)溶液体から基板材料を引き上げ、回転
数1000rpmで30秒間溶融体上で溶融体を振り切
った後、室温まで徐冷し、基板材料上に約12μmの厚
さのナトリウム、マグネシウム含有ニオブ酸リチウム単
結晶薄膜を得た。 (4)得られたニオブ酸リチウム単結晶薄膜(以下、LN
膜という)中に含有されていたナトリウム、マグネシウ
ムの量は、それぞれ3モル%、2モル%であった。又、
薄膜の格子定数(a軸)は5.156Å、入射光波長0.8
3μmで測定した屈折率は2.173±0.001、0.
415μmで測定した屈折率は、2.314であった。
この膜を研磨して、厚さ2μmとした。この時、830
nmのレ−ザ光の導波モ−ドでの屈折率は2.165で
あった。また、415nmのレ−ザ光の導波モ−ドでの
屈折率は2.295であった。(3) After pulling up the substrate material from the solution body, shaking off the melted material on the melted material at a rotation speed of 1000 rpm for 30 seconds, and then gradually cooling it to room temperature, sodium and magnesium having a thickness of about 12 μm on the substrate material. A contained lithium niobate single crystal thin film was obtained. (4) The obtained lithium niobate single crystal thin film (hereinafter, LN
The amounts of sodium and magnesium contained in the film) were 3 mol% and 2 mol%, respectively. or,
The lattice constant (a-axis) of the thin film is 5.156Å, the incident light wavelength is 0.8
The refractive index measured at 3 μm is 2.173 ± 0.001, 0.00
The refractive index measured at 415 μm was 2.314.
This film was polished to a thickness of 2 μm. At this time, 830
The refractive index of the laser beam of nm in the waveguide mode was 2.165. The refractive index of the 415 nm laser light in the waveguide mode was 2.295.
【0029】この上にフォトリソグラフィ−により、間
隔1.60μmのスプライトパタ−ンを形成した。ここ
でTiを真空蒸着させて、500Åの膜を形成した。ス
プライトパタ−ンを除去し、LN膜中にTiのパタ−ン
を形成した。これを管状炉にて1036℃で処理し、T
iをLN膜中に拡散させ、ついで急冷することにより、
ドメイン反転層を有するLN膜を得た。この膜の一部を
切り出し、HFエッチングを行い、顕微鏡で観察したと
ころ、Ti拡散部分だけ、分極反転していることを確認
した。A sprite pattern with a spacing of 1.60 μm was formed on this by photolithography. Here, Ti was vacuum-deposited to form a 500 Å film. The sprite pattern was removed, and a Ti pattern was formed in the LN film. This is treated in a tubular furnace at 1036 ° C.
By diffusing i into the LN film and then quenching,
An LN film having a domain inversion layer was obtained. A part of this film was cut out, subjected to HF etching, and observed under a microscope. As a result, it was confirmed that only Ti-diffused portions had polarization inversion.
【0030】このTiパタ−ンに対し、垂直に幅5μm
の一本線のパタ−ンをフォトリソグラフィ−により形成
し、Tiを真空蒸着してリフトオフすることにより、L
N膜上にTiパタ−ンを形成し、イオンビ−ムエッチン
グによりLN膜を削りリッジ型の導波路を形成した。
(図1参照)この導波路の端面を研磨し波長830nm
で50mWの半導体レ−ザの光を入射したところ反対側
の端面から波長415nmのレ−ザ光が出た。この時の
変換効率は7.0%であった。このことから本素子は極
めて優れたSHG素子であることが確認された。本素子
のドメイン周期は次の通りである。 (2m+1)λ/4(np−nsh)=1.60μmA width of 5 μm is perpendicular to the Ti pattern.
A single line pattern is formed by photolithography, and Ti is vacuum-deposited and lifted off to obtain L
A Ti pattern was formed on the N film, and the LN film was shaved by ion beam etching to form a ridge type waveguide.
(Refer to FIG. 1) The end face of this waveguide is polished to a wavelength of 830 nm.
Then, when the light of the semiconductor laser of 50 mW was made incident, the laser light having the wavelength of 415 nm was emitted from the end face on the opposite side. The conversion efficiency at this time was 7.0%. From this, it was confirmed that this element is an extremely excellent SHG element. The domain period of this device is as follows. (2m + 1) λ / 4 (np-nsh) = 1.60 μm
【0031】実施例2 (1)Na2CO3 13モル%、V2O5 39モル%、N
b2O5 10モル%、Li2CO3を38モル%、MgO
を前記溶融物組成から析出可能なLiNbO3の理論量
に対して、5モル%添加した混合物を白金ルツボに入
れ、エピタキシャル成長育成装置中で空気雰囲気下で1
100℃まで加熱してルツボの内容物を溶解した。 (2)溶融体を1時間当り60℃の冷却速度で938℃ま
で徐冷した後、タンタル酸リチウム単結晶の(0001)
面を光学研磨したものを基板材料として溶融体中に10
0rpmで回転させながら20分間浸漬した。Example 2 (1) Na 2 CO 3 13 mol%, V 2 O 5 39 mol%, N
b 2 O 5 10 mol%, Li 2 CO 3 38 mol%, MgO
5 mol% was added to the theoretical amount of LiNbO 3 which can be precipitated from the melt composition, and the mixture was put into a platinum crucible and placed in an epitaxial growth and growth apparatus under an air atmosphere at 1
The contents of the crucible were dissolved by heating to 100 ° C. (2) The melt was gradually cooled to 938 ° C. at a cooling rate of 60 ° C. per hour, and then a lithium tantalate single crystal (0001) was formed.
Optically polished surface is used as substrate material in melt
It was immersed for 20 minutes while rotating at 0 rpm.
【0032】(3)溶融体から基板材料を引き上げ、回転
数1000rpmで30秒間溶融体上で、溶融体を振り
切った後、室温まで徐冷し、基板材料上に約23μmの
厚さのナトリウム、マグネシウム含有ニオブ酸リチウム
単結晶薄膜を得た。 (4)得られたニオブ酸リチウム単結晶薄膜中に含有され
ていたナトリウム、マグネシウムの量は、それぞれ1モ
ル%、6モル%であった。又、格子定数(a軸)は5.1
53Å、入射光波長0.83μmで測定した屈折率は、
2.231±0.001、入射光波長0.415μmで測
定した屈折率は、2.372±0.001あった。(3) The substrate material was pulled up from the melt, the melt was shaken off on the melt at a rotation speed of 1000 rpm for 30 seconds, then gradually cooled to room temperature, and sodium having a thickness of about 23 μm was deposited on the substrate material. A magnesium-containing lithium niobate single crystal thin film was obtained. (4) The amounts of sodium and magnesium contained in the obtained lithium niobate single crystal thin film were 1 mol% and 6 mol%, respectively. The lattice constant (a-axis) is 5.1
The refractive index measured at 53Å and the incident light wavelength 0.83 μm is
The refractive index measured at 2.231 ± 0.001 and the incident light wavelength of 0.415 μm was 2.372 ± 0.001.
【0033】(5)これを研磨することにより1.9μmの
膜とした。この時、830nmのレ−ザ光の導波モ−ド
での屈折率は2.162であった。また、415nmの
レ−ザ光の導波モ−ドでの屈折率は2.294であっ
た。この上にフォトリソグラフにより間隔4.72μm
のスプライトパタ−ンを形成した。ここにSiO2をス
パッタして0.5μmの膜を形成した。スプライトパタ
−ンをリフトオフすることによりLN膜上にSiO2の
パタ−ンを形成した。これを管状炉により1000℃で
処理した。この膜の一部を切り出しHFエッチングを行
ない顕微鏡で観察したところSiO2が乗っていたとこ
ろだけ分極が反転していることが観察された。表面のS
iO2を反応性イオンエッチングにより除去し、ドメイ
ン反転ニオブ酸リチウム酸結晶薄膜を得た。(図2参
照)(5) This was polished to form a 1.9 μm film. At this time, the refractive index of the 830 nm laser light in the waveguide mode was 2.162. The refractive index of the 415 nm laser light in the waveguide mode was 2.294. Spacing 4.72 μm on this by photolithography
Sprite pattern was formed. SiO 2 was sputtered here to form a 0.5 μm film. A SiO 2 pattern was formed on the LN film by lifting off the sprite pattern. This was processed in a tube furnace at 1000 ° C. When a part of this film was cut out and subjected to HF etching and observed with a microscope, it was observed that the polarization was inverted only where SiO 2 was on. Surface S
iO 2 was removed by reactive ion etching to obtain a domain-inverted lithium niobate crystal thin film. (See Figure 2)
【0034】この膜から導波路を切り出し、その端面を
研磨し波長830nm、50mWの半導体レ−ザの光を
入射したところ反対側の端面から波長415nmのレ−
ザ光が出た。この時の変換効率は4.8%であった。こ
のことから本素子は極めて優れたSHG素子であること
が確認された。本素子のドメイン周期は、次のとおりで
あった。 (2m+1)λ/4(np−nsh)=4.72μmA waveguide was cut out from this film, its end face was polished, and when light from a semiconductor laser having a wavelength of 830 nm and a wavelength of 50 mW was incident, the end face on the opposite side had a laser beam of 415 nm wavelength.
The light came out. The conversion efficiency at this time was 4.8%. From this, it was confirmed that this element is an extremely excellent SHG element. The domain period of this device was as follows. (2m + 1) λ / 4 (np-nsh) = 4.72 μm
【0035】実施例3 (1)Na2CO3 12.8モル%、Li2CO3 37.2
モル%、V2O5 39.0モル%、Nb2O5 11.0モ
ル%、Nb2O3を前記溶融物組成から析出可能なLiN
bO3の理論量に対して、0.8モル%添加した混合物を
白金ルツボに入れ、エピタキシャル成長育成装置中で空
気雰囲気下で1100℃まで加熱してルツボの内容物を
溶解した。 (2)溶融体を1時間当り60℃の冷却速度で925℃ま
で徐冷した後、タンタル酸リチウム単結晶の(0001)
面を光学研磨した後、化学エッチングしたものを基板材
料として溶融体中に100rpmで回転させながら5分
間浸漬した。 (3)溶融体から基本材料を引き上げ、回転数1000r
pmで30秒間溶融体上で、溶融体を振り切った後、室
温まで徐冷し、基板材料上に約8μmの厚さのナトリウ
ム、ネオジム含有ニオブ酸リチウム単結晶薄膜を得た。Example 3 (1) Na 2 CO 3 12.8 mol%, Li 2 CO 3 37.2
LiN capable of precipitating mol%, V 2 O 5 39.0 mol%, Nb 2 O 5 11.0 mol% and Nb 2 O 3 from the melt composition.
A mixture in which 0.8 mol% was added to the theoretical amount of bO 3 was put into a platinum crucible and heated to 1100 ° C. under an air atmosphere in an epitaxial growth and growth apparatus to melt the contents of the crucible. (2) The melt was gradually cooled to 925 ° C. at a cooling rate of 60 ° C. per hour, and then (0001) of lithium tantalate single crystal was obtained.
After the surface was optically polished, the chemically etched product was used as a substrate material and immersed in the melt for 5 minutes while rotating at 100 rpm. (3) Withdrawing the basic material from the melt and rotating at 1000 r
The melt was shaken off at pm for 30 seconds and then gradually cooled to room temperature to obtain a sodium-neodymium-containing lithium niobate single crystal thin film having a thickness of about 8 μm on the substrate material.
【0036】(4)得られたニオブ酸リチウム単結晶薄膜
中に含有されていたナトリウム、ネオジウムの量は、そ
れぞれ1.2モル%、0.4モル%であった。又、格子定
数(a軸)は5.153Å、入射光波長0.83μm、50
mWで測定した屈折率は、2.232±0.001、入射
光波長0.415μmで測定した屈折率は、2.373±
0.001であった。 (5)これを研磨することにより2.1μmの膜とした。こ
の時、830nmのレ−ザ光の導波モ−ドでの屈折率は
2.166であった。また、415nmのレ−ザ光の導
波モ−ドでの屈折率は2.297であった。次いでフォ
トリソグラフにより4.75μmのスプライトパタ−ン
を形成した。ここにSiO2をスパッタして0.5μmの
膜を形成した。SiO2膜をリフトオフすることにより
LN膜上にSiO2のパタ−ンを形成した。これを管状
炉により空気中1000℃で処理した。この膜の一部を
切り出しHFエッチングを行ない顕微鏡で観察したとこ
ろSiO2が乗っていたところだけ分極が反転している
ことが観察された(図3参照)。(4) The amounts of sodium and neodymium contained in the obtained lithium niobate single crystal thin film were 1.2 mol% and 0.4 mol%, respectively. The lattice constant (a-axis) is 5.153Å, the incident light wavelength is 0.83 μm, 50
The refractive index measured at mW is 2.232 ± 0.001, and the refractive index measured at incident light wavelength 0.415 μm is 2.373 ±.
It was 0.001. (5) This was polished to form a film having a thickness of 2.1 μm. At this time, the refractive index of the 830 nm laser beam in the waveguide mode was 2.166. The refractive index of the 415 nm laser light in the waveguide mode was 2.297. Then, a 4.75 μm sprite pattern was formed by photolithography. SiO 2 was sputtered here to form a 0.5 μm film. By lifting off the SiO 2 film, a pattern of SiO 2 was formed on the LN film. This was processed in a tube furnace at 1000 ° C. in air. When a part of this film was cut out and subjected to HF etching and observed with a microscope, it was observed that the polarization was inverted only where SiO 2 was on (see FIG. 3).
【0037】この膜から導波路を切り出し、端面を研磨
し波長830nmの半導体レ−ザの光を入射したところ
反対側の端面から波長415nmのレ−ザ光が出た。こ
の時の変換効率は4.8%であった。このことから本素
子は極めて優れたSHG素子であることが確認された。
本素子のドメイン周期は次のとおりであった。 (2m+1)λ/4(np−nsh)=4.75μmWhen a waveguide was cut out from this film and the end face was polished and light of a semiconductor laser having a wavelength of 830 nm was incident, laser light having a wavelength of 415 nm was emitted from the opposite end face. The conversion efficiency at this time was 4.8%. From this, it was confirmed that this element is an extremely excellent SHG element.
The domain period of this device was as follows. (2m + 1) λ / 4 (np-nsh) = 4.75 μm
【0038】実施例4 (1)Na2CO3 21モル%、Li2CO3 29モル
%、V2O5 40モル%、Nb2O5 10モル%、Mg
Oを前記溶融物組成から析出可能なLiNbO3の理論
量に対して、2モル%添加した混合物を白金ルツボに入
れ、エピタキシャル成長育成装置中で空気雰囲気下で1
100℃まで加熱してルツボの内容物を溶解した。 (2)溶融体を1時間当り60℃の冷却速度で914℃ま
で徐冷した。タンタル酸リチウム単結晶の(0001)面
を光学研磨した後、RFスパッタ法により、膜厚500
ÅのMg膜を形成した後、1000℃にて熱拡散させた
250Åの拡散層を形成したものを基板材料とした。こ
の基板材料は、Mgを拡散させない基板材料に比べて常
光屈折率が1×10-3減少していた。この基板材料を溶
融体中に100rpmで回転させながら13分間浸漬し
た。Example 4 (1) Na 2 CO 3 21 mol%, Li 2 CO 3 29 mol%, V 2 O 5 40 mol%, Nb 2 O 5 10 mol%, Mg
A mixture in which 2 mol% of O was added to the theoretical amount of LiNbO 3 capable of precipitating from the melt composition was placed in a platinum crucible, and the mixture was placed in an epitaxial growth / growing apparatus under an air atmosphere at 1
The contents of the crucible were dissolved by heating to 100 ° C. (2) The melt was gradually cooled to 914 ° C at a cooling rate of 60 ° C per hour. After optically polishing the (0001) plane of the lithium tantalate single crystal, a film thickness of 500 is obtained by the RF sputtering method.
A substrate material was formed by forming a Mg film of Å and then forming a diffusion layer of 250 Å which was thermally diffused at 1000 ° C. This substrate material had an ordinary refractive index reduced by 1 × 10 −3 as compared with the substrate material in which Mg was not diffused. This substrate material was immersed in the melt for 13 minutes while rotating at 100 rpm.
【0039】(3)溶融体から基板材料を引き上げ、回転
数1000rpmで30秒間溶融体上で溶融体を振り切
った後、室温まで徐冷し、基板材料上に約11μmの厚
さのナトリウム、マグネシウム含有ニオブ酸リチウム単
結晶薄膜を得た。 (4)得られたニオブ酸リチウム単結晶薄膜中に含有され
ていたナトリウム、マグネシウムの量は、それぞれ3モ
ル%、2モル%であった。又、薄膜の格子定数(a軸)は
5.156Å、入射光波長0.83μmで測定した屈折率
は、2.235±0.001、入射光波長0.415μm
で測定した屈折率は、2.376±0.001であった。
この膜を実施例1と同様にしてドメイン反転層が形成さ
れたニオブ酸リチウム単結晶薄膜を得た。(3) The substrate material was pulled up from the melt, the melt was shaken off on the melt for 30 seconds at a rotation speed of 1000 rpm, then gradually cooled to room temperature, and sodium and magnesium having a thickness of about 11 μm were deposited on the substrate material. A contained lithium niobate single crystal thin film was obtained. (4) The amounts of sodium and magnesium contained in the obtained lithium niobate single crystal thin film were 3 mol% and 2 mol%, respectively. The lattice constant (a-axis) of the thin film is 5.156Å, the refractive index measured at an incident light wavelength of 0.83 μm is 2.235 ± 0.001, the incident light wavelength is 0.415 μm.
The refractive index measured by 1. was 2.376 ± 0.001.
This film was processed in the same manner as in Example 1 to obtain a lithium niobate single crystal thin film in which a domain inversion layer was formed.
【0040】この膜から導波路を切り出し、その端面を
研磨し波長830nm、50mWの半導体レ−ザの光を
入射したところ反対側の端面から波長415nmのレ−
ザ光が出た。この時の変換効率は5.8%であった。こ
のことから本素子は極めて優れたSHG素子であること
が確認された。本素子のドメイン周期は、次のとおりで
あった。 (2m+1)λ/4(np−nsh)=4.44μmA waveguide was cut out from this film, its end face was polished, and light from a semiconductor laser having a wavelength of 830 nm and 50 mW was incident on it.
The light came out. The conversion efficiency at this time was 5.8%. From this, it was confirmed that this element is an extremely excellent SHG element. The domain period of this device was as follows. (2m + 1) λ / 4 (np-nsh) = 4.44 μm
【0041】実施例5 (1)Li2CO3 27.7モル%、Nb2O5 29.3モ
ル%、K2CO3 21.5モル%、V2O5 21.5モル
%、MgOをニオブ酸リチウムの理論量に対して6モル
%添加した混合物を白金ルツボに入れ、エピタキシャル
成長育成装置中で空気雰囲気下で1100℃まで加熱し
てルツボの内容物を溶解した。 (2)溶融体を1時間当り60℃の冷却速度で896℃ま
で徐冷した。タンタル酸リチウム単結晶の(0001)面
を光学研磨した後、フォトリソグラフィ−およびRFス
パッタ法により、膜厚800Å、幅5μmのMgO膜
と、この幅5μmのMgO膜以外の部分に膜厚400Å
のCr膜を形成した後、1000℃にて熱拡散させ、幅
5μmのMgO拡散チャンネルをもつものを化学エッチ
ングし、基板材料とした。MgOを拡散させたチャンネ
ル部分およびチャンネル部分以外のCrを拡散させた部
分は、何も拡散させない基板材料に比べて、常光屈折率
はそれぞれ10×10-3減少および1×10-3増大して
いた。この基板材料を溶融体中に100rpmで回転さ
せながら11分間浸漬した。Example 5 (1) Li 2 CO 3 27.7 mol%, Nb 2 O 5 29.3 mol%, K 2 CO 3 21.5 mol%, V 2 O 5 21.5 mol%, MgO A mixture of 6 mol% of lithium niobate added to the theoretical amount was placed in a platinum crucible and heated to 1100 ° C. under an air atmosphere in an epitaxial growth and growth apparatus to dissolve the contents of the crucible. (2) The melt was gradually cooled to 896 ° C at a cooling rate of 60 ° C per hour. After optically polishing the (0001) plane of the lithium tantalate single crystal, a MgO film having a film thickness of 800 μm and a width of 5 μm and a film thickness of 400 μm was formed on a portion other than the MgO film having a width of 5 μm by photolithography and RF sputtering.
After the Cr film was formed, the film was thermally diffused at 1000 ° C., and one having a MgO diffusion channel with a width of 5 μm was chemically etched to obtain a substrate material. In the channel portion in which MgO was diffused and the portion other than the channel portion in which Cr was diffused, the ordinary refractive index was decreased by 10 × 10 −3 and increased by 1 × 10 −3, respectively, as compared with the substrate material in which nothing was diffused. It was This substrate material was immersed in the melt for 11 minutes while rotating at 100 rpm.
【0042】(3)溶融体から基本材料を引き上げ、回転
数1000rpmで30秒間溶融体上で、溶融体を振り
切った後、室温まで徐冷し、基板材料上に約7μmの厚
さのMgO含有ニオブ酸リチウム単結晶薄膜を得た。 (4)実施例2と同様にして、ドメイン反転層が形成され
たニオブ酸リチウム単結晶薄膜を形成した。波長830
nmに対してLNの屈折率は、2.173、波長415
nmに対して、2.314であった。この膜から導波路
を切り出し、導波路の端面を研磨し波長830nm、5
0mWの半導体レ−ザの光を入射したところ反対側の端
面から波長415nmのレ−ザ光が出た。この時の変換
効率は6.8%であった。このことから本素子は極めて
優れたSHG素子であることが確認された。本素子のド
メイン周期は、次のとおりであった。 (2m+1)λ/4(np−nsh)=4.44μm(3) The basic material was pulled up from the melt, the melt was shaken off on the melt at a rotation speed of 1000 rpm for 30 seconds, and then gradually cooled to room temperature to contain MgO having a thickness of about 7 μm on the substrate material. A lithium niobate single crystal thin film was obtained. (4) In the same manner as in Example 2, a lithium niobate single crystal thin film having a domain inversion layer was formed. Wavelength 830
LN has a refractive index of 2.173 and a wavelength of 415 with respect to nm.
It was 2.314 with respect to nm. A waveguide is cut out from this film, and the end face of the waveguide is polished to obtain a wavelength of 830 nm.
When light from a semiconductor laser of 0 mW was incident, laser light with a wavelength of 415 nm was emitted from the end face on the opposite side. The conversion efficiency at this time was 6.8%. From this, it was confirmed that this element is an extremely excellent SHG element. The domain period of this device was as follows. (2m + 1) λ / 4 (np-nsh) = 4.44 μm
【0043】実施例6 本実施例は、基本的には、実施例1と同様であるが、基
板、薄膜中に異種元素を含有させ、基板と薄膜を格子整
合させた後、SHG素子を作成した。表1に、SHG素
子の変換効率を記載する。Example 6 This example is basically the same as Example 1, except that a different element is contained in the substrate and the thin film, and the substrate and the thin film are lattice-matched, and then an SHG element is produced. did. Table 1 shows the conversion efficiency of the SHG element.
【0044】[0044]
【表1】 [Table 1]
【0045】比較例 図4において、LN基板1上にフォトリソグラフにより
1.47μmのスプライトパタ−ン3を形成した(b
図)。ここにTiを真空蒸着して550Åの膜を形成し
た(c図)。Ti膜をリフトオフすることによりLN基
板上にTiのパタ−ンを形成した(d図)。これを管状
炉により1035℃で処理し、TiをLN基板上に拡散
させた(e図)。この膜の一部を切り出しHFエッチン
グを行ない顕微鏡で観察したところTiが拡散したとこ
ろだけが分極が反転していることが観察された。このT
iのパタ−ンに対し垂直に幅7μmの一本線のパタ−ン
をフォトリソグラフにより形成しTiを真空蒸着してリ
フトオフすることによりLN膜上にTiのパタ−ンを形
成した。パタ−ンのところだけ安息香酸で250℃で処
理した。このようにして、プロトン交換導波路を作製し
た(f図)。この導波路の端面を研磨し波長830n
m、50mWの半導体レ−ザの光を入射したところ反対
側の端面から波長415nmのレ−ザ光が出た。この時
の変換効率は0.78であった。波長830nmに対し
てLNの屈折率は、2.169、波長415nmに対し
て、2.310であった。Comparative Example In FIG. 4, a 1.47 μm sprite pattern 3 was formed on the LN substrate 1 by photolithography (b).
Figure). Here, Ti was vacuum-deposited to form a 550 Å film (Fig. C). A Ti pattern was formed on the LN substrate by lifting off the Ti film (FIG. D). This was treated at 1035 ° C. in a tubular furnace to diffuse Ti on the LN substrate (Fig. E). When a part of this film was cut out and subjected to HF etching and observed with a microscope, it was observed that the polarization was inverted only where Ti was diffused. This T
A single line pattern having a width of 7 μm was formed perpendicular to the i pattern by photolithography, and Ti was vacuum-deposited and lifted off to form a Ti pattern on the LN film. Only the pattern was treated with benzoic acid at 250 ° C. In this way, a proton exchange waveguide was prepared (Fig. F). The end face of this waveguide is polished to a wavelength of 830n.
When light from a semiconductor laser of m or 50 mW was incident, laser light with a wavelength of 415 nm was emitted from the end face on the opposite side. The conversion efficiency at this time was 0.78. The refractive index of LN was 2.169 for a wavelength of 830 nm and 2.310 for a wavelength of 415 nm.
【0046】[0046]
【発明の効果】以上述べたように、本発明においてはニ
オブ酸リチウム単結晶薄膜は基板であるタンタル酸リチ
ウムと格子整合されているので、厚い膜厚で形成するこ
とができると共に、本発明においては従来のようにプロ
トン交換を行うことなくキュリ−点よりやや高い温度に
加熱後、急冷することによってドメイン反転処理を行う
ので、ニオブ酸リチウム単結晶薄膜の結晶構造に変化を
生じること無く高い変換効率のSHGを提供することが
出来る。As described above, in the present invention, since the lithium niobate single crystal thin film is lattice-matched with the substrate lithium tantalate, it can be formed with a large film thickness, and in the present invention. Is heated to a temperature slightly higher than the Curie point without performing proton exchange as in the conventional case, and is then subjected to domain inversion treatment by rapid cooling, so that high conversion can be achieved without changing the crystal structure of the lithium niobate single crystal thin film. An efficient SHG can be provided.
【図1】本発明にかかるニオブ酸リチウム単結晶薄膜の
実施例1,4,6の製造工程を示す図である。FIG. 1 is a diagram showing a manufacturing process of Examples 1, 4, and 6 of a lithium niobate single crystal thin film according to the present invention.
【図2】本発明にかかるニオブ酸リチウム単結晶薄膜の
実施例2,5の製造工程を示す図である。FIG. 2 is a diagram showing a manufacturing process of Examples 2 and 5 of a lithium niobate single crystal thin film according to the present invention.
【図3】本発明にかかるニオブ酸リチウム単結晶薄膜の
実施例3の製造工程を示す図である。FIG. 3 is a diagram showing a manufacturing process of Example 3 of the lithium niobate single crystal thin film according to the invention.
【図4】従来のニオブ酸リチウム単結晶薄膜の製造工程
を示す図である。FIG. 4 is a diagram showing a manufacturing process of a conventional lithium niobate single crystal thin film.
1 タンタル酸リチウム基板 2 ニオブ酸リチウム単結晶薄膜(LN膜) 3 スプライトパタ−ン 4 Ti薄膜 4’ Ti拡散部分 5 ドメイン反転層 6 導波路 7 SiO2膜 7’ SiO2拡散部分 8 プロトン交換導波路1 Lithium tantalate substrate 2 Lithium niobate single crystal thin film (LN film) 3 Sprite pattern 4 Ti thin film 4'Ti diffusion part 5 Domain inversion layer 6 Waveguide 7 SiO 2 film 7 'SiO 2 diffusion part 8 Proton exchange conduction Waveguide
Claims (1)
れ、周期毎に結晶軸方向に分極が反転されるようにドメ
イン反転処理が施されたニオブ酸リチウム単結晶薄膜。Claim: What is claimed is: 1. A lithium niobate single crystal thin film which is lattice-matched on a lithium tantalate substrate and which has been domain-inverted so that the polarization is inverted in the crystal axis direction at every period.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3191221A JPH0517295A (en) | 1991-07-05 | 1991-07-05 | Lithium niobate single crystal thin film subjected to domain inversion treatment |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3191221A JPH0517295A (en) | 1991-07-05 | 1991-07-05 | Lithium niobate single crystal thin film subjected to domain inversion treatment |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0517295A true JPH0517295A (en) | 1993-01-26 |
Family
ID=16270915
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3191221A Pending JPH0517295A (en) | 1991-07-05 | 1991-07-05 | Lithium niobate single crystal thin film subjected to domain inversion treatment |
Country Status (1)
Country | Link |
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JP (1) | JPH0517295A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0863117A3 (en) * | 1997-03-04 | 1998-10-07 | Ngk Insulators, Ltd. | A process for forming a microstructure in a substrate of a ferroelectric single crystal |
WO1998046813A1 (en) * | 1997-04-17 | 1998-10-22 | The Secretary Of State For Defence | Etching method |
US6334008B2 (en) | 1998-02-19 | 2001-12-25 | Nec Corporation | Optical circuit and method of fabricating the same |
JP2003270467A (en) * | 2002-01-09 | 2003-09-25 | Matsushita Electric Ind Co Ltd | Method of manufacturing optical waveguide device, optical waveguide device, and coherent light source and optical apparatus using the optical waveguide device |
JP2011064895A (en) * | 2009-09-16 | 2011-03-31 | Nippon Telegr & Teleph Corp <Ntt> | Wavelength conversion device and wavelength conversion apparatus |
CN110568551A (en) * | 2019-08-22 | 2019-12-13 | 易锐光电科技(安徽)有限公司 | Lithium niobate optical waveguide chip |
-
1991
- 1991-07-05 JP JP3191221A patent/JPH0517295A/en active Pending
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0863117A3 (en) * | 1997-03-04 | 1998-10-07 | Ngk Insulators, Ltd. | A process for forming a microstructure in a substrate of a ferroelectric single crystal |
US6117346A (en) * | 1997-03-04 | 2000-09-12 | Ngk Insulators, Ltd. | Process for forming a microstructure in a substrate of a ferroelectric single crystal |
WO1998046813A1 (en) * | 1997-04-17 | 1998-10-22 | The Secretary Of State For Defence | Etching method |
GB2339554A (en) * | 1997-04-17 | 2000-02-02 | Secr Defence | Etching method |
GB2339554B (en) * | 1997-04-17 | 2001-11-28 | Secr Defence | Etching method |
US6344150B1 (en) | 1997-04-17 | 2002-02-05 | Qinetiq Limited | Etching method |
US6334008B2 (en) | 1998-02-19 | 2001-12-25 | Nec Corporation | Optical circuit and method of fabricating the same |
JP2003270467A (en) * | 2002-01-09 | 2003-09-25 | Matsushita Electric Ind Co Ltd | Method of manufacturing optical waveguide device, optical waveguide device, and coherent light source and optical apparatus using the optical waveguide device |
JP2011064895A (en) * | 2009-09-16 | 2011-03-31 | Nippon Telegr & Teleph Corp <Ntt> | Wavelength conversion device and wavelength conversion apparatus |
CN110568551A (en) * | 2019-08-22 | 2019-12-13 | 易锐光电科技(安徽)有限公司 | Lithium niobate optical waveguide chip |
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