JPS6032843B2 - Method for forming lithium tantalate optical waveguide - Google Patents
Method for forming lithium tantalate optical waveguideInfo
- Publication number
- JPS6032843B2 JPS6032843B2 JP15240976A JP15240976A JPS6032843B2 JP S6032843 B2 JPS6032843 B2 JP S6032843B2 JP 15240976 A JP15240976 A JP 15240976A JP 15240976 A JP15240976 A JP 15240976A JP S6032843 B2 JPS6032843 B2 JP S6032843B2
- Authority
- JP
- Japan
- Prior art keywords
- lithium tantalate
- optical waveguide
- lita03
- refractive index
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Optical Integrated Circuits (AREA)
Description
【発明の詳細な説明】
近年、光導波路や光変調等の能動機能を有する光IC素
子の研究、開発が盛んになっている。DETAILED DESCRIPTION OF THE INVENTION In recent years, research and development of optical IC elements having active functions such as optical waveguides and optical modulation have become active.
光導波略は基板上に高屈折率を有する単結晶薄膜の層を
形成することにより実現でき、これらの作成法としてス
パッタ法、液相ヱピタキシャル法(LPE法)、電界拡
散法、逆拡散法等が試みられている。ニオブ酸リシウム
(LiNb03)はタンタル酸リシウム(LITa03
)よりも屈折率が大きく、かつこれらの二つは格子定数
がほぼ等しいため、LITa03基板上に育成されたL
iNb03薄膜から成る光導波路の研究が非常によく行
なわれている。Optical waveguide can be realized by forming a single crystal thin film layer with a high refractive index on a substrate, and methods for creating these include sputtering, liquid phase epitaxial method (LPE method), electric field diffusion method, and back diffusion method. etc. are being attempted. Lithium niobate (LiNb03) is lithium tantalate (LITa03)
), and since these two have almost the same lattice constant, the L grown on the LITa03 substrate
Optical waveguides made of iNb03 thin films have been extensively studied.
しかしながら、周知のようにLiNb03は光損傷を極
めて受け易く、特に光導波路のように狭い領域にレーザ
光を閉じ込める場合にはしーザ光の密度が増大し、光損
傷が極めて起り易くなる。このためLiNb03を光変
調素子のような機能素子として動作させるには、使用す
るレーザ光の強度が制限され、実用上障害となる。一方
、LITa03はLINO03に比べて光損傷の閥値が
非常に高く、実用上のレーザ光密度に対してはほとんど
問題がないことが判明している。However, as is well known, LiNb03 is extremely susceptible to optical damage, and especially when laser light is confined in a narrow area such as in an optical waveguide, the density of laser light increases, making optical damage extremely likely to occur. Therefore, in order to operate LiNb03 as a functional element such as a light modulation element, the intensity of the laser light used is limited, which is a practical obstacle. On the other hand, LITa03 has a much higher optical damage threshold than LINO03, and it has been found that there is almost no problem with practical laser light density.
そのため光に材料の本命はLITa03であると考えら
れ、最近LITa03を用いる試みがなされはじめてき
た。一例としてLITa03に銅等の不純物を熱拡散法
により拡散させて高屈折率層を形成し、光導波路とする
試みがなされている。しかしながら、この不純物拡散に
より作成された光導波略は、本質的に‘1}屈折率分布
になだらかな勾配をもつこと、■レーザ光の吸収が増大
すること、脚光損傷を起し易いこと等の欠点があり、光
導波路として、またこれを利用した光変調器の特性とし
て好ましくないものといえる。本発明はこれらの欠点の
ない屈折率分布が一様なLITa03から成る新しい光
導波略の形成方法を提供するものである。Therefore, it is thought that LITa03 is the most suitable material for light, and recently attempts have been made to use LITa03. As an example, an attempt has been made to form a high refractive index layer by diffusing impurities such as copper into LITa03 using a thermal diffusion method to form an optical waveguide. However, optical waveguides created by this impurity diffusion essentially have the following problems: (1) They have a gentle slope in their refractive index distribution, (2) Increased absorption of laser light, and are susceptible to beam damage. It has drawbacks, and it can be said that it has unfavorable characteristics as an optical waveguide and as an optical modulator using it. The present invention provides a new method for forming an optical waveguide structure made of LITa03 with a uniform refractive index distribution that does not have these drawbacks.
以下、図面を参照しながら一実施例について詳細に説明
する。LITa03を光導波路として用いるためには、
基板の屈折率がLITa03のそれよりも小さくなけれ
ばならない。そこで格子定数が近く、LITaQよりも
屈折率の小さな基板を探策した。酸化マグネシウム(M
g○)を1モル%添加して、引上げ法により育成したタ
ンタル酸リシウムのキュリー温度を測定すると、無添加
のタンタル酸リシウムよりも約40℃上昇した。Hereinafter, one embodiment will be described in detail with reference to the drawings. In order to use LITa03 as an optical waveguide,
The refractive index of the substrate must be smaller than that of LITa03. Therefore, we searched for a substrate with a similar lattice constant and a lower refractive index than LITaQ. Magnesium oxide (M
When the Curie temperature of lithium tantalate grown by the pulling method with the addition of 1 mol % of g○) was measured, it was approximately 40° C. higher than that of lithium tantalate without additives.
ところで、Liが過剰な溶融液から育成したタンタル酸
リシウムのキュリー温度は、Li成分の増加と共に上昇
することが明らかにされており、(Y.Fujino、
日.TsuyaandK.Sugb比hi、Fen肥l
ecbics誌、2巻113〜117ページ、1971
年)、またLi成分の増加に対応して異常光線に対する
屈折率が小さくなることも知られている。(AABal
lmon、日.J.Uvi船tein、C.D.Cap
ioa他日.Brown、J.Am.Ceram.S肌
.誌5頂登657〜659ページ、1967年)。した
がってMg0を添加することによりキュリー温度が上昇
したことは、Mg0の添加が屈折率をもつ・さくするで
あろうと推定された。そこでMg○を添加して育成した
LITa03単結晶について斑93Aおよび6328A
の波長について屈折率を測定すると、図に示すように異
常光線および常光線に対して屈折率は減少することが判
った。By the way, it has been revealed that the Curie temperature of lithium tantalate grown from a melt containing excess Li increases as the Li content increases (Y. Fujino,
Day. Tsuya and K. Sugb ratio, Fen fertilizer
ecbics magazine, volume 2, pages 113-117, 1971
It is also known that the refractive index for extraordinary rays decreases as the Li component increases. (AABal
lmon, day. J. Uvi ship tein, C. D. Cap
ioa other day. Brown, J. Am. Ceram. S skin. Magazine 5 Choto, pages 657-659, 1967). Therefore, the fact that the Curie temperature increased due to the addition of Mg0 was inferred from the fact that the addition of Mg0 would increase the refractive index. Therefore, spots 93A and 6328A were observed for LITa03 single crystals grown by adding Mg○.
When the refractive index was measured for wavelengths of , it was found that the refractive index decreased for extraordinary and ordinary rays, as shown in the figure.
添加濃度に対する屈折率変化の関係式は異常光線および
常光線に対する変化量を△舵および△noとし、添加濃
度をCとすると、△ne2一0.001Cおよび△no
2一0.0008Cとなり、ほゞ比例して減少する。例
えば5モルのMg○を添加すると屈折率は約0.005
減少する。したがってMg○をより多く添加すれば屈折
率の減少はより著しくなるが、例えば、Mg0を10%
以上添加して育成すると、結晶は亀裂を生じて結晶性が
著しく悪化し使用できなかった。またMg○の偏折係数
を原子吸光分析法により求めたところ、ほぼ1.0であ
り、添加濃度と結晶内の濃度はほゞ等しかった。そこで
Mやを添加したLITa03を基板としてLPE法によ
りLITaQ膜を作成した。The relational expression of the refractive index change with respect to the doping concentration is as follows: If the amount of change for the extraordinary ray and the ordinary ray is △rudder and △no, and the doping concentration is C, then △ne2 - 0.001C and △no
2-0.0008C, and decreases almost proportionally. For example, when 5 mol of Mg○ is added, the refractive index is approximately 0.005.
Decrease. Therefore, if more Mg○ is added, the decrease in the refractive index becomes more remarkable.
When grown with the above addition, the crystals cracked and the crystallinity deteriorated significantly, making them unusable. Furthermore, when the polarization coefficient of Mg○ was determined by atomic absorption spectrometry, it was approximately 1.0, and the concentration added was approximately equal to the concentration within the crystal. Therefore, a LITaQ film was created by the LPE method using LITa03 doped with M as a substrate.
フラックスとして、よく知られているV2Qを用い、V
205:LITa03=80:20の溶融液から約12
00qoで育成したLITa03膜にプリズムを用いて
レーザ光を導入すると、レーザ光はLITa03薄膜の
中を導波することが確かめられた。また光損傷も起らな
いことが判明した。以上詳述したように、本発明により
新しく提供したMg○添加LITa○裏基板とLITa
Q薄膜から成る光導波路は極めて光損傷に強い性質を有
している。Using the well-known V2Q as the flux, V
Approximately 12 from the melt of 205:LITa03=80:20
When laser light was introduced into the LITa03 film grown at 00qo using a prism, it was confirmed that the laser light was guided through the LITa03 thin film. It was also found that no photodamage occurred. As detailed above, the Mg○ doped LITa○ back substrate newly provided by the present invention and the LITa○
Optical waveguides made of Q thin films are extremely resistant to optical damage.
図は屈折率とM奴の添加濃度との関係を示す図である。 The figure shows the relationship between the refractive index and the concentration of Mn added thereto.
Claims (1)
タル酸リシウム単結晶を引上法により育成し、この単結
晶を基板として成形し、この基板上に液相エピタキシヤ
ル法によりタンタル酸リシウム膜を形成することを特徴
とするタンタル酸リシウム光導波路の形成方法。1. Grow a lithium tantalate single crystal to which 10 mol% or less of magnesium oxide has been added by a pulling method, mold this single crystal as a substrate, and form a lithium tantalate film on this substrate by a liquid phase epitaxial method. A method for forming a lithium tantalate optical waveguide, characterized by:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15240976A JPS6032843B2 (en) | 1976-12-17 | 1976-12-17 | Method for forming lithium tantalate optical waveguide |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP15240976A JPS6032843B2 (en) | 1976-12-17 | 1976-12-17 | Method for forming lithium tantalate optical waveguide |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5376048A JPS5376048A (en) | 1978-07-06 |
JPS6032843B2 true JPS6032843B2 (en) | 1985-07-30 |
Family
ID=15539870
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP15240976A Expired JPS6032843B2 (en) | 1976-12-17 | 1976-12-17 | Method for forming lithium tantalate optical waveguide |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6032843B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4775208A (en) * | 1986-06-06 | 1988-10-04 | Polaroid Corporation | Planar waveguide mode converter device |
US5015066A (en) * | 1990-05-29 | 1991-05-14 | Eastman Kodak Company | Multichannel waveguide print head with symmetric output |
JP2574602B2 (en) * | 1992-07-08 | 1997-01-22 | 松下電器産業株式会社 | Optical waveguide device |
-
1976
- 1976-12-17 JP JP15240976A patent/JPS6032843B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS5376048A (en) | 1978-07-06 |
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