JPH05107579A - Production of optical wavelength conversion element - Google Patents
Production of optical wavelength conversion elementInfo
- Publication number
- JPH05107579A JPH05107579A JP3255161A JP25516191A JPH05107579A JP H05107579 A JPH05107579 A JP H05107579A JP 3255161 A JP3255161 A JP 3255161A JP 25516191 A JP25516191 A JP 25516191A JP H05107579 A JPH05107579 A JP H05107579A
- Authority
- JP
- Japan
- Prior art keywords
- polarization inversion
- inversion layer
- wavelength conversion
- proton exchange
- layer
- 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.)
- Granted
Links
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
- G02F1/35—Non-linear optics
- G02F1/355—Non-linear optics characterised by the materials used
- G02F1/3558—Poled materials, e.g. with periodic poling; Fabrication of domain inverted structures, e.g. for quasi-phase-matching [QPM]
-
- 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
- G02F1/35—Non-linear optics
- G02F1/37—Non-linear optics for second-harmonic generation
- G02F1/377—Non-linear optics for second-harmonic generation in an optical waveguide structure
- G02F1/3775—Non-linear optics for second-harmonic generation in an optical waveguide structure with a periodic structure, e.g. domain inversion, for quasi-phase-matching [QPM]
-
- 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
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
- G02F1/3544—Particular phase matching techniques
- G02F1/3548—Quasi phase matching [QPM], e.g. using a periodic domain inverted structure
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、コヒ−レント光を利用
する光情報処理分野、あるいは光応用計測制御分野に使
用する光波長変換素子の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical wavelength conversion element used in the field of optical information processing utilizing coherent light or in the field of optical measurement and control.
【０００２】[0002]
【従来の技術】図４に従来の光導波路を基本とした光波
長変換素子の構成図を示す。以下0.84μｍの波長の基本
波に対する高調波発生（波長0.42μｍ）について図を用
いて詳しく述べる。（K.Mizuuchi, K.Yamamoto and T.T
aniuchi, Applied Physics Letters, Vol 58, 2732ペー
ジ, 1991年６月号、参照）．図４に示されるようにLiTa
O3基板１に光導波路２が形成され、さらに光導波路２に
は周期的に分極の反転した層３（分極反転層）が形成さ
れている。基本波Ｐ１と発生する高調波Ｐ２の伝搬定数
の不整合を分極反転層３および非分極反転層４の周期構
造で補償することにより高効率に高調波Ｐ２を出すこと
ができる。光導波路２の入射面１０に基本波Ｐ１を入射
すると、光導波路２から高調波Ｐ２が効率良く発生さ
れ、光波長変換素子として動作する。2. Description of the Related Art FIG. 4 shows a block diagram of a conventional optical wavelength conversion element based on an optical waveguide. The harmonic generation (wavelength 0.42 μm) with respect to the fundamental wave having a wavelength of 0.84 μm will be described in detail below with reference to the drawings. (K.Mizuuchi, K.Yamamoto and TT
aniuchi, Applied Physics Letters, Vol 58, page 2732, June 1991 issue). As shown in Figure 4, LiTa
An optical waveguide 2 is formed on an O 3 substrate 1, and a layer 3 (polarization inversion layer) whose polarization is periodically inverted is further formed on the optical waveguide 2. By compensating for the mismatch between the propagation constants of the fundamental wave P1 and the generated harmonic wave P2 by the periodic structure of the polarization inversion layer 3 and the non-polarization inversion layer 4, the harmonic wave P2 can be generated with high efficiency. When the fundamental wave P1 is incident on the incident surface 10 of the optical waveguide 2, the harmonic P2 is efficiently generated from the optical waveguide 2 and operates as an optical wavelength conversion element.
【０００３】このような従来の光波長変換素子はプロト
ン交換法により作製された光導波路２を基本構成要素と
していた。この素子の製造方法について図を用いて説明
する。図５は従来の光波長変換素子の製造工程図であ
る。まず同図（ａ）でLiTaO3基板１に通常のフォトプロ
セスとドライエッチングを用いてＴａ６を周期状にパタ
ーニングする。次に同図（ｂ）でＴａ６パターンが形成
されたLiTaO3基板１に２６０℃、３０分間プロトン交換
を行いＴａ６で覆われていないスリット直下に厚み０．
８μｍのプロトン交換層８を形成する。次にＨＦ：ＨＮ
Ｆ3の１：１混合液にて２分間エッチングしＴａを除去
する。次に同図（ｃ）で５５０℃の温度で１分間熱処理
する。熱処理の上昇レートは５０℃／秒、冷却レートは
１０℃／秒である。これにより分極反転層３が形成され
る。プロトン交換層８はＬｉが減少しておりキュリー温
度が低下するため部分的に分極反転を行うことができ
る。さらに同図（ｄ）で上記分極反転層３中にプロトン
交換を用いて光導波路２を形成する。光導波路用マスク
としてＴａをストライプ状にパターニングを行うことで
Ｔａマスクに幅４μｍ、長さ１２ｍｍのスリットを形成
する。このＴａマスクで覆われた基板に２６０℃、１６
分間プロトン交換を行い０．５μｍの高屈折率層を形成
する。Ｔａマスクを除去した後４２０℃で３０秒間熱処
理を行う。プロトン交換された保護マスクのスリット直
下の領域は屈折率が０．０３程度上昇した光導波路２と
なる。分極反転層３の周期は１０．８μｍであり３次の
擬似位相整合構造となっていた。この従来の方法により
作製される光波長変換素子は波長0.84μｍの基本波Ｐ１
に対して、光導波路２の長さを９ｍｍ、基本波Ｐ１のパ
ワーを２７ｍＷにしたとき高調波Ｐ２のパワー０．１３
ｍＷ、変換効率０．５％が得られていた。Such a conventional optical wavelength conversion element has an optical waveguide 2 manufactured by a proton exchange method as a basic constituent element. A method of manufacturing this element will be described with reference to the drawings. FIG. 5 is a manufacturing process diagram of a conventional light wavelength conversion element. First, in FIG. (A) the LiTaO 3 substrate 1 by using the ordinary photo process and dry etching to pattern the Ta6 to periodic. Next, in FIG. 3B, the LiTaO 3 substrate 1 on which the Ta6 pattern was formed was subjected to proton exchange at 260 ° C. for 30 minutes, and a thickness of 0.
An 8 μm proton exchange layer 8 is formed. Then HF: HN
Ta is removed by etching with a 1: 1 mixed solution of F 3 for 2 minutes. Next, as shown in FIG. 3C, heat treatment is performed at a temperature of 550 ° C. for 1 minute. The rising rate of the heat treatment is 50 ° C./sec, and the cooling rate is 10 ° C./sec. Thereby, the domain inversion layer 3 is formed. Since the Li content of the proton exchange layer 8 is reduced and the Curie temperature is lowered, polarization reversal can be partially performed. Further, in FIG. 3D, the optical waveguide 2 is formed in the polarization inversion layer 3 by using proton exchange. By patterning Ta as an optical waveguide mask in a stripe shape, a slit having a width of 4 μm and a length of 12 mm is formed in the Ta mask. The substrate covered with this Ta mask is 260 ° C.
Proton exchange is performed for a minute to form a 0.5 μm high refractive index layer. After removing the Ta mask, heat treatment is performed at 420 ° C. for 30 seconds. The region directly under the slit of the proton-exchanged protective mask becomes the optical waveguide 2 having a refractive index increased by about 0.03. The period of the domain inversion layer 3 was 10.8 μm, and the structure was a third-order quasi phase matching structure. The optical wavelength conversion element manufactured by this conventional method has a fundamental wave P1 with a wavelength of 0.84 μm.
On the other hand, when the length of the optical waveguide 2 is 9 mm and the power of the fundamental wave P1 is 27 mW, the power of the harmonic wave P2 is 0.13.
mW and conversion efficiency of 0.5% were obtained.
【０００４】また、１次の擬似位相整合構造の場合周期
は３．６μｍと小さく、そのため分極反転層の厚みは
１．５μｍとなる。この場合基本波Ｐ１が２７ｍＷで
０．３ｍＷの高調波Ｐ２が得られていた。変換効率は１
％であった。Further, in the case of the first-order quasi phase matching structure, the period is as small as 3.6 μm, and therefore the thickness of the domain inversion layer is 1.5 μm. In this case, the fundamental wave P1 was 27 mW and the harmonic wave P2 of 0.3 mW was obtained. Conversion efficiency is 1
%Met.
【０００５】[0005]
【発明が解決しようとする課題】上記のような光導波路
を基本とした光波長変換素子では高効率変換が可能な１
次の擬似位相整合の場合、分極反転層の厚みが光導波路
に比べて小さく、そのため光導波路を伝搬する光と分極
反転層のオーバーラップも小さくなっていた。この従来
の作製方法では分極反転層は半円形状となるため分極反
転層幅と厚みが比例しこれ以上深くすることができなか
った。そのため変換効率が理論にたいして１／４程度に
低下してしまうといった問題があった。The optical wavelength conversion element based on the above-mentioned optical waveguide is capable of high efficiency conversion.
In the case of the following quasi-phase matching, the thickness of the polarization inversion layer was smaller than that of the optical waveguide, and therefore the overlap between the light propagating through the optical waveguide and the polarization inversion layer was also small. In this conventional manufacturing method, since the domain-inverted layer has a semicircular shape, the domain-inverted layer width is proportional to the thickness, and it cannot be made deeper than this. Therefore, there is a problem that the conversion efficiency is reduced to about 1/4 of the theory.
【０００６】[0006]
【課題を解決するための手段】本発明は、上記問題点を
解決するため光波長変換素子の製造方法に新たな工夫を
加えることにより高効率変換可能な光波長変換素子の製
造方法を提供するものである。つまり、非線形光学結晶
内部にスラブ状に分極反転層を形成する工程と、前記非
線形光学結晶表面に周期状に分極反転層を形成する工程
と、前記非線形光学結晶表面に光導波路を形成する工程
とを有するものである。The present invention provides a method of manufacturing an optical wavelength conversion element capable of highly efficient conversion by adding a new device to the method of manufacturing an optical wavelength conversion element in order to solve the above problems. It is a thing. That is, a step of forming a polarization inversion layer in a slab shape inside the nonlinear optical crystal, a step of forming periodically a polarization inversion layer on the surface of the nonlinear optical crystal, and a step of forming an optical waveguide on the surface of the nonlinear optical crystal. Is to have.
【０００７】[0007]
【作用】本発明の光波長変換素子の製造方法によれば、
非線形光学結晶であるLiTaO3内部に形成されたスラブ状
の分極反転層を利用することで、分極反転層の形状を縦
長にし、LiTaO3基板中に深い周期状の分極反転層を形成
できる。これにより光導波路とのオーバーラップが増し
変換効率が大幅に向上する。According to the method of manufacturing the optical wavelength conversion element of the present invention,
By using the slab-shaped polarization inversion layer formed inside LiTaO 3 which is a nonlinear optical crystal, the polarization inversion layer can be made vertically long and deep periodic polarization inversion layers can be formed in the LiTaO 3 substrate. As a result, the overlap with the optical waveguide is increased and the conversion efficiency is significantly improved.
【０００８】[0008]
【実施例】第１の実施例として本発明の光波長変換素子
の製造方法について図を使って説明する。図１はその製
造工程図である。同図（ａ）でまずLiTaO3基板１にピロ
燐酸中でのプロトン交換により厚み２．５μｍのプロト
ン交換層５を形成する。次に同図（ｂ）で赤外線加熱装
置を用いて５５０℃、１５秒間熱処理を行いLiTaO3基板
１の内部にスラブ状の分極反転層７を形成する。プロト
ン交換層５はＬｉが減少しておりキュリー温度が低下す
るため部分的に分極反転ができる。また、分極反転層は
プロトン交換層と基板の境界１ａから発生しまわりに広
がる。そのため、この分極反転層７は表面から２．２μ
ｍのところから２．８μｍまでの深さまで形成された。
次に同図（ｃ）で通常のフォトプロセスとドライエッチ
ングを用いてＴａ６を周期状にパターニングした後、Ｔ
ａ６によるパターンが形成されたLiTaO3基板１に２６０
℃、３０分間プロトン交換を行いスリット直下に厚み
０．８μｍのプロトン交換層８を形成する。その後Ｈ
Ｆ：ＨＮＦ3の１：１混合液にて２分間エッチングしＴ
ａを除去する。次に同図（ｄ）で赤外線加熱装置を用い
て５５０℃の温度で１分間熱処理する。熱処理の上昇レ
ートは５０℃／秒、冷却レートは１０℃／秒である。こ
れにより分極反転層３が形成される。これは分極反転層
３が近傍の分極反転層７と結合しようとする作用によ
る。この分極反転層３はスラブ状の分極反転層７と接続
された形となる。そのため分極反転層３の深さは２．２
μｍとなる。次に上記分極反転層３に対してプロトン交
換を用いて光導波路２を形成する。同図（ｅ）で光導波
路用マスクとしてＴａをストライプ状にパターニングを
行った後、Ｔａマスクに幅４μｍ、長さ１２ｍｍのスリ
ットが形成されたものに２６０℃、１６分間ピロ燐酸中
でプロトン交換を行った後、赤外線加熱装置を用いて４
２０℃で３０秒熱処理を行った。これにより屈折率が
０．０３程度上昇した光導波路２が形成される。最後に
Ｔａを除去した後、蒸着によりSiO2を３０００Ａ付加し
た。EXAMPLE As a first example, a method for manufacturing an optical wavelength conversion device of the present invention will be described with reference to the drawings. FIG. 1 is a manufacturing process diagram thereof. In FIG. 3A, first, a proton exchange layer 5 having a thickness of 2.5 μm is formed on the LiTaO 3 substrate 1 by proton exchange in pyrophosphoric acid. Next, as shown in FIG. 2B, a slab-shaped polarization inversion layer 7 is formed inside the LiTaO 3 substrate 1 by heat treatment at 550 ° C. for 15 seconds using an infrared heating device. In the proton exchange layer 5, Li is reduced and the Curie temperature is lowered, so that the polarization can be partially inverted. The polarization inversion layer is generated from the boundary 1a between the proton exchange layer and the substrate and spreads around. Therefore, the domain-inverted layer 7 is 2.2 μm from the surface.
It was formed up to a depth of 2.8 μm from m.
Next, in the same figure (c), after Ta6 is patterned in a periodic shape by using a normal photo process and dry etching,
260 on the LiTaO 3 substrate 1 on which the pattern of a6 is formed
Proton exchange is performed at 30 ° C. for 30 minutes to form a proton exchange layer 8 having a thickness of 0.8 μm just below the slit. Then H
Etching for 2 minutes with a 1: 1 mixture of F: HNF 3 and T
a is removed. Next, as shown in FIG. 3D, heat treatment is performed for 1 minute at a temperature of 550 ° C. using an infrared heating device. The rising rate of the heat treatment is 50 ° C./sec, and the cooling rate is 10 ° C./sec. Thereby, the domain inversion layer 3 is formed. This is due to the action of the domain-inverted layer 3 attempting to combine with the domain-inverted layer 7 in the vicinity. The domain-inverted layer 3 is connected to the slab-shaped domain-inverted layer 7. Therefore, the depth of the domain inversion layer 3 is 2.2.
μm. Next, the optical waveguide 2 is formed on the polarization inversion layer 3 by using proton exchange. In the same figure (e), after Ta was patterned into a stripe shape as an optical waveguide mask, a Ta mask with slits of 4 μm in width and 12 mm in length was formed, and proton exchange was performed in pyrophosphoric acid for 16 minutes at 260 ° C. After performing the
Heat treatment was performed at 20 ° C. for 30 seconds. As a result, the optical waveguide 2 having a refractive index increased by about 0.03 is formed. Finally, after removing Ta, 3000 A of SiO 2 was added by vapor deposition.
【０００９】上記のような工程により分極反転層３およ
び光導波路２が製造された。この分極反転層３の厚み
２．２μｍは光導波路２の厚みｄは１．８μｍに比べ大
きく完全にオーバーラップされておりこのため有効に波
長変換が行われる。分極反転層３の周期は３．６μｍで
あり波長０．８４ｎｍに対して動作する。また、この光
導波路２の非分極反転層４と分極反転層３の屈折率変化
はなく、光が導波する場合の伝搬損失は小さい。光導波
路２に垂直な面を光学研磨し入射部および出射部を形成
した。このようにして光波長変換素子が製造できる。The polarization inversion layer 3 and the optical waveguide 2 are manufactured by the above steps. The thickness 2.2 μm of the domain inversion layer 3 is larger than the thickness d of the optical waveguide 2 which is 1.8 μm and completely overlaps each other, so that wavelength conversion is effectively performed. The period of the domain inversion layer 3 is 3.6 μm and operates for a wavelength of 0.84 nm. Further, there is no change in the refractive index of the non-polarization inversion layer 4 and the polarization inversion layer 3 of the optical waveguide 2, and the propagation loss when light is guided is small. A plane perpendicular to the optical waveguide 2 was optically polished to form an incident portion and an emission portion. In this way, the light wavelength conversion element can be manufactured.
【００１０】また、この素子の長さは９ｍｍである。基
本波Ｐ１として半導体レーザ光（波長０．８４μｍ）を
入射部より導波させたところシングルモード伝搬し、波
長０．４２μｍの高調波Ｐ２が出射部より基板外部に取
り出された。光導波路２の伝搬損失は1dB/cmと小さく高
調波Ｐ２が有効に取り出された。低損失化の原因の１つ
として燐酸により均一な光導波路が形成されたことがあ
る。基本波２７ｍＷの入力で１．２ｍＷの高調波（波長
０．４２μｍ）を得た。この場合の変換効率は４．５％
であり従来のものにくらべて４倍の高効率化が図られて
いる。図２に分極反転層幅と分極反転層厚みの関係を示
す。本発明の光波長変換素子の製造方法によれば従来の
方法にくらべ１次の擬次位相整合周期に必要な幅１．８
μｍのところで分極反転層の厚みが１．４倍も深くなっ
ている。The length of this element is 9 mm. When semiconductor laser light (wavelength 0.84 μm) was guided as the fundamental wave P1 from the incident portion, it propagated in a single mode, and a harmonic wave P2 having a wavelength of 0.42 μm was extracted from the emitting portion to the outside of the substrate. The propagation loss of the optical waveguide 2 was as small as 1 dB / cm, and the harmonic P2 was effectively extracted. One of the causes of low loss is that phosphoric acid forms a uniform optical waveguide. A 1.2 mW harmonic (wavelength 0.42 μm) was obtained with a fundamental wave input of 27 mW. The conversion efficiency in this case is 4.5%
The efficiency is four times higher than the conventional one. FIG. 2 shows the relationship between the polarization inversion layer width and the polarization inversion layer thickness. According to the method of manufacturing an optical wavelength conversion element of the present invention, the width required for the first-order pseudo-order phase matching period is 1.8 as compared with the conventional method.
At μm, the thickness of the domain inversion layer is 1.4 times as deep.
【００１１】なおこのような短時間処理を行うには急速
加熱が可能な赤外線加熱装置が適している。An infrared heating device capable of rapid heating is suitable for performing such a short-time treatment.
【００１２】次に本発明の光波長変換素子の製造方法を
用いた第２の実施例について説明する。図３はその製造
工程図である。同図（ａ）でまずLiTaO3基板１にピロ燐
酸中でのプロトン交換により厚み１μｍのプロトン交換
層５を形成する。次に同図（ｂ）で５５０℃、２分熱処
理を行いLiTaO3基板１の表面にスラブ状の分極反転層７
を形成する。プロトン交換層はＬｉが減少しておりキュ
リー温度が低下するため部分的に分極反転ができる。こ
の分極反転層７は表面から厚み２．２μｍのところまで
形成された。次に同図（ｃ）で通常のフォトプロセスと
ドライエッチングを用いてＴａ６を周期状にパターニン
グする。次にＴａ６によるパターンが形成されたLiTaO3
基板１に２６０℃、２０分間プロトン交換を行いスリッ
ト直下に厚み０．５μｍのプロトン交換層８を形成す
る。次にＨＦ：ＨＮＦ3の１：１混合液にて２分間エッ
チングしＴａ６を除去する。次に同図（ｄ）で赤外線加
熱装置により５５０℃の温度で１分間熱処理する。熱処
理の上昇レートは５０℃／秒、冷却レートは１０℃／秒
である。これにより分極反転層７中に再反転層９が形成
される。この再反転層９は分極反転層７を越え反転され
てない領域に達したところで停止する。次に上記再反転
層９の残りの部分である分極反転層３に対してプロトン
交換を用いて光導波路２を形成する。同図（ｅ）で光導
波路用マスクとしてＴａをストライプ状にパターニング
を行った後、Ｔａマスクに幅４μｍ、長さ１２ｍｍのス
リットが形成されたものに２６０℃、１６分間ピロ燐酸
中でプロトン交換を行った後、Ｔａマスクを除去する。
次に、赤外線加熱装置を用いて４２０℃で３０秒熱処理
を行い屈折率が０．０３程度上昇した光導波路２が形成
される。最後に蒸着によりSiO2を３０００Ａ付加した。Next, a second embodiment using the method of manufacturing an optical wavelength conversion device of the present invention will be described. FIG. 3 is a manufacturing process drawing thereof. In FIG. 3A, first, a proton exchange layer 5 having a thickness of 1 μm is formed on a LiTaO 3 substrate 1 by proton exchange in pyrophosphoric acid. Next, as shown in FIG. 3B, heat treatment is performed at 550 ° C. for 2 minutes, and a slab-shaped polarization inversion layer 7 is formed on the surface of the LiTaO 3 substrate 1.
To form. Since the Li content of the proton exchange layer is reduced and the Curie temperature is lowered, polarization inversion can be partially performed. The domain-inverted layer 7 was formed to a thickness of 2.2 μm from the surface. Next, in FIG. 6C, Ta6 is patterned in a periodic shape by using a normal photo process and dry etching. Next, a LiTaO 3 pattern formed of Ta6 was formed.
Proton exchange is performed on the substrate 1 at 260 ° C. for 20 minutes to form a 0.5 μm-thick proton exchange layer 8 immediately below the slit. Next, Ta6 is removed by etching with a 1: 1 mixture of HF: HNF 3 for 2 minutes. Next, as shown in FIG. 3D, heat treatment is performed for 1 minute at a temperature of 550 ° C. by an infrared heating device. The rising rate of the heat treatment is 50 ° C./sec, and the cooling rate is 10 ° C./sec. As a result, the re-inversion layer 9 is formed in the polarization inversion layer 7. This re-inversion layer 9 stops when it reaches the region which has not been inverted, beyond the domain inversion layer 7. Next, the optical waveguide 2 is formed on the polarization inversion layer 3 which is the remaining part of the re-inversion layer 9 by using proton exchange. In the same figure (e), after Ta was patterned into a stripe shape as an optical waveguide mask, a Ta mask with slits of 4 μm in width and 12 mm in length was formed, and proton exchange was performed in pyrophosphoric acid for 16 minutes at 260 ° C. After that, the Ta mask is removed.
Next, an infrared heating device is used to perform heat treatment at 420 ° C. for 30 seconds to form the optical waveguide 2 having a refractive index increased by about 0.03. Finally, 3000 A of SiO 2 was added by vapor deposition.
【００１３】上記のような工程により分極反転層３およ
び光導波路２が製造された。この光導波路２の厚みｄは
１．８μｍであり分極反転層３の厚み２．２μｍに比べ
小さく有効に波長変換される。分極反転層３の周期は
３．６μｍであり波長０．８４ｎｍに対して動作する。
また、この光導波路２の非分極反転層４と分極反転層３
の屈折率変化はなく、光が導波する場合の伝搬損失は小
さい。光導波路２に垂直な面を光学研磨し入射部および
出射部を形成した。このようにして光波長変換素子が製
造できる。また、この素子の長さは９ｍｍである。基本
波Ｐ１として半導体レーザ光（波長０．８４μｍ）を入
射部より導波させたところ、波長０．４２μｍの高調波
Ｐ２が出射部より基板外部に取り出された。基本波８０
ｍＷの入力で１０ｍＷの高調波（波長０．４２μｍ）を
得た。この場合の変換効率は１２％る。光損傷はなく高
調波出力は非常に安定していた。The polarization inversion layer 3 and the optical waveguide 2 are manufactured by the above-mentioned steps. The thickness d of the optical waveguide 2 is 1.8 μm, which is smaller than the thickness 2.2 μm of the domain inversion layer 3 and the wavelength is effectively converted. The period of the domain inversion layer 3 is 3.6 μm and operates for a wavelength of 0.84 nm.
Further, the non-polarization inversion layer 4 and the polarization inversion layer 3 of this optical waveguide 2
There is no change in the refractive index and the propagation loss when light is guided is small. A plane perpendicular to the optical waveguide 2 was optically polished to form an incident portion and an emission portion. In this way, the light wavelength conversion element can be manufactured. The length of this element is 9 mm. When semiconductor laser light (wavelength 0.84 μm) was guided as the fundamental wave P1 from the incident portion, a harmonic wave P2 having a wavelength of 0.42 μm was taken out of the substrate from the emitting portion. Fundamental wave 80
A harmonic of 10 mW (wavelength 0.42 μm) was obtained with an input of mW. The conversion efficiency in this case is 12%. There was no optical damage and the harmonic output was very stable.
【００１４】なお実施例では非線形光学結晶としてLiTa
O3を用いたがLiNbO3、KNbO3、ＫＴＰ等の強誘電体にも
適用可能である。In the embodiment, LiTa is used as the nonlinear optical crystal.
Although O 3 is used, it is also applicable to ferroelectrics such as LiNbO 3 , KNbO 3 and KTP.
【００１５】[0015]
【発明の効果】以上説明したように本発明の光波長変換
素子の製造方法によれば、スラブ状の分極反転層を作製
しこのスラブ状の分極反転層に対して後から形成される
周期状の分極反転層の結合を利用することで、従来の方
法に比べて深い分極反転層を形成することができ光波長
変換素子の変換効率を大幅に向上させることができる。As described above, according to the method of manufacturing an optical wavelength conversion element of the present invention, a slab-shaped domain-inverted layer is formed and a periodic pattern formed later is formed on the slab-shaped domain-inverted layer. By utilizing the coupling of the polarization inversion layer, the deep polarization inversion layer can be formed and the conversion efficiency of the optical wavelength conversion element can be significantly improved as compared with the conventional method.
【図１】本発明の第１の実施例の光波長変換素子の製造
方法の工程断面図FIG. 1 is a process sectional view of a method for manufacturing an optical wavelength conversion device according to a first embodiment of the present invention.
【図２】分極反転層幅と分極反転層厚みとの関係を示す
図FIG. 2 is a diagram showing the relationship between the width of the domain inversion layer and the thickness of the domain inversion layer.
【図３】本発明の第２の実施例の光波長変換素子の製造
方法の工程断面図FIG. 3 is a process sectional view of a method for manufacturing an optical wavelength conversion device according to a second embodiment of the present invention.
【図４】従来の光波長変換素子の構成図FIG. 4 is a configuration diagram of a conventional optical wavelength conversion element.
【図５】従来の方法による光波長変換素子の製造方法の
工程断面図FIG. 5 is a process sectional view of a method for manufacturing an optical wavelength conversion element by a conventional method.
１ LiTaO3基板 ２ 光導波路 ３ 分極反転層 ５ 高屈折率層 ７ スラブ状の分極反転層 Ｐ１ 基本波 Ｐ２ 高調波1 LiTaO 3 substrate 2 optical waveguide 3 polarization inversion layer 5 high refractive index layer 7 slab polarization inversion layer P1 fundamental wave P2 harmonic
【手続補正書】[Procedure amendment]
【提出日】平成４年１１月１６日[Submission date] November 16, 1992
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００１５[Correction target item name] 0015
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００１５】[0015]
【発明の効果】以上説明したように本発明の光波長変換
素子の製造方法によれば、スラブ状の分極反転層を作製
しこのスラブ状の分極反転層に対して後から形成される
周期状の分極反転層の結合を利用することで、従来の方
法に比べて深い分極反転層を形成することができ光波長
変換素子の変換効率を大幅に向上させることができる。As described above, according to the method of manufacturing an optical wavelength conversion element of the present invention, a slab-shaped domain-inverted layer is formed and a periodic pattern formed later is formed on the slab-shaped domain-inverted layer. By utilizing the coupling of the polarization inversion layer, the deep polarization inversion layer can be formed and the conversion efficiency of the optical wavelength conversion element can be significantly improved as compared with the conventional method.
【手続補正２】[Procedure Amendment 2]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】図面の簡単な説明[Name of item to be corrected] Brief description of the drawing
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【図面の簡単な説明】[Brief description of drawings]
【図１】本発明の第１の実施例の光波長変換素子の製造
方法の工程断面図FIG. 1 is a process sectional view of a method for manufacturing an optical wavelength conversion device according to a first embodiment of the present invention.
【図２】分極反転層幅と分極反転層厚みとの関係を示す
図FIG. 2 is a diagram showing the relationship between the width of the domain inversion layer and the thickness of the domain inversion layer.
【図３】本発明の第２の実施例の光波長変換素子の製造
方法の工程断面図FIG. 3 is a process sectional view of a method for manufacturing an optical wavelength conversion device according to a second embodiment of the present invention.
【図４】従来の光波長変換素子の構成図FIG. 4 is a configuration diagram of a conventional optical wavelength conversion element.
【図５】従来の方法による光波長変換素子の製造方法の
工程断面図FIG. 5 is a process sectional view of a method for manufacturing an optical wavelength conversion element by a conventional method.
【符号の説明】 １ ＬｉＴａＯ3基板 ２ 光導波路 ３ 分極反転層 ５ 高屈折率層 ７ スラブ状の分極反転層 Ｐ１ 基本波 Ｐ２ 高調波[Explanation of Codes] 1 LiTaO 3 substrate 2 optical waveguide 3 polarization inversion layer 5 high refractive index layer 7 slab polarization inversion layer P1 fundamental wave P2 harmonic
Claims (4)
層を形成する工程と、前記非線形光学結晶表面に周期状
に分極反転層を形成する工程と、前記非線形光学結晶表
面に光導波路を形成する工程とを含むことを特徴とする
光波長変換素子の製造方法。1. A step of forming a polarization inversion layer in a slab shape inside a nonlinear optical crystal, a step of periodically forming a polarization inversion layer on the surface of the nonlinear optical crystal, and an optical waveguide formed on the surface of the nonlinear optical crystal. The manufacturing method of the optical wavelength conversion element characterized by including the process of performing.
層を形成する工程と、前記スラブ状の分極反転層にプロ
トン交換法により周期状の高屈折率層を形成する工程
と、前記高屈折率層を熱処理し周期状の再反転層を形成
する工程と、前記非線形光学結晶表面に光導波路を形成
する工程とを含むことを特徴とする光波長変換素子の製
造方法。2. A step of forming a slab-shaped polarization inversion layer on a surface of a nonlinear optical crystal, a step of forming a periodic high refractive index layer on the slab-shaped polarization inversion layer by a proton exchange method, and the high refractive index. A method of manufacturing an optical wavelength conversion element, comprising: a step of heat-treating the index layer to form a periodic re-inversion layer; and a step of forming an optical waveguide on the surface of the nonlinear optical crystal.
3（０≦Ｘ≦１）基板である請求項１または同２記載の
光波長変換素子の製造方法。3. The nonlinear optical crystal is LiNb x Ta 1-x O.
3. The method for manufacturing an optical wavelength conversion element according to claim 1, wherein the substrate is a 3 (0 ≦ X ≦ 1) substrate.
特徴とする請求項１または同２記載の光波長変換素子の
製造方法。4. The method of manufacturing an optical wavelength conversion element according to claim 1, wherein the heat treatment is carried out by using an infrared heating device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3255161A JP3006217B2 (en) | 1991-10-02 | 1991-10-02 | Optical wavelength conversion element and method of manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3255161A JP3006217B2 (en) | 1991-10-02 | 1991-10-02 | Optical wavelength conversion element and method of manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05107579A true JPH05107579A (en) | 1993-04-30 |
| JP3006217B2 JP3006217B2 (en) | 2000-02-07 |
Family
ID=17274913
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3255161A Expired - Fee Related JP3006217B2 (en) | 1991-10-02 | 1991-10-02 | Optical wavelength conversion element and method of manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3006217B2 (en) |
-
1991
- 1991-10-02 JP JP3255161A patent/JP3006217B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3006217B2 (en) | 2000-02-07 |
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