JPH0827969B2 - Waveguide type optical head - Google Patents
Waveguide type optical headInfo
- Publication number
- JPH0827969B2 JPH0827969B2 JP1306794A JP30679489A JPH0827969B2 JP H0827969 B2 JPH0827969 B2 JP H0827969B2 JP 1306794 A JP1306794 A JP 1306794A JP 30679489 A JP30679489 A JP 30679489A JP H0827969 B2 JPH0827969 B2 JP H0827969B2
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- Prior art keywords
- waveguide
- optical
- layer
- light
- waveguide layer
- Prior art date
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は光ディスクや光磁気ディスク等の光ピックア
ップ部に用いるに最適な光学ヘッドに関し、特に、光が
伝搬される導波層を有する光導波路を用いた導波路型光
学ヘッドに関する。Description: TECHNICAL FIELD The present invention relates to an optical head most suitable for use in an optical pickup section such as an optical disk or a magneto-optical disk, and particularly to an optical waveguide having a waveguide layer through which light is propagated. The present invention relates to a waveguide type optical head using.
コンパクトディスクやレーザーディスク等の再生専用
の光ディスクや、追記型の光ディスク、あるいは、磁気
光学効果を利用して情報の記録再生を可能とした光磁気
ディスク等の光ピックアップ部としては、従来、バルク
型の光学部品を組合せた光学ヘッドが用いられていた
が、この種の光学ヘッドは、多数の光学部品と光源及び
光検知器とを組合せて構成されるため、光学ヘッド全体
が大きく且つ重くなり、また、構成も複雑となり組付け
や調整に手間がかかり、しかも、部品点数が多いため、
生産コストが増大するという問題があった。Conventionally, bulk type optical discs such as compact discs, laser discs, and other read-only optical discs, write-once optical discs, and magneto-optical discs that use the magneto-optical effect to record and reproduce information have been used. Although an optical head combining a plurality of optical components has been used, this type of optical head is configured by combining a large number of optical components with a light source and a photodetector, so that the entire optical head becomes large and heavy, In addition, the structure is complicated and assembly and adjustment are time-consuming, and the number of parts is large,
There was a problem that the production cost increased.
そこで、このような従来の光学ヘッドの問題を解決す
るため、基板上に光導波路を形成すると共に、その基板
上にレンズ素子、発光素子、受光素子等を集積化した導
波路型の光学ヘッドが提案されている（例えば、特開昭
62−217434号公報等）。Therefore, in order to solve such a problem of the conventional optical head, there is provided a waveguide type optical head in which an optical waveguide is formed on a substrate and a lens element, a light emitting element, a light receiving element and the like are integrated on the substrate. Proposed (eg
62-217434, etc.).
ここで、第５図は従来の導波路型光学ヘッドの一例を
示すものであって、この導波路型光学ヘッドは、基板上
に、レーザー光源LDと光検知器113とを備えると共に、
レーザー光源LD及び光検知器113と出射端111間を接続す
る光ピックアップ用導波路117と、この光ピックアップ
用導波路117の両側に設けられトラック方向の集束位置
ずれを検出するための導波路A1,A2と、焦点位置の前後
を検知する導波路B1,B2とが形成されていることを特徴
としており、出射端111と光ディスク106の間には対物レ
ンズ115が配置されている。中央の光ピックアップ用導
波路117から出射した光は、対物レンズ115を介して光デ
ィスク106に照射され、その反射光が対物レンズ115を介
して光ピックアップ用導波路117に入射する。そして導
波路117を伝搬した光は光検知器113で検知され、電気信
号に変換され、情報の読み取りが行われる。Here, FIG. 5 shows an example of a conventional waveguide type optical head, and this waveguide type optical head is provided with a laser light source LD and a photodetector 113 on a substrate, and
An optical pickup waveguide 117 that connects the laser light source LD and the photodetector 113 to the emission end 111, and a waveguide A1 provided on both sides of the optical pickup waveguide 117 for detecting a focusing position shift in the track direction. , A2 and waveguides B1, B2 for detecting the front and rear of the focus position are formed, and an objective lens 115 is arranged between the emitting end 111 and the optical disc 106. The light emitted from the central optical pickup waveguide 117 is irradiated onto the optical disc 106 via the objective lens 115, and the reflected light is incident on the optical pickup waveguide 117 via the objective lens 115. The light propagating through the waveguide 117 is detected by the photodetector 113, converted into an electric signal, and information is read.
尚、光ディスク106からの反射光が導波路117の出射端
111位置に正確に絞られておれば、他の導波路A1,A2やB
1,B2への入射光パワーは小さいため、これら導波路A1,A
2,B1,B2用の光検知器118,119,120,121からの検知信号に
よって、光ピックアップ導波路117に焦点が有っている
ことが検知できる。The reflected light from the optical disk 106 is the output end of the waveguide 117.
If it is accurately focused to the 111 position, the other waveguides A1, A2 and B
Since the incident light power to 1 and B2 is small, these waveguides A1 and A2
The detection signals from the photo detectors 118, 119, 120 and 121 for 2, B1 and B2 make it possible to detect that the optical pickup waveguide 117 is in focus.
このように、第５図に示す構成の導波路型光学ヘッド
では、基板上に光導波路、レンズ素子、レーザ光源、光
検知器等が集積比されているため、小型化、軽量化が容
易であり、且つ、製造時に各素子の位置決めを正確に行
うことができ、組付け後の調整等の作業が不要となり、
また、検出精度も向上する。また、部品点数も大幅に削
減されるため、生産コストを大幅に低減することができ
る。As described above, in the waveguide type optical head having the configuration shown in FIG. 5, since the optical waveguide, the lens element, the laser light source, the photodetector and the like are integrated on the substrate, it is easy to reduce the size and weight. Yes, and each element can be accurately positioned at the time of manufacture, and adjustment work after assembly is unnecessary,
Also, the detection accuracy is improved. Moreover, since the number of parts is significantly reduced, the production cost can be significantly reduced.
ところで、第５図に示す構成の導波路型光学ヘッドで
は、レーザー光源LDからの出射光と、光ディスク106か
らの反射光とが、同一の光ピックアップ用導波路117内
を伝搬されるが、このような構成の場合、合焦（on Fo
cus）の状態においては、光ディスクからの反射光は導
波路117にほぼ完全に戻ることになる。By the way, in the waveguide type optical head having the configuration shown in FIG. 5, the emitted light from the laser light source LD and the reflected light from the optical disc 106 propagate through the same optical pickup waveguide 117. In the case of such a configuration, focusing (on Fo
In the state of (cus), the reflected light from the optical disc returns to the waveguide 117 almost completely.
ところが、このように光ピックアップ用導波路117内
に戻された光は、導波路内を出射時とは逆方向に伝搬さ
れるため、一部の伝搬光がレーザー光源LDに戻されてし
まう。このように、レーザー光源LDに光ディスクからの
反射光が戻されてしまうと、レーザー光源LDの発振が不
安定となり、結果的に、光学ヘッド全体の性能の劣化を
招く虞れがあり問題となる。However, since the light thus returned to the optical pickup waveguide 117 is propagated in the waveguide in the opposite direction to that at the time of emission, a part of the propagated light is returned to the laser light source LD. In this way, if the reflected light from the optical disc is returned to the laser light source LD, the oscillation of the laser light source LD becomes unstable, and as a result, the performance of the entire optical head may be deteriorated, which is a problem. .
本発明は上記事情に鑑みてなされたものであって、光
情報記録媒体からの戻り光の影響を排除し、高性能化、
性能の安定化を容易に図り得る導波路型光学ヘッドを提
供することを目的とする。The present invention has been made in view of the above circumstances, eliminates the influence of the return light from the optical information recording medium, high performance,
An object of the present invention is to provide a waveguide type optical head that can easily stabilize the performance.
上記目的を達成するための第１の構成として、本発明
の導波路型光学ヘッドは、半導体レーザーからの出射光
を伝搬する第１導波層を有する第１光導波路と、上記出
射光を光情報記録媒体上に放射するためのテーパ状導波
層よりなる放射部と、上記テーパ状導波層よりなる放射
部から照射され光情報記録媒体で反射された光を光検出
部に伝搬する第２導波層を有する第２光導波路とを基板
上に備え、上記基板上に第２光導波路を積層形成し、さ
らに第２光導波路上に第１光導波路を積層形成し、且
つ、上記第２光導波路は上記基板上の上記放射部が形成
された面と同一面上に形成され第２導波層が放射部と連
接されると共に上記放射部からの光が出射される側の基
板端面に対し略直角な向きに形成されたことを特徴とす
る。As a first configuration for achieving the above object, a waveguide type optical head according to the present invention includes: a first optical waveguide having a first waveguide layer for propagating emitted light from a semiconductor laser; A radiation part made up of a tapered waveguide layer for radiating onto an information recording medium, and a light which is emitted from the radiation part made up of the tapered waveguide layer and reflected by the optical information recording medium is propagated to a photodetection part. A second optical waveguide having two waveguide layers is provided on a substrate, the second optical waveguide is laminated on the substrate, the first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide is laminated on the substrate. The two optical waveguides are formed on the same surface as the surface on which the radiation portion is formed on the substrate, the second waveguide layer is connected to the radiation portion, and the end surface of the substrate on the side from which the light from the radiation portion is emitted. It is characterized in that it is formed in a direction substantially perpendicular to.
また、第２の構成として、本発明の導波路型光学ヘッ
ドは、半導体レーザーからの出射光を伝搬する第１導波
層を有する第１光導波路と、上記出射光を光情報記録媒
体上に放射するためのテーパ状導波層よりなる放射部
と、上記放射部から照射され光情報記録媒体で反射され
た光を光検出部に伝搬する第２導波層を有する第２光導
波路とを基板上に備え、上記基板上に第２光導波路を積
層形成し、さらに第２光導波路上に第１光導波路を積層
形成し、且つ、上記第２光導波路は上記基板上の上記放
射部が形成された面と同一面上に形成され第２導波層が
放射部と連接されると共に上記放射部からの光が出射さ
れる側の基板端面に対し略直角な向きに形成され、上記
第２導波層の屈折率n2と上記第１導波層の屈折率n1との
関係が、n2＞n1となることを特徴とする。Further, as a second configuration, the waveguide type optical head of the present invention comprises a first optical waveguide having a first waveguide layer for propagating emitted light from a semiconductor laser, and the emitted light on an optical information recording medium. And a second optical waveguide having a second waveguide layer for propagating the light emitted from the tapered waveguide layer and reflected by the optical information recording medium to the photodetector. The second optical waveguide is provided on the substrate, the second optical waveguide is laminated on the substrate, the first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide has the radiation portion on the substrate. The second waveguide layer, which is formed on the same surface as the formed surface, is connected to the radiation part and is formed in a direction substantially perpendicular to the end face of the substrate on the side from which the light from the radiation part is emitted. 2 the relationship between the refractive index n 1 of the refractive index of the waveguiding layer n 2 and the first waveguide layer, the n 2> n 1 It is characterized by the following.
また、第３の構成として、本発明の導波路型光学ヘッ
ドは、半導体レーザーからの出射光を伝搬する第１導波
層を有する第１光導波路と、上記出射光を光情報記録媒
体上に放射するためのテーパ状導波層よりなる放射部
と、上記放射部から照射され光情報記録媒体で反射され
た光を光検出部に伝搬する第２導波層を有する第２光導
波路とを基板上に備え、上記基板上に第２光導波路を積
層形成し、さらに第２光導波路上に第１光導波路を積層
形成し、且つ、上記第２光導波路は上記基板上の上記放
射部が形成された面と同一面上に形成され第２導波層が
放射部と連接されると共に上記放射部からの光が出射さ
れる側の基板端面に対し略直角な向きに形成され、上記
第２導波層の巾若しくは層厚を上記第１導波層の巾若し
くは層厚より大きくしたことを特徴とする。Further, as a third configuration, the waveguide type optical head of the present invention comprises a first optical waveguide having a first waveguide layer for propagating the emitted light from the semiconductor laser, and the emitted light on an optical information recording medium. And a second optical waveguide having a second waveguide layer for propagating the light emitted from the tapered waveguide layer and reflected by the optical information recording medium to the photodetector. The second optical waveguide is provided on the substrate, the second optical waveguide is laminated on the substrate, the first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide has the radiation portion on the substrate. The second waveguide layer, which is formed on the same surface as the formed surface, is connected to the radiation part and is formed in a direction substantially perpendicular to the end face of the substrate on the side from which the light from the radiation part is emitted. 2 The width or layer thickness of the waveguide layer is made larger than the width or layer thickness of the first waveguide layer. It is characterized in.
本発明の導波路型光学ヘッドでは、半導体レーザーか
らの出射光を放射部に向けて伝搬する第１導波層を有す
る第１光導波路と、テーパ状導波層よりなる放射部から
照射され光情報記録媒体で反射された光を光検出部に伝
搬する第２導波層を有する第２光導波路とを基板上に備
え、上記基板上に第２光導波路を積層形成し、さらに第
２光導波路上に第１光導波路を積層形成し、第１光導波
路と第２光導波路とを上下に別けて設けた構成のため、
光情報記録媒体からの戻り光が半導体レーザー側に戻さ
れることがなく、戻り光の影響をほぼ完全に防止でき
る。In the waveguide type optical head of the present invention, the first optical waveguide having the first waveguide layer that propagates the light emitted from the semiconductor laser toward the radiation portion, and the light emitted from the radiation portion formed of the tapered waveguide layer. A second optical waveguide having a second waveguide layer that propagates the light reflected by the information recording medium to the photodetector is provided on the substrate, and the second optical waveguide is laminated on the substrate, and the second optical waveguide is further formed. Since the first optical waveguide is laminated on the waveguide and the first optical waveguide and the second optical waveguide are separately provided on the upper and lower sides,
The return light from the optical information recording medium is not returned to the semiconductor laser side, and the influence of the return light can be almost completely prevented.
また、前記第２の構成に示すように、第２導波層の屈
折率n2と第１導波層の屈折率n1との関係が、n2＞n1とな
るように構成することにより、第２導波層から第１導波
層への光の洩れが防止される。Further, as shown in the second structure, the relationship between the refractive index n 2 of the second waveguide layer and the refractive index n 1 of the first waveguide layer is such that n 2 > n 1. This prevents light from leaking from the second waveguide layer to the first waveguide layer.
また、前記第３の構成に示すように、第２導波層の巾
若しくは層厚が第１導波層の巾若しくは層厚より大きく
なるように構成することにより、光情報記録媒体からの
戻り光が第１導波層側に入り込むことが防止される。Further, as shown in the third structure, the width or the layer thickness of the second waveguide layer is made larger than the width or the layer thickness of the first waveguide layer, so that the return from the optical information recording medium is achieved. Light is prevented from entering the first waveguide layer side.
以下、本発明を図示の実施例に基づいて詳細に説明す
る。Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
第１図は本発明の一実施例を示す導波路型光学ヘッド
の側面構成図、第２図は同上導波路型光学ヘッドをｘ軸
方向から見たときの各層部分の平面図であって、同図
（ａ）は第１光導波路部分の平面図、同図（ｂ）は第２
光導波路部分の平面図、同図（ｃ）は基板部分の平面図
を夫々示している。また、第３図は同上導波路型光学ヘ
ッドの半導体レーザー側の端面図である。FIG. 1 is a side view of a waveguide type optical head showing an embodiment of the present invention, and FIG. 2 is a plan view of each layer portion when the waveguide type optical head is viewed from the x-axis direction. FIG. 7A is a plan view of the first optical waveguide portion, and FIG.
The plan view of the optical waveguide portion and the same figure (c) show the plan view of the substrate portion, respectively. FIG. 3 is an end view of the waveguide type optical head on the semiconductor laser side.
第１図乃至第３図において、本実施例における導波路
型光学ヘッドは、半導体レーザー１からの出射光を伝搬
する層厚が均一な第１導波層20とこの第１導波層20に形
成され上記出射光を平行光束とするコリメータレンズ30
と上記第１導波層20に連接されるアイソレータ部22及び
第１バッファ層４とを有する第１光導波路と、上記第１
導波層20及びアイソレータ部22を伝搬されて来た上記出
射光を上記第１光導波路のアイソレータ部22から取り出
し第２バッファ層５を介してその端面5aから光情報記録
媒体９に向けて放射するためのテーパ結合器（テーパ状
導波層）23を備えた放射部と、上記放射部から放射され
対物レンズ８を介して光情報記録媒体９に照射され光情
報記録媒体９で反射された光を集光レンズ33,分波器32,
集光レンズ31を介してフォトダイオード等の光検知器７
からなる光検出部に伝搬する第２導波層21及び第２バッ
ファ層５を有する第２光導波路とを、同一の基板６上に
備え、上記第２光導波路は上記基板６上の放射部が形成
された面と同一面上に形成され上記第２導波層21が放射
部のテーパ結合器23と連接されると共に上記放射部から
の光が出射される側の第２バッファ層端面5aに対し略直
角な向きに形成され、且つ、上記第１光導波路は上記第
２光導波路上に積層形成されたことを特徴とするもので
ある。1 to 3, a waveguide type optical head according to the present embodiment has a first waveguide layer 20 having a uniform layer thickness for propagating emitted light from a semiconductor laser 1 and a first waveguide layer 20. A collimator lens 30 that is formed and collimates the emitted light into a parallel light flux.
And a first optical waveguide having an isolator portion 22 and a first buffer layer 4 connected to the first waveguide layer 20, and the first optical waveguide.
The emitted light propagated through the waveguide layer 20 and the isolator portion 22 is taken out from the isolator portion 22 of the first optical waveguide and radiated from the end face 5a toward the optical information recording medium 9 through the second buffer layer 5. And a light emitting portion having a taper coupler (tapered waveguide layer) 23 for emitting light, and emitted from the light emitting portion to the optical information recording medium 9 through the objective lens 8 and reflected by the optical information recording medium 9. Light condensing lens 33, demultiplexer 32,
Photodetector 7 such as a photodiode through the condenser lens 31
A second optical waveguide having a second buffer layer 5 and a second optical waveguide layer 21 propagating to a photo-detecting section, which are formed on the same substrate 6, and the second optical waveguide is a radiation section on the substrate 6. The second waveguide layer 21 is formed on the same surface as the surface on which the second waveguide layer 21 is connected to the taper coupler 23 of the radiating portion, and the end face 5a of the second buffer layer on the side where the light from the radiating portion is emitted. It is characterized in that it is formed in a direction substantially at right angles to, and the first optical waveguide is laminated on the second optical waveguide.
ここで、上記半導体レーザー１の発光面は第１光導波
路の第１導波層20の端面に接合されており、半導体レー
ザー１からの出射光は確実に第１導波層20に伝搬され
る。第１導波層20は層厚が均一な均一導波層であり、第
１導波層20に入射された光束を内部に閉じ込め、アイソ
レータ部22に向けて伝搬する。第１導波層20に設けられ
たコリメータレンズ30は、第１導波層20を伝搬される光
束を略平行光束とするように作用する。また、第１導波
層20と一体に連接されるアイソレータ部22の出射端は第
２導波層21に結合されており、第１導波層20からの伝搬
光を第２導波層21に導波するように作用する。この第２
導波層21に導波された光束は第２導波層21と連接された
放射部のテーパ結合器（テーパ状導波層）23によってカ
ットオフされ、導波光に対して透明な第２バッファ層５
側に出射され、その第２バッファ層の端面5aから空気中
へ放射される。空気中に放射された放射光は、対物レン
ズ８によって光情報記録媒体９の記録面に集光される
が、フォーカス及びトラッキングのためのサーボは対物
レンズ８の駆動により行われる。Here, the light emitting surface of the semiconductor laser 1 is bonded to the end face of the first waveguide layer 20 of the first optical waveguide, and the emitted light from the semiconductor laser 1 is reliably propagated to the first waveguide layer 20. . The first waveguiding layer 20 is a uniform waveguiding layer having a uniform layer thickness, and confines the light flux incident on the first waveguiding layer 20 inside and propagates it toward the isolator portion 22. The collimator lens 30 provided on the first waveguide layer 20 acts so that the light flux propagating through the first waveguide layer 20 becomes a substantially parallel light flux. Further, the emission end of the isolator portion 22 that is integrally connected to the first waveguide layer 20 is coupled to the second waveguide layer 21, and the propagation light from the first waveguide layer 20 is transmitted to the second waveguide layer 21. It acts as a wave guide to. This second
The light beam guided to the waveguiding layer 21 is cut off by the taper coupler (tapered waveguiding layer) 23 of the radiating portion connected to the second waveguiding layer 21 and is transparent to the waveguiding light. Layer 5
And is emitted to the air from the end surface 5a of the second buffer layer. The radiated light emitted into the air is focused on the recording surface of the optical information recording medium 9 by the objective lens 8, and the servo for focusing and tracking is performed by driving the objective lens 8.
光情報記録媒体９の記録面によって反射された戻り光
は、上述とは逆の光路を通って第２バッファ層端面5aか
ら入射され、テーパ結合器23を介して第２導波層21に伝
搬される。第２導波層21は層厚が均一な均一層厚導波層
であり、光情報記録媒体９からの戻り光を光検出部に向
けて伝搬する。また、第２導波層21には集光レンズ33が
設けられており、この集光レンズ33によって伝搬光は略
平行光とされ、さらに第２導波層21を伝搬される。ま
た、第２導波層21の光検出部側には分波器32が設けられ
ており、分波器32によって伝搬光が２方向に分割され
る。この２方向に分割された伝搬光は、夫々集光レンズ
31によって集束光となり、第２導波層21のテーパ部24に
よって第２バッファ層５側に出射され、基板６に設けら
れた光検知器７（7a,7b）に導かれる。この光検知器７
（7a,7b）はフォトダイオード等からなり、例えばSiか
らなる基板６中にモノリシックに形成されていて、その
受光部は各々２分割されている。The return light reflected by the recording surface of the optical information recording medium 9 enters the second buffer layer end face 5a through the optical path opposite to that described above, and propagates to the second waveguide layer 21 via the taper coupler 23. To be done. The second waveguide layer 21 is a uniform-thickness waveguide layer having a uniform layer thickness, and propagates the return light from the optical information recording medium 9 toward the photodetection section. Further, the second waveguide layer 21 is provided with a condenser lens 33, and by this condenser lens 33, the propagating light is made into substantially parallel light and further propagates through the second waveguide layer 21. Further, a demultiplexer 32 is provided on the photodetector side of the second waveguide layer 21, and the demultiplexer 32 divides the propagating light into two directions. The propagating lights split into these two directions are respectively collected by a condenser lens.
The light becomes focused light by 31 and is emitted to the second buffer layer 5 side by the tapered portion 24 of the second waveguide layer 21 and guided to the photodetectors 7 (7a, 7b) provided on the substrate 6. This light detector 7
(7a, 7b) is composed of a photodiode or the like, and is formed monolithically in the substrate 6 made of, for example, Si, and the light receiving portions thereof are each divided into two.
尚、上述のアイソレータ部22、テーパ結合器23、テー
パ部24は、シャドーマスクスパッタリング法で作製され
る。また、第１、第２導波層中に設けられるコリメータ
レンズ30、集光レンズ31,33、分波器32は、イオン交換
法等で作製される。The isolator portion 22, taper coupler 23, and taper portion 24 described above are manufactured by the shadow mask sputtering method. The collimator lens 30, the condenser lenses 31 and 33, and the demultiplexer 32 provided in the first and second waveguide layers are manufactured by an ion exchange method or the like.
また、第１導波層20、第２導波層21、第１バッファ層
４は光学ガラス等で形成され、第２バッファ層５はSiO2
等で形成される。The first waveguide layer 20, the second waveguide layer 21, and the first buffer layer 4 are made of optical glass, and the second buffer layer 5 is made of SiO 2.
Etc.
また、第１導波層20の屈折率をn1、第２導波層21の屈
折率をn2、第１バッファ層４の屈折率をns1、第２バッ
ファ層５の屈折率をns2とした場合に、これらの関係
は、 n2＞n1＞（ns1，ns2） と定められる。The refractive index of the first waveguide layer 20 is n 1 , the refractive index of the second waveguide layer 21 is n 2 , the refractive index of the first buffer layer 4 is ns 1 , and the refractive index of the second buffer layer 5 is ns. If 2 , then these relationships are defined as n 2 > n 1 > (ns 1 , ns 2 ).
すなわち、第２導波層21の屈折率n2を第１導波層20の
屈折率n1より大きくし、且つ、両導波層の間に、これら
より低屈折率の第１バッファ層４を介在させたことによ
り、第２導波層21から第１導波層20への光の洩れが防止
され、且つ、第２導波層21と基板６との間に第２導波層
21より低屈折率の第２バッファ層５を設けたことによ
り、第２導波層21から、基板６への光の洩れが防止され
る。尚、第１バッファ層４の屈折率ns1と第２バッファ
層５の屈折率ns2の関係は、ns1＝ns2としてもよい。That is, the refractive index n 2 of the second waveguide layer 21 is made larger than the refractive index n 1 of the first waveguide layer 20, and the first buffer layer 4 having a lower refractive index than these is provided between both waveguide layers. With the interposition of the above, the leakage of light from the second waveguide layer 21 to the first waveguide layer 20 is prevented, and the second waveguide layer 21 is provided between the second waveguide layer 21 and the substrate 6.
By providing the second buffer layer 5 having a refractive index lower than that of 21, it is possible to prevent light from leaking from the second waveguide layer 21 to the substrate 6. The refractive index of the first buffer layer 4 ns 1 relationship of the refractive index ns 2 of the second buffer layer 5 may be ns 1 = ns 2.
次に、第１図乃至第３図に示す構成の導波路型光学ヘ
ッドの作製手順の一例について簡単に説明する。Next, an example of a manufacturing procedure of the waveguide type optical head having the configuration shown in FIGS. 1 to 3 will be briefly described.
先ずSi基板６を作製し、第２図（ｃ）に示すよう
に、このSi基板６にドーピング法等によりフォトダイオ
ード等の光検知器７を形成する。First, the Si substrate 6 is manufactured, and as shown in FIG. 2C, a photodetector 7 such as a photodiode is formed on the Si substrate 6 by a doping method or the like.
次に、上記Si基板６上にスパッタリング等によりSi
O2層を堆積させ、第２バッファ層５を形成する。Next, Si is sputtered on the Si substrate 6 described above.
The O 2 layer is deposited to form the second buffer layer 5.
次に、第２バッファ層５の上に、シャドーマスクス
パッタリング法により第２導波層21及び放射部のテーパ
結合器（テーパ状導波層）23を形成する。すなわち、第
２導波層部分は均一層厚に形成されるが、この第２導波
層21に連接されるテーパ結合器23と、第２導波層21のテ
ーパ部24とは、漸次層厚が減少する構造のため、シャド
ウマスクスパッタリング法により、スパッタリング時に
シャドウマスクをテーパの傾斜方向に移動させつつスパ
ッタリングを行い、マスクの移動速度を制御することで
所望の形状のテーパ結合器23及びテーパ部24を形成する
わけである。Next, the second waveguide layer 21 and the taper coupler (tapered waveguide layer) 23 of the radiation portion are formed on the second buffer layer 5 by the shadow mask sputtering method. That is, although the second waveguide layer portion is formed to have a uniform layer thickness, the taper coupler 23 connected to the second waveguide layer 21 and the taper portion 24 of the second waveguide layer 21 are gradually formed into layers. Since the thickness is reduced, the shadow mask sputtering method performs sputtering while moving the shadow mask in the taper inclination direction during sputtering, and controls the moving speed of the mask to form a taper coupler 23 and a taper having a desired shape. The part 24 is formed.
次に、上述のようにして形成された第２導波層21
に、第２図（ｂ）に示すように、イオン交換により集光
レンズ31,33及び分波器32を形成する。Next, the second waveguide layer 21 formed as described above.
Then, as shown in FIG. 2B, the condenser lenses 31 and 33 and the demultiplexer 32 are formed by ion exchange.
次に、シャドウマスクスパッタ法により、上記第２
導波層21上に第１バッファ層４を積層形成する。Next, by the shadow mask sputtering method, the second
The first buffer layer 4 is laminated on the waveguide layer 21.
次に、マスクスパッタリングにより、上記第１バッ
ファ層４の上に第１導波層20及びアイソレータ部22を積
層形成し、第２図（ｂ）に示すように、この第１導波層
20にイオン交換によりコリメータレンズ30を形成する。
尚、第１導波層20の巾は第２導波層21の巾より小さく形
成される。Next, the first waveguide layer 20 and the isolator portion 22 are laminated and formed on the first buffer layer 4 by mask sputtering, and as shown in FIG.
A collimator lens 30 is formed on 20 by ion exchange.
The width of the first waveguide layer 20 is smaller than that of the second waveguide layer 21.
次に、第１導波層20の端面に半導体レーザー１の発
光面を接合して、第１図乃至第３図に示す構造の導波路
型光学ヘッドが作製される。Next, the light emitting surface of the semiconductor laser 1 is joined to the end face of the first waveguide layer 20 to manufacture the waveguide type optical head having the structure shown in FIGS.
次に第１図乃至第３図に示す構成の導波路型光学ヘッ
ドの動作についてより詳しく説明する。Next, the operation of the waveguide type optical head having the configuration shown in FIGS. 1 to 3 will be described in more detail.
第１図乃至第３図において、半導体レーザー１から出
射された光束は、第１導波層20に閉じ込められて伝搬
し、コリメータレンズ30により平行光束にコリメートさ
れて、さらに第１導波層20を伝搬される。そして、アイ
ソレータ部22に到達された伝搬光は、アイソレータ部22
の傾斜に沿って伝搬され、第２導波層21側に導波され
る。第２導波層21側に導波された光束は、導波層の巾方
向（図中ｙ方向）に集束作用を持つ集光レンズ33によっ
てに集束され、その集束光となった光束は、第２導波層
21と連接されたテーパ結合器（テーパ状導波層）23のテ
ーパ部の作用により、層厚方向（図中ｘ方向）にも集束
され、テーパ結合器23の層内の図中ａ点で一度焦点を結
び、このａ点でカットオフされて第２バッファ層５中に
放射され、第２バッファ層端面5aから外部に放射され
る。この外部に放射された光束は発散球面波であり、対
物レンズ８によって集光されて光情報記録媒体９の記録
ピットに焦点を結ぶ。ここで、上述の集光レンズ33は、
テーパ結合器23のテーパ部の作用による層厚方向の光束
の集光点ａに対して巾方向の光束の集光点を一致させ、
第２バッファ層端面5aからの放射光のｘ方向とｙ方向の
発散角α，βを同一にするために設けられている。尚、
テーパ状導波層23及び上述の集光レンズ33の作用につい
ては、本出願人が先に特許出願した、特願昭63−230247
号明細書及び特願平１−54657号明細書に詳細な説明が
記載されている。In FIGS. 1 to 3, the light beam emitted from the semiconductor laser 1 is confined in the first waveguide layer 20 and propagates, is collimated into a parallel light beam by the collimator lens 30, and is further propagated to the first waveguide layer 20. Is propagated. Then, the propagating light that has reached the isolator section 22 is
Is propagated along the inclination of and is guided to the second waveguide layer 21 side. The light flux guided to the second waveguide layer 21 side is focused by the condenser lens 33 having a focusing action in the width direction (y direction in the drawing) of the waveguide layer, and the light flux which becomes the focused light is Second waveguiding layer
By the action of the taper portion of the taper coupler (tapered waveguiding layer) 23 connected to 21, it is also focused in the layer thickness direction (x direction in the drawing), and at the point a in the drawing of the taper coupler 23. Once focused, the laser beam is cut off at the point a, radiated into the second buffer layer 5, and radiated from the second buffer layer end face 5a to the outside. The light flux radiated to the outside is a divergent spherical wave, which is condensed by the objective lens 8 and focused on the recording pit of the optical information recording medium 9. Here, the condenser lens 33 described above is
The converging point of the light flux in the width direction is made to coincide with the converging point a of the light flux in the layer thickness direction due to the action of the taper portion of the taper coupler 23,
It is provided in order to make the divergence angles α and β in the x direction and the y direction of the emitted light from the end surface 5a of the second buffer layer the same. still,
Regarding the operation of the tapered waveguide layer 23 and the above-mentioned condensing lens 33, Japanese Patent Application No. 63-230247 filed by the applicant of the present invention earlier.
The detailed description is described in Japanese Patent Application No. 1-54657 and Japanese Patent Application No. 1-54657.
さて、光情報記録媒体９によって反射された光は、上
述とは逆の過程を経て、第２バッファ層５の端面5aから
テーパ結合器23に入射され、テーパ結合器23から第２導
波層21中へ伝搬される。そして、第２導波層21に伝搬さ
れた戻り光は集光レンズ33を通過して略平行光とされ
る。この第２導波層21へ伝搬された戻り光は、前述した
ように、第２導波層21の屈折率n2が第１導波層20及びア
イソレータ部22の屈折率n1より大きく設定されており、
また、第１導波層20及びアイソレータ部22の巾は第２導
波層21の巾より狭いため、アイソレータ22側へはほとん
ど戻らず、そのまま第２導波層21中を伝搬し、分波器32
によって２方向に分割される。そして、２方向に分割さ
れた光束は集光レンズ31によって夫々集束光となった
後、第２導波層21のテーパ部24によって第２バッファ層
５側にカットオフされ、基板６に形成された光検知器7
a,7bに夫々集光される。この時、トラッキングのずれに
より、分波器32によって分割される光のパワーが5:5か
ら6:4又は7:3又は3:7というように変化した場合には、
光検出器7aと7bの受光光量の比較からトラッキングエラ
ー信号を検出することができる。また、フォーカス位置
にずれが生じた場合には、２分割された光束の焦点位置
b,cが夫々移動するので、夫々の光検出器7a,7bの各分割
受光面の受光光量差からフォーカスエラー信号を検出す
ることができる。The light reflected by the optical information recording medium 9 enters the taper coupler 23 from the end face 5a of the second buffer layer 5 through the process reverse to the above, and the light is reflected from the taper coupler 23 to the second waveguide layer. Propagated into 21. Then, the return light propagated to the second waveguide layer 21 passes through the condenser lens 33 to be substantially parallel light. The return light propagated to the second waveguide layer 21 is set such that the refractive index n 2 of the second waveguide layer 21 is larger than the refractive index n 1 of the first waveguide layer 20 and the isolator portion 22, as described above. Has been done,
Further, since the widths of the first waveguide layer 20 and the isolator portion 22 are narrower than the width of the second waveguide layer 21, they hardly return to the isolator 22 side, and propagate through the second waveguide layer 21 as they are and demultiplex. Container 32
Is divided into two directions. Then, the light beams divided in the two directions are converged by the condenser lens 31, respectively, and then cut off toward the second buffer layer 5 side by the taper portion 24 of the second waveguide layer 21 and formed on the substrate 6. Photo detector 7
Focused on a and 7b respectively. At this time, if the power of the light split by the demultiplexer 32 changes from 5: 5 to 6: 4 or 7: 3 or 3: 7 due to tracking deviation,
The tracking error signal can be detected by comparing the received light amounts of the photodetectors 7a and 7b. When the focus position is deviated, the focus position of the light beam divided into two
Since b and c respectively move, the focus error signal can be detected from the received light amount difference between the respective divided light receiving surfaces of the respective photodetectors 7a and 7b.
次に、第４図は本発明の別の実施例を示す導波路型光
学ヘッドの側面構成図であって、第１図と同様の符号を
付したものは同様の作用効果を奏する構成部である。Next, FIG. 4 is a side view of a waveguide type optical head showing another embodiment of the present invention, in which components having the same reference numerals as those in FIG. 1 are components having the same effects. is there.
ここで、第４図に示す導波路型光学ヘッドは、第１導
波層20の層厚t1と、第２導波層21の層厚t2との関係をt1
＜t2としたものであり、このように、第１導波層20側の
層厚を第２導波層21の層厚より小さくすることにより、
光情報記録媒体９からの戻り光が第１導波層側に戻され
ることがより一層防止される。Here, in the waveguide type optical head shown in FIG. 4, the relationship between the layer thickness t 1 of the first waveguide layer 20 and the layer thickness t 2 of the second waveguide layer 21 is t 1
<T 2 , and in this way, by making the layer thickness on the first waveguide layer 20 side smaller than the layer thickness of the second waveguide layer 21,
The return light from the optical information recording medium 9 is further prevented from returning to the first waveguide layer side.
尚、先の第１図乃至第３図に示した実施例、及び第４
図に示した実施例において、第２光導波路の分波器32及
び集光レンズ31は一緒にすることも可能である。また、
光検出器７（7a,7b）は基板６内に形成せずに、半導体
レーザー１と同様に第２導波層端面にハイブリット化し
てもよく、この場合には、第２導波層21のテーパ部24は
不要となる。The embodiment shown in FIGS. 1 to 3 and the fourth embodiment
In the illustrated embodiment, the demultiplexer 32 and the condenser lens 31 of the second optical waveguide can be combined. Also,
The photodetector 7 (7a, 7b) may be hybridized to the end face of the second waveguide layer similarly to the semiconductor laser 1 without being formed in the substrate 6. In this case, the second waveguide layer 21 The tapered portion 24 is unnecessary.
尚、本発明による、多層膜構造の光導波路は、実施例
で示した光学ヘッドのみでなく、一般的な光集積回路中
においても十分に利用できるものである。The optical waveguide having a multilayer film structure according to the present invention can be sufficiently used not only in the optical head shown in the embodiment but also in a general optical integrated circuit.
また、図示の実施例においては、第１光導波路と第２
光導波路とを基板上に積層して形成した例について示し
たが、第１光導波路と第２光導波路とを基板の同一平面
上に並設して形成しても同様の作用効果が得られる。Also, in the illustrated embodiment, the first optical waveguide and the second optical waveguide
The example in which the optical waveguide and the optical waveguide are laminated and formed is shown, but the same effect can be obtained by forming the first optical waveguide and the second optical waveguide in parallel on the same plane of the substrate. .
〔発明の効果〕 以上、図示の実施例に基づいて説明したように、本発
明の導波路型光学ヘッドは、半導体レーザーからの出射
光を放射部に向けて伝搬する第１導波層を有する第１光
導波路と、放射部から照射され光情報記録媒体で反射さ
れた光を光検出部に伝搬する第２導波層を有する第２光
導波路とを基板上に上下に積層形成して設け、且つ、第
２導波層が放射部と同一面上に形成され且つ光出射端面
に対して直角な方向に形成されているため、光情報記録
媒体からの戻り光は第２導波層内に伝搬され、半導体レ
ーザー側に戻されることがないため、戻り光による悪影
響を略完全に防止できる。[Effects of the Invention] As described above with reference to the illustrated embodiment, the waveguide type optical head of the present invention has the first waveguide layer for propagating the light emitted from the semiconductor laser toward the radiation portion. A first optical waveguide and a second optical waveguide having a second waveguide layer for propagating the light emitted from the radiation section and reflected by the optical information recording medium to the photodetection section are provided on the substrate in a vertically stacked manner. Moreover, since the second waveguide layer is formed on the same surface as the radiation portion and in the direction perpendicular to the light emitting end face, the return light from the optical information recording medium is in the second waveguide layer. Since it is not transmitted to the semiconductor laser and returned to the semiconductor laser side, the adverse effect of the returning light can be almost completely prevented.
また、第２導波層の屈折率n2と第１導波層の屈折率n1
との関係が、n2＞n1となるように構成することにより、
上記戻り光による悪影響と、第２導波層から第１導波層
への光の洩れとが略完全に防止される。In addition, the refractive index n 2 of the second waveguide layer and the refractive index n 1 of the first waveguide layer
By configuring so that the relationship with and n 2 > n 1 ,
The adverse effect of the return light and the leakage of light from the second waveguide layer to the first waveguide layer are almost completely prevented.
また、第２導波層の巾若しくは層厚が第１導波層の巾
若しくは層厚より大きくなるように構成することによ
り、光情報記録媒体からの戻り光が第１導波層側に戻さ
れることがより一層防止され、戻り光による悪影響をよ
り一層防止できる。Further, by making the width or layer thickness of the second waveguide layer larger than the width or layer thickness of the first waveguide layer, the return light from the optical information recording medium is returned to the first waveguide layer side. Is further prevented, and the adverse effect of returning light can be further prevented.
以上のように、本発明によれば、光情報記録媒体から
半導体レーザーへの戻り光の問題が解消され、高性能
化、性能の安定化を容易に図り得る新規な構成の導波路
型光学ヘッドを提供することができる。As described above, according to the present invention, the problem of the returning light from the optical information recording medium to the semiconductor laser is solved, and the waveguide type optical head having a novel structure capable of easily achieving high performance and stable performance is provided. Can be provided.
第１図は本発明の一実施例を示す導波路型光学ヘッドの
側面構成図、第２図は同上導波路型光学ヘッドの各層部
分の平面図であって、同図（ａ）は第１光導波路部分の
平面図、同図（ｂ）は第２光導波路部分の平面図、同図
（ｃ）は基板部分の平面図である。第３図は第１図に示
す導波路型光学ヘッドの半導体レーザー側の端面図であ
る。第４図は本発明の別の実施例を示す導波路型光学ヘ
ッドの側面構成図、第５図は従来技術の一例を示す導波
路型光学ヘッドの平面構成図である。 １……半導体レーザー、４……第１バッファ層、５……
第２バッファ層、5a……光出射側端面、６……基板、７
……光検知器、８……対物レンズ、９……光情報記録媒
体、20……第１導波層、21……第２導波層、22……アイ
ソレータ部、23……テーパ結合器、24……テーパ部、30
……コリメータレンズ、31,33……集光レンズ、32……
分波器。FIG. 1 is a side view of a waveguide type optical head showing an embodiment of the present invention, and FIG. 2 is a plan view of each layer portion of the same waveguide type optical head. FIG. FIG. 3B is a plan view of the optical waveguide portion, FIG. 3B is a plan view of the second optical waveguide portion, and FIG. FIG. 3 is an end view of the waveguide type optical head shown in FIG. 1 on the semiconductor laser side. FIG. 4 is a side view of a waveguide type optical head showing another embodiment of the present invention, and FIG. 5 is a plan view of a waveguide type optical head showing an example of the prior art. 1 ... Semiconductor laser, 4 ... First buffer layer, 5 ...
Second buffer layer, 5a ... End face on light emitting side, 6 ... Substrate, 7
...... Photo detector, 8 ...... Objective lens, 9 ...... Optical information recording medium, 20 ...... First waveguide layer, 21 ...... Second waveguide layer, 22 ...... Isolator part, 23 ...... Taper coupler , 24 …… Taper part, 30
…… Collimator lens, 31, 33 …… Condenser lens, 32 ……
Duplexer.
Claims (3)
１導波層を有する第１光導波路と、上記出射光を光情報
記録媒体上に放射するためのテーパ状導波層よりなる放
射部と、上記放射部から照射され光情報記録媒体で反射
された光を光検出部に伝搬する第２導波層を有する第２
光導波路とを基板上に備え、上記基板上に第２光導波路
を積層形成し、さらに第２光導波路上に第１光導波路を
積層形成し、且つ、上記第２光導波路は上記基板上の上
記放射部が形成された面と同一面上に形成され第２導波
層が放射部と連接されると共に上記放射部からの光が出
射される側の基板端面に対し略直角な向きに形成された
ことを特徴とする導波路型光学ヘッド。1. A radiation section comprising a first optical waveguide having a first waveguide layer for propagating emitted light from a semiconductor laser and a tapered waveguide layer for radiating the emitted light onto an optical information recording medium. And a second waveguide layer that propagates the light, which is emitted from the radiation section and reflected by the optical information recording medium, to the photodetection section.
An optical waveguide on a substrate, a second optical waveguide is laminated on the substrate, a first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide is on the substrate. The second waveguide layer is formed on the same surface as the surface on which the radiating portion is formed, is connected to the radiating portion, and is formed in a direction substantially perpendicular to the end face of the substrate on the side where the light from the radiating portion is emitted. A waveguide type optical head characterized in that
１導波層を有する第１光導波路と、上記出射光を光情報
記録媒体上に放射するためのテーパ状導波層よりなる放
射部と、上記放射部から照射され光情報記録媒体で反射
された光を光検出部に伝搬する第２導波層を有する第２
光導波路とを基板上に備え、上記基板上に第２光導波路
を積層形成し、さらに第２光導波路上に第１光導波路を
積層形成し、且つ、上記第２光導波路は上記基板上の上
記放射部が形成された面と同一面上に形成され第２導波
層が放射部と連接されると共に上記放射部からの光が出
射される側の基板端面に対し略直角な向きに形成され、
上記第２導波層の屈折率n2と上記第１導波層の屈折率n1
との関係が、n2＞n1となることを特徴とする導波路型光
学ヘッド。2. A radiation section comprising a first optical waveguide having a first waveguide layer for propagating light emitted from a semiconductor laser and a tapered waveguide layer for radiating the light emitted onto the optical information recording medium. And a second waveguide layer that propagates the light, which is emitted from the radiation section and reflected by the optical information recording medium, to the photodetection section.
An optical waveguide on a substrate, a second optical waveguide is laminated on the substrate, a first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide is on the substrate. The second waveguide layer is formed on the same surface as the surface on which the radiating portion is formed, is connected to the radiating portion, and is formed in a direction substantially perpendicular to the end face of the substrate on the side where the light from the radiating portion is emitted. Is
The refractive index of the refractive index n 2 and the first waveguide layer of said second waveguide layer n 1
Waveguide type optical head, characterized in that the relationship between becomes the n 2> n 1.
１導波層を有する第１光導波路と、上記出射光を光情報
記録媒体上に放射するためのテーパ状導波層よりなる放
射部と、上記放射部から照射され光情報記録媒体で反射
された光を光検出部に伝搬する第２導波層を有する第２
光導波路とを基板上に備え、上記基板上に第２光導波路
を積層形成し、さらに第２光導波路上に第１光導波路を
積層形成し、且つ、上記第２光導波路は上記基板上の上
記放射部が形成された面と同一面上に形成され第２導波
層が放射部と連接されると共に上記放射部からの光が出
射される側の基板端面に対し略直角な向きに形成され、
上記第２導波層の巾若しくは層厚を上記第１導波層の巾
若しくは層厚より大きくしたことを特徴とする導波路型
光学ヘッド。3. A radiation section comprising a first optical waveguide having a first waveguide layer for propagating emitted light from a semiconductor laser and a tapered waveguide layer for radiating the emitted light onto an optical information recording medium. And a second waveguide layer that propagates the light, which is emitted from the radiation section and reflected by the optical information recording medium, to the photodetection section.
An optical waveguide on a substrate, a second optical waveguide is laminated on the substrate, a first optical waveguide is laminated on the second optical waveguide, and the second optical waveguide is on the substrate. The second waveguide layer is formed on the same surface as the surface on which the radiating portion is formed, is connected to the radiating portion, and is formed in a direction substantially perpendicular to the end face of the substrate on the side where the light from the radiating portion is emitted. Is
A waveguide type optical head characterized in that the width or layer thickness of the second waveguide layer is made larger than the width or layer thickness of the first waveguide layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1306794A JPH0827969B2 (en) | 1989-11-27 | 1989-11-27 | Waveguide type optical head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1306794A JPH0827969B2 (en) | 1989-11-27 | 1989-11-27 | Waveguide type optical head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03168938A JPH03168938A (en) | 1991-07-22 |
| JPH0827969B2 true JPH0827969B2 (en) | 1996-03-21 |
Family
ID=17961328
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1306794A Expired - Lifetime JPH0827969B2 (en) | 1989-11-27 | 1989-11-27 | Waveguide type optical head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0827969B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01271931A (en) * | 1988-04-22 | 1989-10-31 | Sony Corp | Optical reproducing head |
-
1989
- 1989-11-27 JP JP1306794A patent/JPH0827969B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03168938A (en) | 1991-07-22 |
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