JP2004020794A - Optical recording apparatus using optical waveguide array - Google Patents

Optical recording apparatus using optical waveguide array Download PDF

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Publication number
JP2004020794A
JP2004020794A JP2002174047A JP2002174047A JP2004020794A JP 2004020794 A JP2004020794 A JP 2004020794A JP 2002174047 A JP2002174047 A JP 2002174047A JP 2002174047 A JP2002174047 A JP 2002174047A JP 2004020794 A JP2004020794 A JP 2004020794A
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JP
Japan
Prior art keywords
waveguide
optical
incident
array
waveguide array
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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.)
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JP2002174047A
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Japanese (ja)
Inventor
Susumu Monma
門馬 進
Keiji Kataoka
片岡 慶二
Original Assignee
Hitachi Printing Solutions Ltd
日立プリンティングソリューションズ株式会社
Priority date (The priority date 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 date listed.)
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Priority to JP2002174047A priority Critical patent/JP2004020794A/en
Publication of JP2004020794A publication Critical patent/JP2004020794A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To reduce reflection loss at the time of making a laser beam incident on an optical waveguide array. <P>SOLUTION: In an optical recording apparatus by which a photosensitive material is scanned by modulating several laser beams emitted by the optical waveguide array and performing scanning with them, an angle θ obtained by the normal line of the incident end plane of a waveguide formed on a base plate in the optical waveguide array constituted of the base plate, the waveguide and a clad layer formed on the base plate and the waveguide and the light advancing axis of the waveguide satisfies a specified relational expression. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、光導波路アレイを用いて複数のレーザ光を感光材料上に走査し、光記録を行う電子写真装置、光ディスク装置等の光記録装置に関するものである。
【0002】
【従来の技術】
光記録装置を代表するレーザプリンタにおいて、複数のレーザビームを回転多面鏡で同時に走査して光記録を行うと、回転多面鏡の回転速度が高速にできない場合でも、ビーム本数分の高速化が実現できる。複数のレーザビームを発生させる方法として光ファイバアレイを用いる方法がある。光ファイバアレイを用いて複数のレーザビームを感光材料上に走査して光記録を行う光記録装置は、例えば特開平9−146023号公報により公知である。
【0003】
【発明が解決しようとする課題】
レーザプリンタの更なる高速化、高解像度化を行うためには、走査するレーザビームの更なる多ビーム化、狭ピッチ化が必要である。その為には、マルチビーム発生素子として光導波路アレイを用いることが必要となってくる。しかし半導体レーザから出射するレーザ光を導波路に入射する際に、導波路入射端面で約4%の反射損失がある。
【0004】
本発明の目的は、光導波路アレイにレーザ光を入射した時の反射損失を低減することにある。
【0005】
【課題を解決するための手段】
光導波路アレイから出射した複数本のレーザ光を変調走査し、感光材料上に走査する光記録装置において、基板と該基板上に形成されている導波路と、前記基板と前記導波路上に形成されているクラット層とからなる前記光導波路アレイ内の前記導波路の入射端面の法線と、前記導波路の光進行軸とのなす角度θが次式を満たすことにより達成される。
θ=sin−1(n/n・sinθβ
但し、θβ=arctan(n/n)、nは導波路の屈折率、nは空気中の屈折率である。
【0006】
【発明の実施の形態】
導波路の入射端面に半導体レーザから出射したレーザ光を入射する時、ブリュースタ角で入射すれば反射率が0となる。導波路の屈折率n=1.5とし、空気中の屈折率n=1とすると、ブリュースタ角は56.3°となる。レーザ光をブリュースタ−角で入射した時、導波路に入射されたレーザ光が導波路の光進行軸と一致する為には導波路の光進行軸と導波路の入射端面の法線とのなす角度θが(1)式を満たさなければならない。
【0007】
【数1】
【0008】
もしファイバ入射端面への入射角度がブリュースタ角度から+10°ずれてθβ=46.3°となれば、反射率が1.8%、−10°ずれてθβ=66.3°となれば反射率は0.7%と大きくなる。しかし、ファイバ入射端面への入射角度がブリュースタ角度から±5°のずれ以内に収まっていれば、ファイバ入射端面での反射率が0.35%以下となり、垂直に入射した場合の反射率である4%に比べて十分小さくすることができる。したがって、導波路の光進行軸と導波路入射端面の法線とのなす角度θを(2)式を満たすことによって、導波路の入射端面での反射損失が少ない状態で、高効率にレーザ光を導波路に結合することが可能となる。
【0009】
【数2】
【0010】
以下、本発明の光導波路アレイを用いた光記録装置の実施例を図1、図2、図3で説明する。複数の半導体レーザ5から出射したレーザ光は、光導波路アレイ6内の導波路9の入射端面8に導かれ、光導波路アレイ6から出射した複数のレーザ光はレンズ4によりポリゴンミラ3上に集光されて走査され、Fθレンズ2により感光ドラム1上に結像され、走査される。
【0011】
光導波路アレイ6の詳細な構造を図2、図3に示す。光導波路アレイ6の入射端面8は(2)式を満たす角度になるように研磨され、半導体レーザ光9が導波路入射端面8の法線に対して(2)式を満たすθβの角度でP偏向になるように入射されている。
【0012】
光導波路アレイ6の出射端面10の角度θαは、ブリュースタ角以上では反射率が大きくなる為、ブリュースタ角以下となるように研磨されている。
【0013】
なお、図3において、11は導波路の出射面、12は導波路の出射面の法線、13は導波路の光進行軸、14は導波路の入射端面、15は導波路の入射端面の法線を示す。
【0014】
【発明の効果】
本発明によれば、光導波路アレイにレーザ光を入射した時の反射損失を低減することができる。
【図面の簡単な説明】
【図1】本発明の光導波路アレイを用いた光記録装置の光学系を示す図。
【図2】本発明の光導波路アレイを用いた光記録装置の光導波路アレイ部を示す図。
【図3】本発明の光導波路アレイを用いた光記録装置の導波路部の入射、出射面の角度の説明図。
【符号の説明】
1は感光ドラム、2はFθレンズ、3はポリゴンミラ、4はレンズ、6は光導波路アレイ、7はレンズ、8は入射端面、9は導波路、10は出射端面、11は導波路の出射端面、12は導波路の出射面の法線、13は導波路の光進行軸、14は導波路の入射端面、15は導波路の入射端面の法線である。
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical recording apparatus such as an electrophotographic apparatus and an optical disk apparatus that performs optical recording by scanning a plurality of laser beams on a photosensitive material using an optical waveguide array.
[0002]
[Prior art]
In a laser printer that represents an optical recording device, when multiple laser beams are scanned simultaneously by a rotating polygon mirror to perform optical recording, even if the rotating speed of the rotating polygon mirror cannot be increased, the speed can be increased by the number of beams. it can. As a method for generating a plurality of laser beams, there is a method using an optical fiber array. An optical recording apparatus that performs optical recording by scanning a plurality of laser beams on a photosensitive material using an optical fiber array is known, for example, from Japanese Patent Application Laid-Open No. 9-146023.
[0003]
[Problems to be solved by the invention]
In order to further increase the speed and resolution of a laser printer, it is necessary to further increase the number of scanning laser beams and narrow the pitch. For that purpose, it is necessary to use an optical waveguide array as a multi-beam generating element. However, when the laser light emitted from the semiconductor laser enters the waveguide, there is a reflection loss of about 4% at the waveguide incident end face.
[0004]
An object of the present invention is to reduce reflection loss when laser light is incident on an optical waveguide array.
[0005]
[Means for Solving the Problems]
In an optical recording apparatus that modulates and scans a plurality of laser beams emitted from an optical waveguide array and scans on a photosensitive material, a substrate, a waveguide formed on the substrate, and the substrate and the waveguide formed on the waveguide are formed. The angle θ between the normal to the incident end face of the waveguide in the optical waveguide array composed of the clat layer and the light traveling axis of the waveguide satisfies the following expression.
θ = sin −1 (n 2 / n 1 · sin θ β )
Here, θ β = arctan (n 2 / n 1 ), n 2 is the refractive index of the waveguide, and n 1 is the refractive index in air.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
When the laser light emitted from the semiconductor laser is incident on the incident end face of the waveguide, the reflectance becomes 0 if the laser light is incident at a Brewster angle. Assuming that the refractive index of the waveguide is n 2 = 1.5 and the refractive index in air is n 1 = 1, the Brewster angle is 56.3 °. When the laser light is incident at Brewster's angle, the laser light incident on the waveguide must be aligned with the light traveling axis of the waveguide and the normal of the incident end face of the waveguide so that the laser light enters the waveguide. The angle θ must satisfy the expression (1).
[0007]
(Equation 1)
[0008]
If the angle of incidence on the fiber incident end face is shifted by + 10 ° from the Brewster angle and becomes θ β = 46.3 °, the reflectivity can be 1.8% and -10 ° and θ β = 66.3 °. In this case, the reflectance becomes as large as 0.7%. However, if the angle of incidence on the fiber incident end face is within ± 5 ° of the Brewster angle, the reflectivity at the fiber incident end face will be 0.35% or less, which is the reflectivity at normal incidence. This can be made sufficiently smaller than a certain 4%. Therefore, by satisfying the expression (2) with the angle θ between the light traveling axis of the waveguide and the normal to the waveguide incident end face, the laser light can be efficiently emitted with a small reflection loss at the waveguide incident end face. Can be coupled to the waveguide.
[0009]
(Equation 2)
[0010]
Hereinafter, an embodiment of an optical recording apparatus using the optical waveguide array of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. Laser light emitted from the plurality of semiconductor lasers 5 is guided to the incident end face 8 of the waveguide 9 in the optical waveguide array 6, and the plurality of laser lights emitted from the optical waveguide array 6 are collected on the polygon mirror 3 by the lens 4. The light is scanned, the image is formed on the photosensitive drum 1 by the Fθ lens 2, and the light is scanned.
[0011]
The detailed structure of the optical waveguide array 6 is shown in FIGS. The incident end face 8 of the optical waveguide array 6 is polished so as to have an angle satisfying the expression (2), and the semiconductor laser light 9 is formed at an angle θ β that satisfies the expression (2) with respect to a normal to the waveguide incident end face 8. The light is incident so as to be P-polarized.
[0012]
When the angle θ α of the output end face 10 of the optical waveguide array 6 is larger than the Brewster angle, the reflectance is large.
[0013]
In FIG. 3, reference numeral 11 denotes an exit surface of the waveguide, 12 denotes a normal to the exit surface of the waveguide, 13 denotes a light traveling axis of the waveguide, 14 denotes an incident end surface of the waveguide, and 15 denotes an incident end surface of the waveguide. Shows the normal.
[0014]
【The invention's effect】
According to the present invention, it is possible to reduce reflection loss when a laser beam is incident on an optical waveguide array.
[Brief description of the drawings]
FIG. 1 is a diagram showing an optical system of an optical recording apparatus using an optical waveguide array according to the present invention.
FIG. 2 is a diagram showing an optical waveguide array section of an optical recording device using the optical waveguide array of the present invention.
FIG. 3 is an explanatory diagram of angles of incident and outgoing surfaces of a waveguide portion of an optical recording device using the optical waveguide array of the present invention.
[Explanation of symbols]
1 is a photosensitive drum, 2 is an Fθ lens, 3 is a polygon mirror, 4 is a lens, 6 is an optical waveguide array, 7 is a lens, 8 is an incident end face, 9 is a waveguide, 10 is an exit end face, and 11 is an exit of the waveguide. The end face, 12 is the normal to the exit face of the waveguide, 13 is the light traveling axis of the waveguide, 14 is the incidence end face of the waveguide, and 15 is the normal to the incidence end face of the waveguide.

Claims (2)

光導波路アレイから出射した複数本のレーザ光を変調走査し、感光材料上に走査する光記録装置において、基板と該基板上に形成されている導波路と、前記基板と前記導波路上に形成されているクラット層とからなる前記光導波路アレイ内の前記導波路の入射端面の法線と、前記導波路の光進行軸とのなす角度θが次式を満たすことを特徴とする光導波路アレイを用いた光記録装置。
θ=sin−1(n/n・sinθβ
但し、θβ=arctan(n/n)、nは導波路の屈折率、nは空気中の屈折率である。
In an optical recording apparatus that modulates and scans a plurality of laser beams emitted from an optical waveguide array and scans on a photosensitive material, a substrate, a waveguide formed on the substrate, and the substrate and the waveguide formed on the waveguide are formed. An optical waveguide array, wherein an angle θ between a normal to an incident end face of the waveguide and an optical traveling axis of the waveguide in the optical waveguide array composed of a clat layer satisfying the following formula: Optical recording device using a.
θ = sin −1 (n 2 / n 1 · sin θ β )
Here, θ β = arctan (n 2 / n 1 ), n 2 is the refractive index of the waveguide, and n 1 is the refractive index in air.
前記導波路の出射面の角度をブリュースタ角以下とすることを特徴とする請求項1記載の光導波路アレイを用いた光記録装置。2. An optical recording apparatus using an optical waveguide array according to claim 1, wherein an angle of an exit surface of the waveguide is set to be equal to or less than a Brewster angle.
JP2002174047A 2002-06-14 2002-06-14 Optical recording apparatus using optical waveguide array Pending JP2004020794A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007192896A (en) * 2006-01-17 2007-08-02 Ricoh Printing Systems Ltd Multibeam light source, method of manufacturing the same, optical scanner and image forming apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007192896A (en) * 2006-01-17 2007-08-02 Ricoh Printing Systems Ltd Multibeam light source, method of manufacturing the same, optical scanner and image forming apparatus
US7477813B2 (en) 2006-01-17 2009-01-13 Ricoh Printing Systems, Ltd. Multi-beam light source, method for manufacturing the same, light scanning unit using the same, and image forming apparatus using the same

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