JP4706162B2 - OPTICAL DEVICE, OPTICAL DISK DEVICE, AND LIGHT BEAM POSITION ADJUSTING METHOD THEREOF - Google Patents

Description

が広い場合には、対物レンズの振れ（レンズシフト）によりスポットバランスを適切に調整することができ、レンズシフトを行っても特性への影響は少ない。
【００７７】
【発明の実施の形態】
本発明群においては、前記複数の発光素子を固定した前記ブロックが前記基体上に固定されていて、この固定後に、前記ブロックと共に前記基体が前記正規の光軸又はこれと平行な軸の周りに回転されて前記位置調整があおり補正として行われるか、或いは、前記複数の発光素子を固定した前記ブロックが前記基体上に固定されていて、この固定前に、前記ブロックがその面内にて前記基体上で回転されて前記位置調整がθ補正として行われるのがよい。
【００７８】
また、前記所定の発光素子は前記他の発光素子に比べて規格がより厳しく、ビーム発散角が前記他の発光素子のそれよりも小さい場合に、本発明の効果が大きい。この場合、これらの複数の発光素子が、互いに異なる波長のレーザ光を出射し、規格がより厳しい発光素子からのレーザ光の波長が前記他の発光素子のそれよりも短いのがよい。
【００７９】
そして、前記複数の発光素子の出射光が前記対物レンズを通して被照射体、例えばディスク状情報記録媒体に入射され、この反射光が前記対物レンズを通して前記複数の受光素子にそれぞれ入射されるのがよい。
【００８０】
この場合、前記複数の発光素子を固定した前記ブロックと、前記複数の発光素子の各出射光を前記被照射体へ導きかつ前記反射光を前記複数の受光素子へ導くための光学部材と、前記受光素子とが共通の前記基体上に設けられ、光カプラが構成され、また、この光カプラが光ピックアップの一部として光ディスク装置に組み込まれる。
【００８１】
以下、本発明の好ましい実施の形態を図面について説明する。
【００８２】
実施の形態１
本実施の形態では、図１（Ａ）に示すように、図２１において示したと同様に、例えば、７８０ｎｍ帯の光を受光する前部第１フォトダイオード１６及び後部第１フォトダイオード１７と、６５０ｎｍ帯の光を受光する前部第２フォトダイオード１８及び後部第２フォトダイオード１９とが、基板１１上に固定されたプリズム２０下に形成されている。
【００８３】
ここで、前部第１フォトダイオード１６は４分割（ａ１、ｂ１、ｃ１、ｄ１）され、後部第１フォトダイオード１７も４分割（ｉ１、ｊ１、ｋ１、ｌ１）された構成を有している。
【００８４】
基板１１上に固定されたブロック１３上に第１レーザダイオードＬＤ１がマウントされ、このレーザダイオードから出射された７８０ｎｍ帯のレーザ光Ｌ１はプリズム２０の分光面で反射され、更に上記光学系を経て、光ディスク（ＣＤ）からの反射光として、プリズム２０を通して前部及び後部第１フォトダイオード１６、１７上に１つずつのスポットＳ１ａ、Ｓ１ｂとして入射する。
【００８５】
また、前部第２フォトダイオード１８は８分割（ａ２、ｂ２、ｃ２、ｄ２、ｅ２、ｆ２、ｇ２、ｈ２）され、後部第２フォトダイオード１９は４分割（ｉ２、ｊ２、ｋ２、ｌ２）された構成を有している。
【００８６】
第２レーザダイオードＬＤ２から出射された６５０ｎｍ帯のレーザ光Ｌ２も、上記光学系を経て、光ディスク（ＤＶＤ）からの反射光として、前部及び後部第２フォトダイオード１８、１９上に１つずつのスポットＳ２ａ、Ｓ２ｂとして入射する。
【００８７】
上記の前部第１フォトダイオード１６及び前部第２フォトダイオード１８の間隔、及び、後部第１フォトダイオード１７及び後部第２フォトダイオード１９の間隔は、例えば２００μｍ程度以下の範囲（例えば１００μｍ程度）に設定される。ここでは、例えば、上記の第１レーザダイオードＬＤ１のレーザ光出射部Ｅ１と第２レーザダイオードＬＤ２のレーザ光出射部Ｅ２との間隔と実質的に等しくなるように設定される。
【００８８】
上記のように、第１及び第２レーザダイオードのレーザ光出射部の間隔、および、第１および第２フォトダイオードの間隔を設定することにより、共通の光学部材を用いて、第１レーザダイオード及び第２レーザダイオードの出射光をＣＤやＤＶＤなどの光ディスクに照射し、光ディスクからの反射光を第１フォトダイオードおよび第２フォトダイオードにそれぞれ入射させることが可能となる。
【００８９】
上記のフォトダイオード（前後部第１フォトダイオード１６、１７及び前後部第２フォトダイオード１８、１９）においては、上記のように入射するレーザ光のスポットＳ１ａ、Ｓ１ｂ、Ｓ２ａ、Ｓ２ｂのスポット径、位置変化等を検出することができる。
【００９０】
このレーザカプラを用いて光ディスク装置の光ピックアップを構成した場合には、上記のフォトダイオードＰＤにより得られる信号から、光ディスクに記録された情報信号、トラッキングエラー信号、フォーカスエラー信号の読み取りが行われる。これら信号の取り出しは、ＣＤなどの光ディスクでは、それぞれ図２１について説明した上述の式（６）、（７）、（８）に基づいて行なわれ、信号の再生及び各サーボコントロールが行われる。
【００９１】
一方、前後部第２フォトダイオード１８、１９においては、それぞれ８分割および４分割された前後部第２フォトダイオード１８、１９上に入射するスポットＳ２ａ、Ｓ２ｂにおいて得られた信号ａ２、ｂ２、ｃ２、ｄ２、ｅ２、ｆ２、ｇ２、ｈ２、ｉ２、ｊ２、ｋ２及びｌ２を用いて図２１について説明した上述の式（９）、（１０）及びＤＰＤ法に基づいて、光ディスクに記録された情報信号、フォーカスエラー信号及びトラッキングエラー信号が読み出され、信号の再生及び各サーボコントロールが行われる。
【００９２】
このレーザカプラを用いる光ディスクの再生／記録装置においては、上記のようにして、ＣＤ又はＤＶＤなどの光ディスクの上下の振れによるフォーカスエラー信号の検出を行い、得られたフォーカスエラー信号に従ってフォーカシングサーボをかける。また、トラッキングエラー信号の検出を行い、得られたトラッキングエラー信号に従ってトラッキングサーボをかける。
【００９３】
このレーザカプラは、ＣＤ用のレーザダイオードＬＤ１（発振波長７８０ｎｍ）とＤＶＤ用のレーザダイオードＬＤ２（発振波長６５０ｎｍ）を搭載し、ＣＤとＤＶＤの再生を可能にするコンパチブル光ピックアップを構成することが可能である。
【００９４】
そして、このレーザカプラは、互いに隣接して並列に配置された第１レーザダイオードＬＤ１及び第２レーザダイオードＬＤ２と、互いに隣接して並列に配置された前後部第１フォトダイオード１６、１７及び前後部第２フォトダイオード１８、１９とを有しており、発振波長の異なるレーザダイオードからの光軸を合わせる必要がなく、共通の光学部材を用いて、第１レーザダイオードＬＤ１及び第２レーザダイオードＬＤ２の出射光をＣＤやＤＶＤなどの光ディスクに照射し、光ディスクからの反射光を前後部第１フォトダイオード１６、１７及び前後部第２フォトダイオード１８、１９にそれぞれ入射させる。従って、図１５及び図１６に示したものよりも部品点数が少なく、容易に組み立てられ、小型化やコスト削減が可能である。
【００９５】
ところが、このレーザカプラにおいて、図２１において述べたように、ＣＤ用の７８０ｎｍ帯のレーザダイオードＬＤ１とＤＶＤ用の６５０ｎｍ帯のレーザダイオードＬＤ２は、製造のばらつきや、ブロック１３又は基板１１へのマウント精度のばらつきにより、各レーザからのレーザ光Ｌ１、Ｌ２の出射方向がばらつくことがある。
【００９６】
例えば、図１（Ａ）に示すように、レーザダイオードＬＤ１のレーザ光Ｌ１の出射方向は正規の光軸（即ち、フォトダイオード１６及び１７の前後配列方向に沿う光軸）ＯＡ１と一致するが、他方のレーザダイオードＬＤ２のレーザ光Ｌ２の出射方向が正規の光軸（即ち、フォトダイオード１８及び１９の前後配列方向に沿う光軸）ＯＡ２から外側へずれている場合には、対物レンズを介してのディスクからの反射光のスポットＳ１ａ、Ｓ１ｂ、Ｓ２ａ、Ｓ２ｂはフォトダイオード上で位置変化しないが、そのスポット中のビーム強度が最大となる点（図中、黒点で示す）がスポットＳ２ａとＳ２ｂとで光軸に関し反対側に振れてしまう。
【００９７】
この結果、ＤＶＤ側のフォトダイオード１８、１９での受光量バランスがくずれ、特に高精度な規格が要求されるＤＶＤの信号読み取り及びサーボコントロールに支障を来たす。これを防止する上で、本実施の形態では、従来のようにＤＶＤ用の信号読み取り時に対物レンズを光軸ＯＡ２に対して上記ずれ方向とは反対側へ振る（シフトさせる）のではなく、次のようにあおり調整することによってＤＶＤ側のスポット位置を調整する。そして、その際にＣＤ側のバランスがくずれるが、これについては、ＣＤ使用時に、対物レンズのシフトによってＣＤ側のバランスを調整する。
【００９８】
即ち、図１（Ｂ）に示すように、レーザダイオードＬＤ１及びＬＤ２を固定し終ったブロック１３をマウントした基板１１の全体を正規の光軸ＯＡ１及びＯＡ２と平行な中心軸の周りに例えば矢印方向に回転させて厚み方向に傾けることにより、レーザ光Ｌ１、Ｌ２をレーザ光Ｌ１’、Ｌ２’に出射方向を変化させ、ＰＤ上のスポットを動かすことができる。すなわち、そうすることにより、バランス調整をする。
【００９９】
こうしてＤＶＤ側のレーザ光の出射方向を正規の光軸に重ね合わせると、ＤＶＤ側のフォトダイオード１８、１９上に形成される反射光のスポットＳ２ａ及びＳ２ｂのビーム強度が最大となる点が光軸上に並んで形成されることになり、規格の厳しいＤＶＤに要求される条件を満たすことになる。
【０１００】
但し、この状態では、今度はＣＤ側ではＰＤ上のスポットがずれて、バランスがくずれてしまうが、対物レンズをＣＤ側の方向へ移動させることにより、ＣＤ側でもフォトダイオード１６、１７上のスポットＳ１ａ、Ｓ１ｂのビーム強度が最大となる点を光軸ＯＡ１上に来るように調整することができる。
【０１０１】
このように、厳しい規格が要求されるＤＶＤ側は、レーザスポットを正規の光軸上に形成できると同時に、その強度バランスを容易にかつ正確に安定化させることができる上に、ＣＤ側もビーム強度を容易にバランス良く調整することができる。この調整は、ＣＤ側の
【数２】

がＤＶＤ側に比べ大きいために有利であるが、これは、許容される強度分布が広いため対物レンズを動かしてもフォトダイオードの出力バランスの変化に影響がなく、信号の再生やサーボコントロールの性能が良好に保持されるからである。
【０１０２】
図１（Ｂ）に示した基板は光軸ＯＡ２の周りに回転させてもよいし、また図１（Ａ）においてレーザ光Ｌ２の出射方向が光軸の内方へ向いてずれている場合にも同様に調整可能である。その場合は、基板回転方向は上記とは逆方向となる。
【０１０３】
実施の形態２
本実施の形態では、図２（Ａ）に示すように、図１（Ａ）と同様の状態ではあるが、レーザダイオードＬＤ１及びＬＤ２を設けたブロック１３を基板１１上にマウント（固定）していない状態において、図１（Ａ）で示したと同様にレーザ光Ｌ２の出射方向が光軸からずれている場合、図２（Ｂ）に示すように、ブロック１３を基板１１上で（即ち、その面内で）矢印方向に回転させて平面的にみて傾けることによって、ＤＶＤ側のレーザ光のスポットＳ２ａ及びＳ２ｂの強度が最大の点を光軸ＯＡ２と一致させて又は重ねて位置調整（θ補正）する。
【０１０４】
次いで、実施の形態１で述べたと同様に、ＣＤ側において光軸ＯＡ１からずれたレーザ光Ｌ１’の光出射方向を対物レンズの移動によって調整する。
【０１０５】
このように、厳しい規格が要求されるＤＶＤ側は、レーザスポットを正規の光軸上に形成できると同時にその強度バランスを容易にかつ正確に安定化させることができる上に、ＣＤ側もビーム強度を容易にバランス良く調整することができる。この調整は、ＣＤ側の
【数３】

がＤＶＤ側に比べて大きいために有利であり、また、
【数４】

が大きいために対物レンズのシフト量が小さくても光強度分布のバランスをとり易く、この点でレンズシフト量をより小さくでき、光ピックアップを設計し易くなる。
【０１０６】
参考例
この参考例では、図３（Ａ）に示すように、図２（Ａ）と同様の状態ではあるが、レーザダイオードＬＤ１及びＬＤ２を設けたブロック１３を基板１１上にマウントしていない状態において、図１（Ａ）で示したと同様にレーザ光Ｌ２の出射方向が光軸からずれている場合、図３（Ｂ）に示すように、ブロック１３を基板１１上で（即ち、その面内で）矢印方向に幾分過度に回転させて平面的にみて幾分過度に傾ける（過補正する）。この過補正の角度α（レーザ光Ｌ２’の出射方向と光軸ＯＡ２とのなす角度）は０°以上、１°以下程度とし、０°以上、０．５°以下が好ましい。
【０１０７】
次いで、ブロック１３を基板１１上にマウント（固定）し、更に図３（Ｂ）に相当する図４（Ｂ）の状態から、図４（Ｃ）に示すように、基板１１を光軸ＯＡ１又はＯＡ２と平行な中心軸の周りに矢印方向に回転させて、ＤＶＤ側のレーザ光Ｌ２’の出射方向をＬ２”のように変化させて光軸ＯＡ２に重ねる。こうしてあおり補正を付加することによって、ＤＶＤ側のレーザ光のスポットＳ２ａ及びＳ２ｂの強度が最大の点を光軸ＯＡ２上に位置させる。
【０１０８】
次いで、実施の形態１で述べたと同様に、ＣＤ側において光軸ＯＡ１からずれたレーザ光Ｌ１”の光出射方向を対物レンズの移動によって調整する。
【０１０９】
このように、厳しい規格が要求されるＤＶＤ側は、レーザスポットを正規の光軸上に形成できると同時に、その強度バランスを容易にかつ正確に安定化させることができる上に、ＣＤ側もビーム強度を容易にバランス良く調整することができる。この調整は、ＣＤ側の
【数５】

がＤＶＤ側に比べて大きいために有利であり、また、
【数６】

が大きいために対物レンズのシフト量が小さくても光強度分布のバランスをとり易く、この点でレンズシフト量をより小さくでき、光ピックアップを設計し易くなる。
【０１１０】
しかも、この場合、図３（Ｂ）のように面内でまず過補正した後に図４（Ｃ）のようにあおり補正をすることにより、結果的にＣＤ側のスポットバランスを調整するために動かさなくてはならない対物レンズのシフト量を一層減らすことができる。
【０１１１】
次に、上述した各実施の形態に共通の構成を説明する。
【０１１２】
図５は、例えば７８０ｎｍ帯の波長のレーザ光を出射する第１レーザダイオードＬＤ１と６５０ｎｍ帯の波長のレーザ光を出射する第２レーザダイオードＬＤ２を１チップ上に搭載するモノリシックレーザダイオード１４ａを示すものである。
【０１１３】
例えば、円盤状の基台２１に設けられた突起部２１ａ上に、モニター用の光検出素子としてのＰＩＮダイオード１２が形成された半導体ブロック１３が固着され、その上部に、第１及び第２レーザダイオードＬＤ１、ＬＤ２を１チップ上に有するモノリシックレーザダイオード１４ａが配置されている。また、基台２１を貫通して端子２２が設けられており、リード２３により上記の第１及び第２レーザダイオードＬＤ１、ＬＤ２、或いはＰＩＮダイオード１２に接続されて、それぞれのダイオードの駆動電源が供給される。
【０１１４】
図６（ａ）は上記のレーザダイオードのレーザ光の出射方向と垂直な方向からの要部平面図であり、図６（ｂ）はレーザダイオードのレーザ光の出射方向と垂直な平面での断面図である。ＰＩＮダイオード１２が形成された半導体ブロック１３の上部に第１レーザダイオードＬＤ１と第２レーザダイオードＬＤ２を１チップ上に有するモノリシックレーザダイオード１４ａが配置されている。
【０１１５】
ＰＩＮダイオード１２においては、第１及び第２レーザダイオードＬＤ１、ＬＤ２のリア側に出射されたレーザ光を感知し、その強度を測定して、レーザ光の強度が一定となるように第１及び第２レーザダイオードＬＤ１、ＬＤ２の駆動電流を制御するＡＰＣ制御が行われるように構成されている。
【０１１６】
上記のモノリシックレーザダイオード１４ａについて説明する。第１レーザダイオードＬＤ１として、ｎ型ＧａＡｓ基板３０上に、ｎ型ＧａＡｓバッファ層３１、ｎ型ＡｌＧａＡｓクラッド層３２、活性層３３、ｐ型ＡｌＧａＡｓクラッド層３４、ｐ型ＧａＡｓキャップ層３５が積層している。ｐ型ＧａＡｓキャップ層３５表面からｐ型ＡｌＧａＡｓクラッド層３４の途中の深さまで絶縁化された領域４１となって、電流狭窄構造となるストライプを形成している。
【０１１７】
一方、第２レーザダイオードＬＤ２として、ｎ型ＧａＡｓ基板３０上に、ｎ型ＧａＡｓバッファ層３１、ｎ型ＩｎＧａＰバッファ層３６、ｎ型ＡｌＧａＩｎＰクラッド層３７、活性層３８、ｐ型ＡｌＧａＩｎＰクラッド層３９、ｐ型ＧａＡｓキャップ層４０が積層している。ｐ型ＧａＡｓキャップ層４０表面からｐ型ＡｌＧａＩｎＰクラッド層３９の途中の深さまで絶縁化された領域４１となって、電流狭窄構造となるストライプを形成している。
【０１１８】
上記の第１レーザダイオードＬＤ１及び第２レーザダイオードＬＤ２においては、ｐ型ＧａＡｓキャップ層３５、４０にはｐ電極４２が、ｎ型ＧａＡｓ基板３０にはｎ電極４３が接続して形成されている。このモノリシックレーザダイオード１４ａは、ｐ電極４２側から、半導体ブロック１３上に形成された電極１３ａにハンダなどにより接続及び固定されている。
【０１１９】
上記の第１レーザダイオードＬＤ１のレーザ光出射部と第２レーザダイオードＬＤ２のレーザ光出射部の間隔ｄは例えば２００μｍ程度以下の範囲（例えば１００μｍ程度）に設定される。各レーザ光出射部からは、例えば７８０ｎｍ帯の波長のレーザ光Ｌ１及び６５０ｎｍ帯の波長のレーザ光Ｌ２がほぼ同一の方向（ほぼ平行）に出射される。
【０１２０】
一方、上記した第１及び第２フォトダイオード１６−１７、１８−１９間の間隔も上記と同様に２００μｍ程度以下の範囲（例えば１００μｍ程度）に設定され、共通の光学部材を用いて、第１レーザダイオード及び第２レーザダイオードの出射光をＣＤやＤＶＤなどの光ディスクに照射し、光ディスクからの反射光を第１フォトダイオード及び第２フォトダイオードにそれぞれ結合させることが可能となる。
【０１２１】
次に、上記の第１レーザダイオードＬＤ１と第２レーザダイオードＬＤ２をチップ上に搭載するモノリシックレーザダイオード１４ａの形成方法について説明する。
【０１２２】
まず、図７（ａ）に示すように、例えば有機金属気相エピタキシャル成長法（ＭＯＶＰＥ）などのエピタキシャル成長法により、ｎ型ＧａＡｓ基板３０上に、ｎ型ＧａＡｓバッファ層３１、ｎ型ＡｌＧａＡｓクラッド層３２、活性層（発振波長７８０ｎｍの多重量子井戸構造）３３、ｐ型ＡｌＧａＡｓクラッド層３４、ｐ型ＧａＡｓキャップ層３５を順に積層させる。
【０１２３】
次に、図７（ｂ）に示すように、第１レーザダイオードＬＤ１として残す領域をレジスト膜（図示せず）で保護して、硫酸系の無選択エッチング、及び、フッ酸系のＡｌＧａＡｓ選択エッチングなどのウエットエッチング（ＥＣ１）により、第１レーザダイオードＬＤ１領域以外の領域でｎ型ＡｌＧａＡｓクラッド層３２までの上記の積層体を除去する。
【０１２４】
次に、図８（ｃ）に示すように、例えば有機金属気相エピタキシャル成長法（ＭＯＶＰＥ）などのエピタキシャル成長法により、ｎ型ＧａＡｓバッファ層３１上に、ｎ型ＩｎＧａＰバッファ層３６、ｎ型ＡｌＧａＩｎＰクラッド層３７、活性層（発振波長６５０ｎｍの多重量子井戸構造）３８、ｐ型ＡｌＧａＩｎＰクラッド層３９、ｐ型ＧａＡｓキャップ層４０を順に積層させる。
【０１２５】
次に、図８（ｄ）に示すように、第２レーザダイオードＬＤ２として残す領域をレジスト膜（図示せず）で保護して、硫酸系のキャップエッチング、リン酸−塩酸系の４元選択エッチング、塩酸系の分離エッチングなどのウエットエッチング（ＥＣ２）により、第２レーザダイオードＬＤ２領域以外の領域でｎ型ＩｎＧａＰバッファ層３６までの上記の積層体を除去し、第１レーザダイオードＬＤ１と第２レーザダイオードＬＤ２を分離する。
【０１２６】
次に、図９（ｅ）に示すように、レジスト膜（図示せず）で電流注入領域となる部分を保護して、不純物Ｄをイオン注入などにより導入し、ｐ型ＧａＡｓキャップ層３５、４０の表面からｐ型ＡｌＧａＡｓクラッド層３４、３９の途中の深さまで絶縁化された領域４１を形成し、電流狭窄構造となるストライプとする。
【０１２７】
次に、図９（ｆ）に示すように、ｐ型ＧａＡｓキャップ層３５、４０に接続するように、Ｔｉ／Ｐｔ／Ａｕなどのｐ型電極４２を形成し、一方、ｎ型ＧａＡｓ基板３０に接続するように、ＡｕＧｅ／Ｎｉ／Ａｕなどのｎ型電極４３を形成し、ペレタイズ工程を経て、所望の第１レーザダイオードＬＤ１と第２レーザダイオードＬＤ２を１チップ上に搭載するモノリシックレーザダイオード１４ａとする。
【０１２８】
図１０は、上記したフォトダイオードの配置（ａ）を示し、このフォトダイオードにより得られる信号から、トラッキングエラー信号、フォーカスエラー信号、及び光ディスクに記録された情報信号の読み取りが図２１において説明したと同様にして行われる。そして、上記のようにして、ＣＤ又はＤＶＤなどの光ディスクの上下の振れによるフォーカスエラー信号の検出を行い、得られたフォーカスエラー信号に従ってフォーカシングサーボをかける。また、トラッキングエラー信号の検出を行い、得られたトラッキングエラー信号に従ってトラッキングサーボをかける。
【０１２９】
図１１は、上記の本実施の形態によるレーザカプラを用いた光ピックアップの構成を示す。このレーザカプラ１ａに内蔵される第１及び第２レーザダイオードからの出射レーザ光Ｌ１、Ｌ２をコリメータＣ、ミラーＭ、ＣＤ用開口制限アパーチャＲ及び対物レンズＯＬを介して、ＣＤ又はＤＶＤなどの光ディスクＤに入射する。光ディスクＤからの反射光は、入射光と同一の経路をたどってレーザカプラに戻り、レーザカプラに内蔵される第１及び第２フォトダイオードにより受光される。
【０１３０】
このレーザカプラにおいては、第１及び第２フォトダイオードを図１２に示すように分割することも可能である。この場合、前部第１フォトダイオード１６の領域ｄ１と、前部第２フォトダイオード１８の領域ａ２とｅ２が共通化されており、信号ａ２とｅ２を加算することで信号ｄ１が得られる。また、後部第１フォトダイオード１７の領域ｌ１と、後部第２フォトダイオード１９の領域ｉ２が共通化されている。
【０１３１】
図１３（ａ）は、本実施の形態にかかるレーザカプラ１ａの概略構成を示す説明図である。レーザカプラ１ａは、第１パッケージ部材２の凹部に装填され、ガラスなどの透明な第２パッケージ部材３により封止されている。
【０１３２】
図１３（ｂ）は上記のレーザカプラ１ａの要部斜視図である。例えば、シリコンの単結晶を切り出した基板である集積回路基板１１上に、モニター用の光検出素子としてのＰＩＮダイオード１２が形成された半導体ブロック１３が配置され、さらに、この半導体ブロック１３上に、発光素子として第１レーザダイオードＬＤ１及び第２レーザダイオードＬＤ２を１チップ上に搭載するモノリシックレーザダイオード１４ａが配置されている。
【０１３３】
第１レーザダイオードＬＤ１から出射されたレーザ光Ｌ１は、プリズム２０の分光面２０ａで一部反射して進行方向を屈曲し、第２パッケージに形成された出射窓から出射方向に出射し、反射ミラーや対物レンズ（図示せず）などを介して光ディスク（ＣＤ）などの被照射対象物に照射される。
【０１３４】
上記の被照射対象物からの反射光は、被照射対象物への入射方向と反対方向に進み、レーザカプラ１ａのプリズム２０の分光面２０ａに入射する。このプリズム２０の上面で焦点を結びながら、プリズム２０の下面となる集積回路基板１１上に形成された前部第１フォトダイオード１６及び後部第１フォトダイオード１７に入射する。
【０１３５】
一方、第２レーザダイオードＬＤ２から出射されたレーザ光Ｌ２は、上記と同様に、プリズム２０の分光面２０ａで一部反射して進行方向を屈曲し、第２パッケージに形成された出射窓から出射し、反射ミラーや対物レンズなど（図示せず）を介して光ディスク（ＤＶＤ）などの被照射対象物に照射される。
【０１３６】
上記の被照射対象物からの反射光は、被照射対象物への入射方向と反対方向に進み、レーザカプラ１ａのプリズム２０の分光面２０ａに入射する。このプリズム２０の上面で焦点を結びながら、プリズム２０の下面となる集積回路基板１１上に形成された前部第２フォトダイオード１８および後部第２フォトダイオード１９に入射する。
【０１３７】
このように、本実施の形態のレーザカプラは、ＣＤ用のレーザダイオードＬＤ１（発振波長７８０ｎｍ）とＤＶＤ用のレーザダイオードＬＤ２（発振波長６５０ｎｍ）を搭載し、ＣＤとＤＶＤの再生を可能にするコンパチブル光ピックアップを構成することが可能である。さらに、第１レーザダイオードと第２レーザダイオードを１チップ上に搭載するモノリシックレーザダイオードを用いることから、光学系の組み立てがさらに容易となる。
【０１３８】
以上、本発明を実施の形態により説明したが、本発明はこれらの実施の形態に何ら限定されるものではない。
【０１３９】
例えば、本発明に用いる発光素子としては、レーザダイオードに限定されず、発光ダイオード（ＬＥＤ）を用いることも可能である。
【０１４０】
また、第１及び第２レーザダイオードの発振波長は、７８０ｎｍ帯と６５０ｎｍ帯に限定されるものではなく、その他の光ディスクシステムに採用されている波長とすることができる。すなわち、種々の波長の組み合せを用い、ＣＤとＤＶＤ以外の他の組み合わせの光ディスクシステムを採用することができる。また、波長が同じであっても、パワーが異なる光や偏光方向が異なる光を用いてもよい。また、波長など、物性の異なる光は２種類に限らず、それ以上としてもよい。
【０１４１】
また、ＡＰＣ制御を行うためのＰＩＮダイオードは、第１及び第２フォトダイオードが形成されている集積回路基板上に形成する構成としてもよい。この場合には、プリズムの構成を変更して、第１及び第２レーザダイオードのフロント側の出射光の一部を取り出してＰＩＮダイオードに結合する構成とすることが好ましい。再生信号やトラッキング、フォーカスエラー信号の読み取りは、図２０で述べたように行ってもよい。
【０１４２】
また、図１４に示すように、レーザダイオード１４（ＬＤ１）と１５（ＬＤ２）を別々に（即ち、ディスクリートに）作製し、それぞれをマウントする構成としたレーザカプラ１ｂとしてもよい。
【０１４３】
その他、フォトダイオードのパターン、レイアウトなどは種々変更してよく、ダイオード以外のディテクタ構造としてもよい。
【０１４４】
【発明の作用効果】
本発明は上述した如く、前記ブロック上での前記複数の発光素子の位置を固定したまま前記ブロックを傾けることにより、前記複数の発光素子を共通に傾けて、所定の発光素子の光出射方向を正規の光軸と重ねているので、例えば規格の厳しい高精度化が要求される前記所定の発光素子からの出射光の出射方向を前記要求を満たすように設定でき、しかもこれを前記ブロックを傾けることによって行える（従って、発光素子自体は直接回転調整しない）ために、前記所定の発光素子の出射光の位置調整が容易となる。
【０１４５】
そして、前記他の発光素子からの出射光については、対物レンズの位置調整によって光軸を正規の光軸に重ねるが、この際、
【数７】

が広い場合には、対物レンズの振れ（レンズシフト）によりスポットバランスを適切に調整することができ、レンズシフトを行っても特性への影響は少ない。
【図面の簡単な説明】
【図１】本発明の実施の形態１によるレーザカプラの光ビーム位置調整方法を示す概略平面図である。
【図２】本発明の実施の形態２によるレーザカプラの光ビーム位置調整方法を示す概略平面図である。
【図３】参考例によるレーザカプラの光ビーム位置調整方法の第１段階を示す概略平面図である。
【図４】同、レーザカプラの光ビーム位置調整方法の第２段階を示す概略平面図である。
【図５】本発明の各実施の形態に用いるレーザダイオードの要部斜視図である。
【図６】同、レーザダイオードのレーザ光の出射方向を示す要部平面図（ａ）と同出射方向と垂直方向における断面図（ｂ）である。
【図７】同、レーザダイオードの製造方法を工程順に示す断面図である。
【図８】同、レーザダイオードの製造方法を工程順に示す断面図である。
【図９】同、レーザダイオードの製造方法を工程順に示す断面図である。
【図１０】同、フォトダイオードの要部平面図（ａ）とＤＰＤ法を説明するためのブロック図（ｂ）である。
【図１１】同、レーザカプラを用いた光ピックアップの概略構成図である。
【図１２】同、フォトダイオードの変形例の要部平面図である。
【図１３】同、レーザカプラのパッケージの斜視図（ａ）と同レーザカプラの斜視図（ｂ）である。
【図１４】同、レーザカプラの他のパッケージの斜視図（ａ）と同レーザカプラの斜視図（ｂ）である。
【図１５】従来例による光ピックアップの概略構成図である。
【図１６】他の従来例による光ピックアップの概略構成図である。
【図１７】本発明者が既に提案した光ピックアップの概略構成図である。
【図１８】同、レーザダイオードの要部斜視図である。
【図１９】同、レーザダイオードのレーザ光の出射方向を示す要部平面図（ａ）と同出射側の要部側面図（ｂ）と他のレーザダイオードのレーザ光の出射方向を示す要部平面図（ｃ）である。
【図２０】同、フォトダイオードの要部平面図（ａ）とＤＰＤ法を説明するためのブロック図（ｂ）である。
【図２１】同、レーザカプラでの光ビーム出射方向とそのスポットを示す概略平面図である。
【符号の説明】
１ａ、１ｂ…レーザカプラ、１１…集積回路基板、１２…ＰＩＮダイオード、
１３…半導体ブロック、１４、ＬＤ１…第１レーザダイオード、
１４ａ…モノリシックレーザダイオード、
１５、ＬＤ２…第２レーザダイオード、１６…前部第１フォトダイオード、
１７…後部第１フォトダイオード、１８…前部第２フォトダイオード、
１９…後部第２フォトダイオード、２０…プリズム、２０ａ…分光面、
Ｅ１、Ｅ２…レーザ光出射部、ＢＳ…ビームスプリッタ、Ｃ…コリメータ、
Ｒ…ＣＤ用の開口制限アパーチャ、ＭＬ…マルチレンズ、
ＰＤ…フォトダイオード、Ｇ…グレーティング、Ｍ…ミラー、
ＯＬ…対物レンズ、Ｄ…光ディスク、Ｌ１、Ｌ１’、Ｌ１”…第１レーザ光、
Ｌ２、Ｌ２’、Ｌ２”…第２レーザ光、ＰＣ…位相比較器、ＡＤ…加算器、
ＯＡ１、ＯＡ２…正規の光軸、Ｓ１ａ、Ｓ１ｂ、Ｓ２ａ、Ｓ２ｂ…スポット[0001]
BACKGROUND OF THE INVENTION
According to the present invention, a plurality of light emitting elements that respectively emit a plurality of different lights are juxtaposed on a common block in a direction intersecting with the light emitting direction, and the blocks are fixed on a base. An optical device (especially an optical pickup) in which light emitted from the light beam is guided to a corresponding plurality of light receiving elements through an objective lens, an optical disk device that irradiates the disk-shaped information recording medium with the plurality of lights and reads information by the reflected light, And a light beam position adjusting method.
[0002]
[Prior art]
It is recorded on an optical recording medium (hereinafter sometimes referred to as an optical disc) that optically records and / or reproduces information, such as a CD (compact disc), a DVD (digital video disc), or an MD (mini disc). A device that reads (reproduces) information or writes (records) information on the information (hereinafter sometimes referred to as an optical disk device) has a built-in optical pickup.
[0003]
In such an optical disc apparatus and optical pickup, in general, when the type of optical disc (optical disc system) is different, laser beams having different wavelengths are used. For example, a laser beam having a wavelength of 780 nm is used for reproducing a CD, and a laser beam having a wavelength of 650 nm is used for reproducing a DVD.
[0004]
Thus, in a situation where the wavelength of the laser light varies depending on the type of the optical disk, a compatible optical pickup capable of reproducing a CD with an optical disk device for DVD, for example, is desired.
[0005]
FIG. 15 shows a conventional compatible light in which the above-described CD laser diode LD1 (oscillation wavelength 780 nm) and DVD laser diode LD2 (oscillation emission wavelength 650 nm) are mounted, enabling reproduction of a CD and a DVD. 1 is a schematic configuration diagram of a pickup 100. FIG.
[0006]
The optical pickup 100 includes, for example, a first laser diode LD1, a grating G, a first beam splitter BS1, a first mirror M1, a first objective lens OL1, a first multilens ML1, and a laser beam having a wavelength of 780 nm. Each of the first photodiodes PD1 has a CD optical system that is individually (ie, discretely) disposed at a predetermined position.
[0007]
Further, the optical pickup 100 includes, for example, a second laser diode LD2, a second beam splitter BS2, a collimator C, a second mirror M2, a second objective lens OL2, and a second multilens ML2 that emit laser light having a wavelength of 650 nm. , And the second photodiode PD2 each have a DVD optical system disposed individually (that is, discretely) at predetermined positions.
[0008]
In the CD optical system of the optical pickup 100 configured as described above, the first laser light L1 from the first laser diode LD1 passes through the grating G, is partially reflected by the first beam splitter BS1, and is reflected by the first mirror. The path is bent by M1, and the light is condensed on the optical disc D by the first objective lens OL1.
[0009]
The reflected light from the optical disk D passes through the first multi-lens ML1 via the first objective lens OL1, the first mirror M1, and the first beam splitter BS1, and is incident on the first photodiode PD1, and this reflected light. Due to this change, the information recorded on the CD recording surface of the optical disc D is read out.
[0010]
Also in the DVD optical system of the optical pickup 100, the second laser light L2 from the second laser diode LD2 is partially reflected by the second beam splitter BS2 and passes through the collimator C, as described above. The path is bent by the second mirror M2, and is condensed on the optical disc D by the second objective lens OL2.
[0011]
The reflected light from the optical disc D passes through the second multi-lens ML2 via the second objective lens OL2, the second mirror M2, the collimator C, and the second beam splitter BS2, and is incident on the second photodiode PD2. Information recorded on the DVD recording surface of the optical disc D is read out by the change in the reflected light.
[0012]
According to the optical pickup 100, a CD laser diode and a DVD laser diode are mounted, and each has an optical system, thereby enabling reproduction of a CD and a DVD.
[0013]
FIG. 16 shows another conventional CD-ROM that can reproduce CDs and DVDs by mounting the above-described CD laser diode LD1 (emission wavelength 780 nm) and DVD laser diode LD2 (emission wavelength 650 nm). 1 is a schematic configuration diagram of a compatible optical pickup 101. FIG.
[0014]
The optical pickup 101 includes, for example, a first laser diode LD1, a grating G, a first beam splitter BS1, a dichroic beam splitter DBS, a collimator C, a mirror M, and a CD aperture limiting aperture R that emit laser light having a wavelength of 780 nm. The objective lens OL, the first multi-lens ML1, and the first photodiode PD1 each have a CD optical system disposed individually (that is, discretely) at predetermined positions.
[0015]
Further, the optical pickup 101 includes, for example, a second laser diode LD2, a second beam splitter BS2, a dichroic beam splitter DBS, a collimator C, a mirror M, an objective lens OL, and a second multilens that emit laser light having a wavelength of 650 nm. The ML2 and the second photodiode PD2 each have a DVD optical system disposed individually (that is, discretely) at predetermined positions.
[0016]
In each optical system, some optical members are shared. For example, the dichroic beam splitter DBS, the collimator C, the mirror M, and the objective lens OL are shared by both optical systems. Further, since the optical axis between the dichroic beam splitter DBS and the optical disc D is shared, the CD aperture limiting aperture R is also disposed on the optical axis of the DVD optical system.
[0017]
In the CD optical system of the optical pickup 101 configured as described above, the first laser light L1 from the first laser diode LD1 passes through the grating G, is partially reflected by the first beam splitter BS1, and is dichroic beam splitter. The light passes through or reflects through the DBS, collimator C, and mirror M, and is focused on the optical disc D by the objective lens OL1 through the CD aperture limiting aperture R.
[0018]
The reflected light from the optical disk D passes through the first multi-lens ML1 via the objective lens OL, the CD aperture limiting aperture R, the mirror M, the collimator C, the dichroic beam splitter DBS, and the first beam splitter BS1, and the first Information recorded on the CD recording surface of the optical disc D is read out by the change of the reflected light that is incident on the photodiode PD1.
[0019]
Also in the DVD optical system of the optical pickup 101, the second laser light L2 from the second laser diode LD2 is partially reflected by the second beam splitter BS2 in the same manner as described above, and the dichroic beam splitter DBS, collimator C, The light passes through or reflects through the mirror M, and is focused on the optical disc D by the objective lens OL1 through the aperture limiting aperture R for CD.
[0020]
The reflected light from the optical disk D passes through the second multi-lens ML2 via the objective lens OL, the CD aperture limiting aperture R, the mirror M, the collimator C, the dichroic beam splitter DBS, and the second beam splitter BS2, and the second Information incident on the photodiode PD2 and recorded on the DVD recording surface of the optical disc D is read out by the change in the reflected light.
[0021]
According to this optical pickup 101, similarly to the optical pickup 100 shown in FIG. 15, a CD laser diode and a DVD laser diode are mounted, and the respective optical systems can be used to reproduce CDs and DVDs. I have to.
[0022]
[Course to Invention]
The present inventor can construct an optical disc system having a different wavelength such as CD and DVD with respect to such a conventional optical pickup, can be easily assembled with a reduced number of parts, and can be reduced in size and cost. An optical device and an optical disk device using the same have already been proposed.
[0023]
An example is shown in FIGS. 17 to 20, and according to the compatible optical pickup 1a shown in FIG. 17, a laser diode LD1 for CD (oscillation wavelength 780 nm) and a laser diode LD2 for DVD (oscillation wavelength 650 nm) are mounted. is doing.
[0024]
The optical pickup 1a has optical systems configured individually (that is, discretely) or on a common substrate (that is, monolithically), and is formed adjacent to each other in parallel, for example, with a wavelength of 780 nm band. A laser diode LD having a first laser diode LD1 that emits a laser beam and a second laser diode LD2 that emits a laser beam having a wavelength of 650 nm, and a grating G for the 780 nm band that is transparent to the 650 nm band , A beam splitter BS, a collimator C, a mirror M, an aperture limiting aperture R for CD, an objective lens OL, a multilens ML, and a photodiode PD are arranged at predetermined positions. In the photodiode PD, a first photodiode that receives light in the 780 nm band and a second photodiode that receives light in the 650 nm band are formed adjacent to each other in parallel.
[0025]
In the optical pickup 1a, the first laser light L1 from the first laser diode LD1 passes through the grating G, is partially reflected by the beam splitter BS, and passes through the collimator C, the mirror M, and the aperture limiting aperture R for CD. (Reflected), and is focused on the optical disk D by the objective lens OL.
[0026]
Reflected light from the optical disk D passes through the multi-lens ML via the objective lens OL, the CD aperture limiting aperture R, the mirror M, the collimator C, and the beam splitter BS, and onto the photodiode PD (first photodiode). The information recorded on the recording surface of the optical disc D such as a CD is read out by the change in the reflected light.
[0027]
In the optical pickup 1a, the second laser light L2 from the second laser diode LD2 is also collected on the optical disc D along the same path as described above, and the reflected light is reflected on the photodiode PD (second photodiode). The information recorded on the recording surface of the optical disc D such as a DVD is read out by the change in the reflected light.
[0028]
In this optical pickup 1a, a laser diode for CD and a laser diode for DVD are mounted, and the reflected light is coupled to the photodiode for CD and the photodiode for DVD by a common optical system to reproduce CD and DVD. enable.
[0029]
FIG. 18 is a perspective view of a main part of the laser diode LD. For example, a semiconductor block 13 in which a PIN diode 12 as a light detection element for monitoring is formed is fixed on a protrusion 21a provided on a disk-shaped base 21, and a first laser diode 14 (LD1) is formed on the semiconductor block 13. And a second laser diode 15 (LD2). Further, a terminal 22 is provided through the base 21, and is connected to the first and second laser diodes 14 and 15 or the PIN diode 12 by leads 23, and the drive power supply voltage of each diode is Supplied.
[0030]
FIG. 19A is a plan view of the main part from the direction perpendicular to the laser beam emission direction of the laser diode, and FIG. 19B is the main part of the laser diode from the laser beam emission direction. It is a top view. A first laser diode 14 (LD1) and a second laser diode 15 (LD2) are discretely arranged above the semiconductor block 13 on which the PIN diode 12 is formed. These laser diodes may be arranged monolithically as will be described later, as shown in FIG.
[0031]
Here, the PIN diode 12 has, for example, a region divided into two, and laser light emitted to the rear (rear part) side of each of the first and second laser diodes 14 and 15 or LD1 and LD2 is emitted. An APC (Automatic Power Control) control is performed to control the drive current of the first and second laser diodes 14 and 15 or LD1 and LD2 so that the intensity of the laser beam is detected and the intensity of the laser light is constant. It is configured as follows. One PIN diode 12 may be used without being divided (switchable and usable).
[0032]
The distance d between the laser light emitting part E1 of the first laser diode 14 and the laser light emitting part E2 of the second laser diode 15 is set to a range of about 200 μm or less (for example, about 100 μm). For example, laser light L1 having a wavelength of 780 nm band and laser light L2 having a wavelength of 650 nm band are emitted in the same direction (parallel) from the laser light emitting portions E1 and E2, respectively.
[0033]
FIG. 20A is a plan view of the main part of the photodiode PD. For example, a first photodiode 16 that receives light in the 780 nm band and a second photodiode 18 that receives light in the 650 nm band are formed adjacent to each other in parallel.
[0034]
Here, the first photodiode 16 has a configuration divided into six parts (a1, b1, c1, d1, e1, f1) as shown in the drawing. The laser beam in the 780 nm band emitted from the first laser diode 14 is divided into three laser beams by the grating G, and then passes through the optical system as reflected light from the optical disc D such as a CD. As shown to (a), it injects on the 1st photodiode 16 as three spots (S1a, S1b, S1c).
[0035]
The second photodiode 18 has a configuration divided into four (a2, b2, c2, d2) as shown in the drawing. The laser light in the 650 nm band emitted from the second laser diode 15 passes through the optical system and is reflected on the second photodiode 18 as reflected light from the optical disk D such as a DVD as shown in FIG. Incident as two spots S2.
[0036]
The distance between the first and second photodiodes 16, 18, for example, the distance d between the center line of the first photodiode 16 and the center line of the second photodiode 18 is, for example, in a range of about 200 μm or less (for example, about 100 μm). Set to Here, for example, the distance between the laser beam emitting part E1 of the first laser diode 14 and the laser beam emitting part E2 of the second laser diode 15 is set to be substantially equal.
[0037]
As described above, by setting the interval between the laser beam emitting portions of the first and second laser diodes and the interval between the first and second photodiodes, the first laser diode and the first laser diode can be formed using a common optical member. The light emitted from the two laser diodes can be irradiated onto an optical disk such as a CD or DVD, and the reflected light from the optical disk can be incident on the first photodiode and the second photodiode, respectively.
[0038]
In the photodiode PD (the first photodiode 16 and the second photodiode 18), it is possible to detect spot diameters, position changes, and the like of the spots S1a, S1b, S1c, and S2 of the incident laser light as described above. it can.
[0039]
As an optical pickup of the optical disc apparatus, a tracking error signal, a focus error signal, and an information signal recorded on the optical disc are read from a signal obtained by the photodiode PD. These signals are extracted as follows.
[0040]
That is, in the first photodiode 16, the signals a1, b1, c1, and d1 obtained at the central spot S1a incident on the first divided photodiode 16 are divided by the following equation (1). An information signal RF1 recorded on an optical disc such as a CD can be obtained.
RF1 = a1 + b1 + c1 + d1 (1)
[0041]
Further, the focus error signal FE1 can be obtained by the following equation (2) using the signals a1, b1, c1, and d1.
FE1 = (a1 + c1) − (b1 + d1) (2)
[0042]
Also, the tracking error signal TE1 can be obtained by the following equation (3) using the signals e1 and f1 obtained at the spots S1b and S1c on both sides incident on the first photodiode 16 divided into six. .
TE1 = e1-f1 (3)
[0043]
On the other hand, in the second photodiode 18, the signals a2, b2, c2, and d2 obtained at the central spot S2 incident on the second divided photodiode 18 are divided by the following equation (4). An information signal RF2 recorded on an optical disk such as a DVD can be obtained.
RF2 = a2 + b2 + c2 + d2 (4)
[0044]
Further, the focus error signal FE2 can be obtained by the following equation (5) using the signals a2, b2, c2, and d2.
FE2 = (a2 + c2) − (b2 + d2) (5)
[0045]
Further, as shown in FIG. 20 (b), the tracking error signal TE2 can be obtained by the DPD (Differential Phase Detection) method using the signals a2, b2, c2 and d2. For example, after the phases of the signals a2 and b2 and the signals c2 and d2 are compared by the phase comparator PC, the addition operation processing is performed by the adder AD to obtain the tracking error signal TE2. According to the DPD method, stable tracking with no offset at one spot is possible.
[0046]
In an optical disk reproducing / recording device incorporating an optical pickup, as described above, a focus error signal is detected due to vertical shake of an optical disk such as a CD or DVD, and focusing servo is applied according to the obtained focus error signal. . Also, a tracking error signal is detected, and tracking servo is applied according to the obtained tracking error signal.
[0047]
The optical pickup 1a described above is a compatible optical pickup that mounts a laser diode LD1 for CD (emission wavelength 780 nm) and a laser diode LD2 for DVD (emission wavelength 650 nm), and enables reproduction of CDs and DVDs.
[0048]
This optical pickup has a first laser diode LD1 and a second laser diode LD2 arranged in parallel adjacent to each other, and a first photodiode 16 and a second photodiode 18 arranged in parallel adjacent to each other. Therefore, it is not necessary to align the optical axes from laser diodes having different oscillation wavelengths, and the light emitted from the first laser diode LD1 and the second laser diode LD2 is applied to an optical disk such as a CD or DVD using a common optical member. The reflected light from the optical disk is incident on the first photodiode and the second photodiode, respectively. Therefore, the number of parts is smaller than that shown in FIGS. 15 and 16, and the parts can be easily assembled, and downsizing and cost reduction are possible.
[0049]
FIG. 21 illustrates signal reading by a laser coupler using the laser diode 14a of FIG. 19 (c), different from that shown in FIG. 20 (however, for APC provided behind the laser diode). The PIN diode is omitted from the drawing: the same applies hereinafter).
[0050]
In FIG. 21, for example, a front first photodiode 16 and a rear first photodiode 17 that receive light in the 780 nm band, and a front second photodiode 18 and a rear second photodiode 19 that receive light in the 650 nm band. Are formed as shown in the drawing.
[0051]
Here, the front first photodiode 16 has a configuration divided into four (a1, b1, c1, d1). The rear first photodiode 17 is also divided into four parts (i1, j1, k1, and l1).
[0052]
The laser light in the 780 nm band emitted from the first laser diode LD1 is reflected by the spectral surface of the prism 20, and further passes through the optical system and passes through the prism 20 as the reflected light from the optical disk (CD). The light is incident as one spot S1a, S1b on one photodiode 16, 17 respectively.
[0053]
The front second photodiode 18 has a configuration divided into eight parts (a2, b2, c2, d2, e2, f2, g2, h2). The rear second photodiode 19 has a configuration divided into four (i2, j2, k2, and l2).
[0054]
The 650 nm band laser light emitted from the second laser diode LD2 also passes through the optical system, and is reflected as a reflected light from the optical disk (DVD), one spot on each of the front and rear second photodiodes 18 and 19. Incident as S2a and S2b.
[0055]
The distance between the front first photodiode 16 and the front second photodiode 18 and the distance between the rear first photodiode 17 and the rear second photodiode 19 are, for example, in the range of about 200 μm or less (for example, about 100 μm). Set to Here, for example, the distance is set to be substantially equal to the distance between the laser beam emitting portion E1 of the first laser diode LD1 and the laser beam emitting portion E2 of the second laser diode LD2.
[0056]
As described above, by setting the interval between the laser beam emitting portions of the first and second laser diodes and the interval between the first and second photodiodes, the first laser diode and Light emitted from the second laser diode can be irradiated onto an optical disk such as a CD or DVD, and reflected light from the optical disk can be incident on the first photodiode and the second photodiode, respectively.
[0057]
In the above photodiodes (in the front and rear first photodiodes 16 and 17 and the front and rear second photodiodes 18 and 19, the spot diameters and position changes of the laser light spots S1a, S1b, S2a, S2b as described above. Etc. can be detected.
[0058]
When the optical pickup of the optical disk apparatus is configured using this laser coupler, the tracking error signal, the focus error signal, and the information signal recorded on the optical disk are read from the signal obtained by the photodiode PD. . These signals are extracted as follows.
[0059]
That is, in the front and rear first photodiodes 16 and 17, the signals a1, b1, c1, d1, and i1 obtained at the spots S1a and S1b incident on the front and rear first photodiodes 16 and 17 divided into four parts, respectively. , J1, k1, and l1, the information signal RF1 recorded on an optical disk such as a CD can be obtained by the following equation (6).
RF1 = a1 + b1 + c1 + d1 + i1 + j1 + k1 + l1 (6)
[0060]
Further, the focus error signal FE1 can be obtained by the following equation (7) using the signals a1, b1, c1, d1, i1, j1, k1, and l1.
FE1 [(a1 + d1) − (b1 + c1)]
-[(I1 + l1)-(j1 + k1)] (7)
[0061]
Further, the tracking error signal TE1 can be obtained by the following equation (8) using the signals a1, b1, c1, d1, i1, j1, k1, and l1.
TE1 = [(a1 + b1) − (c1 + d1)]
+ [(I1 + j1)-(k1 + l1)] (8)
[0062]
On the other hand, in the front and rear second photodiodes 18 and 19, the signals a2, b2, c2 obtained at the spots S2a and S2b incident on the front and rear second photodiodes 18 and 19 divided into 8 and 4 respectively. By using d2, e2, f2, g2, h2, i2, j2, k2, and l2, the information signal RF2 recorded on an optical disk such as a DVD can be obtained by the following equation (9).
RF2 = a2 + b2 + c2 + d2 + e2 + f2 + g2 + h2
+ I2 + j2 + k2 + l2 (9)
[0063]
Further, the focus error signal FE2 can be obtained by the following equation (10) using the signals a2, b2, c2, d2, e2, f2, g2, h2, i2, j2, k2, and l2.
FE2 = [(a2 + d2 + e2 + h2) − (b2 + c2 + f2 + g2)]
-[(I2 + l2)-(j2 + k2)] (10)
[0064]
Further, using the signals a2, b2, c2, d2, e2, f2, g2, and h2 obtained by the front second photodiode 18, as shown in FIG. 10B described later, DPD (phase difference detection; The tracking error signal TE2 can be obtained by the Differential Phase Detection method. For example, the first adder (broadband) AD1 performs addition arithmetic processing of the signals a2 and b2, the signals c2 and d2, the signals e2 and f2, and the signals g2 and h2, and the phase comparator PC performs the signals a2 and b2. And the sum signal of the signals c2 and d2 and the sum signal of the signals g2 and h2 and the sum signal of the signals e2 and f2 are compared, and the second adder AD2 performs addition calculation processing. A tracking error signal TE2 is obtained. According to the DPD method, stable tracking with no offset at one spot is possible.
[0065]
In the optical disk reproducing / recording apparatus using the laser coupler, as described above, the focus error signal is detected by the vertical shake of the optical disk such as CD or DVD, and the focusing servo is applied according to the obtained focus error signal. . Also, a tracking error signal is detected, and tracking servo is applied according to the obtained tracking error signal.
[0066]
This laser coupler is equipped with a laser diode LD1 for CD (oscillation wavelength 780 nm) and a laser diode LD2 for DVD (oscillation wavelength 650 nm), and can constitute a compatible optical pickup capable of reproducing CDs and DVDs. It is.
[0067]
The laser coupler includes a first laser diode LD1 and a second laser diode LD2 that are arranged adjacent to each other in parallel, front and rear first photodiodes 16 and 17 that are arranged adjacent to each other in parallel, and front and rear parts. The second photodiodes 18 and 19 are provided, and there is no need to align the optical axes from laser diodes having different oscillation wavelengths, and the first laser diode LD1 and the second laser diode LD2 are made of a common optical member. The emitted light is irradiated onto an optical disk such as a CD or DVD, and the reflected light from the optical disk is incident on the front and rear first photodiodes 16 and 17 and the front and rear second photodiodes 18 and 19, respectively. Therefore, the number of parts is smaller than that shown in FIGS. 15 and 16, and the parts can be easily assembled, and downsizing and cost reduction are possible.
[0068]
[Problems to be solved by the invention]
However, the laser coupler shown in FIG. 21 has been found to have the following problems to be improved.
[0069]
In this laser coupler, for example, a 780 nm band laser diode LD1 for CD and a 650 nm band laser diode LD2 for DVD as two-wavelength lasers are formed in one chip. In addition, the emission directions of the laser beams L1 and L2 from the lasers may vary due to variations in mounting accuracy on the block 13 or the substrate.
[0070]
For example, the emission direction of the laser light L1 of the laser diode LD1 coincides with the normal optical axis (that is, the optical axis along the front-rear arrangement direction of the photodiodes 16 and 17) OA1, but the laser light L2 of the other laser diode LD2 When the emission direction deviates from the normal optical axis (that is, the optical axis along the front-rear arrangement direction of the photodiodes 18 and 19) OA2, the spot S1a of the reflected light from the disc through the objective lens, S1b, S2a, and S2b do not change their position on the photodiode, but the point where the beam intensity in the spot is maximum (indicated by a black dot in the figure: the same applies hereinafter) is the opposite side of the optical axis at the spots S2a and S2b. Will shake.
[0071]
As a result, the balance of the amount of light received by the photodiodes 18 and 19 on the DVD side is lost, and this impedes the signal reading and servo control of a DVD that requires a highly accurate standard. In order to prevent this, it is necessary to adjust the balance of the spot.
[0072]
Further, in the case of a design in which the DVD side is aligned with the optical axis, the spot balance is slightly lost because the CD side emits light from a position slightly away from the optical axis. This is adjusted by shifting the objective lens. At this time, it is desirable to reduce the lens shift amount as much as possible due to restrictions on the movable range of the lens.
[0073]
Accordingly, an object of the present invention is to easily and accurately adjust the balance of the emitted light spots having different wavelengths and the like, as in the above-described CD and DVD, and to reduce the shift amount of the objective lens for the adjustment. It is an object of the present invention to provide an optical device capable of performing the above, and to provide an optical disk device using the optical device and a method for adjusting the position of the light beam.
[0074]
[Means for Solving the Problems]
That is, the present invention relates to a plurality of light emitting elements (for example, first and second laser beams that emit different light (for example, first and second laser beams for CD and DVD having different wavelengths), respectively). The second laser diode (hereinafter the same) is juxtaposed on a common block (for example, a semiconductor block in which a PIN diode is formed: the same applies below) in a direction crossing the light emitting direction, and this block is further connected to the base ( For example, a plurality of light receiving elements (for example, first for CD and DVD), which are fixed on a semiconductor substrate for constituting a laser coupler (hereinafter, the same applies), and emitted light from the plurality of light emitting elements passes through an objective lens. And an optical device guided to the second photodiode (hereinafter the same),
Among the plurality of light emitting elements, a light emitting direction of a predetermined light emitting element (for example, a laser diode for DVD: hereinafter the same) is a normal optical axis (that is, an optical axis along the front-rear arrangement direction of the light receiving elements: , And the like (hereinafter, this may be expressed as “overlap” or “overlap”) so that the blocks are fixed with the positions of the plurality of light emitting elements on the block being fixed. By being tilted, the plurality of light emitting elements are tilted in common and adjusted in position,
In this position adjustment state, the light emitting direction of a light emitting element other than the predetermined light emitting element (for example, a laser diode for CD: hereinafter the same) is superimposed on the normal optical axis by the position adjustment of the objective lens.
An optical apparatus configured as described above, an optical disk apparatus using the optical apparatus, and a light beam position adjusting method for adjusting the position as described above (hereinafter sometimes referred to as the present invention group). It is related to.
[0075]
According to the optical device, the optical disk device, and the light beam position adjusting method according to the present invention group, the plurality of light emission units can be obtained by tilting the block while fixing the positions of the plurality of light emitting elements on the block. Since the light emitting direction of the predetermined light emitting element is overlapped with the regular optical axis by tilting the elements in common, for example, the direction of the outgoing light from the predetermined light emitting element that requires high precision with strict standards is set. Since it can be set so as to satisfy the above requirements, and this can be performed by tilting the block (the light emitting element itself is not directly rotated and adjusted), the position adjustment of the emitted light of the predetermined light emitting element is facilitated.
[0076]
And about the emitted light from the other light emitting elements, the optical axis is superimposed on the regular optical axis by adjusting the position of the objective lens.
[Expression 1]

Is wide, the spot balance can be appropriately adjusted by the deflection (lens shift) of the objective lens, and even if the lens shift is performed, the influence on the characteristics is small.
[0077]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention group, the block to which the plurality of light emitting elements are fixed is fixed on the base, and after the fixing, the base together with the block is around the normal optical axis or an axis parallel thereto. The position adjustment is performed as a tilt correction by rotation, or the block on which the plurality of light emitting elements are fixed is fixed on the base body, and before the fixing, the block is in the plane It is preferable that the position adjustment is performed as θ correction by being rotated on the base.
[0078]
The predetermined light-emitting element has a stricter standard than the other light-emitting elements, and the effect of the present invention is great when the beam divergence angle is smaller than that of the other light-emitting elements. In this case, it is preferable that the plurality of light emitting elements emit laser beams having different wavelengths, and the wavelength of the laser light from the light emitting element having a stricter standard is shorter than that of the other light emitting elements.
[0079]
The emitted light from the plurality of light emitting elements is preferably incident on an object to be irradiated, for example, a disk-shaped information recording medium, through the objective lens, and the reflected light is incident on the plurality of light receiving elements through the objective lens. .
[0080]
In this case, the block to which the plurality of light emitting elements are fixed, an optical member for guiding each emitted light of the plurality of light emitting elements to the irradiated body and guiding the reflected light to the plurality of light receiving elements, The light receiving element is provided on the common base to constitute an optical coupler, and this optical coupler is incorporated in the optical disc apparatus as a part of the optical pickup.
[0081]
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0082]
Embodiment 1
In the present embodiment, as shown in FIG. 1A, as shown in FIG. 21, for example, the front first photodiode 16 and the rear first photodiode 17 that receive light in the 780 nm band, and 650 nm. A front second photodiode 18 and a rear second photodiode 19 that receive the band light are formed below the prism 20 fixed on the substrate 11.
[0083]
Here, the front first photodiode 16 is divided into four (a1, b1, c1, d1), and the rear first photodiode 17 is also divided into four (i1, j1, k1, l1). .
[0084]
The first laser diode LD1 is mounted on the block 13 fixed on the substrate 11, and the laser light L1 of 780 nm band emitted from the laser diode is reflected by the spectral surface of the prism 20, and further passes through the optical system. As reflected light from the optical disc (CD), it enters through the prism 20 onto the front and rear first photodiodes 16 and 17 as one spot S1a and S1b.
[0085]
The front second photodiode 18 is divided into eight (a2, b2, c2, d2, e2, f2, g2, h2), and the rear second photodiode 19 is divided into four (i2, j2, k2, l2). It has a configuration.
[0086]
The 650 nm band laser light L2 emitted from the second laser diode LD2 is also reflected on the front and rear second photodiodes 18 and 19 one by one as reflected light from the optical disk (DVD) through the optical system. Incidents are incident as spots S2a and S2b.
[0087]
The distance between the front first photodiode 16 and the front second photodiode 18 and the distance between the rear first photodiode 17 and the rear second photodiode 19 are, for example, in the range of about 200 μm or less (for example, about 100 μm). Set to Here, for example, the distance is set to be substantially equal to the distance between the laser beam emitting portion E1 of the first laser diode LD1 and the laser beam emitting portion E2 of the second laser diode LD2.
[0088]
As described above, by setting the interval between the laser beam emitting portions of the first and second laser diodes and the interval between the first and second photodiodes, the first laser diode and Light emitted from the second laser diode can be irradiated onto an optical disk such as a CD or DVD, and reflected light from the optical disk can be incident on the first photodiode and the second photodiode, respectively.
[0089]
In the photodiodes (front and rear first photodiodes 16 and 17 and front and rear second photodiodes 18 and 19), the spot diameters and positions of the incident laser light spots S1a, S1b, S2a, and S2b as described above. A change or the like can be detected.
[0090]
When an optical pickup of an optical disc apparatus is configured using this laser coupler, an information signal, a tracking error signal, and a focus error signal recorded on the optical disc are read from a signal obtained by the photodiode PD. In the case of an optical disc such as a CD, these signals are extracted based on the above-described equations (6), (7), and (8) described with reference to FIG. 21, and signal reproduction and servo control are performed.
[0091]
On the other hand, in the front and rear second photodiodes 18 and 19, the signals a2, b2, c2 obtained at the spots S2a and S2b incident on the front and rear second photodiodes 18 and 19 divided into 8 and 4 respectively. Information signals recorded on the optical disc based on the above-described equations (9), (10) and DPD method described with reference to FIG. 21 using d2, e2, f2, g2, h2, i2, j2, k2, and l2. A focus error signal and a tracking error signal are read out, and signal reproduction and servo control are performed.
[0092]
In the optical disk reproducing / recording apparatus using this laser coupler, as described above, a focus error signal is detected due to vertical shake of an optical disk such as a CD or a DVD, and focusing servo is applied according to the obtained focus error signal. . Also, a tracking error signal is detected, and tracking servo is applied according to the obtained tracking error signal.
[0093]
This laser coupler is equipped with a laser diode LD1 for CD (oscillation wavelength 780 nm) and a laser diode LD2 for DVD (oscillation wavelength 650 nm), and can constitute a compatible optical pickup capable of reproducing CDs and DVDs. It is.
[0094]
The laser coupler includes a first laser diode LD1 and a second laser diode LD2 that are arranged adjacent to each other in parallel, front and rear first photodiodes 16 and 17 that are arranged adjacent to each other in parallel, and front and rear parts. The second photodiodes 18 and 19 are provided, and there is no need to align the optical axes from laser diodes having different oscillation wavelengths, and the first laser diode LD1 and the second laser diode LD2 are made of a common optical member. The emitted light is irradiated onto an optical disk such as a CD or DVD, and the reflected light from the optical disk is incident on the front and rear first photodiodes 16 and 17 and the front and rear second photodiodes 18 and 19, respectively. Therefore, the number of parts is smaller than that shown in FIGS. 15 and 16, and the parts can be easily assembled, and downsizing and cost reduction are possible.
[0095]
However, in this laser coupler, as described in FIG. 21, the 780 nm band laser diode LD1 for CD and the 650 nm band laser diode LD2 for DVD have manufacturing variations and mounting accuracy on the block 13 or the substrate 11. The emission directions of the laser beams L1 and L2 from the respective lasers may vary due to variations in.
[0096]
For example, as shown in FIG. 1A, the emission direction of the laser light L1 of the laser diode LD1 coincides with the normal optical axis (that is, the optical axis along the front-rear arrangement direction of the photodiodes 16 and 17) OA1, When the emission direction of the laser beam L2 of the other laser diode LD2 is shifted outward from the normal optical axis (that is, the optical axis along the front-rear arrangement direction of the photodiodes 18 and 19) OA2, it passes through the objective lens. The spots S1a, S1b, S2a, S2b of the reflected light from the disk of FIG. 3 do not change the position on the photodiode, but the points where the beam intensity in the spot becomes maximum (indicated by black dots in the figure) are spots S2a and S2b. Therefore, it swings to the opposite side with respect to the optical axis.
[0097]
As a result, the balance of the amount of light received by the photodiodes 18 and 19 on the DVD side is lost, and this impedes the signal reading and servo control of a DVD that requires a highly accurate standard. In order to prevent this, in the present embodiment, the objective lens is not shaken (shifted) to the side opposite to the shift direction with respect to the optical axis OA2 at the time of DVD signal reading as in the prior art. The spot position on the DVD side is adjusted by adjusting the tilt as shown in FIG. At this time, the balance on the CD side is lost. For this, the balance on the CD side is adjusted by shifting the objective lens when the CD is used.
[0098]
That is, as shown in FIG. 1B, the entire substrate 11 on which the block 13 that has fixed the laser diodes LD1 and LD2 is mounted is moved around the central axis parallel to the normal optical axes OA1 and OA2, for example, in the direction of the arrow. The laser beam L1 and L2 can be changed to the laser beam L1 ′ and L2 ′, and the spot on the PD can be moved. That is, the balance is adjusted by doing so.
[0099]
Thus, when the emission direction of the laser beam on the DVD side is superimposed on the normal optical axis, the point where the beam intensity of the reflected light spots S2a and S2b formed on the photodiodes 18 and 19 on the DVD side becomes maximum is the optical axis. It will be formed side by side and will meet the requirements for strict DVD standards.
[0100]
However, in this state, the spot on the PD is shifted on the CD side and the balance is lost. However, the spot on the photodiodes 16 and 17 is also moved on the CD side by moving the objective lens in the direction of the CD side. Adjustment can be made so that the point at which the beam intensities of S1a and S1b are maximum is on the optical axis OA1.
[0101]
Thus, on the DVD side where strict standards are required, a laser spot can be formed on the regular optical axis, and at the same time, the intensity balance can be easily and accurately stabilized. The strength can be easily adjusted with good balance. This adjustment is done on the CD side.
[Expression 2]

Is advantageous compared to the DVD side, but this is because the allowable intensity distribution is wide, so even if the objective lens is moved, there is no effect on changes in the output balance of the photodiode, and signal reproduction and servo control performance This is because it is maintained well.
[0102]
The substrate shown in FIG. 1B may be rotated around the optical axis OA2, or when the emission direction of the laser light L2 is shifted inward of the optical axis in FIG. 1A. Can be adjusted as well. In that case, the substrate rotation direction is opposite to the above.
[0103]
Embodiment 2
In this embodiment, as shown in FIG. 2 (A), the block 13 provided with the laser diodes LD1 and LD2 is mounted (fixed) on the substrate 11 in the same state as in FIG. 1 (A). 1A, when the emission direction of the laser beam L2 is deviated from the optical axis as shown in FIG. 1A, the block 13 is placed on the substrate 11 (that is, as shown in FIG. 2B). By rotating in the direction of the arrow (in-plane) and tilting it in a plan view, the point where the intensity of the laser beam spots S2a and S2b on the DVD side is the maximum is aligned with or overlapped with the optical axis OA2 (θ correction) )
[0104]
Next, as described in the first embodiment, the light emission direction of the laser light L1 'shifted from the optical axis OA1 on the CD side is adjusted by moving the objective lens.
[0105]
Thus, on the DVD side where strict standards are required, the laser spot can be formed on the regular optical axis, and at the same time, the intensity balance can be easily and accurately stabilized, and the CD side also has a beam intensity. Can be easily adjusted in a well-balanced manner. This adjustment is done on the CD side.
[Equation 3]

Is advantageous compared to the DVD side, and
[Expression 4]

Therefore, even if the shift amount of the objective lens is small, it is easy to balance the light intensity distribution. In this respect, the lens shift amount can be further reduced and the optical pickup can be easily designed.
[0106]
Reference example
In this reference example, as shown in FIG. 3A, the state is the same as in FIG. 2A, but in the state where the block 13 provided with the laser diodes LD1 and LD2 is not mounted on the substrate 11, When the emission direction of the laser beam L2 is deviated from the optical axis as shown in FIG. 1A, the block 13 is placed on the substrate 11 (that is, in the plane) as shown in FIG. Rotate somewhat in the direction of the arrow and tilt slightly (overcorrect) in plan view. The overcorrection angle α (angle formed between the emission direction of the laser beam L2 ′ and the optical axis OA2) is about 0 ° to 1 °, preferably 0 ° to 0.5 °.
[0107]
Next, the block 13 is mounted (fixed) on the substrate 11, and the substrate 11 is moved from the state of FIG. 4B corresponding to FIG. 3B to the optical axis OA1 or as shown in FIG. By rotating in the direction of the arrow around the central axis parallel to OA2, the emission direction of the laser beam L2 ′ on the DVD side is changed to L2 ″ and superimposed on the optical axis OA2. Thus, by adding the tilt correction, A point where the intensity of the laser beam spots S2a and S2b on the DVD side is maximum is positioned on the optical axis OA2.
[0108]
Next, as described in the first embodiment, the light emission direction of the laser light L1 ″ shifted from the optical axis OA1 on the CD side is adjusted by moving the objective lens.
[0109]
Thus, on the DVD side where strict standards are required, a laser spot can be formed on the regular optical axis, and at the same time, the intensity balance can be easily and accurately stabilized. The strength can be easily adjusted with good balance. This adjustment is done on the CD side.
[Equation 5]

Is advantageous compared to the DVD side, and
[Formula 6]

Therefore, even if the shift amount of the objective lens is small, it is easy to balance the light intensity distribution. In this respect, the lens shift amount can be further reduced and the optical pickup can be easily designed.
[0110]
In addition, in this case, after over-correcting first in the plane as shown in FIG. 3 (B), it is moved to adjust the spot balance on the CD side as a result of correcting the tilt as shown in FIG. 4 (C). The amount of shift of the objective lens that must be reduced can be further reduced.
[0111]
Next, a configuration common to the above-described embodiments will be described.
[0112]
FIG. 5 shows a monolithic laser diode 14a in which, for example, a first laser diode LD1 that emits laser light with a wavelength of 780 nm band and a second laser diode LD2 that emits laser light with a wavelength of 650 nm band are mounted on one chip. It is.
[0113]
For example, a semiconductor block 13 on which a PIN diode 12 as a light detection element for monitoring is formed is fixed on a protrusion 21a provided on a disk-shaped base 21, and the first and second lasers are formed thereon. A monolithic laser diode 14a having diodes LD1 and LD2 on one chip is disposed. Further, a terminal 22 is provided through the base 21, and is connected to the first and second laser diodes LD1, LD2 or PIN diode 12 by a lead 23 and supplied with driving power for each diode. Is done.
[0114]
FIG. 6A is a plan view of a main part from a direction perpendicular to the laser beam emission direction of the laser diode, and FIG. 6B is a cross section of the laser diode in a plane perpendicular to the laser beam emission direction. FIG. A monolithic laser diode 14a having a first laser diode LD1 and a second laser diode LD2 on one chip is disposed above the semiconductor block 13 where the PIN diode 12 is formed.
[0115]
The PIN diode 12 senses the laser light emitted to the rear side of the first and second laser diodes LD1 and LD2, measures its intensity, and controls the first and second laser diodes so that the intensity of the laser light becomes constant. APC control for controlling the drive current of the two laser diodes LD1 and LD2 is performed.
[0116]
The monolithic laser diode 14a will be described. As the first laser diode LD1, an n-type GaAs buffer layer 31, an n-type AlGaAs cladding layer 32, an active layer 33, a p-type AlGaAs cladding layer 34, and a p-type GaAs cap layer 35 are stacked on an n-type GaAs substrate 30. Yes. A region 41 that is insulated from the surface of the p-type GaAs cap layer 35 to a depth in the middle of the p-type AlGaAs cladding layer 34 forms a stripe having a current confinement structure.
[0117]
On the other hand, as the second laser diode LD2, on the n-type GaAs substrate 30, an n-type GaAs buffer layer 31, an n-type InGaP buffer layer 36, an n-type AlGaInP clad layer 37, an active layer 38, a p-type AlGaInP clad layer 39, p A type GaAs cap layer 40 is laminated. A region 41 that is insulated from the surface of the p-type GaAs cap layer 40 to a depth in the middle of the p-type AlGaInP cladding layer 39 forms a stripe that forms a current confinement structure.
[0118]
In the first laser diode LD1 and the second laser diode LD2, the p-type GaAs cap layers 35 and 40 are connected to the p-electrode 42, and the n-type GaAs substrate 30 is connected to the n-electrode 43. The monolithic laser diode 14a is connected and fixed to the electrode 13a formed on the semiconductor block 13 from the p-electrode 42 side by solder or the like.
[0119]
The distance d between the laser beam emitting part of the first laser diode LD1 and the laser beam emitting part of the second laser diode LD2 is set to a range of about 200 μm or less (for example, about 100 μm). From each laser beam emitting section, for example, a laser beam L1 having a wavelength of 780 nm band and a laser beam L2 having a wavelength of 650 nm band are emitted in substantially the same direction (substantially parallel).
[0120]
On the other hand, the interval between the first and second photodiodes 16-17 and 18-19 is also set to a range of about 200 μm or less (for example, about 100 μm) in the same manner as described above. Light emitted from the laser diode and the second laser diode is irradiated onto an optical disk such as a CD or a DVD, and reflected light from the optical disk can be coupled to the first photodiode and the second photodiode, respectively.
[0121]
Next, a method for forming the monolithic laser diode 14a in which the first laser diode LD1 and the second laser diode LD2 are mounted on a chip will be described.
[0122]
First, as shown in FIG. 7A, an n-type GaAs buffer layer 31, an n-type AlGaAs cladding layer 32, and the like are formed on an n-type GaAs substrate 30 by an epitaxial growth method such as metal organic vapor phase epitaxy (MOVPE). An active layer (multiple quantum well structure with an oscillation wavelength of 780 nm) 33, a p-type AlGaAs cladding layer 34, and a p-type GaAs cap layer 35 are stacked in this order.
[0123]
Next, as shown in FIG. 7B, the region to be left as the first laser diode LD1 is protected with a resist film (not shown), and sulfuric acid-based non-selective etching and hydrofluoric acid-based AlGaAs selective etching are performed. The above stacked body up to the n-type AlGaAs cladding layer 32 is removed in a region other than the first laser diode LD1 region by wet etching (EC1).
[0124]
Next, as shown in FIG. 8C, the n-type InGaP buffer layer 36 and the n-type AlGaInP cladding layer are formed on the n-type GaAs buffer layer 31 by an epitaxial growth method such as metal organic vapor phase epitaxy (MOVPE). 37, an active layer (multiple quantum well structure with an oscillation wavelength of 650 nm) 38, a p-type AlGaInP cladding layer 39, and a p-type GaAs cap layer 40 are laminated in this order.
[0125]
Next, as shown in FIG. 8D, the region to be left as the second laser diode LD2 is protected by a resist film (not shown), and sulfuric acid-based cap etching, phosphoric acid-hydrochloric acid-based quaternary selective etching are performed. The stacked body up to the n-type InGaP buffer layer 36 is removed in a region other than the second laser diode LD2 region by wet etching (EC2) such as hydrochloric acid-based separation etching, and the first laser diode LD1 and the second laser are removed. The diode LD2 is isolated.
[0126]
Next, as shown in FIG. 9E, a resist film (not shown) is used to protect a portion that becomes a current injection region, and an impurity D is introduced by ion implantation or the like, and p-type GaAs cap layers 35 and 40 are formed. A region 41 that is insulated from the surface of the substrate to a depth in the middle of the p-type AlGaAs cladding layers 34 and 39 is formed to form a stripe having a current confinement structure.
[0127]
Next, as shown in FIG. 9 (f), a p-type electrode 42 such as Ti / Pt / Au is formed so as to be connected to the p-type GaAs cap layers 35, 40, while on the n-type GaAs substrate 30. An n-type electrode 43 such as AuGe / Ni / Au is formed so as to be connected, and a monolithic laser diode 14a mounting a desired first laser diode LD1 and second laser diode LD2 on one chip through a pelletizing process; To do.
[0128]
FIG. 10 shows the arrangement (a) of the photodiode described above, and the reading of the tracking error signal, the focus error signal, and the information signal recorded on the optical disc from the signal obtained by the photodiode has been described with reference to FIG. The same is done. Then, as described above, a focus error signal is detected due to vertical deflection of an optical disk such as a CD or DVD, and focusing servo is applied according to the obtained focus error signal. Also, a tracking error signal is detected, and tracking servo is applied according to the obtained tracking error signal.
[0129]
FIG. 11 shows a configuration of an optical pickup using the laser coupler according to the present embodiment. The laser beams L1 and L2 emitted from the first and second laser diodes built in the laser coupler 1a are passed through a collimator C, a mirror M, a CD aperture limiting aperture R, and an objective lens OL, and an optical disk such as a CD or a DVD. D is incident. The reflected light from the optical disk D returns to the laser coupler along the same path as the incident light, and is received by the first and second photodiodes built in the laser coupler.
[0130]
In this laser coupler, the first and second photodiodes can be divided as shown in FIG. In this case, the region d1 of the front first photodiode 16 and the regions a2 and e2 of the front second photodiode 18 are shared, and the signal d1 is obtained by adding the signals a2 and e2. Further, the region 11 of the rear first photodiode 17 and the region i2 of the rear second photodiode 19 are shared.
[0131]
FIG. 13A is an explanatory diagram showing a schematic configuration of the laser coupler 1a according to the present embodiment. The laser coupler 1a is loaded in the recess of the first package member 2, and is sealed by a transparent second package member 3 such as glass.
[0132]
FIG. 13B is a perspective view of a main part of the laser coupler 1a. For example, a semiconductor block 13 in which a PIN diode 12 as a light detection element for monitoring is formed is disposed on an integrated circuit substrate 11 which is a substrate obtained by cutting a silicon single crystal. Further, on the semiconductor block 13, A monolithic laser diode 14a on which a first laser diode LD1 and a second laser diode LD2 are mounted on one chip as a light emitting element is disposed.
[0133]
The laser light L1 emitted from the first laser diode LD1 is partially reflected by the spectral surface 20a of the prism 20, bent in the traveling direction, emitted from the emission window formed in the second package in the emission direction, and reflected mirror And an object to be irradiated such as an optical disk (CD) through an objective lens (not shown) or the like.
[0134]
The reflected light from the irradiated object travels in the direction opposite to the incident direction to the irradiated object and enters the spectral surface 20a of the prism 20 of the laser coupler 1a. While focusing on the upper surface of the prism 20, the light enters the front first photodiode 16 and the rear first photodiode 17 formed on the integrated circuit substrate 11 serving as the lower surface of the prism 20.
[0135]
On the other hand, the laser beam L2 emitted from the second laser diode LD2 is partially reflected by the spectral surface 20a of the prism 20 and bent in the traveling direction, and emitted from the emission window formed in the second package, as described above. Then, the object to be irradiated such as an optical disk (DVD) is irradiated through a reflection mirror, an objective lens, etc. (not shown).
[0136]
The reflected light from the irradiated object travels in the direction opposite to the incident direction to the irradiated object and enters the spectral surface 20a of the prism 20 of the laser coupler 1a. While focusing on the upper surface of the prism 20, the light enters the front second photodiode 18 and the rear second photodiode 19 formed on the integrated circuit substrate 11 which is the lower surface of the prism 20.
[0137]
As described above, the laser coupler according to the present embodiment is equipped with the CD laser diode LD1 (oscillation wavelength 780 nm) and the DVD laser diode LD2 (oscillation wavelength 650 nm), and is compatible with CD and DVD playback. An optical pickup can be configured. Further, since the monolithic laser diode in which the first laser diode and the second laser diode are mounted on one chip is used, the assembly of the optical system is further facilitated.
[0138]
As mentioned above, although this invention was demonstrated by embodiment, this invention is not limited to these embodiment at all.
[0139]
For example, the light-emitting element used in the present invention is not limited to a laser diode, and a light-emitting diode (LED) can also be used.
[0140]
In addition, the oscillation wavelengths of the first and second laser diodes are not limited to the 780 nm band and the 650 nm band, and may be wavelengths employed in other optical disk systems. In other words, various combinations of wavelengths can be used, and other combinations of optical disc systems other than CD and DVD can be employed. Moreover, even if the wavelength is the same, light having different power or light having different polarization directions may be used. Moreover, the number of light having different physical properties such as wavelength is not limited to two, and may be more than that.
[0141]
Further, the PIN diode for performing APC control may be formed on an integrated circuit substrate on which the first and second photodiodes are formed. In this case, it is preferable to change the configuration of the prism so that a part of the emitted light on the front side of the first and second laser diodes is extracted and coupled to the PIN diode. The reproduction signal, tracking, and focus error signal may be read as described with reference to FIG.
[0142]
Further, as shown in FIG. 14, the laser diode 14 (LD1) and 15 (LD2) may be separately manufactured (that is, discretely), and the laser coupler 1b may be mounted.
[0143]
In addition, the pattern and layout of the photodiode may be variously changed, and a detector structure other than the diode may be used.
[0144]
[Effects of the invention]
In the present invention, as described above, by tilting the block while fixing the positions of the plurality of light emitting elements on the block, the plurality of light emitting elements are tilted in common, and the light emitting direction of a predetermined light emitting element is set. Since it is overlapped with the regular optical axis, for example, the emission direction of the emitted light from the predetermined light emitting element that requires high precision of strict standards can be set so as to satisfy the requirement, and the block is tilted. (Accordingly, the light emitting element itself is not directly rotated and adjusted), so that the position adjustment of the emitted light of the predetermined light emitting element is facilitated.
[0145]
And about the emitted light from the other light emitting elements, the optical axis is superimposed on the regular optical axis by adjusting the position of the objective lens.
[Expression 7]

Is wide, the spot balance can be appropriately adjusted by the deflection (lens shift) of the objective lens, and even if the lens shift is performed, the influence on the characteristics is small.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a light beam position adjusting method of a laser coupler according to a first embodiment of the present invention.
FIG. 2 is a schematic plan view showing a light beam position adjusting method of a laser coupler according to a second embodiment of the present invention.
FIG. 3 is a schematic plan view showing a first stage of a light beam position adjusting method of a laser coupler according to a reference example.
FIG. 4 is a schematic plan view showing a second stage of the light beam position adjusting method of the laser coupler.
FIG. 5 is a perspective view of a main part of a laser diode used in each embodiment of the present invention.
FIG. 6 is a main part plan view (a) showing a laser beam emission direction of the laser diode, and a cross-sectional view (b) in the direction perpendicular to the emission direction;
FIG. 7 is a cross-sectional view showing the method of manufacturing the laser diode in the order of steps.
FIG. 8 is a cross-sectional view showing the method of manufacturing the laser diode in the order of steps.
FIG. 9 is a cross-sectional view showing the method of manufacturing the laser diode in the order of steps.
FIG. 10 is a plan view (a) of the main part of the photodiode and a block diagram (b) for explaining the DPD method.
FIG. 11 is a schematic configuration diagram of an optical pickup using a laser coupler.
FIG. 12 is a plan view of an essential part of a modification of the photodiode;
FIG. 13 is a perspective view (a) of the laser coupler package and a perspective view (b) of the laser coupler.
FIG. 14 is a perspective view (a) of another package of the laser coupler and a perspective view (b) of the laser coupler.
FIG. 15 is a schematic configuration diagram of an optical pickup according to a conventional example.
FIG. 16 is a schematic configuration diagram of an optical pickup according to another conventional example.
FIG. 17 is a schematic configuration diagram of an optical pickup already proposed by the inventors.
FIG. 18 is a perspective view of essential parts of the laser diode.
FIG. 19 is a main part plan view (a) showing the emission direction of the laser light of the laser diode, a side view (b) of the main part on the same emission side, and a main part showing the emission direction of the laser light of another laser diode. It is a top view (c).
FIG. 20 is a plan view (a) of the principal part of the photodiode and a block diagram (b) for explaining the DPD method;
FIG. 21 is a schematic plan view showing a light beam emitting direction and its spot in the laser coupler.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a, 1b ... Laser coupler, 11 ... Integrated circuit board, 12 ... PIN diode,
13 ... Semiconductor block, 14, LD1 ... First laser diode,
14a ... monolithic laser diode,
15, LD2 ... second laser diode, 16 ... front first photodiode,
17 ... rear first photodiode, 18 ... front second photodiode,
19 ... rear second photodiode, 20 ... prism, 20a ... spectral plane,
E1, E2 ... Laser beam emitting part, BS ... Beam splitter, C ... Collimator,
R: Aperture limiting aperture for CD, ML: Multi lens,
PD ... photodiode, G ... grating, M ... mirror,
OL ... objective lens, D ... optical disc, L1, L1 ', L1 "... first laser beam,
L2, L2 ', L2 "... second laser beam, PC ... phase comparator, AD ... adder,
OA1, OA2 ... regular optical axis, S1a, S1b, S2a, S2b ... spot

Claims (12)

A plurality of light emitting elements that respectively emit a plurality of lights having different wavelengths are juxtaposed on a common block in a direction intersecting the light emitting direction, and the block is fixed on a base. In the optical device in which the emitted light is respectively guided to the corresponding light receiving elements through the objective lens, in order to adjust the beam position of the emitted light when fixing the position of the plurality of light emitting elements,
In the optical device manufacturing stage, out of the plurality of light emitting elements, the light having a shorter wavelength is emitted on the block so that the light emission direction of the light emitted from the predetermined light emitting element overlaps the normal optical axis. By tilting the block while fixing the positions of the plurality of light emitting elements, the plurality of light emitting elements are tilted in common and adjusted in position,
In this position adjustment state, in addition to the predetermined light emitting element, light having a longer wavelength is emitted. At the use stage of another light emitting element , before the tracking servo, the emitted light of the other light emitting element is converted to the objective lens. A light beam position adjusting method for adjusting the position of the objective lens so that the light emission direction of the emitted light overlaps with a normal optical axis when exiting from the objective lens after being incident on the objective lens. The position adjustment is performed by rotating the substrate together with the block around the normal optical axis or an axis parallel to the block after fixing the block on which the plurality of light emitting elements are fixed on the substrate. The light beam position adjusting method described in 1. The light beam position according to claim 1, wherein the position adjustment is performed by rotating the block on the base in the plane before fixing the block on which the plurality of light emitting elements are fixed on the base. Adjustment method. The light beam position adjusting method according to claim 1, wherein a beam divergence angle of the predetermined light emitting element is smaller than that of the other light emitting element. 2. The light beam position adjusting method according to claim 1, wherein the light emitted from the plurality of light emitting elements is incident on an object to be irradiated through the objective lens, and the reflected light is incident on the plurality of light receiving elements through the objective lens . The block to which the plurality of light emitting elements are fixed; an optical member for guiding the emitted light of the plurality of light emitting elements to the irradiated body and the reflected light to the plurality of light receiving elements; and the light receiving element; 6. The light beam position adjusting method according to claim 5, wherein the method is applied to an optical coupler provided on the common base. 6. The light beam position adjusting method according to claim 5, which is applied to an optical pickup of an optical disk device. A plurality of light emitting elements that respectively emit a plurality of lights having different wavelengths are juxtaposed on a common block in a direction intersecting the light emitting direction, and the block is fixed on a base. In the optical disk apparatus in which the emitted light is irradiated onto the disk-shaped information recording medium through the objective lens and the reflected light is guided to the corresponding light receiving elements through the objective lens, the output light is fixed when the plurality of light emitting elements are fixed. To adjust the beam position of the light,
In the optical disk device manufacturing stage, the light emitting direction of a predetermined light emitting element that emits light having a shorter wavelength among the plurality of light emitting elements is overlapped with the normal optical axis. By tilting the block while fixing the position of the plurality of light emitting elements at
Inclining the plurality of light emitting elements in common and adjusting the position,
In this position adjustment state, in addition to the predetermined light emitting element, light having a longer wavelength is emitted. At the use stage of another light emitting element , before the tracking servo, the emitted light of the other light emitting element is converted to the objective lens. A light beam position adjusting method for adjusting the position of the objective lens so that the light emission direction of the emitted light overlaps with a normal optical axis when exiting from the objective lens after being incident on the objective lens. The position adjustment is performed by rotating the substrate together with the block around the normal optical axis or an axis parallel to the block after fixing the block on which the plurality of light emitting elements are fixed on the substrate. 8. The light beam position adjusting method according to 8. The light beam position according to claim 8, wherein the position adjustment is performed by rotating the block on the base in the plane before fixing the block on which the plurality of light emitting elements are fixed on the base. Adjustment method. The light beam position adjusting method according to claim 8, wherein a beam divergence angle of the predetermined light emitting element is smaller than that of the other light emitting element. The block to which the plurality of light emitting elements are fixed; an optical member for guiding the emitted light of the plurality of light emitting elements to the disk-shaped information recording medium and the reflected light to the plurality of light receiving elements; The light beam position adjusting method according to claim 8, wherein the light beam position adjusting method is applied to an optical coupler provided on the base body in common with an element.

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