JP6739067B2

JP6739067B2 - Semiconductor laser device

Info

Publication number: JP6739067B2
Application number: JP2016208492A
Authority: JP
Inventors: 櫻井　努; 努櫻井; 永田　毅; 毅永田; 和行井上; 敏幸岡田; 勝啓木田; 正明坂井
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2016-10-25
Filing date: 2016-10-25
Publication date: 2020-08-12
Anticipated expiration: 2036-10-25
Also published as: JP2018073881A

Description

本発明は、複数個の半導体レーザを１点に精密に集光して高輝度及び高出力化できる半導体レーザ装置に関するものである。 The present invention relates to a semiconductor laser device capable of accurately focusing a plurality of semiconductor lasers at one point to achieve high brightness and high output.

従来の半導体レーザ装置としては、高出力化できるものがある（例えば、特許文献１参照。）。図９は、特許文献１に記載された、従来の多数の半導体レーザを光ファイバに１点に集光する構成図であり、図９はその断面図である
図９において、複数の半導体レーザ７０３からそれぞれ放出されるレーザ光７０２は、ボールレンズ７０４を介してファイバ７０１の端面にそれぞれ集光することで高出力化している。 2. Description of the Related Art As a conventional semiconductor laser device, there is one that can achieve high output (for example, see Patent Document 1). FIG. 9 is a configuration diagram in which a large number of conventional semiconductor lasers described in Patent Document 1 are focused on an optical fiber at one point, and FIG. 9 is a cross-sectional view thereof. In FIG. The laser light 702 emitted from each of them is focused on the end surface of the fiber 701 via the ball lens 704 to increase the output.

特開２００７−２４８５８１号公報JP, 2007-248581, A

しかしながら、特許文献１の図９の従来の構成では、光ファイバ７０１の端面に集光する調整機構がないため、光ファイバ７０１の端面の１点に集光する場合に精密に集光調整できず、実装面７１０に対する半導体レーザ７０３の実装精度及びボールレンズ７０４の実装精度を高くすることが困難であった。
本発明は、前記従来の課題を全て解決するもので、光ファイバの端面に対して１点に精密に集光して高輝度及び高出力化できる半導体レーザ装置を提供することを目的とする。 However, in the conventional configuration of FIG. 9 of Patent Document 1, since there is no adjusting mechanism for condensing on the end face of the optical fiber 701, it is not possible to precisely condense and adjust when converging on one point on the end face of the optical fiber 701. It was difficult to increase the mounting accuracy of the semiconductor laser 703 and the ball lens 704 on the mounting surface 710.
An object of the present invention is to solve all the above-mentioned conventional problems, and an object thereof is to provide a semiconductor laser device capable of precisely converging at one point on the end face of an optical fiber to achieve high brightness and high output.

上記目的を達成するために、本発明の半導体レーザ装置は、
複数の半導体レーザと、
前記複数の半導体レーザからの半導体レーザ光がそれぞれ入射する光学系と、
前記複数の半導体レーザをそれぞれ先端に保持し、かつ、外側部でかつ長手方向の中間部の前記長手方向周りに少なくとも部分的に前記長手方向と直交する方向に突出して配置された突起部をそれぞれ有する複数の棒状部材と、
それぞれの前記突起部を介して前記棒状部材を保持するホルダと、
前記外側部における前記突起部以外の部分をホルダ側から押圧して前記棒状部材の前記先端の位置を前記光学系の光軸に対して調整する調整機構と、を備える。 In order to achieve the above object, the semiconductor laser device of the present invention,
A plurality of semiconductor lasers,
An optical system in which semiconductor laser light from each of the plurality of semiconductor lasers is incident,
The plurality of semiconductor lasers are respectively held at their tips, and projecting portions which are arranged outside and project at least partially around the longitudinal direction of the longitudinal intermediate portion in a direction orthogonal to the longitudinal direction are arranged. A plurality of bar-shaped members having,
A holder for holding the rod-shaped member via each of the protrusions,
An adjusting mechanism that adjusts the position of the tip of the rod-shaped member with respect to the optical axis of the optical system by pressing a portion of the outer portion other than the protrusion from the holder side.

以上のように、本発明の半導体レーザ装置によれば、前記棒状部材の前記外側部における前記突起部以外の部分をホルダ側から押圧して、てこの原理を利用して、前記棒状部材の前記先端の位置を前記光学系の光軸に対して調整する調整機構で光軸調整を行うことができる。この結果、例えば光ファイバの端面の所望の位置に焦点が位置するように速やかに光軸調整することができ、長期的にもクリープもなく、振動及び衝撃による光軸ずれが起きにくく安定した半導体レーザ装置を実現でき、複数個の半導体レーザからのレーザ光を１点に精密に集光して高輝度及び高出力化できる半導体レーザ装置を実現することができる。 As described above, according to the semiconductor laser device of the present invention, a portion of the rod-shaped member other than the protrusion is pressed from the holder side in the outer side portion, and the lever principle is utilized to make the rod-shaped member The optical axis can be adjusted by an adjusting mechanism that adjusts the position of the tip with respect to the optical axis of the optical system. As a result, for example, the optical axis can be swiftly adjusted so that the focal point is located at a desired position on the end face of the optical fiber, there is no creep in the long term, and the optical axis shift due to vibration and shock does not easily occur. It is possible to realize a laser device, and it is possible to realize a semiconductor laser device capable of precisely focusing laser light from a plurality of semiconductor lasers at one point to achieve high brightness and high output.

本発明の実施の形態における半導体レーザ装置の平面図Plan view of a semiconductor laser device according to an embodiment of the present invention 本発明の実施の形態における半導体レーザ装置の側面図Side view of a semiconductor laser device according to an embodiment of the present invention 本発明の実施の形態における半導体レーザ装置の縦断面図A longitudinal sectional view of a semiconductor laser device according to an embodiment of the present invention. 本発明の実施の形態における図１ＣのＡ−Ａ断面図1C is a cross-sectional view taken along the line AA of FIG. 1C in the embodiment of the present invention. 本発明の実施の形態における図１ＣのＢ―Ｂ断面図FIG. 1C is a sectional view taken along line BB in FIG. 1C according to the embodiment of the present invention. 本発明の実施の形態における図１ＣのＣ―Ｃ断面図FIG. 1C is a cross-sectional view taken along the line CC of FIG. 1C according to the embodiment of the present invention. 本発明の実施の形態における螺子１８のプランジャピンの縦断面図The longitudinal cross-sectional view of the plunger pin of the screw 18 in the embodiment of the invention. 光軸調整することはできないという課題を説明するための図Diagram for explaining the problem that the optical axis cannot be adjusted 本発明の実施の形態における光軸調整機構の構成を示す説明図Explanatory drawing which shows the structure of the optical axis adjustment mechanism in embodiment of this invention. 光軸調整方法の説明図Illustration of optical axis adjustment method 従来のレーザ光分布図Conventional laser light distribution map 正反射時の説明図Illustration of specular reflection 従来と本発明の戻り光分布図Return light distribution map of conventional and present invention 戻り光レベルと寿命（破損率）との関係を示す図Diagram showing the relationship between return light level and life (damage rate) 特許文献１に記載された従来の半導体レーザ装置を示す図The figure which shows the conventional semiconductor laser device described in patent document 1.

以下、本発明の実施形態について、図面を参照しながら説明する。
（実施形態）
図１Ａ〜図１Ｆは、本発明の実施形態における半導体レーザ装置の図である。
尚、図１Ａは半導体レーザ装置の平面図、図１Ｂは半導体レーザ装置の側面図、図１Ｃは半導体レーザ装置の縦断面図、図１Ｄ図１ＣのＡ−Ａ断面図、図１Ｅは図１ＣのＢ―Ｂ断面図、図１Ｆは図１ＣのＣ―Ｃ断面図である。図１Ａ〜図１Ｆにおいて、同じ構成要素については同じ符号を用い、説明を省略する。
（装置構成）
半導体レーザ装置は、複数の半導体レーザ１と、光学系３０と、複数の棒状部材９と、第１ホルダ１２と、調整機構４１とを備える。
各棒状部材９は、一例として高熱伝導体で構成され、複数の半導体レーザ１をそれぞれ先端に固定保持し、かつ、外側部の中間部に突起部１３をそれぞれ有する。
光学系３０は、複数の半導体レーザ１からの半導体レーザ光２が入射する。
第１ホルダ１２は、棒状部材９のそれぞれの突起部１３を介して各棒状部材９を保持する。例えば、第１ホルダ１２は、円柱状であって、棒状部材９の個数に対応した円形貫通穴１２ａを有して、各円形貫通穴１２ａ内に棒状部材９を収納保持する。
調整機構４１は、外側部における突起部１３以外の部分を第１ホルダ側から棒状部材９の長手軸方向と直交する方向に中心に向けて押圧して、てこの原理を利用して、それぞれの棒状部材９の先端の位置を調整するものであり、例えば、第１ホルダ１２の第１〜第３螺子穴１２ｂ，１２ｃ，１２ｄにそれぞれねじ込まれて配置された螺子１６，１７，１８などで構成する。螺子１６，１７，１８は、押圧部材の一例として機能する。特に、螺子１６，１７は、第２押圧部材の一例として機能し、螺子１８は、第１押圧部材の一例として機能する。
以下、各構成要素について詳細に説明する。
複数の半導体レーザ１として、例えば少なくとも４個の半導体レーザ（以下、「ＬＤ」と省略する。）１の先端面側から出射されたレーザ光２は、コリメートレンズ３でそれぞれコリメートされたのち、集光レンズ４により１点の焦点６に集光して光ファイバ５の端面５ａより入射される。ここでは、４個のＬＤ１を例示するが、ＬＤ１は複数個、すなわち、少なくとも２つ以上備えればよい。
また、コリメートレンズ３でそれぞれコリメートされ、集光レンズ４により１点の焦点６に集光して、光ファイバ５の端面５ａに入る。このとき、コリメートレンズ３と集光レンズ４と光ファイバ５とを合わせて、一例として、光学系３０と呼ぶ。
各棒状部材９は、中空円筒状の高熱伝導体の棒状部材９である。各棒状部材９は、各ＬＤ１の背面を長手方向の先端に半田などの接合材で接合されて固定保持されている。前記ＬＤ１の背面に接合されたリード線１０が、棒状部材９の中空空間１１内を貫通して配置され、後端が棒状部材９から露出している。
各棒状部材９のそれぞれの外側部の全周において棒状部材９の長手方向の例えば中央部が径方向に膨らむことで、円環状の突起部１３が形成されている。突起部１３は、外側部の全周に限定されず、間欠的に配置されていてもよい。突起部１３の表面は平面でもよいし、湾曲面でもよい。突起部１３の高さの例としては、０．３ｍｍ程度である。
各棒状部材９は、例えば円柱状の第１ホルダ１２の各円形貫通穴１２ａ内に嵌合されて、支点１３である突起部１３を、円形貫通穴１２ａの内周面に対する接触部として保持される。よって、支点１３を境に、長手方向の両側に各棒状部材９と第１ホルダ１２の円形貫通穴１２ａの内周面との間に、円筒状の空間である隙間１４，１５を形成している。隙間１４，１５の高さの例としては、０．３ｍｍ程度である。
また、各棒状部材９は、突起部１３、すなわち、支点１３を接触部として、円形貫通穴１２ａ内で軸方向に進退移動を可能とし、かつ、当該支点１３を中心に隙間１４，１５内で図１Ｃ〜図１Ｅにおける上下及び図１Ｄ〜図１Ｅにおける左右に首振りを行って、当該隙間１４，１５により、各棒状部材９の先端に設けられたＬＤ１の光軸を調整可能とする。すなわち、各ＬＤ１の光軸調整の支点１３が、各棒状部材９の突起部１３になる。なお、一例として、棒状部材９は銅のような高熱伝導体で構成し、第１ホルダ１２はアルミニウム又は銅のような高熱伝導体で構成している。また、コリメートレンズ３は、接着材を使用せずに、レンズ押さえねじ３０で第１ホルダ１２に固定するのが好適である。
ここで、ＬＤ１の光軸調整の支点の突起部１３をＬＤ１の近傍でなく、棒状部材９の長手方向の中央部にしている理由を説明する。ＬＤ１から出射されるレーザ光２の角度及び位置は、製造上の誤差などにより大きくばらついている。よって、ＬＤ１を支点にすると、レーザ光２の位置が調整できず、レーザ光２の角度だけしか調整できない。さらに、レーザ光２の角度が調整できても、コリメートレンズ３の焦点位置にＬＤ１があるので、コリメート光が何らずれることがなく、光軸調整することはできないという課題がある。
この理由を、図２で説明する。ＬＤ１から出射されたレーザ光９０２は、焦点がＬＤ１になる位置に配置されたコリメートレンズ３でコリメート光９０３になり、その後、集光レンズ４により集光されたレーザ光９０４となる。このレーザ光９０４は、ある焦点９０５に結像する。この焦点９０５は、第１ホルダ１２からの４つのＬＤ１のレーザ光９０２の出口の光軸中心９０６に対して、ずれ量ΔＤを有している。ところが、焦点６に焦点９０５が来るように光軸調整したくても、コリメートレンズ３は、ＬＤ１の発光点９０１がレンズ３の焦点になるように配置されているため、発光点９０１を回転中心として光軸調整しようとコリメートレンズ３を傾けても、レーザ光９０７は、レンズ３，４を介して再度同じ焦点９０５にて結像するので、ずれ量ΔＤを０に光軸調整することはできない。
よって、ＬＤ１の光軸調整の支点１３としての突起部１３をＬＤ１近傍に配置した場合には、棒状部材９の外側部における突起部以外の部分を大きく動かす必要がある。当該部分の動かす距離を小さくして調整しやすくするためには、支点１３を中空円筒状の棒状部材９の長手方向の少なくとも中央部より後ろ（進行方向とは逆側）に、より好ましくは、中央部に設ける必要がある。
なお、図１Ｄ〜図１Ｅにおける左右首振りは、ＬＤ１の棒状部材９との接続部の近傍、すなわち、支点１３よりも先端側において、棒状部材９の中心に対して左右方向と上下方向、すなわち、Ｘ方向及びＹ方向沿いにそれぞれ進退する調整螺子１６，１７が、第１ホルダ１２の第１及び第２螺子穴１２ｂ，１２ｃに配置されている。具体的には、第１螺子穴１２ｂ内に、各棒状部材９に対してＸ方向沿いに１個の調整螺子１６が正逆回転により進退可能に配置され、第２螺子穴１２ｃ内に、Ｘ方向と９０度交差するＹ方向沿いに１個の調整螺子１７が正逆回転により進退可能に配置されている。
各棒状部材９に対して螺子１６，１７の２つの螺子だけでは，Ｘ方向及びＹ方向にそれぞれ調整しようとしても、螺子１６，１７に対応する図１Ｅに記載の反力１１０が無い場合には、棒状部材９がＸ方向及びＹ方向に単に自由に移動するだけで、棒状部材９を固定することができない。また、Ｘ方向及びＹ方向のみならず、Ｘ方向及びＹ方向とそれぞれ交差する焦点方向のＺ方向にもずれることがあり、光軸調整することができない。
よって、ＬＤ１の接続部に対し、支点１３より後端側にはＸ方向及びＹ方向と同じ側でかつＸ方向とＹ方向との間の４５度のＵ方向（図１Ｄ参照）沿いに、第３螺子穴１２ｄ内に調整螺子１８を第１ホルダ１２の第３螺子穴１２ｄ内に配置して、第３螺子穴１２ｄ内で正逆回転により進退可能とする。調整螺子１８を回転して第３螺子穴１２ｄ内から棒状部材９の後端側の部分９ｃに向けてＵ方向とは反対方向に接近させて接触させ、螺子１８を棒状部材９の後端側の部分９ｃに押し付けることにより、てこの原理で、支点１３を支点として調整螺子１６，１７の近傍にて、押し付ける方向とは反対方向の反力１１０が発生する。この結果、Ｕ方向の反力１１０に対して、Ｘ方向及びＹ方向沿いに螺子１６，１７で棒状部材９を押圧することにより、反力１１０と螺子１６，１７からの２つの押圧力とで棒状部材９を固定しながら、螺子１６，１７でＸ方向及びＹ方向の微調整することができる。
なお、反力１１０を常時発生させるために、各螺子１８は、プランジャピン１８が好適である。ここで、プランジャピン１８とは、図１Ｇに示すように、外周におねじ１８ｄを有する円筒状のプランジャ本体１８ａにバネ１８ｂを内蔵し、バネ１８ｂの先端でピン１８ｃを押圧してプランジャ本体１８ａの先端から突出させるように構成している。よって、おねじ１８ｄを第３螺子穴１２ｄにねじ込んでピン１８ｃの先端を棒状部材９に接触させてばね力でピン１８ｃにより棒状部材９に押圧力を付与し続けることができる。
なお、フォーカス方向Ｚの調整は、各棒状部材９を貫通穴１２ａに対して軸方向（Ｚ方向）に抜き差しした後、調整螺子１８を固定したのち、残りの２個の調整螺子１６，１７を棒状部材９に対して固定することで実現している。
次に、図３を用いて、棒状部材９の好適形状を述べる。ＬＤ１を接合している棒状部材９の先端９ａから支点１３の長手方向の中心までの距離をＬ１とし、棒状部材９の後端９ｂから支点１３の長手方向の中心までの距離をＬ２とすると、焦点６は数ミクロンオーダの光軸調整が必要なため、Ｌ１：Ｌ２＝１：０．５〜５が好適である。この比率未満では光軸調整が十分に行えない一方、この比率を越えると、螺子１６，１７，１８に過負荷がかかり、螺子１６，１７，１８又は第１〜第３螺子穴１２ｂ〜１２ｄなどが破損する恐れがあるためである。
また、調整螺子１６，１７，１８のそれぞれの内側の棒状部材９と接触する端面は、研磨をして、数ミクロン以下の平面度でかつ所定の表面粗さにしておくのが好適である。また、光軸調整代となる隙間１４，１５の隙間量は、径方向の寸法が０．５〜１ｍｍ、例えば０．３ｍｍと大きくしておくのが好適である。さらに、突起部（支点１３）と第１ホルダ１２との嵌め合い精度は、Ｈ７公差が最適であり、１〜５ｍｍ幅ほどが好適である。なお、これらの数値は、試作検討にて実験的に得られたものである。
第１ホルダ１２の集光レンズ４側の外周には、薄い円筒状の第２ホルダ１９とのはめあい部２６以外は、第２ホルダ１９が、Ｘ方向及びＹ方向の光軸調整用隙間２１を設けて配置されている。はめあい部２６は、第２ホルダ１９の嵌め込み先端部と、第１ホルダ１２の集光レンズ４側の外周の最奥部とが嵌合する部分である。第２ホルダ１９は銅のような高熱伝導体で構成している。Ｘ方向及びＹ方向の調整螺子２２，２３は、第１ホルダ１２の先端近傍に相当する第２ホルダ１９の先端側の部分に、光軸周りにＸ方向沿い及びＹ方向沿いにそれぞれ配置されている。
このような構成により、Ｘ方向及びＹ方向の調整螺子２２，２３を正逆回転させて進退させて光軸調整することにより、光ファイバ端面５ａに集光されたレーザ光２を光ファイバ５に入射できるように構成されている。光ファイバ５を内蔵する光コネクタ７は、第２ホルダ１９の先端の蓋部１９ａの貫通穴１９ｂに挿入され、複数本の固定螺子２４にて、光ファイバ５のフォーカス調整時に固定される。
なお、集光レンズ４は、カラー３１と螺子リング３２とで第１ホルダ１２に固定されていて、集光レンズ４の焦点距離は、光ファイバ５の入射ＮＡけられが発生しない値が好適である。
（光軸調整方法）
次に、上記のように構成された断面図の図１ＣとＣ−Ｃ断面図の図１Ｆとを用いて半導体レーザ装置組立時の光軸調整方法を順に説明する。
（ア）第１ホルダ１２の各貫通穴１２ａ内で各棒状部材９を軸方向に前後させて、１つ目のＬＤ１から出射されたレーザ光２がレンズ３を通過した後、コリメート光２５になる位置に１つ目のＬＤ１を固定した棒状部材９を配置して、フォーカス調整を終えておく。
なお、１つ目のＬＤ１の光軸周りの回転調整もあるので、ファスト方向及びスロー方向がわかりやすいように、棒状部材９のＬＤ取り付けの逆端面に、１つ目のＬＤ１の取り付け位置に対応する切り欠きなどのマークを予め形成するのが好適である。なお、ＬＤ１の各活性層の厚さ方向すなわちＬＤアレイの積層方向をファスト方向と称し、ＬＤアレイの活性層の列方向をスロー方向と称する。
（イ）次に、１つ目のＬＤ１から出射されたレーザ光２のファスト方向１０２が、図１Ｆに示すように、１つの円１１３に内接するように、ＬＤ１に接合されている棒状部材９を、レーザ照射させながら軸周りにそれぞれ回転させて、３個の螺子１６，１７，１８にて固定する。なお、図１Ｆでは、便宜上、４つのＬＤ１のレーザ光２の像を合わせて表示している。ここで、ファスト方向１０２が、図１Ｆに示すように、１つの円１１３に内接するとは、１つの円１１３すなわち出射可能なレーザ光の範囲を区切る１つの円１１３に内接する多角形の辺上に、ファスト方向１０２が位置するようにレーザ光１０１を配置することを意味している。また、３個の螺子１６，１７，１８にて固定するとき、螺子１６，１７，１８をそれぞれ回転して内側にねじ込むようにすると、螺子１６，１７，１８の回転により棒状部材９の先端９ａが前後方向に移動して焦点位置がずれ、コリメートで無くなることがある。これを防止するため、棒状部材９は、外部治具（図示せず）を用いて前後方向（光軸方向）に動かないように固定してから、螺子１６，１７，１８の正逆回転による棒状部材９の先端９ａの首振による光軸調整するのが好適である。
（ウ）次に、集光レンズ４を第１ホルダ１２に挿入し、集光レーザ光２０が光ファイバ５の入射点である焦点（基準焦点）６の焦点位置に位置するように、調整螺子１６，１７，１８を締緩させて、この焦点６を基準とする。
なお、焦点６は、第１ホルダ１２の集光レンズ４の光軸中心上が、好適である。
（エ）次に、２つ目のＬＤ１も（ア）〜（ウ）と同様に調整し、前記焦点６に一致するようにして調整螺子１６，１７，１８を調整後、固定する。
（オ）残る２つのＬＤ１も、（ア）〜（ウ）と同様に、同じ焦点６にて集光するように、調整螺子１６，１７，１８を調整後、固定する。
（カ）次に、集光レンズ４をカラー３１と螺子リング３２とで第１ホルダ１２に固定したのち、第２ホルダ１９を第１ホルダ１２にかぶせ、嵌め合い部２６を支点にＸ方向及びＹ方向に調整螺子２３を正逆回転させて締緩、すなわち、各棒状部材９がＺ方向の前後に動かないように、３本の螺子２３を締めたり緩めたりしながら、ファイバ５の端面５ａにレーザ光が最高パワーになるように、ファイバ５の出口にパワーメータを配置して、測定しながら、螺子２３の締緩調整する。
（キ）第２ホルダ１９に螺子２４で固定された光コネクタ７をＺ方向の前後に動かしながら、光ファイバ５に入射したレーザ光が最高パワーになるように、パワーメータ（図示せず）で測定しながら、各螺子２４を締緩調整する。
上記（ア）〜（キ）の調整において、図３に示すように、ＣＣＤ２００を焦点位置６に配置することで、モニタ画面２０１にて拡大して可視観察できるので、大変、光軸調整しやすくなる。また、定規（図示せず）をモニタ画面２０１で予め写し、スケール（図示せず）をモニタ画面２０１に明記しておくのも好適である。
（光軸調整方法の詳細）
次に、図４の（ａ）〜（ｆ）にてモニタ画面２０１を用いて、螺子１６，１７，１８による光軸調整方法の詳細を説明する。
図４の（ａ）は、ＬＤ１を１つだけ発光させた時のモニタ画面２０１に写る像であって、焦点が合っていないため、点線で示すように、ぼけた像３０１になっている。ぼけた像３０１は、１つ目のＬＤ１のファスト方向１０２の広がりが、スロー方向１０３より遥かに大きいので、ファスト方向１０２の方が長くなっている。ここで、モニタ２０１画面にある十字線３０２の交差点３０３は、集光すべき基準位置（焦点）６である。この交差点３０３が、第１ホルダ１２のレーザ出口２０４（図３参照）における光軸中心９０６（図３参照）上にある基準焦点位置２０２と一致する位置となるように、モニタ画面２０１のＣＣＤ２００が配置されている。
図１Ｄに示す４個の螺子１８のうち、右上の棒状部材９に加圧する右上の螺子１８はプランジャピンで構成されて、右斜め下方向の押圧力を棒状部材９に付与しているため、支点１３を介して、図１ＥのＢ−Ｂ断面にて右斜め上方向の反力１１０を生み出している。
第１螺子穴１２ｂ内でＸ方向沿いの右上側の調整螺子１６を左右に進退するように正逆回転させると、図４の（ａ）のモニタ画面２０１に写っている像３０３は、左右のＸ方向に進退移動する。
一方、図１Ｄの右上の螺子１８で加圧しながら４個のＹ方向の調整螺子１７の内の図１Ｅの右上の螺子１７を正逆回転させて第２螺子穴１２ｃ内で上下方向沿いに進退するように正逆回転させると、図４の（ａ）のモニタ画面２０１に写っている像３０３は、上下のＹ方向に進退移動する。
なお、前記したように、このＸ方向及びＹ方向の光軸調整の前に、焦点方向Ｚを予め光軸調整する必要がある。
図４の（ｂ）は、図４の（ａ）の状態から、棒状部材９を光軸方向の前後方向に動かして少し集光させた時の画像３０４を含むモニタ画面２０１である。ファスト方向１０２は大幅に短くなっているが、スロー方向１０３はあまり短くなっていない。このように、方向１０２は、焦点調整でサイズが早く変わることから、ファスト方向と名づけられている。
図４の（ｃ）は、更に、棒状部材９を光軸方向の前後に精度良く動かして焦点６に集光させた時の画像３０５を含むモニタ画面２０１である。図４の（ａ）及び図４の（ｂ）のようなデフォーカス時には、ファスト方向１０２が長手方向であったが、焦点６ではスロー方向１０３が長手方向になることに注意して、光軸調整を行う。
図４の（ｄ）は、焦点６に集光させ、更にモニタ画面２０１上にある十字線３０２の交差点３０３を焦点６に、調整螺子１６，１７を正逆回転させながら合わせ込んだ１つ目の画像３０６を含むモニタ画面２０１である。
図４の（ｅ）は、１つ目の画像３０６と、１つ目のＬＤ１と９０度回転した位置にある２つ目のＬＤ１を発光させた時の２つ目の画像３０７を含むモニタ画面２０１である、２つ目の画像３０７は、１つ目の画像３０６とは９０度回転した方向で観測される。
図４の（ｆ）は、２つ目のＬＤ１のレーザ光も焦点６に集光させ、図４の（ａ）〜（ｄ）と同様な方法で、更にモニタ画面２０１上にある十字線３０２の交差点３０３を焦点６に、調整螺子１６，１７を正逆回転させながら合わせ込んで光軸調整された２つ目の画像３０８と、１つ目の画像３０６とを含むモニタ画面２０１である。
最後に、ＬＤ１を接合した棒状部材９と第１ホルダ１２との間の光軸調整用隙間である隙間１４には、熱電導性を高め、更にクリープによる調整ずれをなくすために、硬化型熱電導性接着材の例として硬化型熱電導性ペーストを光軸調整直前（例えば光軸方向の前後方向の位置決め調整したのち）に塗布し、光軸調整完了後に硬化させるのが、好適である。なお、前記硬化型熱電導性ペーストとしては、窒化アルミニウムが好適であり、硬化剤としてはエポキシ硬化剤との配合が好適である。
（作用）
上記構成で上記調整を行うことで、光ファイバ５に速やかに光軸調整でき、長期的にもクリープもなく、振動及び衝撃による光軸ずれを起きにくい、安定した半導体レーザ装置を実現している。
（効果）
図１Ｆに示すように、リング状にＬＤ１のレーザ光１０１のファスト方向１０２を、出射可能なレーザ光の範囲である１つの円１１３に内接するように配置することにより、次の２つの効果がある。
まず、第１の効果を図５にて説明する。従来はＬＤ１を回転させずに、図５に示すように、例えば、１つの円４０３に対して横長の同じ方向にレーザ光４００を配列している。
一方、光ファイバには、入射可能な入射角及びＮＡ（開口数（numerical aperture））が物性的に決まっている。図５における１つの円４０３は、光ファイバに入射可能な範囲を示す。すると、円４０３の範囲の外側に位置するレーザ光４００の一部は光ファイバ５に入射することができない。これを、ＮＡけられ４０４（図５では、ハッチング部分）と呼ぶ。このＮＡけられ４０４により、光ファイバ５に入射できるレーザ光量が減り、結合効率の低下及び光コネクタ７の発熱を招き、大出力が発熱の問題で不可能となる。
これに対して、本実施の形態では、リング状にＬＤ１のレーザ光１０１のファスト方向１０２を、出射可能なレーザ光の範囲である１つの円１１３に内接するように配置することにより、ＮＡけられが無く、高効率に光ファイバ５に入射することができる。
次に、図６と図７とを用いて、第２の効果を説明する。図６において、光ファイバ５の出口からレンズ５０１を介してミラー５０２にて正反射させると、光ファイバ５に殆どそのままレーザ光が戻り、ファイバ端面５ａから、ファイバのＮＡ角５０３で、戻り光５０４が放出される。
図７の（ａ）は、リング状にＬＤ１を配置した時の戻り光５０４の半値の範囲６０１を斜線の円で示した図である。戻り光５０４は、図７の（ｂ）に示すように、中心部の強度が強くなる物性があるが、戻り光は４個のＬＤ１のレーザ光１０１の発光部に殆ど戻らない。これに対して、従来の図５の配置では、図７の（ｃ）に示すように、戻り光５０４の半値の範囲６０１と４個のＬＤ１のレーザ光１０１の発光部とが一部重なり、動作が不安定になり、戻り光により破損する可能性があった。このような不具合は、本実施形態では解消することができる。
図８に示すように、ＬＤには、戻り光が通常１０％程度より高くなるにつれて動作が不安定になり、５０％程度の戻り光により破損が始まることが知られている、しかし、その間の１０〜５０％の戻り光レベルの挙動はよく、まだ知られていないことが多い。発明者は数１００件に及ぶ量産導入後の寿命調査を行い、図２に示すように、戻り光レベルが高いほど寿命が短くなることを見出した。また、寿命が短くなるのは、戻り光による疲労現象であることをつきとめた。
本実施形態は、半導体レーザ１のそれぞれのファスト方向１０２が、出射可能なレーザ光の範囲の１つの円１１３に内接する多角形の辺上に位置するように配置することにより、戻り光を１０％程度まで抑えるものであり、寿命劣化も防止する効果もある。
また、本実施形態において、コリメートレンズ３としては、通常の平凸でコリメートもしてもよいが、シリンドリカルレンズでファスト方向のみコリメートしてもよい。その場合は、価格が高くなるが、集光性が向上するので、細いファイバに入射することができる。
また、Ｘ方向及びＹ方向の調整螺子１６，１７，１８の各端面は、銅からなる棒状部材９に接触するので、平面研磨されたものが好適である。またさらに、調整螺子１６，１７，１８が振動等で緩まないように、調整螺子１６，１７，１８をそれぞれ先の尖った螺子で追加固定するのが、より好適である。
上記実施形態によれば、棒状部材９の外側部における突起部１３以外の部分をホルダ側から押圧して、てこの原理を利用して、棒状部材９の先端９ａの位置を光学系３０の光軸に対して調整する調整機構４１で光軸調整を行うことができる。この結果、例えば光ファイバ５の端面５ａの所望の位置に焦点６が位置するように速やかに光軸調整することができ、長期的にもクリープもなく、振動及び衝撃による光軸ずれが起きにくく安定した半導体レーザ装置を実現でき、複数個の半導体レーザ１からのレーザ光２を１点に精密に集光して高輝度及び高出力化できる半導体レーザ装置を実現することができる。
なお、上記様々な実施形態又は変形例のうちの任意の実施形態又は変形例を適宜組み合わせることにより、それぞれの有する効果を奏するようにすることができる。また、実施形態同士の組み合わせ又は実施例同士の組み合わせ又は実施形態と実施例との組み合わせが可能であると共に、異なる実施形態又は実施例の中の特徴同士の組み合わせも可能である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment)
1A to 1F are diagrams of a semiconductor laser device according to an embodiment of the present invention.
1A is a plan view of the semiconductor laser device, FIG. 1B is a side view of the semiconductor laser device, FIG. 1C is a vertical sectional view of the semiconductor laser device, FIG. 1D is a sectional view taken along line AA of FIG. 1C, and FIG. 1E is of FIG. 1C. 1B is a sectional view taken along line BB and FIG. 1F is a sectional view taken along line CC of FIG. 1C. 1A to 1F, the same components are designated by the same reference numerals, and the description thereof will be omitted.
(Device configuration)
The semiconductor laser device includes a plurality of semiconductor lasers 1, an optical system 30, a plurality of rod-shaped members 9, a first holder 12, and an adjusting mechanism 41.
Each rod-shaped member 9 is made of, for example, a high thermal conductor, and holds a plurality of semiconductor lasers 1 at their tips, and has protrusions 13 at the outer middle portions thereof.
The semiconductor laser light 2 from a plurality of semiconductor lasers 1 enters the optical system 30.
The first holder 12 holds each rod-shaped member 9 via each protrusion 13 of the rod-shaped member 9. For example, the first holder 12 has a cylindrical shape and has circular through holes 12a corresponding to the number of the rod-shaped members 9, and the rod-shaped members 9 are housed and held in each circular through-hole 12a.
The adjusting mechanism 41 presses the portion of the outer portion other than the protruding portion 13 toward the center from the first holder side in the direction orthogonal to the longitudinal axis direction of the rod-shaped member 9, and utilizes the principle of lever to The position of the tip of the rod-shaped member 9 is adjusted. For example, the first to third screw holes 12b, 12c, 12d of the first holder 12 are screwed into the screw 16, 17, 18, and the like. To do. The screws 16, 17, 18 function as an example of a pressing member. In particular, the screws 16 and 17 function as an example of the second pressing member, and the screw 18 functions as an example of the first pressing member.
Hereinafter, each component will be described in detail.
As a plurality of semiconductor lasers 1, for example, laser light 2 emitted from the front end surface side of at least four semiconductor lasers (hereinafter, abbreviated as “LD”) 1 is collimated by a collimator lens 3 and then collected. The light is focused on one point 6 by the optical lens 4 and is incident from the end face 5 a of the optical fiber 5. Here, four LD1 are illustrated, but a plurality of LD1 may be provided, that is, at least two LD1 may be provided.
Further, they are collimated by the collimator lens 3, condensed by the condenser lens 4 at one focal point 6, and enter the end face 5 a of the optical fiber 5. At this time, the collimator lens 3, the condenser lens 4, and the optical fiber 5 are collectively referred to as an optical system 30 as an example.
Each rod-shaped member 9 is a hollow cylindrical high-thermal-conductor rod-shaped member 9. Each rod-shaped member 9 is fixedly held by bonding the back surface of each LD 1 to the tip in the longitudinal direction with a bonding material such as solder. The lead wire 10 joined to the back surface of the LD 1 is arranged so as to penetrate through the hollow space 11 of the rod-shaped member 9, and the rear end is exposed from the rod-shaped member 9.
A ring-shaped protrusion 13 is formed by radially swelling, for example, the central portion in the longitudinal direction of the rod-shaped member 9 over the entire circumference of the outer side of each rod-shaped member 9. The protrusions 13 are not limited to the entire circumference of the outer portion, and may be arranged intermittently. The surface of the protrusion 13 may be a flat surface or a curved surface. An example of the height of the protrusion 13 is about 0.3 mm.
For example, each rod-shaped member 9 is fitted into each circular through hole 12a of the cylindrical first holder 12, and the projection 13 that is the fulcrum 13 is held as a contact portion with the inner peripheral surface of the circular through hole 12a. It Therefore, with the fulcrum 13 as a boundary, between the rod-shaped members 9 and the inner peripheral surface of the circular through hole 12a of the first holder 12, gaps 14 and 15 that are cylindrical spaces are formed on both sides in the longitudinal direction. There is. An example of the height of the gaps 14 and 15 is about 0.3 mm.
In addition, each bar-shaped member 9 can be moved forward and backward in the axial direction within the circular through hole 12a by using the protrusion 13, that is, the fulcrum 13, as a contact portion, and within the gaps 14 and 15 centering on the fulcrum 13. By swinging vertically in FIGS. 1C to 1E and horizontally in FIGS. 1D to 1E, the optical axes of the LDs 1 provided at the tips of the rod-shaped members 9 can be adjusted by the gaps 14 and 15. That is, the fulcrum 13 for adjusting the optical axis of each LD 1 becomes the protrusion 13 of each rod-shaped member 9. As an example, the rod-shaped member 9 is made of a high thermal conductor such as copper, and the first holder 12 is made of a high thermal conductor such as aluminum or copper. Further, the collimator lens 3 is preferably fixed to the first holder 12 with the lens pressing screw 30 without using an adhesive material.
Here, the reason why the protrusion 13 at the fulcrum of the optical axis adjustment of the LD1 is not in the vicinity of the LD1 but in the central portion in the longitudinal direction of the rod-shaped member 9 will be described. The angle and position of the laser beam 2 emitted from the LD 1 greatly vary due to manufacturing errors and the like. Therefore, when the LD 1 is used as a fulcrum, the position of the laser light 2 cannot be adjusted, and only the angle of the laser light 2 can be adjusted. Further, even if the angle of the laser light 2 can be adjusted, the LD 1 is located at the focal position of the collimator lens 3, so that the collimated light does not leak and the optical axis cannot be adjusted.
The reason for this will be described with reference to FIG. The laser light 902 emitted from the LD1 becomes the collimated light 903 by the collimator lens 3 arranged at the position where the focal point becomes the LD1, and then becomes the laser light 904 condensed by the condenser lens 4. The laser light 904 forms an image at a focus 905. The focal point 905 has a deviation amount ΔD with respect to the optical axis center 906 at the exit of the laser light 902 of the four LDs 1 from the first holder 12. However, even if it is desired to adjust the optical axis so that the focal point 905 comes to the focal point 6, the collimating lens 3 is arranged so that the light emitting point 901 of the LD 1 becomes the focal point of the lens 3, and therefore the light emitting point 901 is the center of rotation. Even if the collimator lens 3 is tilted to adjust the optical axis, the laser beam 907 forms an image again at the same focus point 905 via the lenses 3 and 4, so that the optical axis cannot be adjusted so that the deviation amount ΔD is zero. ..
Therefore, when the protrusion 13 as the fulcrum 13 for adjusting the optical axis of the LD1 is arranged in the vicinity of the LD1, it is necessary to largely move the portion other than the protrusion on the outer side of the rod-shaped member 9. In order to reduce the moving distance of the portion to facilitate the adjustment, the fulcrum 13 is located at least behind the central portion of the hollow cylindrical rod-shaped member 9 in the longitudinal direction (on the side opposite to the traveling direction), and more preferably, It must be provided in the center.
1D to 1E, the left and right swings are in the left-right direction and the vertical direction with respect to the center of the rod-shaped member 9 in the vicinity of the connecting portion of the LD 1 with the rod-shaped member 9, that is, nearer to the tip than the fulcrum 13. , Adjustment screws 16 and 17 that move forward and backward along the X direction and the Y direction are arranged in the first and second screw holes 12b and 12c of the first holder 12, respectively. Specifically, one adjusting screw 16 is arranged in the first screw hole 12b along the X direction with respect to each rod-shaped member 9 so as to be able to advance and retreat by forward and reverse rotation, and in the second screw hole 12c, X One adjustment screw 17 is arranged so as to be able to advance and retreat by forward and reverse rotations along the Y direction that intersects the direction 90 degrees.
If there are no reaction forces 110 shown in FIG. 1E corresponding to the screws 16 and 17 even when trying to adjust in the X direction and the Y direction by using only two screws 16 and 17 for each rod-shaped member 9, The rod-shaped member 9 cannot be fixed because the rod-shaped member 9 simply moves freely in the X and Y directions. Further, not only the X direction and the Y direction, but also the Z direction of the focal direction intersecting the X direction and the Y direction, respectively, may shift, and the optical axis cannot be adjusted.
Therefore, with respect to the connecting portion of the LD1, on the rear end side of the fulcrum 13 on the same side as the X direction and the Y direction and along the U direction of 45 degrees between the X direction and the Y direction (see FIG. 1D), The adjusting screw 18 is arranged in the third screw hole 12d of the first holder 12 in the three screw hole 12d so that the adjusting screw 18 can be moved forward and backward by the forward and reverse rotations in the third screw hole 12d. The adjusting screw 18 is rotated to approach the portion 9c on the rear end side of the rod-shaped member 9 from the inside of the third screw hole 12d in the direction opposite to the U direction to bring the screw 18 into contact with the rear end portion of the rod-shaped member 9. By pressing against the portion 9c, a reaction force 110 in the direction opposite to the pressing direction is generated in the vicinity of the adjusting screws 16 and 17 with the fulcrum 13 as a fulcrum by the lever principle. As a result, against the reaction force 110 in the U direction, by pressing the rod-shaped member 9 with the screws 16 and 17 in the X direction and the Y direction, the reaction force 110 and the two pressing forces from the screws 16 and 17 are generated. While fixing the rod-shaped member 9, the screws 16 and 17 can be used for fine adjustment in the X and Y directions.
The plunger 18 is suitable for each screw 18 in order to constantly generate the reaction force 110. Here, as shown in FIG. 1G, the plunger pin 18 includes a spring 18b built in a cylindrical plunger body 18a having a screw 18d on the outer periphery, and the tip of the spring 18b presses the pin 18c to push the plunger body 18a. It is configured to project from the tip of the. Therefore, the male screw 18d can be screwed into the third screw hole 12d to bring the tip of the pin 18c into contact with the rod-shaped member 9, and the pin 18c can continue to apply a pressing force to the rod-shaped member 9 by the spring force.
In the adjustment of the focus direction Z, after each rod-shaped member 9 is axially (Z direction) inserted into and removed from the through hole 12a, the adjustment screw 18 is fixed, and then the remaining two adjustment screws 16 and 17 are attached. It is realized by fixing it to the rod-shaped member 9.
Next, a preferable shape of the rod-shaped member 9 will be described with reference to FIG. Let L1 be the distance from the tip 9a of the rod-shaped member 9 joining the LD1 to the center of the fulcrum 13 in the longitudinal direction, and let L2 be the distance from the rear end 9b of the rod-shaped member 9 to the center of the fulcrum 13 in the longitudinal direction. Since the focal point 6 requires optical axis adjustment on the order of several microns, L1:L2=1:0.5 to 5 is preferable. If it is less than this ratio, the optical axis cannot be adjusted sufficiently, while if it exceeds this ratio, the screws 16, 17, 18 are overloaded, and the screws 16, 17, 18 or the first to third screw holes 12b to 12d, etc. This is because there is a risk of damage.
Further, it is preferable that the end surfaces of the adjusting screws 16, 17, 18 that come into contact with the rod-shaped member 9 are polished to have a flatness of several microns or less and a predetermined surface roughness. Further, it is preferable that the gap amount between the gaps 14 and 15 that serves as an optical axis adjustment allowance is large in the radial direction of 0.5 to 1 mm, for example, 0.3 mm. Further, the fitting accuracy of the protrusion (fulcrum 13) and the first holder 12 is optimally H7 tolerance, and is preferably about 1 to 5 mm width. It should be noted that these numerical values were obtained experimentally in trial production.
On the outer periphery of the first holder 12 on the side of the condenser lens 4, the second holder 19 has an optical axis adjusting gap 21 in the X direction and the Y direction, except for the fitting portion 26 with the thin cylindrical second holder 19. It is provided and arranged. The fitting portion 26 is a portion where the fitting tip end portion of the second holder 19 and the innermost inner peripheral portion of the first holder 12 on the condenser lens 4 side are fitted. The second holder 19 is made of a high thermal conductor such as copper. The adjustment screws 22 and 23 for the X direction and the Y direction are arranged along the X direction and the Y direction around the optical axis at the tip end side portion of the second holder 19 corresponding to the tip end of the first holder 12, respectively. There is.
With such a configuration, the adjustment screws 22 and 23 in the X and Y directions are normally and reversely rotated to advance and retreat to adjust the optical axis, whereby the laser light 2 focused on the optical fiber end face 5a is guided to the optical fiber 5. It is configured to be incident. The optical connector 7 containing the optical fiber 5 is inserted into the through hole 19b of the lid portion 19a at the tip of the second holder 19, and is fixed by a plurality of fixing screws 24 when the focus of the optical fiber 5 is adjusted.
The condensing lens 4 is fixed to the first holder 12 by the collar 31 and the screw ring 32, and the focal length of the condensing lens 4 is preferably a value that does not cause the incident NA eclipse of the optical fiber 5. is there.
(Optical axis adjustment method)
Next, the optical axis adjusting method at the time of assembling the semiconductor laser device will be described in order with reference to FIG. 1C which is a sectional view and FIG. 1F which is a sectional view taken along line CC of the above configuration.
(A) Each rod-shaped member 9 is moved back and forth in the axial direction in each through hole 12a of the first holder 12, and the laser light 2 emitted from the first LD 1 passes through the lens 3 and then becomes collimated light 25. The rod-shaped member 9 to which the first LD 1 is fixed is arranged at the position, and the focus adjustment is completed.
Since there is also rotation adjustment of the first LD 1 around the optical axis, the reverse end face of the LD attachment of the rod-shaped member 9 corresponds to the attachment position of the first LD 1 so that the fast direction and the slow direction can be easily understood. It is preferable to previously form a mark such as a notch. The thickness direction of each active layer of the LD1, that is, the laminating direction of the LD array is referred to as a fast direction, and the column direction of the active layers of the LD array is referred to as a slow direction.
(A) Next, as shown in FIG. 1F, the rod-shaped member 9 joined to the LD 1 so that the fast direction 102 of the laser light 2 emitted from the first LD 1 is inscribed in one circle 113. Is rotated around the axis while being irradiated with laser, and is fixed by the three screws 16, 17, and 18. Note that in FIG. 1F, for convenience, the images of the laser beams 2 of the four LDs 1 are displayed together. Here, as shown in FIG. 1F, when the fast direction 102 is inscribed in one circle 113, a side of a polygon inscribed in one circle 113, that is, one circle 113 that divides the range of laser light that can be emitted. This means that the laser light 101 is arranged so that the fast direction 102 is located above. Further, when fixing with the three screws 16, 17, 18, if the screws 16, 17, 18 are respectively rotated and screwed inward, the tips 9a of the rod-shaped member 9 are rotated by the rotation of the screws 16, 17, 18. May move in the front-back direction and the focus position may shift, resulting in loss of collimation. In order to prevent this, the rod-shaped member 9 is fixed so as not to move in the front-rear direction (optical axis direction) by using an external jig (not shown), and then the forward rotation of the screws 16, 17, 18 is performed. It is preferable to adjust the optical axis by swinging the tip 9a of the rod-shaped member 9.
(C) Next, the condenser lens 4 is inserted into the first holder 12, and an adjusting screw is placed so that the condensed laser light 20 is located at the focal point of the focal point (reference focal point) 6 which is the incident point of the optical fiber 5. The focal point 6 is used as a reference by loosening the screws 16, 17, and 18.
The focus 6 is preferably on the center of the optical axis of the condenser lens 4 of the first holder 12.
(D) Next, the second LD 1 is also adjusted in the same manner as (a) to (c), and the adjusting screws 16, 17, 18 are adjusted so as to match the focal point 6, and then fixed.
(E) The adjustment screws 16, 17, and 18 are adjusted and fixed so that the remaining two LDs 1 are also focused at the same focal point 6 as in (A) to (C).
(F) Next, after fixing the condenser lens 4 to the first holder 12 with the collar 31 and the screw ring 32, the second holder 19 is covered on the first holder 12, and the fitting portion 26 is used as a fulcrum in the X direction and The adjustment screw 23 is normally and reversely rotated in the Y direction to tighten or loosen, that is, while the three screws 23 are tightened or loosened so that each rod-shaped member 9 does not move back and forth in the Z direction, the end face 5a of the fiber 5 is tightened. A power meter is arranged at the exit of the fiber 5 so that the laser light has the highest power, and the screw 23 is tightened or loosened while measuring.
(G) While moving the optical connector 7 fixed to the second holder 19 with the screw 24 back and forth in the Z direction, a power meter (not shown) is used so that the laser light incident on the optical fiber 5 has the maximum power. While measuring, each screw 24 is tightened and loosened.
In the above adjustments (a) to (g), by arranging the CCD 200 at the focal position 6 as shown in FIG. 3, it is possible to magnify and visually observe the monitor screen 201, which makes it very easy to adjust the optical axis. Become. It is also preferable to copy a ruler (not shown) on the monitor screen 201 in advance and to clearly indicate a scale (not shown) on the monitor screen 201.
(Details of optical axis adjustment method)
Next, the details of the optical axis adjusting method using the screws 16, 17, and 18 will be described with reference to the monitor screen 201 in FIGS.
FIG. 4A shows an image that appears on the monitor screen 201 when only one LD 1 emits light, and is out of focus, so that a blurred image 301 is obtained as shown by the dotted line. Since the spread of the first LD 1 in the fast direction 102 is much larger than that in the slow direction 103, the blurred image 301 is longer in the fast direction 102. Here, the intersection 303 of the crosshairs 302 on the screen of the monitor 201 is the reference position (focus point) 6 at which light should be collected. The CCD 200 on the monitor screen 201 is adjusted so that the intersection 303 is located at the reference focus position 202 on the optical axis center 906 (see FIG. 3) at the laser exit 204 (see FIG. 3) of the first holder 12. It is arranged.
Of the four screws 18 shown in FIG. 1D, the upper right screw 18 that presses the upper right bar-shaped member 9 is composed of a plunger pin and imparts a pressing force in a diagonally right downward direction to the bar-shaped member 9. Through the fulcrum 13, a reaction force 110 in the diagonally right upward direction is generated in the BB cross section of FIG. 1E.
When the adjustment screw 16 on the upper right side along the X direction is rotated forward and backward in the first screw hole 12b so as to move forward and backward, the image 303 displayed on the monitor screen 201 in FIG. Move back and forth in the X direction.
On the other hand, while pressing with the screw 18 on the upper right of FIG. 1D, the screw 17 on the upper right of FIG. 1E out of the four adjusting screws 17 in the Y direction is rotated in the forward and reverse directions to advance and retreat along the vertical direction in the second screw hole 12c. When it is rotated forward and backward as described above, the image 303 shown in the monitor screen 201 of FIG. 4A moves forward and backward in the Y direction.
As described above, it is necessary to adjust the optical axis of the focal direction Z in advance before adjusting the optical axes of the X direction and the Y direction.
FIG. 4B is a monitor screen 201 including an image 304 when the rod-shaped member 9 is moved in the front-rear direction along the optical axis from the state of FIG. The fast direction 102 is significantly shorter, but the slow direction 103 is not much shorter. As described above, the direction 102 is named as the fast direction because the size changes quickly with focus adjustment.
FIG. 4C is a monitor screen 201 including an image 305 when the rod-shaped member 9 is accurately moved back and forth in the optical axis direction and focused on the focus 6. At the time of defocusing as shown in FIGS. 4A and 4B, the fast direction 102 was the longitudinal direction, but at the focus 6, the slow direction 103 is the longitudinal direction. Make adjustments.
4D shows the first one in which the focus is focused on the focus 6 and the intersection 303 of the crosshair 302 on the monitor screen 201 is further focused on the focus 6 while the adjusting screws 16 and 17 are rotated in forward and reverse directions. Is a monitor screen 201 including an image 306 of.
FIG. 4E is a monitor screen including the first image 306 and the second image 307 when the second LD1 at a position rotated by 90 degrees with respect to the first LD1 is made to emit light. The second image 307, which is 201, is observed in a direction rotated by 90 degrees with respect to the first image 306.
In FIG. 4F, the laser light from the second LD 1 is also focused on the focal point 6, and the crosshair line 302 on the monitor screen 201 is further processed in the same manner as in FIGS. 4A to 4D. Is a monitor screen 201 including a second image 308 whose optical axis is adjusted by adjusting the intersection 303 to the focal point 6 while rotating the adjusting screws 16 and 17 in forward and reverse directions and the first image 306.
Finally, in the gap 14 which is a gap for adjusting the optical axis between the rod-shaped member 9 to which the LD 1 is joined and the first holder 12, in order to improve the thermoconductivity and further eliminate the adjustment deviation due to the creep, the hardening type heat is applied. As an example of the electrically conductive adhesive, it is preferable to apply a curable thermoconductive paste immediately before adjusting the optical axis (for example, after positioning adjustment in the front-rear direction of the optical axis) and to cure it after completing the optical axis adjustment. Aluminum nitride is suitable as the curable thermoconductive paste, and a compound with an epoxy curing agent is suitable as the curing agent.
(Action)
By performing the above adjustment with the above configuration, it is possible to quickly adjust the optical axis of the optical fiber 5, no creep occurs for a long period of time, and it is possible to realize a stable semiconductor laser device in which optical axis deviation due to vibration and shock does not easily occur. ..
(effect)
As shown in FIG. 1F, by arranging the laser light 101 of the LD 1 in the fast direction 102 so as to be inscribed in one circle 113 that is the range of the laser light that can be emitted, the following two effects are obtained. is there.
First, the first effect will be described with reference to FIG. Conventionally, without rotating the LD 1, as shown in FIG. 5, for example, the laser light 400 is arranged in the same horizontal direction with respect to one circle 403.
On the other hand, the incident angle and NA (numerical aperture) that can be incident on the optical fiber are physically determined. One circle 403 in FIG. 5 indicates a range that can enter the optical fiber. Then, a part of the laser light 400 located outside the range of the circle 403 cannot enter the optical fiber 5. This is referred to as the NA break 404 (hatched portion in FIG. 5). Due to the NA beam 404, the amount of laser light that can be incident on the optical fiber 5 is reduced, the coupling efficiency is lowered and the optical connector 7 is heated, and a large output is impossible due to the problem of heat generation.
On the other hand, in the present embodiment, by arranging the fast direction 102 of the laser light 101 of the LD 1 in a ring shape so as to be inscribed in one circle 113 that is the range of laser light that can be emitted, NA Therefore, the light can be incident on the optical fiber 5 with high efficiency.
Next, the second effect will be described with reference to FIGS. 6 and 7. In FIG. 6, when the light is specularly reflected by the mirror 502 from the exit of the optical fiber 5 through the lens 501, the laser light returns to the optical fiber 5 almost as it is, and the return light 504 is emitted from the fiber end face 5a at the NA angle 503 of the fiber. Is released.
FIG. 7A is a diagram in which a half-value range 601 of the return light 504 when the LD 1 is arranged in a ring shape is shown by a shaded circle. As shown in FIG. 7B, the return light 504 has the property that the intensity of the central portion becomes strong, but the return light 504 hardly returns to the light emitting portions of the laser light 101 of the four LDs 1. On the other hand, in the conventional arrangement of FIG. 5, the half-value range 601 of the return light 504 partially overlaps with the light emitting portions of the laser light 101 of the four LDs 1, as shown in FIG. 7C, The operation became unstable and could be damaged by the returning light. Such a problem can be solved in this embodiment.
As shown in FIG. 8, it is known that the operation of the LD becomes unstable as the return light becomes higher than about 10%, and the damage starts by about 50% of the return light, but in the meantime. The 10-50% return light level behavior is good and often unknown yet. The inventor conducted several hundred lifespan surveys after introduction of mass production, and as shown in FIG. 2, found that the higher the returning light level, the shorter the lifespan. We also found that the shortening of the life was due to the fatigue phenomenon caused by the returning light.
In this embodiment, the respective fast directions 102 of the semiconductor laser 1 are arranged so as to be positioned on the sides of a polygon inscribed in one circle 113 in the range of the laser light that can be emitted, so that the return light 10 is emitted. %, and also has the effect of preventing life deterioration.
Further, in the present embodiment, the collimator lens 3 may be an ordinary plano-convex collimator, but a cylindrical lens may be collimated only in the fast direction. In that case, the cost is increased, but the light converging property is improved, so that the light can be incident on a thin fiber.
Further, since each end surface of the adjusting screws 16, 17, 18 in the X direction and the Y direction comes into contact with the rod-shaped member 9 made of copper, it is preferable that the surface-polished one is used. Furthermore, it is more preferable to additionally fix the adjusting screws 16, 17, 18 with pointed screws so that the adjusting screws 16, 17, 18 are not loosened by vibration or the like.
According to the above-described embodiment, a portion of the rod-shaped member 9 other than the protrusion 13 is pressed from the holder side, and the lever principle is utilized to determine the position of the tip 9a of the rod-shaped member 9 from the optical system 30. The optical axis can be adjusted by the adjusting mechanism 41 for adjusting with respect to the axis. As a result, for example, the optical axis can be quickly adjusted so that the focal point 6 is located at a desired position on the end surface 5a of the optical fiber 5, no creep occurs in the long term, and optical axis deviation due to vibration and shock hardly occurs. It is possible to realize a stable semiconductor laser device, and to realize a semiconductor laser device capable of accurately converging the laser light 2 from the plurality of semiconductor lasers 1 at one point to achieve high brightness and high output.
By properly combining the arbitrary embodiments or modifications of the aforementioned various embodiments or modifications, the effects possessed by them can be produced. Further, a combination of the embodiments or a combination of the examples or a combination of the embodiment and the example is possible, and a combination of features in different embodiments or examples is also possible.

本発明の半導体レーザ装置は、複数個の半導体レーザを１点に精密に集光して高輝度及び高出力化することができる。更に、半導体レーザの配列を工夫すれば、戻り光で半導体レーザが破損するのを抑制することができる。また、半導体レーザとして、銅又は金に１５倍以上の吸収を有する青色波長でも製作できるので、従来のＬＤレーザでは反射光が多くてうまくできなかった銅又は金のはんだ付け又は実装、又は溶接などの用途にも適用できる。 The semiconductor laser device of the present invention can precisely condense a plurality of semiconductor lasers at one point to achieve high brightness and high output. Furthermore, by devising the arrangement of the semiconductor lasers, it is possible to prevent the semiconductor lasers from being damaged by the returning light. Further, as a semiconductor laser, it is possible to manufacture even a blue wavelength having absorption of 15 times or more in copper or gold. Therefore, soldering or mounting of copper or gold, welding, etc., which could not be done well with the conventional LD laser due to a large amount of reflected light. It can also be used for.

１ＬＤ（半導体レーザ）
２レーザ光
３コリメートレンズ
４集光レンズ
５光ファイバ
５ａ光ファイバの端面（光ファイバ入射端面）
６集光点（焦点）
７光コネクタ
９棒状部材（高熱伝導体）
９ａ棒状部材の先端
９ｂ棒状部材の後端
９ｃ棒状部材の後端側の部分
１０リード線
１１中空隙間
１２第１ホルダ
１２ａ円形貫通穴
１２ｂ第１螺子穴
１２ｃ第２螺子穴
１２ｄ第３螺子穴
１３支点（突起部）
１６，１７棒状部材の調整螺子
１８棒状部材の調整螺子（プランジャピン）
１８ａプランジャ本体
１８ｂバネ
１８ｃピン
１８ｄおねじ
１９第２ホルダ
２０集光レーザ光
２２，２３第２ホルダの調整螺子
３０光学系
３１カラー
３２螺子リング
４１調整機構
１０１レーザ光
１０２ファスト方向
１０３スロー方向
１１０反力
１１３円
２００ＣＣＤ
２０１モニタ画面
２０４第１ホルダのレーザ出口３０２十字線
４００レーザ光
４０３円
４０４ＮＡけられ
５０１ミラー
５０２ミラー
５０３ＮＡ角
５０４戻り光
６０１戻り光の半値の範囲
９０１ＬＤの発光点
９０２レーザ光
９０３コリメート光
９０４光レンズにより集光されたレーザ光
９０５焦点
９０６ＬＤのレーザ光の出口の光軸中心
９０７レーザ光 1 LD (semiconductor laser)
2 laser light 3 collimating lens 4 condensing lens 5 optical fiber 5a end face of optical fiber (optical fiber incident end face)
6 Focus point (focus)
7 Optical connector 9 Rod-shaped member (high thermal conductor)
9a Tip of rod-shaped member 9b Rear end of rod-shaped member 9c Part on rear end side of rod-shaped member 10 Lead wire 11 Hollow gap 12 First holder 12a Circular through hole 12b First screw hole 12c Second screw hole 12d Third screw hole 13 Support point (projection)
16, 17 Bar-shaped member adjusting screw 18 Bar-shaped member adjusting screw (plunger pin)
18a Plunger body 18b Spring 18c Pin 18d Male thread 19 Second holder 20 Condensed laser light 22,23 Adjustment screw for second holder 30 Optical system 31 Color 32 Screw ring 41 Adjusting mechanism 101 Laser light 102 Fast direction 103 Slow direction 110 Anti Power 113 yen 200 CCD
201 Monitor screen 204 Laser exit 302 of the first holder 302 Crosshair 400 Laser light 403 Circle 404 NA Shake 501 Mirror 502 Mirror 503 NA angle 504 Return light 601 Half range of return light 901 LD emission point 902 Laser light 903 Collimated light 904 Laser light condensed by the optical lens 905 Focus 906 LD laser light outlet optical axis center 907 Laser light

Claims

A plurality of semiconductor lasers,
An optical system into which semiconductor laser light from each of the plurality of semiconductor lasers is incident,
Protrusions that hold the plurality of semiconductor lasers respectively at the tips and that are arranged outside and project at least partially around the longitudinal direction of the intermediate portion in the longitudinal direction in a direction orthogonal to the longitudinal direction. A plurality of bar-shaped members having,
A holder for holding the rod-shaped member via each of the protrusions,
A semiconductor laser device comprising: an adjustment mechanism that presses a portion of the outer portion other than the protrusion from the holder side to adjust the position of the tip of the rod-shaped member with respect to the optical axis of the optical system.

The semiconductor laser device according to claim 1, wherein each of the plurality of semiconductor lasers is arranged so that a fast optical axis direction thereof is located on a side of a polygon inscribed in a circle of a range of laser light that can be emitted.

3. The semiconductor according to claim 1, wherein the adjusting mechanism adjusts the position of the tip of the rod-shaped member by pressing a portion of the outer portion on the tip side of the protrusion as a portion other than the protrusion. Laser device.

There are at least four semiconductor lasers,
The adjusting mechanism includes at least four pressing members that press a portion other than the protrusion to adjust the position of the tip of the rod-shaped member and that are arranged at intervals around the longitudinal direction. 3. The semiconductor laser device according to any one of 3.

With respect to each of the rod-shaped members, the pressing member includes a first pressing member that presses a portion of the outer portion of the rod-shaped member other than the protruding portion and on the rear end side of the protruding portion; And a plurality of second pressing members that are arranged at equal angles on both sides of the first pressing member and that press a portion of the rod-shaped member other than the protruding portion and a portion closer to the tip end side than the protruding portion. Composed,
The first pressing member is a plunger pin, and a portion of the outer portion other than the protruding portion is constantly pressed by the plunger pin from the holder side by an elastic force, and the portion of the outer side portion closer to the tip end than the protruding portion is the optical member. The semiconductor laser device according to claim 4, wherein a reaction force is generated around an axis in a direction opposite to a pressing direction of the first pressing member.

6. The semiconductor laser device according to claim 1, wherein an optical axis adjusting space is provided between the holder and a portion of the outer portion other than the protruding portion and on the tip side of the protruding portion. ..

7. The semiconductor laser device according to claim 6, further comprising a curable thermoconductive adhesive that is filled in the space and holds the position of the tip of the rod-shaped member adjusted with respect to the optical axis of the optical system. ..