JP4452470B2

JP4452470B2 - Method and apparatus for co-correction of multiple laser beams

Info

Publication number: JP4452470B2
Application number: JP2003317246A
Authority: JP
Inventors: 正宣山中; 靖和井澤; 靖史滝沢; 孝七根本; 人志中野; 千代衛山中
Original assignee: Central Research Institute of Electric Power Industry; Tokyo Electric Power Co Inc
Current assignee: Central Research Institute of Electric Power Industry; Tokyo Electric Power Co Inc
Priority date: 2003-09-09
Filing date: 2003-09-09
Publication date: 2010-04-21
Anticipated expiration: 2023-09-09
Also published as: JP2005084421A

Description

この発明は、複数レーザ光に位相共役鏡を組合わせて出力光相互のコヒーレンス結合性を向上させた複数レーザ光のコヒーレンス度相互補正方法及び装置に関する。 The present invention relates to a coherence degree mutual correction method and apparatus for a plurality of laser beams in which a phase conjugate mirror is combined with a plurality of laser beams to improve coherence coupling between output beams.

複数の半導体レーザ（ＬＤと略記）を１次元又は２次元状に配列したＬＤアレイは、穴明け、切断などのレーザ加工、レーザロケット、レーザ医学、非線形光学用光源、分光用光源、あるいはＭＪ級の大出力レーザの励起用の光源など種々の用途に利用される。このようなＬＤアレイの出力光を球面レンズを用いて集光し照射する際に、位相共役鏡を用いて出力光のコヒーレンス結合性を向上させる方法が、例えば非特許文献１により知られている。この方法は位相固定法とも呼ばれ、ＬＤアレイに外部反射鏡として位相共役鏡を組合わせ、ＬＤアレイの出力光の位相を複数のＬＤのそれぞれについて反射された位相共役光により揃えてコヒーレンス結合性を向上させ、出力光の集光度を得んとするものである。 An LD array in which a plurality of semiconductor lasers (abbreviated as LD) are arranged one-dimensionally or two-dimensionally, laser processing such as drilling and cutting, laser rocket, laser medicine, nonlinear optical light source, spectral light source, or MJ class It is used for various applications such as a light source for exciting a high-power laser. For example, Non-Patent Document 1 discloses a method of improving the coherence coupling of output light using a phase conjugate mirror when the output light of such an LD array is collected and irradiated using a spherical lens. . This method is also called the phase locking method. The LD array is combined with a phase conjugate mirror as an external reflector, and the phase of the output light from the LD array is aligned with the phase conjugate light reflected from each of the LDs to provide coherence coupling. In order to improve the concentration of output light.

位相共役鏡としては、例えばＲｈをドープしたチタン酸バリウムＢａＴｉＯ₃（Ｒｈ：ＢａＴｉＯ₃と略記）を用いたフォトリフラクティブ結晶が一般に使用され、ＬＤアレイからの出力光を結晶に対し所定の入射角で入射すると共に、そのＴＥ偏光方向がフォトリフラクティブ結晶のＣ軸（Ｚ軸）と平行となるように入射される。結晶中で発生する４光波混合に基づく位相共役反射光は、時間反転光として正確に元の方向に向い、ＬＤ発光部では最初にＬＤ発光部を出射した時と全く同じ波面の整った位相共役光として戻され、出射光のコヒーレンス結合性を向上させることができる。 As the phase conjugate mirror, for example, a photorefractive crystal using barium titanate BaTiO ₃ doped with Rh (abbreviated as Rh: BaTiO ₃ ) is generally used, and output light from the LD array is incident on the crystal at a predetermined incident angle. At the same time, the TE polarization direction is made parallel to the C-axis (Z-axis) of the photorefractive crystal. The phase conjugate reflected light based on the four-wave mixing generated in the crystal is accurately directed to the original direction as time-reversed light, and the LD light emitting portion has the same phase front as the first time when the LD light emitting portion is emitted. It is returned as light, and the coherence connectivity of the emitted light can be improved.

しかし、上述した従来の位相共役方式のＬＤアレイの構成では、その出力光と出力光相互のスローアクシス方向（ＳＡＤと略記）とファーストアクシス方向（ＦＡＤと略記）でのそれぞれの空間コヒーレンス度γSAD とγFAD の値において、γSAD はγFAD の約１／２程度と大きく異なり、出力光を集光した場合の集光度は必ずしも十分ではない。これはフォトリフラクティブ結晶のＣ軸にＬＤアレイのＴＥ偏光の方向が平行、即ちＴＥ偏光／／Ｃ軸とされているからである。 However, in the configuration of the conventional phase conjugate type LD array described above, the spatial coherence degree γSAD in the slow axis direction (abbreviated as SAD) and the first axis direction (abbreviated as FAD) of the output light and the output light, In terms of the value of γFAD, γSAD differs greatly from about ½ of γFAD, and the degree of condensing when the output light is condensed is not always sufficient. This is because the direction of TE polarization of the LD array is parallel to the C axis of the photorefractive crystal, that is, TE polarization // C axis.

一般には、ＬＤアレイの出力光は、ＴＥ偏光のみを含むレーザ光として出力され、ＴＭ偏光を含まない。従って、ＴＥ偏光の位相共役光を最も有効に生じさせるためにはＴＥ偏光／／Ｃ軸とするのがよい。γSAD とγFAD の値が同一でなければ、コヒーレンス結合されたＬＤ出力光を球面レンズで集光しても中心非対称の形状となり、このため回折限界まで狭く集光することができないという問題がある。
米国光学会誌論文「Ｍ．Ｌｏｂｅｌ，Ｐ．Ｍ．Ｐｅｔｅｒｓｅｎ，ａｎｄＰ．Ｍ．Ｊｏｈａｕｓｅｎ；Ｏｐｔ．Ｌｅｔｔｓ，２３（１９９８）８２５−８２７」 In general, the output light of the LD array is output as laser light including only TE polarized light and does not include TM polarized light. Therefore, in order to generate TE-polarized phase conjugate light most effectively, the TE-polarized light // C-axis is preferable. If the values of γSAD and γFAD are not identical, there is a problem that even if the coherence-coupled LD output light is condensed by the spherical lens, it becomes a shape that is asymmetrical to the center, and therefore cannot be condensed narrowly to the diffraction limit.
American Optical Society paper "M. Lovel, PM Petersen, and PM Johausen; Opt. Letts, 23 (1998) 825-827"

この発明は、上記の問題に留意して、複数のレーザ光を集光する際に位相共役鏡により位相共役光として空間コヒーレンス度を強化するため出力光にＴＥ偏光成分とＴＭ偏光成分を含ませて空間コヒーレンス度γSAD とγFAD を同一の値とし、コヒーレンス結合された出力光を球面レンズで集光すると回折限界まで狭く集光することができる複数レーザ光のコヒーレンス度相互補正方法及び装置を提供することを課題とする。 In consideration of the above problems, the present invention includes a TE-polarized component and a TM-polarized component in the output light in order to enhance the degree of spatial coherence as phase-conjugated light by a phase-conjugate mirror when condensing a plurality of laser beams. Provided is a coherence degree mutual correction method and apparatus for a plurality of laser beams, in which spatial coherence degrees γSAD and γFAD are set to the same value, and when coherently coupled output light is condensed by a spherical lens, it can be condensed to the diffraction limit This is the issue.

この発明は、上記の課題を解決する手段として、振動方向が互いに直交するＴＥ偏光とＴＭ偏光を含む複数のレーザ光を両偏光を同期して発生させ、各レーザ光を屈折面に対し所定の角度で、かつ各レーザ光の両偏光のうち弱偏光の偏光方向が位相共役鏡のＣ軸と平行となるように位相共役鏡へ入射し、この位相共役鏡内で１のレーザ光の弱偏光が光起電力効果に基づいて直交する方向に生じる偏光を位相共役光として出射し、他のレーザ光のそれぞれの発生過程に作用させて他のレーザ光の強偏光の空間位相を上記弱偏光の位相に一致させ、かつ他のレーザ光のうちの１の強偏光が上記弱偏光と同様に光起電力効果で生じる直交する方向の偏光を位相共役光としてこのレーザ光以外のレーザ光の発生過程に作用させて各レーザ光の弱偏光の空間位相を強偏光の位相に一致させ、上記作用を複数のレーザ光相互間に生じさせて各レーザ光相互のＴＥ偏光とＴＭ偏光それぞれのコヒーレント結合度を１又は１に近い値に補正するようにした複数レーザ光のコヒーレンス度相互補正方法としたのである。 As a means for solving the above-mentioned problems, the present invention generates a plurality of laser beams including TE polarized light and TM polarized light whose vibration directions are orthogonal to each other in synchronization with each other, and each laser beam is given to a refracting surface with a predetermined amount. The light is incident on the phase conjugate mirror at an angle so that the polarization direction of the weakly polarized light out of the two polarized lights of each laser light is parallel to the C-axis of the phase conjugate mirror, and the weakly polarized light of one laser light in the phase conjugate mirror Emits the polarized light generated in the orthogonal direction based on the photovoltaic effect as phase conjugate light, and acts on the generation process of the other laser light to change the spatial phase of the strong polarization of the other laser light to that of the weakly polarized light. The generation process of laser light other than this laser light with phase-conjugated light in which the strong polarization of one of the other laser lights coincides with the phase and the orthogonal polarization generated by the photovoltaic effect is the same as the weak polarization The weakly polarized light of each laser beam The interphase is made to coincide with the phase of strong polarization, and the above action is caused between a plurality of laser beams to correct the degree of coherent coupling between the TE and TM polarizations of each laser beam to 1 or a value close to 1. The coherence degree mutual correction method for a plurality of laser beams is used.

そして、上記方法を実施する装置として、振動方向が互いに直交するＴＥ偏光とＴＭ偏光を含むレーザ光を発生する複数のレーザ発振器を並設し、レーザ発振器から両偏光を同期して発生した各レーザ光を入射する位相共役鏡に対し屈折面への角度を所定の角度で、かつ各レーザ光の両偏光のうち弱偏光の偏光方向が位相共役鏡のＣ軸と平行となるように配設した位相共役鏡とを備え、位相共役鏡は入射されたレーザ光の１の弱偏光の散乱光が他のレーザ光の散乱により生じるブラッグ回折格子に作用して光起電力効果に基づいて直交する方向に生じる偏光を順位相共役光として出射し、かつ他のレーザ光の１の強偏光が上記弱偏光と同様に光起電力効果で生じる直交する方向の偏光を逆位相共役光として出射し、上記出射された順・逆位相共役光を各レーザ発振器へ種光として注入し発生過程でそれぞれの偏光の相互のコヒーレント結合度を１又は１に近い値に補正するように構成した複数レーザ光のコヒーレンス度相互補正装置を採用することができる。 As an apparatus for carrying out the above method, a plurality of laser oscillators that generate laser beams including TE polarized light and TM polarized light whose vibration directions are orthogonal to each other are arranged in parallel, and each laser generated by synchronizing both polarizations from the laser oscillator The angle with respect to the refracting surface is set to a predetermined angle with respect to the phase conjugate mirror on which the light is incident, and the polarization direction of the weakly polarized light of the two polarized lights of each laser light is arranged to be parallel to the C axis of the phase conjugate mirror. A phase conjugate mirror, and the phase conjugate mirror is a direction in which one weakly polarized scattered light of incident laser light acts on a Bragg diffraction grating caused by scattering of other laser light and is orthogonal based on the photovoltaic effect The polarized light generated in 1 is emitted as the order phase conjugate light, and the 1 strong polarization of the other laser light is emitted as the antiphase conjugate light in the orthogonal direction generated by the photovoltaic effect in the same manner as the weak polarization. Emitted forward / reverse phase A coherence degree mutual correction device for a plurality of laser beams configured to inject the useful light as seed light into each laser oscillator and correct the mutual coherent coupling degree of each polarization to 1 or a value close to 1 in the generation process is adopted. be able to.

上記の方法及び装置の発明では、複数レーザ光の相互の空間コヒーレンス度が極めて高くなるよう相互に補正が行なわれる。それぞれのレーザ光は、その偏光成分としてＴＥ偏光とＴＭ偏光とを含んで同時に発生され、そのうちＴＭ偏光成分の振動方向が位相共役鏡の結晶のＣ軸と平行となるように配設された位相共役鏡に入射される。その際位相共役鏡の屈折面に対し内部でのブラッグ回折格子が生じ易い所定の角度で入射する。 In the invention of the above method and apparatus, corrections are made so that the mutual spatial coherence of the plurality of laser beams becomes extremely high. Each laser beam is generated simultaneously including TE polarization and TM polarization as its polarization components, and the phase of the TM polarization component is arranged so that the oscillation direction of the TM polarization component is parallel to the C axis of the phase conjugate mirror crystal. Incident on the conjugate mirror. At this time, the incident light is incident on the refractive surface of the phase conjugate mirror at a predetermined angle at which an internal Bragg diffraction grating is likely to be generated.

入射されたレーザ光は、位相共役鏡内の所定領域に生じる干渉縞のブラッグ回折格子領域でブラッグ回折され位相共役光を生じ、この位相共役光を他のレーザ光の発生過程に注入して誘導放出過程で発生するレーザ光の位相を元のレーザ光に合致させることによりレーザ光相互のコヒーレント結合をする。このような位相共役光により位相の補正をする際に、ＴＭ偏光のブラッグ回折格子での回折作用において光起電力効果に基づく作用では直交する方向のＴＥ偏光が生じ、このＴＥ偏光成分の位相共役光が他のレーザ光の発生過程へ注入される。 The incident laser light is Bragg diffracted in the Bragg diffraction grating region of the interference fringes generated in a predetermined region in the phase conjugate mirror to generate phase conjugate light, and this phase conjugate light is injected into other laser light generation processes and guided. By matching the phase of the laser light generated in the emission process with the original laser light, the laser light is coherently coupled. When the phase is corrected by such phase conjugate light, the TE polarization in the orthogonal direction is generated in the action based on the photovoltaic effect in the diffraction action of the TM polarization Bragg diffraction grating. Light is injected into other laser light generation processes.

上記両偏光成分の結合の際、電気光学係数とＴＥ偏光成分のＬＤ強度とＴＭ偏光成分のＬＤ強度の３つの値の積に比例した強度値がＴＥ偏光成分とＴＭ偏光成分の間で交換されＴＥ偏光成分へ伝達される。このため、ＴＭ偏光成分の空間コヒーレンス度の状態がＴＥ偏光成分に対しても、又ＴＥ偏光からＴＭ偏光に対しても適用され、ＴＭ偏光成分の空間コヒーレンス度と同じ状態にＴＥ偏光成分の空間コヒーレンス度が移行され、これによりＴＥ・ＴＭ両偏光成分の空間コヒーレンス度は約１００％又は１００％に近い高い値となり、空間コヒーレンス度γFAD とγSAD はほぼ同じ約１００％の値となる。 When the two polarization components are combined, an intensity value proportional to the product of the electro-optic coefficient, the LD intensity of the TE polarization component, and the LD intensity of the TM polarization component is exchanged between the TE polarization component and the TM polarization component. Transmitted to TE polarization component. Therefore, the state of the spatial polarization coherence of the TM polarization component is applied to the TE polarization component and also from the TE polarization to the TM polarization, and the space of the TE polarization component is in the same state as the spatial polarization of the TM polarization component. The degree of coherence is shifted, so that the spatial coherence degree of both TE and TM polarization components is about 100% or a value close to 100%, and the degree of spatial coherence γFAD and γSAD is about the same value of about 100%.

上記光起電力効果に基づいて位相共役光を生じる作用ではＴＭ偏光はＴＥ偏光に比して弱偏光であるが、結晶のＣ軸に平行な方向で位相共役鏡に入射されるため、ＴＭ偏光をＴＥ偏光に変換する作用は高効率に行なわれ、確実にＴＥ偏光の補正作用をする。他方、ＴＥ偏光は強偏光として入射されるから、ＴＭ偏光への変換効率は低くてもＴＭ偏光への補正作用を得ることができる。 In the action of generating phase conjugate light based on the photovoltaic effect, TM polarized light is weaker than TE polarized light, but is incident on the phase conjugate mirror in a direction parallel to the C axis of the crystal. Is converted to TE polarized light with high efficiency and surely corrects TE polarized light. On the other hand, since TE polarized light is incident as strong polarized light, a correction effect on TM polarized light can be obtained even if conversion efficiency to TM polarized light is low.

上記のように位相共役鏡で生成された位相共役光をレーザ発生過程へ戻し、発生部からの出力光に対しＴＥ偏光成分とＴＭ偏光成分を共に約１００％の空間コヒーレンス度の出力光となるよう補正し、これにより位相共役半導体レーザアレイの出力光を空間コヒーレンス度の高い出力光として出力することができる。従って、この出力光を球面レンズで集光すれば、回折限界に近い集光度で集光できる。 As described above, the phase conjugate light generated by the phase conjugate mirror is returned to the laser generation process, and both the TE polarized light component and the TM polarized light component become output light with a degree of spatial coherence of about 100% with respect to the output light from the generator. Thus, the output light of the phase conjugate semiconductor laser array can be output as output light having a high degree of spatial coherence. Therefore, if this output light is condensed by a spherical lens, it can be condensed with a light concentration close to the diffraction limit.

この発明の複数レーザ光のコヒーレンス度相互補正方法及び装置は、直交するＴＥ偏光成分とＴＭ偏光成分を有する出力光の経路に位相共役鏡をＴＭ偏光の振動方向とＣ軸が平行となるように配置し、位相共役鏡での光起電力効果によりＴＥ偏光成分に対しＴＭ偏光成分の空間コヒーレンス結合作用を及ぼし、ＴＥ偏光成分のＦＡＤ方向モードとＴＭ偏光成分ののＳＡＤ方向モード、またＴＥ偏光成分のＳＡＤ方向モードとＴＭ偏光成分のＦＡＤ方向モードとを結合することによりＴＥ、ＴＭ偏光成分の空間コヒーレンス度を同時に約１００％の値とし、その出射された位相共役光を他のレーザ光の誘導放出過程に作用させて出力光を補正するようにしたため、ＴＥ・ＴＭ偏光成分の両者共に約１００％近い高い空間コヒーレンス度の出力光が出力され、これを集光すれば回折限界まで絞ることが可能であるという利点が得られる。 In the method and apparatus for coherence degree correction of a plurality of laser beams according to the present invention, a phase conjugate mirror is placed in the path of output light having orthogonal TE polarization components and TM polarization components so that the vibration direction of the TM polarization and the C axis are parallel to each other. And a spatial coherence coupling action of the TM polarization component to the TE polarization component due to the photovoltaic effect in the phase conjugate mirror, the FAD direction mode of the TE polarization component, the SAD direction mode of the TM polarization component, and the TE polarization component By combining the SAD direction mode and the FAD direction mode of the TM polarization component, the degree of spatial coherence of the TE and TM polarization components is simultaneously set to about 100%, and the emitted phase conjugate light is guided to other laser beams. Since the output light is corrected by acting on the emission process, both the TE and TM polarized light components have a high spatial coherence degree of nearly 100%. It is output, the advantage that this is possible to narrow to the diffraction limit when the condenser is obtained.

以下、この発明の実施の形態について図面を参照して説明する。図１は実施形態のレーザ光のコヒーレンス度相互補正装置の概略構成図を示す。図示の補正装置は、この発明のコヒーレンス度相互補正方法を実施する原理的な構成の組合わせによる装置を示しており、この原理を実際に応用した半導体レーザアレイのレーザ光のコヒーレンス度相互補正装置については後で説明する。なお、図示の補正装置は、後述する作用の説明を分り易く表示するため位相共役鏡２０の断面をレーザ発振器群１０より大きく拡大して示している。 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a laser beam coherence degree mutual correction apparatus according to an embodiment. The correction apparatus shown in the figure shows an apparatus based on a combination of the fundamental configurations for carrying out the coherence degree mutual correction method of the present invention, and the laser beam coherence degree mutual correction apparatus for a semiconductor laser array to which this principle is actually applied. Will be described later. In the illustrated correction apparatus, the cross section of the phase conjugate mirror 20 is shown larger than that of the laser oscillator group 10 in order to display an explanation of the operation described later in an easily understandable manner.

図示のように、補正装置は複数のレーザ発振器１１、１２、１３・・・を並設したレーザ発振器群１０と、位相共役鏡（位相共役反射鏡又はフォトリフラクティブミラーとも呼ばれる）２０とを備えている。レーザ発振器１１、１２、１３・・・は、後述する実際の例では半導体レーザを採用しているが、固体レーザなどの他の形式のレーザとしてもよい。しかし、それぞれのレーザ発振器が発生するレーザ光については、振動方向が互いに直交するＴＥ偏光とＴＭ偏光を同期して発生させるものでなければならない。各レーザ発振器１１、１２、１３・・・は、それぞれのレーザ光が互いに平行に送られ、各レーザ光は広がりのない平行光束であるとする。 As shown in the figure, the correction device includes a laser oscillator group 10 in which a plurality of laser oscillators 11, 12, 13... Are arranged in parallel, and a phase conjugate mirror (also referred to as a phase conjugate reflector or photorefractive mirror) 20. Yes. The laser oscillators 11, 12, 13,... Employ semiconductor lasers in actual examples to be described later, but may be other types of lasers such as solid-state lasers. However, the laser light generated by each laser oscillator must be generated in synchronization with TE polarized light and TM polarized light whose vibration directions are orthogonal to each other. It is assumed that each laser oscillator 11, 12, 13... Is sent in parallel with each other, and each laser beam is a parallel light beam without spreading.

上記ＴＥ偏光は、図示のように、位相共役鏡２０のＣ軸と直交する方向で、レーザ光の進行方向において水平に振動する偏光、ＴＭ偏光はＴＥ偏光と直交しＣ軸と平行な方向に振動する偏光である。そして、図示の例ではＴＥ偏光は出力大きさがＴＭ偏光より大きく、ＴＥ偏光を強偏光、ＴＭ偏光を弱偏光と呼ぶこととする。但し、出力の比は任意であり、例えば後述する実際の例における１９：１（９５％と５％）の比のように各レーザ光の強偏光の位相を各レーザ光相互に弱偏光により補正し、又反対に弱偏光の位相を各レーザ光相互に強偏光により補正できればよい。 As shown in the figure, the TE polarized light is polarized in the direction orthogonal to the C axis of the phase conjugate mirror 20 and oscillates horizontally in the traveling direction of the laser light, and the TM polarized light is orthogonal to the TE polarized light and parallel to the C axis. Oscillating polarized light. In the illustrated example, the output of TE polarized light is larger than that of TM polarized light, and TE polarized light is called strong polarized light and TM polarized light is called weak polarized light. However, the ratio of the output is arbitrary. For example, the phase of the strong polarization of each laser beam is corrected by the weak polarization between the laser beams as in the ratio of 19: 1 (95% and 5%) in an actual example described later. On the other hand, it is sufficient that the phase of the weakly polarized light can be corrected by the strong polarized light between the laser beams.

各レーザ光は位相共役鏡２０に対しその屈折面ＡＢに対し所定の入射角θを以て入射される。この入射角θは、最も好ましい角度としては４５°であるが、±２０°の範囲内の任意の角度としてもよい。この範囲内であれば後述する光起電力効果に基づく位相共役光が生じるからであり、この位相共役光が最も効率よく起こるのが４５°である。又、位相共役鏡２０は、その結晶構造のＣ軸が各レーザ光のＴＭ偏光と平行となる方向に置かれてレーザ発振器群１０に対置されている。これも、各レーザ光のＴＭ偏光により生じる光起電力効果に基づく位相共役光を最も有効に発生させるためである。 Each laser beam is incident on the phase conjugate mirror 20 with a predetermined incident angle θ with respect to the refractive surface AB. The incident angle θ is 45 ° as the most preferable angle, but may be any angle within a range of ± 20 °. This is because phase conjugate light based on the photovoltaic effect described later is generated within this range, and the phase conjugate light occurs most efficiently at 45 °. Further, the phase conjugate mirror 20 is placed in the laser oscillator group 10 with the C-axis of the crystal structure placed in a direction parallel to the TM polarization of each laser beam. This is also because the phase conjugate light based on the photovoltaic effect generated by the TM polarization of each laser beam is most effectively generated.

位相共役鏡２０は、従来例と同じであり、Ｒｈをドープしたチタン酸バリウムＢａＴｉＯ₃（Ｒｈ：ＢａＴｉＯ₃）を用いたフォトリフラクティブ結晶が用いられている。なお、レーザ発振器群１０で発生され補正されたレーザ光を外部へ取り出すため、位相共役鏡２０との間に各レーザ光毎にビームスプリッタがそれぞれ置かれるが、図示簡略化のため図示を省略している。 The phase conjugate mirror 20 is the same as the conventional example, and a photorefractive crystal using barium titanate BaTiO ₃ (Rh: BaTiO ₃ ) doped with Rh is used. In order to take out the corrected laser light generated by the laser oscillator group 10 to the outside, a beam splitter is placed for each laser light between the phase conjugate mirror 20, but the illustration is omitted for simplification. ing.

上記のように構成した実施形態の補正装置によれば、各レーザ光のＴＥ偏光とＴＭ偏光は次のように補正される。図中の位相共役鏡２０内のＩ₁、Ｉ₂、Ｉ₃、Ｊ₁、Ｊ₂、Ｊ₃はそれぞれブラッグ回折格子を示し、レーザ発振器１１、１２、１３からの入射光とＩ₁、Ｉ₂、Ｉ₃の散乱光によって生じる干渉縞（丸印内に３本の斜線で示す）のブラッグ回折格子領域をそれぞれ示す。Ｅ、Ｆ、Ｇ、Ｈは回折光（散乱光）の進行方向を示す直線を表す記号である。 According to the correction apparatus of the embodiment configured as described above, the TE polarized light and the TM polarized light of each laser beam are corrected as follows. In the figure, I ₁ , I ₂ , I ₃ , J ₁ , J ₂ , and J ₃ in the phase conjugate mirror 20 indicate Bragg diffraction gratings, respectively, and incident light from the laser oscillators 11, 12, and 13 and I ₁ , I The Bragg diffraction grating regions of interference fringes (indicated by three oblique lines in circles) generated by scattered light of ₂ and I ₃ are shown. E, F, G, and H are symbols representing straight lines indicating the traveling direction of diffracted light (scattered light).

なお、上記ブラッグ回折格子Ｉ₁、Ｉ₂、Ｉ₃とＪ₁、Ｊ₂、Ｊ₃は、フォトリフラクティブ結晶に含まれる不純物により所定の入射光Ｌ₁、Ｌ₂、Ｌ₃に対し図示の位置に必然的に生じるものと考えられている。従って、Ｅ、Ｆ、Ｇ、Ｈにより表された直線も上記各点を結ぶ仮想線として示している。 Note that the Bragg diffraction gratings I ₁ , I ₂ , I ₃ and J ₁ , J ₂ , J ₃ are at positions shown in the figure with respect to predetermined incident light L ₁ , L ₂ , L ₃ due to impurities contained in the photorefractive crystal. It is thought to occur inevitably. Therefore, the straight lines represented by E, F, G, and H are also shown as virtual lines connecting the above points.

まず、レーザ発振器１１からのレーザ光は位相共役鏡２０に入射されると、ブラッグ回折格子Ｉ₁でブラッグ回折され、この回折光はブラッグ回折格子Ｉ₂、Ｉ₃を通過してＦ→Ｇ→Ｈの方向に進み、ブラッグ回折格子Ｊ₃、Ｊ₂、Ｊ₁へ至る。一方、レーザ発振器１２からのレーザ光Ｌ₂も同様にブラッグ回折格子Ｉ₂で回折されるが、Ｉ₂で回折されずに直進する光（０次回折光）はＪ₂の位置でブラッグ回折格子Ｊ₂を形成する。 First, when the laser light from the laser oscillator 11 is incident on the phase conjugate mirror 20, it is Bragg diffracted by the Bragg diffraction grating I ₁ , and this diffracted light passes through the Bragg diffraction gratings I ₂ and I ₃ and F → G → Proceeding in the direction of H, it reaches the Bragg diffraction gratings J ₃ , J ₂ and J ₁ . On the other hand, the laser beam L ₂ from the laser oscillator 12 is also diffracted by the Bragg diffraction grating I ₂ , but the light that goes straight without being diffracted by I ₂ (0th order diffracted light) is at the position of J _2. Form _two .

そして、上記Ｉ₁→Ｆ→Ｇ→Ｊ₂へ進んだレーザ発振器１１からのレーザ光Ｌ₁はＪ₂でブラッグ回折され、Ｊ₂からＩ₂を通り過ぎてレーザ発振器１２へ種光（位相共役光）として注入される。従って、レーザ光Ｌ₁はレーザ発振器１２内でレーザ光の発生過程に作用してレーザ光Ｌ₂が種光と同一の性質（位相の揃った）を持ち、レーザ光Ｌ₁とＬ₂の相互のコヒーレント結合が図られる。 The laser light L ₁ from the I ₁ → F → G → laser oscillator 11 advanced to J ₂ is Bragg diffracted by J _2, the seed light from J ₂ to the laser oscillator 12 past the I ₂ (phase conjugate light ) Is injected as. Accordingly, the laser beam L ₁ acts on the generation process of the laser beam in the laser oscillator 12 so that the laser beam L ₂ has the same property (phase aligned) as that of the seed beam, and the laser beams L ₁ and L ₂ are mutually connected. Are coherently coupled.

又、レーザ発振器１２のレーザ光Ｌ₂は、同様にＪ₁で位相共役光（種光）として回折され、レーザ発振器１１へ注入されることによりレーザ光Ｌ₁の位相がレーザ光Ｌ₂の位相に一致するよう作用してコヒーレント結合される。さらに、レーザ発振器１３のレーザ光Ｌ₃は、同様にしてＪ₂でブラッグ回折されてレーザ発振器１２へ注入され、又Ｊ₁でブラッグ回折されてレーザ発振器１１へ注入され、これによりレーザ光Ｌ₁、Ｌ₂、Ｌ₃のコヒーレント結合が図られる。このような作用は相互励起型位相共役作用と呼ばれる。なお、上記のコヒーレント結合は、レーザ光のＴＥ偏光成分とＴＭ偏光成分のいずれにも等しく生じる。 Similarly, the laser light L ₂ of the laser oscillator 12 is diffracted as phase conjugate light (seed light) at J ₁ and injected into the laser oscillator 11, so that the phase of the laser light L ₁ becomes the phase of the laser light L ₂ . And coherently coupled to each other. Further, the laser light L ₃ of the laser oscillator 13 is similarly Bragg diffracted by J ₂ and injected into the laser oscillator 12, and Bragg diffracted by J ₁ and injected into the laser oscillator 11, thereby the laser light L _1. , L ₂ and L ₃ are coherently combined. Such an action is called a mutual excitation type phase conjugation action. Note that the above coherent coupling occurs equally in both the TE polarization component and the TM polarization component of the laser light.

しかし、ＴＥ偏光とＴＭ偏光は上記の作用だけでは互いに相互作用がなく、それぞれのレーザ光のＴＥ偏光とＴＭ偏光はインコヒーレントであるため、複数レーザ光を集光する際の集光度はやはり向上しないが、この実施形態では上記作用に加えてさらに以下の作用が付加される。レーザ発振器１１からのレーザ光Ｌ₁のうちＴＭ偏光に注目すると、このＴＭ偏光はＩ₁を通過してＪ₁へ向い、Ｊ₁でＴＭ偏光は回折されてＧ→Ｆ→Ｉ₂へ進む。そしてＩ₂に出来たブラッグ回折格子により光起電力効果に基づく直交したＴＥ偏光がＩ₂で生じ、回折されてレーザ発振器１２へ位相共役光（種光）として注入される。 However, TE polarized light and TM polarized light do not interact with each other only by the above-described actions, and the TE polarized light and TM polarized light of each laser light are incoherent, so the light condensing degree when condensing multiple laser light is still improved. However, in this embodiment, the following actions are further added to the above actions. When attention is paid to TM polarized light in the laser light L ₁ from the laser oscillator 11, this TM polarized light passes through I ₁ and travels to J _{1. At} J ₁ , TM polarized light is diffracted and proceeds from G → F → I ₂ . Then, an orthogonal TE polarized light based on the photovoltaic effect is generated at I ₂ by the Bragg diffraction grating formed at I ₂ , and is diffracted and injected into the laser oscillator 12 as phase conjugate light (seed light).

なお、上記説明では、ＴＭ偏光の光起電力効果に基づくＴＥ偏光への再生はＩ₂で生じると説明したが、Ｉ₁、Ｊ₁でも同様に発生する。但し、Ｉ₁、Ｊ₁、Ｉ₂のいずれの点でもＴＭ偏光成分は存在するが、Ｉ₂点へ進むにつれてＴＭ偏光成分の割合が減少し、Ｉ₂点ではＴＭ偏光成分が光起電力効果に基づく電気分極により変換され、再生されたＴＥ偏光成分が大きな割合を占め、これによりレーザ発振器１２でのコヒーレント結合による補正が行なわれるのである。 In the above description, it has been described that regeneration to TE polarization based on the photovoltaic effect of TM polarization occurs at I ₂ , but it also occurs at I ₁ and J ₁ in the same manner. However, I _1, J _1, also TM polarized light component in any point of I ₂ is present, the ratio of the TM polarization component decreases as the process proceeds to ₂ points I, TM polarization component at _two points I have photovoltaic effect The TE polarization component converted and regenerated by the electric polarization based on the above occupies a large proportion, and thus correction by coherent coupling in the laser oscillator 12 is performed.

以上のように、レーザ光Ｌ₁のＴＭ偏光がＩ₂で光起電力効果に基づいてＴＥ偏光に変換されレーザ発振器１２へ注入されるため、レーザ発振器１２内での誘導放出過程に作用してＴＭ偏光がＴＥ偏光に結合し、レーザ発振器１２のレーザ光のＴＥ偏光の位相がレーザ発振器１１のＴＭ偏光の位相と一致するようコヒーレント結合が行なわれる。同様に、レーザ発振器１２からのＴＥ偏光はＪ₂→Ｇ→Ｆ→Ｉ₁へ進み、Ｉ₁で光起電力効果に基づいて直交するＴＭ偏光を生じ、Ｉ₁で回折されてレーザ発振器１１へ位相共役光（種光）として注入され、その発生過程に作用してコヒーレント結合される。 As described above, the TM polarized light of the laser light L ₁ is converted into TE polarized light based on the photovoltaic effect at I ₂ and injected into the laser oscillator 12, so that it acts on the stimulated emission process in the laser oscillator 12. The TM polarization is coupled to the TE polarization, and the coherent coupling is performed so that the phase of the TE polarization of the laser light of the laser oscillator 12 matches the phase of the TM polarization of the laser oscillator 11. Similarly, TE polarized light from the laser oscillator 12 passes to _{J 2 → G → F → I} 1, occur TM polarized light orthogonal based on photovoltaic effect in I _1, the laser oscillator 11 is diffracted by I ₁ It is injected as phase conjugate light (seed light) and acts on the generation process to be coherently coupled.

なお、上記各ブラッグ回折格子領域でレーザ光が回折することにより位相共役光が出射される作用において、位相共役鏡の結晶のＣ軸に平行な成分の電界ベクトルは、電界によって屈折率が変化する電気光学効果の係数と作用し、フォトリフラクティブ効果（光屈折効果）は大きくなるが、Ｃ軸に垂直な電界は電気光学係数の小さな係数と作用するためフォトリフラクティブ効果は小さくなる。 Note that, in the operation in which phase conjugate light is emitted by diffracting laser light in each Bragg diffraction grating region, the electric field vector of the component parallel to the C axis of the crystal of the phase conjugate mirror changes the refractive index depending on the electric field. The photorefractive effect (photorefractive effect) is increased by working with the coefficient of the electro-optic effect, but the photorefractive effect is reduced because the electric field perpendicular to the C axis acts with a coefficient of a small electro-optic coefficient.

従って、各レーザ光のＴＥ偏光とＴＭ偏光が入射される際に、ＴＭ偏光成分は弱く、ＴＥ偏光成分は強いレーザ光であっても、ＴＭ偏光成分はＣ軸と平行なためフォトリフラクティブ効果が大きく、ＴＭ偏光によるＴＥ偏光への相互作用でのフォトリフラクティブ効果が大きい。一方、ＴＥ偏光成分はＣ軸と垂直であるため、強いレーザ光であってもフォトリフラクティブ効果は小さい。このため、ＴＥ偏光とＴＭ偏光は相互に補正し合って共にコヒーレント結合度が１又は１に近い値となり、各レーザ光同士のコヒーレント結合性が格段に向上する。 Therefore, when TE polarized light and TM polarized light of each laser beam are incident, even if the TM polarized component is weak and the TE polarized component is strong, the TM polarized component is parallel to the C axis, so that the photorefractive effect is obtained. The photorefractive effect is large in the interaction between the TM polarized light and the TE polarized light. On the other hand, since the TE polarization component is perpendicular to the C-axis, the photorefractive effect is small even with strong laser light. For this reason, the TE polarized light and the TM polarized light are corrected to each other so that the coherent coupling degree becomes 1 or a value close to 1, and the coherent coupling property between the laser beams is remarkably improved.

図２に第２実施形態のレーザ光のコヒーレンス度相互補正装置の概略構成の斜視図を示す。この実施形態では複数のレーザ発振器群１０として半導体レーザ（ＬＤ）アレイを用いている。図示の補正装置は、複数の半導体レーザ１１、１２、１３を一次元状に配列したＬＤアレイの発光窓１４₁〜１４₃から出力される出力光Ｌ₁〜Ｌ₃の縦及び横方向への広がりをほぼ平行光とするコリメートレンズ系１５₁〜１５₃と、上記出力光Ｌ₁〜Ｌ₃を一部反射し、残りを透過させるビームスプリッタ１６₁〜１６₃と、透過したレーザ光のそれぞれを集光する球面レンズ１７₁〜１７₃と、集光したレーザ光を位相共役反射する位相共役鏡２０とを備えている。 FIG. 2 shows a perspective view of a schematic configuration of the laser beam coherence degree mutual correction device of the second embodiment. In this embodiment, a semiconductor laser (LD) array is used as the plurality of laser oscillator groups 10. The illustrated correction apparatus is configured to output light L _{1 to} L ₃ output from light emitting windows 14 _{1 to} 14 _{3 of} an LD array in which a plurality of semiconductor lasers 11, 12, and 13 are arranged in a one-dimensional manner in the vertical and horizontal directions. Each of collimating lens systems 15 ₁ to 15 ₃ having a substantially parallel light spread, beam splitters 16 _{1 to} 16 ₃ for partially reflecting the output lights L _{1 to} L ₃ and transmitting the rest, and the transmitted laser light, respectively. Are provided, and spherical lenses 17 _{1 to} 17 ₃ for condensing light and a phase conjugate mirror 20 for phase conjugate reflection of the condensed laser light.

上記ＬＤアレイの半導体レーザ１１、１２、１３は、図示の例では波長８０８ｎｍを有し、その発光窓１４₁〜１４₃からの出力光Ｌ₁〜Ｌ₃は、発光窓１４₁〜１４₃の長い開口方向と垂直な全広がり角約４０度の回折方向である縦方向（ファーストアクシス方向）（相互コヒーレンス度；γFAD ）と、上記開口方向と平行な全広がり角約１０度の回折方向である横方向（スローアクシス方向）（相互コヒーレンス度；γSAD ）とに広がる性質を一般に有するが、縦方向の広がりは円柱状マイクロ棒（ロッド）レンズにより、横方向の広がりは円柱レンズによりそれぞれの方向の広がりを平行状とするレンズの組合せから成るコリメートレンズ系１５₁〜１５₃によりほぼ平行状に矯正される。 The semiconductor laser 11, 12, 13 of the LD array has a wavelength 808nm in the illustrated example, the output light L ₁ ~L ₃ from the light emitting window 14 _1-14 _3, the light emitting window 14 _1-14 ₃ Longitudinal direction (first axis direction) which is a diffraction direction having a total spread angle of about 40 degrees perpendicular to the long aperture direction (mutual coherence degree; γFAD), and a diffraction direction having a total spread angle of about 10 degrees parallel to the opening direction. In general, it has the property of spreading in the transverse direction (slow axis direction) (degree of mutual coherence; γSAD), but the longitudinal spread is caused by a cylindrical micro rod (rod) lens, and the lateral spread is caused by a cylindrical lens. The collimating lens systems 15 ₁ to 15 _{3 formed} of a combination of lenses having a parallel spread are corrected to be substantially parallel.

又、ＬＤアレイの発光窓１４₁〜１４₃からの出力光Ｌ₁〜Ｌ₃は、一般のＬＤでは長い開口の方向と平行な直線偏光（ＴＥ偏光と略記する）であるのに対し、図示のようにＴＥ偏光成分と、ＴＥ偏光成分と直交する方向のＴＭ偏光成分とを有する形式の半導体レーザが用いられるものとする。但し、ＴＥ偏光成分はＴＭ偏光成分より大きいとする。図示の半導体レーザではＴＥ偏光とＴＭ偏光は次のように設定される。即ち、半導体レーザに対しＴＥ偏光のみで発振する発振閾値の注入電流を越えてＴＭ偏光を同時に発生する閾値以上の注入電流を注入してＴＭ偏光も発振させる。このような作動状態の半導体レーザは、例えばＴＥ偏光出力９５％、ＴＭ偏光出力５％の出力が得られ、ＴＥ偏光とＴＭ偏光の比は１９：１である。 The output light L ₁ ~L ₃ from the light emitting window 14 _1-14 ₃ LD array, whereas a In general LD long opening direction parallel to the linearly polarized light (abbreviated as TE polarization), shown As described above, a semiconductor laser having a TE polarization component and a TM polarization component in a direction orthogonal to the TE polarization component is used. However, it is assumed that the TE polarization component is larger than the TM polarization component. In the semiconductor laser shown in the figure, TE polarized light and TM polarized light are set as follows. That is, the TM polarized light is also oscillated by injecting an injection current equal to or higher than the threshold for simultaneously generating TM polarized light beyond the oscillation threshold injection current oscillated only by TE polarized light into the semiconductor laser. The semiconductor laser in such an operating state can obtain an output of 95% TE polarization output and 5% TM polarization output, for example, and the ratio of TE polarization to TM polarization is 19: 1.

ビームスプリッタ１６₁〜１６₃は、ハーフミラー形式のものが用いられ、上記出力光Ｌ₁〜Ｌ₃は一部が反射されて出力光Ｌ_EXとなり、残りはハーフミラーを透過して球面レンズ１７₁〜１７₃で集光され、位相共役鏡２０で反射されたレーザ光は、ビームスプリッタ１６₁〜１６₃で再びその一部が反射され、残りはそのまま上記出力光Ｌ₁〜Ｌ₃と逆向きに向い、反射された一部のレーザ光Ｉ_Mは出力光Ｌ_EXと反対方向に出てモニタ部へ向う。 The beam splitters 16 _{1 to} 16 ₃ are of a half mirror type, and the output lights L _{1 to} L ₃ are partly reflected to become output light L _EX , and the rest are transmitted through the half mirror and spherical lens 17. A part of the laser light condensed by _{1 to} 17 ₃ and reflected by the phase conjugate mirror 20 is reflected again by the beam splitters 16 _{1 to} 16 ₃ , and the rest is directly opposite to the output light L _{1 to} L _3. A part of the reflected laser light I _M is directed in the opposite direction to the output light L _EX and goes to the monitor unit.

このモニタ部では、横方向１８と縦方向１９に設けた２つのピンホールの前に直線偏光板（図示せず）を置き、これらを通過した光の干渉縞の明瞭度（ｖｉｓｉｂｉｌｉｔｙ）により、反射された位相共役光の空間コヒーレンス度が測定される。上記球面レンズ１７₁〜１７₃により集光されたレーザ光は、位相共役鏡２０へ入射される際に、そのＴＭ偏光が位相共役鏡２０のＣ軸（Ｚ軸）と平行となる方向に位相共役鏡２０が配設されている。 In this monitor unit, a linearly polarizing plate (not shown) is placed in front of two pinholes provided in the horizontal direction 18 and the vertical direction 19 and reflected by the visibility of the interference fringes of the light passing through them. The degree of spatial coherence of the phase conjugate light is measured. When the laser beams condensed by the spherical lenses 17 _{1 to} 17 ₃ are incident on the phase conjugate mirror 20, the TM polarization is phased in a direction parallel to the C axis (Z axis) of the phase conjugate mirror 20. A conjugate mirror 20 is provided.

上記の構成としたこの実施形態の補正装置は、基本的な構成においては第１実施形態と同じであり、作用についても基本的に同じである。従って、作用の説明を繰り返すことは省略するが、ＴＭ偏光→ＴＥ偏光への変換と、相互コヒーレンス度γFAD とγSAD の関係は次の通りである。上記出力光相互のコヒーレンス度を考えるとき、第２実施形態のように、ＴＥ偏光９５％、ＴＭ偏光５％が混在している場合、γSAD とγFAD はＴＥ偏光によるものとＴＭ偏光によるものとが混在していると考えられる。このとき、γFAD の値が１００％近く、γSAD の値が２０〜３０％程度であるとし、ＴＭ偏光の光起電力効果によるＴＥ偏光への変換がないとすると、γSAD の値は元のまま改善されない。 The correction apparatus of this embodiment having the above-described configuration is the same as that of the first embodiment in the basic configuration, and the operation is also basically the same. Therefore, although the description of the operation is not repeated, the relationship between the TM polarization → TE polarization and the mutual coherence degrees γFAD and γSAD is as follows. When considering the degree of coherence between the output lights described above, when TE polarized light 95% and TM polarized light 5% are mixed as in the second embodiment, γSAD and γFAD are either TE polarized light or TM polarized light. It seems to be mixed. At this time, assuming that the value of γFAD is close to 100%, the value of γSAD is about 20-30%, and there is no conversion to TE polarized light due to the photovoltaic effect of TM polarized light, the value of γSAD is improved as it is. Not.

しかし、実際にはＴＭ偏光が光起電力効果に基づきＴＥ偏光へ変換される際、ＴＭ偏光のＦＡＤ方向のモードとＴＥ偏光のＳＡＤ方向のモードが結合され、また同時にＴＥ偏光のＦＡＤ方向のモードとＴＭ偏光のＳＡＤ方向のモードも結合し、ＴＥ偏光とＴＭ偏光のコヒーレンス度が１００％又は１００％近くまで向上することでレンズによる集光の際に対称性が良くなり、高い集光密度が得られることとなる。 However, when TM-polarized light is converted into TE-polarized light based on the photovoltaic effect, the mode of TM-polarized FAD direction and the mode of TE-polarized SAD direction are combined, and at the same time, the mode of TE-polarized FAD direction. And the SAD mode of TM polarized light are combined, and the degree of coherence between TE polarized light and TM polarized light is improved to 100% or close to 100%. Will be obtained.

上記のγFAD 、γSAD の値は、図示の装置では半導体レーザ１１と１２、１２と１３、・・・のように相互に隣接する半導体レーザ間の空間コヒーレンス度として１８の２つのピンホールでγSAD が、１９の２つのピンホールでγFAD が、上述したように光の干渉縞の明瞭度により測定される。なお、図示ＬＤアレイは１次元の配列のものを示しているが、２次元ＬＤアレイでも同様に適用できることは詳細に説明するまでもない。 The values of γFAD and γSAD are the values of γSAD in two pinholes of 18 as the degree of spatial coherence between semiconductor lasers adjacent to each other like the semiconductor lasers 11 and 12, 12 and 13,. , 19 are measured by the clarity of the light interference fringes as described above. Although the illustrated LD array is a one-dimensional array, it is needless to explain in detail that the two-dimensional LD array can be similarly applied.

この発明のコヒーレンス度相互補正装置は、複数のＬＤアレイを光源とし位相共役鏡を用いてレーザ光相互の位相を高精度に補正できるものであり、レーザ加工、レーザロケット、レーザ医学、非線形光学用光源、分光用光源、ＭＴ級大出力レーザの励起用光源など種々の用途に利用できる。 The coherence degree mutual correction device of the present invention is capable of correcting the phase of laser beams with high accuracy using a plurality of LD arrays as light sources and using a phase conjugate mirror. For laser processing, laser rocket, laser medicine, and nonlinear optics It can be used for various applications such as a light source, a spectral light source, and an excitation light source for an MT-class high-power laser.

第１実施形態の位相共役半導体レーザアレイの全体概略構成図1 is an overall schematic configuration diagram of a phase conjugate semiconductor laser array according to a first embodiment. 第２実施形態の位相共役半導体レーザアレイの全体概略構成図Whole schematic block diagram of phase conjugate semiconductor laser array of 2nd Embodiment

符号の説明Explanation of symbols

１１、１２、１３半導体レーザ（レーザ発振器）
１４発光窓
１５コリメートレンズ系
１６ビームスプリッタ
１７球面レンズ
２０位相共役鏡 11, 12, 13 Semiconductor laser (laser oscillator)
14 Light-emitting window 15 Collimating lens system 16 Beam splitter 17 Spherical lens 20 Phase conjugate mirror

Claims

振動方向が互いに直交するＴＥ偏光とＴＭ偏光を含む複数のレーザ光を両偏光を同期して発生させ、各レーザ光を屈折面（ＡＢ）に対し所定の角度（θ）で、かつ各レーザ光の両偏光のうち弱偏光の偏光方向が位相共役鏡（２０）のＣ軸と平行となるように、上記複数のレーザ光のうちの１のレーザ光の弱偏光を上記位相共役鏡（２０）へ入射し、この位相共役鏡（２０）内で、上記入射光と、この光の散乱光との間の干渉光によるフォトリフラクティブ効果によって生じたブラッグ回折格子（Ｉ _１）によって上記入射光を回折させ、この回折光を上記位相共役鏡（２０）内で反射させ、他のレーザ光によって生じたブラッグ回折格子（Ｊ _２、Ｊ _３）によって、上記反射させた回折光を再び回折させ、上記弱偏光が光起電力効果に基づいて直交する方向に生じる偏光を位相共役光として出射し、他のレーザ光のそれぞれの発生過程に作用させて上記複数のレーザ光のうちの他のレーザ光の上記強偏光の空間位相を上記弱偏光の位相に一致させ、かつ上記他のレーザ光のうちの１の強偏光が上記弱偏光と同様に光起電力効果で生じる直交する方向の偏光を位相共役光としてこのレーザ光以外のレーザ光の発生過程に作用させて各レーザ光の弱偏光の空間位相を強偏光の位相に一致させ、上記作用を複数のレーザ光相互間に生じさせて各レーザ光相互のＴＥ偏光とＴＭ偏光それぞれのコヒーレント結合度を１に補正するようにした複数レーザ光のコヒーレンス度相互補正方法。 A plurality of laser light including TE polarized light and TM polarized light vibrating directions perpendicular to each other synchronously by generating both polarizations, at a predetermined angle with respect to the refractive surface (AB) of each laser beam (theta), and the laser beams The weakly polarized light of one of the plurality of laser beams is converted to the phase conjugate mirror (20) so that the polarization direction of the weakly polarized light is parallel to the C axis of the phase conjugate mirror (20). Into the phase conjugate mirror (20) , the incident light is diffracted by the Bragg diffraction grating (I ₁ ) generated by the photorefractive effect caused by the interference light between the incident light and the scattered light. The diffracted light is reflected in the phase conjugate mirror (20), and the reflected diffracted light is again diffracted by the Bragg diffraction grating (J ₂ , J ₃ ) generated by the other laser light, and the weak light Polarization based on photovoltaic effect The polarized light emitted as a phase conjugate light generated in a direction perpendicular, other laser light of the strong polarization the weak polarization spatial phase of one of the allowed to act on each of the developmental process of the other laser beam the plurality of laser beams the match in phase, and the one of the other laser beam strong polarization of the weak polarization and the laser beam than the laser beam in the direction of polarization as the phase conjugate light orthogonal occurring in the photovoltaic effect as well It acts on the generation process to make the spatial phase of the weakly polarized light of each laser beam coincide with the phase of the strongly polarized light, and the above action is generated between a plurality of laser beams to coherent each of the TE polarized light and TM polarized light of each laser light. A method for mutually correcting the coherence degree of a plurality of laser beams, wherein the degree of coupling is corrected to 1 .

前記ＴＥ偏光を強偏光、ＴＭ偏光を弱偏光としたことを特徴とする請求項１に記載の複数レーザ光のコヒーレンス度相互補正方法。 2. The method according to claim 1 , wherein the TE polarized light is strong polarized light and the TM polarized light is weakly polarized light.

前記レーザ光を位相共役鏡（２０）へ入射する所定の角度（θ）を前記弱偏光が光起電力効果を生じ得る２５〜６５°の範囲内としたことを特徴とする請求項１又は２に記載の複数レーザ光のコヒーレンス度相互補正方法。 3. The predetermined angle ([theta]) at which the laser beam is incident on the phase conjugate mirror (20) is within a range of 25 to 65 [deg.] At which the weakly polarized light can produce a photovoltaic effect. A method for mutually correcting the coherence degree of a plurality of laser beams as described in 1.

振動方向が互いに直交するＴＥ偏光とＴＭ偏光を含むレーザ光を発生する複数のレーザ発振器（１１、１２、１３）を並設し、レーザ発振器（１１、１２、１３）から両偏光を同期して発生した各レーザ光を入射する位相共役鏡（２０）に対し屈折面（ＡＢ）への角度を所定の角度（θ）で、かつ各レーザ光の両偏光のうち弱偏光の偏光方向が位相共役鏡（２０）のＣ軸と平行となるように配設した上記位相共役鏡（２０）とを備え、上記位相共役鏡は、上記入射光と、この光の散乱光との間の干渉光によるフォトリフラクティブ効果によって生じたブラッグ回折格子（Ｉ _１）によって上記入射光を回折させ、この回折光を上記位相共役鏡（２０）内で反射させ、他のレーザ光によって生じたブラッグ回折格子（Ｊ _２、Ｊ _３）によって、上記反射させた回折光を再び回折させ、上記複数のレーザ発振器（１１、１２、１３）から入射されたレーザ光のうちの１の弱偏光の散乱光が他のレーザ光の散乱により生じるブラッグ回折格子（Ｊ _２、Ｊ _３）に作用して光起電力効果に基づいて直交する方向に生じる偏光を順位相共役光として出射し、かつ上記複数のレーザ発振器（１１、１２、１３）から入射された他のレーザ光の１の強偏光が上記弱偏光と同様に光起電力効果で生じる直交する方向の偏光を逆位相共役光として出射し、上記出射された順・逆位相共役光を各レーザ発振器（１１、１２、１３）へ種光として注入し発生過程でそれぞれの偏光の相互のコヒーレント結合度を１に補正するように構成した複数レーザ光のコヒーレンス度相互補正装置。 A plurality of laser oscillators (11, 12, 13) that generate laser beams including TE polarization and TM polarization whose vibration directions are orthogonal to each other are arranged in parallel, and both polarizations are synchronized from the laser oscillator (11, 12, 13). The angle to the refracting surface (AB) is set to a predetermined angle (θ) with respect to the phase conjugate mirror (20) on which each generated laser beam is incident, and the polarization direction of weakly polarized light out of both polarizations of each laser beam is phase conjugate. comprising a mirror (20) C-axis parallel to become so disposed the above phase conjugate mirror of the (20), said phase conjugate mirror is due to the interference light between the said incident light, and scattered light of the light The incident light is diffracted by the Bragg diffraction grating (I ₁ ) generated by the photorefractive effect , the diffracted light is reflected in the phase conjugate mirror (20), and the Bragg diffraction grating (J ₂₎ generated by the other laser light is reflected. , by _{J 3),} Serial diffract diffracted light is reflected again, Bragg diffraction of the plurality of first weak polarization of the scattered light of the incident laser beam from a laser oscillator (11, 12, 13) is caused by the scattering of the other laser beam Polarized light that acts on the grating (J ₂ , J ₃ ) and is generated in the orthogonal direction based on the photovoltaic effect is emitted as the ordered phase conjugate light, and is incident from the plurality of laser oscillators (11, 12, 13). As in the case of the weakly polarized light, one strong polarized light of the other laser light emits the polarized light in the orthogonal direction generated by the photovoltaic effect as an antiphase conjugate light, and the emitted forward / reverse phase conjugate light is emitted from each laser. A coherence degree mutual correction apparatus for a plurality of laser beams configured to inject as seed light into an oscillator (11, 12, 13) and correct the mutual coherent coupling degree of each polarization to 1 in the generation process.

前記複数のレーザ発振器を複数の半導体レーザから成る半導体レーザアレイ（１０）とし、半導体レーザアレイ（１０）の発光部からの出力光をコリメートレンズ系（１５）で平行光源とし、その出力光をビームスプリッタ（１６）で一部を反射、残りは球面レンズ（１７）で集光し、所定の入射角（θ）で位相共役鏡（２０）へ入射させるように構成したことを特徴とする請求項４に記載の複数レーザ光のコヒーレンス度相互補正装置。 The plurality of laser oscillators is a semiconductor laser array (10) composed of a plurality of semiconductor lasers, output light from the light emitting part of the semiconductor laser array (10) is used as a parallel light source by a collimator lens system (15) , and the output light is beamed. A part of the light is reflected by the splitter (16) , the rest is collected by the spherical lens (17) , and is incident on the phase conjugate mirror (20) at a predetermined incident angle (θ). 4. The coherence degree mutual correction device for a plurality of laser beams according to 4 .

前記位相共役鏡（２０）をチタン酸バリウムＢａＴｉＯ₃のフォトリフラクティブ結晶により形成したことを特徴とする請求項４又は５に記載の複数レーザ光のコヒーレンス度相互補正装置。 It said phase conjugate mirror (20) degree of coherence mutual correction device of the plurality laser beam according to claim 4 or 5, characterized in that formed by photorefractive crystal barium titanate BaTiO ₃ a.

前記半導体レーザアレイ（１０）の各半導体レーザにおけるＴＥ偏光とＴＭ偏光が１９対１の割合で出力されるように各レーザへの注入電流を発振閾値を超える値に設定したことを特徴とする請求項４乃至６のいずれかに記載の複数レーザ光のコヒーレンス度相互補正装置。
The injection current to each laser is set to a value exceeding an oscillation threshold so that TE polarized light and TM polarized light in each semiconductor laser of the semiconductor laser array (10) are output at a ratio of 19 to 1. Item 7. A coherence degree mutual correction apparatus for a plurality of laser beams according to any one of Items 4 to 6 .