JPH06194705A - Optical higher harmonic generator - Google Patents
Optical higher harmonic generatorInfo
- Publication number
- JPH06194705A JPH06194705A JP34436392A JP34436392A JPH06194705A JP H06194705 A JPH06194705 A JP H06194705A JP 34436392 A JP34436392 A JP 34436392A JP 34436392 A JP34436392 A JP 34436392A JP H06194705 A JPH06194705 A JP H06194705A
- Authority
- JP
- Japan
- Prior art keywords
- light
- harmonic
- optical
- polarization direction
- optical path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、コヒーレンス性の良い
短波長光の発生に係わり、特に高調波光生成による短波
長光の発生に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to generation of short wavelength light having good coherence, and more particularly to generation of short wavelength light by generation of harmonic light.
【０００２】[0002]
【従来の技術】コヒーレンス性の良い光はレーザ発振に
よって得ることができるが、レーザ光は、波長の長い光
ほど発振しやすく、現状では赤外光、可視光、近紫外光
までは実現されている。これらの波長よりも短い波長の
レーザ光の生成が困難な理由は、次の二点がある。2. Description of the Related Art Light with good coherence can be obtained by laser oscillation. However, laser light is more likely to oscillate as light with a longer wavelength, and at present, infrared light, visible light, and near-ultraviolet light are realized. There is. There are two reasons why it is difficult to generate a laser beam having a wavelength shorter than these wavelengths.
【０００３】（１） 自然放射の確率が放射光の周波数
の３乗に比例して増大する問題 このために、励起準位の寿命がきわめて短くなる。一
方、レーザ発振を可能にするには、まず関与する準位間
で反転分布を実現する必要があるが、寿命の短い励起準
位に励起を蓄積して反転分布を作るには、強力なポンプ
光を必要とする。その必要入力強度は周波数の４乗に比
例して増大する。さらに、レーザ発振は反転分布下での
誘導放射で引き起こされるが、強い自然放射に打ち勝つ
誘導放射を実現する困難さがある。(1) The problem that the probability of spontaneous emission increases in proportion to the cube of the frequency of the emitted light. Therefore, the life of the excitation level becomes extremely short. On the other hand, in order to enable laser oscillation, it is first necessary to realize an inversion distribution between the levels involved, but in order to accumulate excitation in the excitation level with a short lifetime and create an inversion distribution, a strong pump Need light. The required input strength increases in proportion to the fourth power of the frequency. Furthermore, lasing is caused by stimulated emission under population inversion, but there is a difficulty in achieving stimulated emission that overcomes the strong spontaneous emission.
【０００４】（２） 反射鏡の問題 可視域では誘電体多層膜により、容易に１００％の反射
鏡が得られるが、短波長領域ではほとんどの物質は屈折
率が１に近くなり、光の干渉を用いた反射鏡は不可能と
なる。(2) Reflector problem In the visible region, a dielectric multilayer film makes it possible to easily obtain a 100% reflector, but in the short wavelength region, most substances have a refractive index close to 1, which causes optical interference. A reflector using is impossible.
【０００５】そこで、Ｎｄ：ガラスレーザやＹＡＧレー
ザの強力な出力光を基本波とし、非線形光学素子を用い
て高調波光を発生させ、コヒーレントな短波長光を得る
ことが実用化されはじめている。この方式を採用した第
３次高調波光を生成する短波長光発生装置として、例え
ば、特開昭６４−６４２８０で開示されたレーザ装置が
ある。この装置の構成を図５に示す。この装置は、アレ
キサンドライトをレーザ媒質として基本周波数光（波長
＝７５０ｎｍ）のレーザ光を出射するレーザ発振器１５
０と、偏光方向が同一方向を有する２つの光に対してタ
イプＩと称される位相整合法をもち、７５０ｎｍのレー
ザ光の素子内光路が第２次高調波光発生の位相整合条件
を満たす方向を有するように配置された第１の非線形光
学素子２５０と、第１の非線形光学素子２５０を出射す
る基本周波数光と偏光方向が基本周波数光と垂直に偏光
した第２次高調波光とを入射し、夫々の偏光方向に異な
る旋回を施して偏光方向を平行化した後に出射する旋光
性物質５５０と、基本周波数光と第２次高調波光との素
子内光路が和周波発生のタイプＩの位相整合条件を満た
す方向を有するように配置された第２の非線形光学素子
２６０と、から構成される。Therefore, it has been put into practical use to obtain coherent short-wavelength light by using a strong output light of an Nd: glass laser or a YAG laser as a fundamental wave and generating a harmonic light by using a non-linear optical element. As a short-wavelength light generating device that uses this method to generate third-order harmonic light, for example, there is a laser device disclosed in Japanese Patent Laid-Open No. 64-64280. The configuration of this device is shown in FIG. This device is a laser oscillator 15 that emits laser light of a fundamental frequency light (wavelength = 750 nm) using alexandrite as a laser medium.
0 and a phase matching method called type I for two lights having the same polarization direction, and the optical path in the element of the laser light of 750 nm is a direction satisfying the phase matching condition for generating the second harmonic light. The first non-linear optical element 250 disposed so as to have the fundamental frequency light emitted from the first non-linear optical element 250 and the second harmonic light whose polarization direction is perpendicular to the fundamental frequency light are incident. , Type I phase matching in which the optical paths in the element of the fundamental frequency light and the second-order harmonic light and the optical rotatory substance 550 that emits after the polarization directions are made parallel by making different rotations in the respective polarization directions The second nonlinear optical element 260 is arranged so as to have a direction that satisfies the condition.
【０００６】レーザ共振器１５０から出射された基本周
波数を有する直線偏光を、第１の非線形光学素子２５０
へ第２次高調波光発生に関する位相整合方向から入射
し、第１の非線形光学素子２５０の有する２次の非線形
光学効果により第２次高調波光（波長＝３７５ｎｍ）を
発生させる。この第２次高調波光は、第１の非線形光学
素子２５０を透過する基本周波数光と同一の進行方向を
有し、基本周波数光の偏光方向と垂直な偏光方向を有す
る。こうして第１の非線形光学素子２５０から出力され
る基本周波数光と第２次高調波光とを、旋光性物質５５
０を介することにより双方の偏光方向を平行化し、基本
周波数光と第２次高調波光とに対するタイプＩでの和周
波光生成の位相整合方向から第２の非線形光学素子２６
０に入射させる。この結果、第２の非線形光学素子２６
０内で２次の非線形光学効果によって基本周波数光と第
２次高調波光との和周波である第３次高調波光（波長＝
２５０ｎｍ）が発生する。この第３次高調波光は、第２
の非線形光学素子２６０を透過する基本周波数光および
第２次高調波光と同一の進行方向を有し、基本周波数光
および第２次高調波光の偏光方向と垂直な偏光方向を有
する。この装置では、以上のようにして、レーザ発信器
１５０の発生するレーザ光の第３次高調波光を得てい
る。The linearly polarized light having the fundamental frequency emitted from the laser resonator 150 is converted into the first nonlinear optical element 250.
The light enters from the phase-matching direction related to the generation of the second-order harmonic light, and the second-order harmonic light (wavelength = 375 nm) is generated by the second-order nonlinear optical effect of the first nonlinear optical element 250. The second harmonic light has the same traveling direction as the fundamental frequency light that passes through the first nonlinear optical element 250 and has a polarization direction perpendicular to the polarization direction of the fundamental frequency light. In this way, the fundamental frequency light and the second harmonic light output from the first nonlinear optical element 250 are converted into the optical rotatory substance 55.
The polarization direction of both polarizations is made parallel by passing through 0, and the second nonlinear optical element 26 from the phase matching direction of the type I sum frequency light generation with respect to the fundamental frequency light and the second harmonic light.
It is incident on 0. As a result, the second nonlinear optical element 26
Due to the second-order nonlinear optical effect within 0, the third harmonic light (wavelength = wavelength = the sum frequency of the fundamental frequency light and the second harmonic light)
250 nm) is generated. This third harmonic light is
Has the same traveling direction as the fundamental frequency light and the second-order harmonic light passing through the nonlinear optical element 260, and has a polarization direction perpendicular to the polarization directions of the fundamental-frequency light and the second-order harmonic light. In this device, the third harmonic light of the laser light generated by the laser oscillator 150 is obtained as described above.
【０００７】[0007]
【発明が解決しようとする課題】従来の高調波発生装置
は以上のように構成されているので、基本周波数光から
第ｎ次高調波光を生成するのに、（ｎ−１）個の２次の
非線形光学効果を有する非線形光学素子を必要とするた
め、非線形光学素子での高調波の発生動作を安定させる
ため非線形光学素子の温度を一定に保持するための機構
が各非線形光学素子ごとに必要となり、装置の電気回路
系等が複雑になってしまうという問題点があった。ま
た、非線形光学素子は高価なものであり、これを複数個
使用する第３次以上の高調波発生装置は非常に高価とな
ってしまう問題点があった。Since the conventional harmonic generator is constructed as described above, (n-1) second-order harmonics are used to generate the nth harmonic light from the fundamental frequency light. Since a non-linear optical element having a non-linear optical effect is required, a mechanism is required for each non-linear optical element to keep the temperature of the non-linear optical element constant in order to stabilize the harmonic generation operation in the non-linear optical element. Therefore, there has been a problem that the electric circuit system of the apparatus becomes complicated. Further, the non-linear optical element is expensive, and there is a problem that a third or higher harmonic generation device using a plurality of such elements is very expensive.
【０００８】本発明は、以上の問題点を解消するために
なされたものであり、簡単な構成を有し、廉価な第３次
ないしは第４次の高調波光を得ることができる光高調波
発生器を提供することを目的とする。The present invention has been made in order to solve the above problems, and has a simple structure and is capable of obtaining inexpensive third-order or fourth-order harmonic light generation. The purpose is to provide a container.
【０００９】[0009]
【課題を解決するための手段】本発明に係わる光高調波
発生器は、（ａ）２次の非線形光学効果を有する単一の
非線形光学素子と、（ｂ）非線形光学素子に同一方向か
ら入射する２つの直線偏光の偏光方向が互いに平行の場
合に、第２次高調波の発生に関して位相整合する方向か
ら非線形素子へ入射する直線偏光した基本周波数光を出
射するレーザ光源と、（ｃ）非線形光学素子から同一方
向に出射される基本周波数光と第２次高調波光とについ
て、第３次高調波の発生に関して位相整合する方向から
非線形光学素子へ入射する光路および偏光方向を設定す
る光路・偏光方向設定手段と、を含んで構成されること
を特徴とする。An optical harmonic generator according to the present invention is provided with (a) a single nonlinear optical element having a second-order nonlinear optical effect and (b) incident on the nonlinear optical element from the same direction. A laser light source that emits linearly polarized fundamental frequency light that is incident on the nonlinear element from a direction that is phase-matched with respect to the generation of the second harmonic when the polarization directions of the two linearly polarized light are parallel to each other; Optical path / polarization for setting the optical path and the polarization direction of the fundamental frequency light and the second-order harmonic light emitted from the optical element in the same direction from the direction in which the third harmonic generation occurs and the phase-matching direction to the nonlinear optical element. And a direction setting means.
【００１０】また、本発明に係わる他の光高調波発生器
は、（ａ）２次の非線形光学効果を有する非線形光学素
子と、（ｂ）非線形光学素子に同一方向から入射する２
つの直線偏光の偏光方向が互いに平行の場合に、第２次
高調波の発生が位相整合する第１の方向から非線形素子
へ入射する直線偏光した基本周波数光を出射するレーザ
光源と、（ｃ）非線形素子から同一方向に出射される基
本周波数光と第２次高調波とについて、第３次高調波の
発生に関して位相整合する方向から前記非線形素子へ入
射する光路および偏光方向を設定する第１の光路・偏光
方向設定手段と、（ｄ）非線形素子から同一方向に出射
される基本周波数光と第３次高調波とについて、第４次
高調波の発生に関して位相整合する方向から非線形素子
へ入射する光路および偏光方向を設定する第２の光路・
偏光方向設定手段と、を含んで構成されることを特徴と
する。Further, another optical harmonic generator according to the present invention has: (a) a nonlinear optical element having a second-order nonlinear optical effect;
A laser light source which emits linearly polarized fundamental frequency light which is incident on the nonlinear element from the first direction in which the generation of the second harmonic is phase-matched when the polarization directions of the two linearly polarized lights are parallel to each other; For the fundamental frequency light and the second harmonic emitted from the nonlinear element in the same direction, a first optical path and a polarization direction are set which are incident on the nonlinear element from a phase-matching direction with respect to the generation of the third harmonic. The optical path / polarization direction setting means and (d) the fundamental frequency light and the third harmonic emitted from the non-linear element in the same direction are incident on the non-linear element from the phase-matching direction with respect to the generation of the fourth harmonic. A second optical path that sets the optical path and polarization direction
And a polarization direction setting means.
【００１１】また、本発明に係わる別の光高調波発生器
は、（ａ）２次の非線形光学効果を有する非線形光学素
子と、（ｂ）非線形光学素子において、同一方向から入
射する２つの直線偏光の偏光方向が互いに垂直の場合に
第２次高調波の発生が位相整合する方向から入射する、
直線偏光した基本周波数光を出射するレーザ光源と、
（ｃ）レーザ光源の出射した直線偏光した基本周波数光
の偏光方向を４５゜回転させる基本周波数光に関する第
１の１／２波長板と、（ｄ）非線形素子から同一方向に
出射される基本周波数光と第２次高調波とについて、第
３次高調波の発生に関して位相整合する方向から前記非
線形素子へ入射する光路および偏光方向を設定する光路
・偏光方向設定手段と、を含んで構成されることを特徴
とする。Another optical harmonic generator according to the present invention is (a) a non-linear optical element having a second-order non-linear optical effect, and (b) a non-linear optical element, in which two straight lines are incident from the same direction. When the polarization directions of polarized light are perpendicular to each other, the second harmonics are incident from the direction in which the phases are matched,
A laser light source that emits linearly polarized fundamental frequency light,
(C) The first half-wave plate for the fundamental frequency light that rotates the polarization direction of the linearly polarized fundamental frequency light emitted from the laser light source by 45 °, and (d) the fundamental frequency emitted from the nonlinear element in the same direction. An optical path / polarization direction setting means for setting the optical path and the polarization direction of the light and the second harmonic that are incident on the non-linear element from the direction in which they are phase-matched with respect to the generation of the third harmonic. It is characterized by
【００１２】また、本発明に係わる更に別の光高調波発
生器は、（ａ）２次の非線形光学効果を有する非線形光
学素子と、（ｂ）非線形光学素子において、同一方向か
ら入射する２つの直線偏光の偏光方向が互いに垂直の場
合に第２次高調波の発生が位相整合する方向から入射す
る、直線偏光した基本周波数光を出射するレーザ光源
と、（ｃ）レーザ光源の出射した直線偏光した基本周波
数光の偏光方向を４５゜回転させる基本周波数光に関す
る第１の１／２波長板と、（ｄ）非線形素子から同一方
向に出射される基本周波数光と第２次高調波とについ
て、第３次高調波の発生に関して位相整合する方向から
前記非線形素子へ入射する光路および偏光方向を設定す
る第１の光路・偏光方向設定手段と、（ｅ）非線形素子
から同一方向に出射される基本周波数光と第３次高調波
とについて、第４次高調波の発生に関して位相整合する
方向から前記非線形素子へ入射する光路および偏光方向
を設定する第２の光路・偏光方向設定手段と、を含んで
構成されることを特徴とする。Still another optical harmonic generator according to the present invention comprises (a) a non-linear optical element having a second-order non-linear optical effect and (b) two non-linear optical elements which are incident from the same direction. A laser light source that emits linearly polarized fundamental frequency light that is incident from a direction in which the generation of second harmonics is phase-matched when the polarization directions of the linearly polarized light are perpendicular to each other; and (c) Linearly polarized light emitted by the laser light source. The first half-wave plate relating to the fundamental frequency light that rotates the polarization direction of the fundamental frequency light by 45 °, and (d) the fundamental frequency light and the second harmonic emitted from the nonlinear element in the same direction, First optical path / polarization direction setting means for setting an optical path and a polarization direction incident on the non-linear element from a phase-matching direction with respect to generation of the third harmonic, and (e) exiting the non-linear element in the same direction. Second optical path / polarization direction setting means for setting an optical path and a polarization direction that are incident on the nonlinear element from a direction in which the fundamental frequency light and the third harmonic are phase-matched with respect to generation of the fourth harmonic. It is characterized in that it is configured to include.
【００１３】[0013]
【作用】本発明の構成によれば、まず、光源から発生す
る基本周波数の直線偏光を基にして、この基本周波数光
を２次の非線形光学効果を有する非線形光学素子に第２
次高調波の発生に関する位相整合方向から入力する。非
線形光学素子の内部では、電磁波としての光が有する電
界によって生じる非線形光学素子の電気分極の電界に関
する第２次成分を種として第２次高調波光を生成する。
生成された第２次高調波光は、位相整合条件により基本
周波数光の透過方向と同一の方向へ進行する。According to the structure of the present invention, first, based on the linearly polarized light of the fundamental frequency generated from the light source, the fundamental frequency light is secondarily converted into a nonlinear optical element having a second-order nonlinear optical effect.
Input from the phase matching direction for the generation of the second harmonic. Inside the nonlinear optical element, second-order harmonic light is generated by using as a seed the second-order component relating to the electric field of electric polarization of the nonlinear optical element generated by the electric field of light as an electromagnetic wave.
The generated second-harmonic light travels in the same direction as the transmission direction of the fundamental frequency light due to the phase matching condition.
【００１４】つぎに、非線形光学素子から同一方向に出
力された、透過した基本周波数光と生成された第２次高
調波光とを、必要に応じて夫々の偏光方向を１／２波長
板によって調整しつつミラーを使用して、基本周波数光
と第２次高調波光と和周波混合による第３次高調波光の
発生に関する位相整合方向から再び非線形光学素子へ入
力する。非線形光学素子の内部では、入力光に伴う電界
によって生じる電気分極の電界に関する第２次の成分の
内、位相整合条件を満たす、基本周波数光と第２次高調
波光との和周波である第３次高調波光が効率良く生成さ
れる。生成された第３次高調波光は、位相整合条件によ
り基本周波数光および第２次高調波光の透過方向と同一
の方向へ進行する。Next, the polarization directions of the transmitted fundamental frequency light and the generated second harmonic light output in the same direction from the non-linear optical element are adjusted by a half-wave plate as necessary. At the same time, using the mirror, the fundamental frequency light, the second harmonic light and the third harmonic light generated by the sum frequency mixing are input to the non-linear optical element again from the phase matching direction. Inside the nonlinear optical element, the third frequency which is the sum frequency of the fundamental frequency light and the second harmonic light, which satisfies the phase matching condition, among the second order components related to the electric field of the electric polarization generated by the electric field accompanying the input light. Second harmonic light is efficiently generated. The generated third harmonic light travels in the same direction as the transmission direction of the fundamental frequency light and the second harmonic light due to the phase matching condition.
【００１５】更に、非線形光学素子から同一方向に出力
された、透過した基本周波数光と生成された第３次高調
波光とを、必要に応じて夫々の偏光方向を１／２波長板
によって調整しつつ、ミラーを使用して基本周波数光と
第３次高調波光と和周波混合による第４次高調波光の発
生に関する位相整合方向から再度非線形光学素子へ入力
する。非線形光学素子の内部では、入力光に伴う電界に
よって生じる電気分極の電界に関する第２次の成分の
内、位相整合条件を満たす、基本周波数と第３次高調波
光との和周波である第４次高調波光が効率良く生成され
る。生成された第４次高調波光は、位相整合条件により
基本周波数光および第３次高調波光の透過方向と同一の
方向へ進行する。Furthermore, if necessary, the polarization directions of the transmitted fundamental frequency light and the generated third harmonic light output from the non-linear optical element in the same direction are adjusted by the half-wave plate. At the same time, a mirror is used to re-enter the non-linear optical element from the phase matching direction relating to the generation of the fundamental frequency light, the third harmonic light, and the fourth harmonic light by the sum frequency mixing. Inside the nonlinear optical element, among the second-order components related to the electric field of electric polarization generated by the electric field accompanying the input light, the fourth-order component, which is the sum frequency of the fundamental frequency and the third-order harmonic light, satisfying the phase matching condition. Harmonic light is efficiently generated. The generated fourth harmonic light travels in the same direction as the transmission direction of the fundamental frequency light and the third harmonic light due to the phase matching condition.
【００１６】[0016]
【実施例】本発明の実施例の説明に先立って、本発明で
利用している非線形光学現象の概要を述べておく。本発
明で利用する非線形光学現象は、光として伝播する電界
と磁界との内で、電界に対する物質の非線形応答の内で
最も低次の現象である２次の非線形光学応答であり、和
周波光・２倍高調波光の発生が該当する。これらの和周
波光・２倍高調波光の発生は、電界を印加された時に生
じる物質の電気分極の電界に対する２次の非線形成分に
由来するものである。本発明の光高調波発生器は、単一
の基本周波数光を出発点として、第２次高調波光、第３
次高調波光、および第４次高調波光を生成する装置であ
り、まず、基本周波数光から２倍高調波光の発生により
第２次高調波光を生成し、次いで和周波混合により順
次、第３次高調波、第４次高調波を生成する。以下、単
一の基本周波数光からの２倍高調波光の発生条件、およ
び２つの入力光による和周波光の発生条件を考察する。EXAMPLES Prior to the description of the examples of the present invention, an outline of the nonlinear optical phenomenon utilized in the present invention will be described. The non-linear optical phenomenon used in the present invention is a second-order non-linear optical response which is the lowest order phenomenon among the non-linear response of a substance to an electric field in an electric field and a magnetic field propagating as light.・ The occurrence of double harmonic light is applicable. The generation of these sum-frequency light and second-harmonic light is derived from the second-order nonlinear component with respect to the electric field of the electric polarization of the substance generated when the electric field is applied. The optical harmonic generator of the present invention uses a single fundamental frequency light as a starting point to generate a second harmonic light and a third harmonic light.
A device for generating second-harmonic light and fourth-harmonic light. First, second-harmonic light is generated by generating double-harmonic light from fundamental-frequency light, and then sequentially mixed by sum-frequency mixing to third-harmonic light. Wave, fourth harmonic is generated. Hereinafter, a generation condition of double harmonic light from a single fundamental frequency light and a generation condition of sum frequency light by two input lights will be considered.
【００１７】（１）２倍高調波の発生条件 単一の基本周波数光から２倍高調波生成により有効に第
２次高調波を発生するには、基本周波数光を入力する物
体を構成する物質が次の条件を満たす必要がある。(1) Generation Condition of Double Harmonics In order to effectively generate the second harmonic by generating double harmonics from a single fundamental frequency light, a substance constituting an object into which the fundamental frequency light is input. Must meet the following conditions.
【００１８】 反転対称性を有する結晶構造を有して
いないこと。Not having a crystal structure with inversion symmetry.
【００１９】反転対称性をもつ結晶では、２次の非線形
分極率が「０」であり、２次の非線形光学効果が発現し
ない。In a crystal having inversion symmetry, the second-order nonlinear polarizability is "0", and the second-order nonlinear optical effect does not appear.
【００２０】 ２倍高調波の発生に対して位相整合条
件を満たす手段が存在すること。物質中を伝播する基本
周波数光の電界成分を、 Ｅ0 ＝Ｅ（ω0 ）ｅｘｐ（ｊ（ｋ0 ・ｒ−ω0 ｔ））・・（１） ここで、ω0 ：基本周波数光の周波数 ｋ0 ：基本周波数光の波数ベクトル として、２倍高調波は発生した場合、基本周波数光の進
行方向と同一方向に進行するが、この進行方向に関して
次の式が成り立つことが位相整合条件である。There should be means for satisfying the phase matching condition for the generation of the second harmonic. The electric field component of the fundamental frequency light propagating in the substance is expressed by E 0 = E (ω 0 ) exp (j (k 0 · r−ω 0 t)) · (1) where ω 0 : Frequency k 0 : As a wave number vector of the fundamental frequency light, when a double harmonic wave is generated, it travels in the same direction as the traveling direction of the fundamental frequency light. is there.
【００２１】 ｎ（ω0 ）＝ｎ（２ω0 ）・・（２） ここで、ｎ（ω）：角速度ωに対する屈折率 この位相整合条件（（２）式）は、正常分散あるいは異
常分散を有する等方あるいは立方対称の結晶では実現で
きないが、対称性の低い結晶では複屈折を用いて、基本
周波数光の入力方向を調整することにより位相整合をと
ることができる。N (ω 0 ) = n (2ω 0 ) ··· (2) where n (ω) is the refractive index with respect to the angular velocity ω. The phase matching condition (equation (2)) is normal dispersion or abnormal dispersion. Although it cannot be realized by the crystal having isotropic or cubic symmetry, the crystal having low symmetry can achieve phase matching by adjusting the input direction of the fundamental frequency light by using birefringence.
【００２２】（２）和周波の発生条件 同一光路にて進行する２つの光から和周波生成により有
効に和周波を発生するには、２つの光を入力する物体を
構成する物質が次の条件を満たす必要がある。(2) Condition for generating sum frequency In order to effectively generate a sum frequency from two lights traveling in the same optical path by generating the sum frequency, the substance constituting the object that inputs the two lights must meet the following conditions. Need to meet.
【００２３】 反転対称性を有する結晶構造を有して
いないこと。Not having a crystal structure having inversion symmetry.
【００２４】反転対称性をもつ結晶では、２次の非線形
分極率が「０」であり、２次の非線形光学効果が発現し
ない。In a crystal having inversion symmetry, the second-order nonlinear polarizability is "0", and the second-order nonlinear optical effect does not appear.
【００２５】 和周波の発生に対して位相整合条件を
満たす手段が存在すること。There should be means for satisfying the phase matching condition for the generation of the sum frequency.
【００２６】物質中を伝播する基本周波数光の電界成分
を、 Ｅi ＝Ｅ（ωi ）ｅｘｐ（ｊ（ｋi ・ｒ−ωi ｔ））・・（３） ここで、ωi ：周波数 ｋi ：波数ベクトル ｉ：１ｏｒ２ として、和周波は発生した場合、基本周波数光の進行方
向と同一方向に進行するが、この進行方向に関して次の
式が成り立つことが位相整合条件である。The electric field component of the fundamental frequency light propagating through the substance is represented by E i = E (ω i ) exp (j (k i · r−ω i t)) ·· (3) where ω i is the frequency When the sum frequency is generated as k i : wave number vector i: 1or2, the sum frequency travels in the same direction as the traveling direction of the fundamental frequency light, and the phase matching condition is that the following expression is satisfied in this traveling direction.
【００２７】 ω1 ｎ（ω1 ）＋ω2 ｎ（ω2 ） ＝（ω1 ＋ω2 ）ｎ（ω1 ＋ω2 ）・・（４） ここで、ｎ（ω）：角速度ωに対する屈折率 この位相整合条件（（４）式）は、正常分散あるいは異
常分散を有する等方あるいは立方対称の結晶では実現で
きないが、対称性の低い結晶では複屈折を用いて、基本
周波数光の入力方向を調整することにより位相整合をと
ることができる。Ω 1 n (ω 1 ) + ω 2 n (ω 2 ) = (ω 1 + ω 2 ) n (ω 1 + ω 2 ) · (4) where n (ω): refractive index for angular velocity ω The phase matching condition (equation (4)) cannot be realized with an isotropic or cubic symmetric crystal having normal dispersion or anomalous dispersion, but in a crystal with low symmetry, birefringence is used to adjust the input direction of the fundamental frequency light. By doing so, phase matching can be achieved.
【００２８】和周波混合にあたっては、入力する２つの
光の偏光方向が互いに平行な場合をタイプＩと呼び、互
いに垂直な場合をタイプＩＩと呼ぶ。２倍高調波の発生
にあったても、このタイプの呼称を拡張して使用する。
なお、以下の実施例の説明にあたっては、座標系は光学
主軸系を使用する。In the case of sum frequency mixing, the case where the polarization directions of two input lights are parallel to each other is called type I, and the case where they are perpendicular to each other is called type II. This type of designation is expanded and used even when there is a generation of double harmonics.
In the following description of the embodiments, the coordinate system uses an optical principal axis system.
【００２９】（第１実施例）本実施例は、非線形光学素
子としてＬｉＢ3 Ｏ5 結晶（結晶構造：ｍｍ２、以後、
ＬＢＯ結晶と呼ぶ）を、基本周波数光としてＮｄ：ＹＡ
Ｇレーザの発生する波長＝１０６４ｎｍのレーザ光を用
い、第２次高調波光の生成および第３高調波光の生成を
タイプＩで行ったものである。(First Example) In this example, a LiB 3 O 5 crystal (crystal structure: mm 2, hereinafter referred to as a nonlinear optical element) was used.
LBO crystal) is used as the fundamental frequency light in Nd: YA
Generation of the second harmonic light and generation of the third harmonic light are performed by the type I using the laser light having a wavelength of 1064 nm generated by the G laser.
【００３０】図１は、本実施例の装置の構成を示す。こ
の装置は、非線形光学素子１１０と、非線形光学素子１
１０のｚ軸（すなわち、光学主軸系において最も屈折率
の大きな方向を示す軸）に平行な偏光方向を有し、波長
＝１０６４ｎｍのレーザ光を、タイプＩによる第２次高
調波光の発生に関して位相整合する方向（光学主軸系
で、θ＝９０゜、φ＝１２゜）へ出力するＮｄ：ＹＡＧ
レーザを含む光源２１０と、非線形光学素子１１０から
出力される第２次高調波光とこの第２高調波と同一光路
で出力される透過した基本周波数光とに対してタイプＩ
で和周波混合による第３次高調波光の発生に関する位相
整合方向（θ＝９０゜、φ＝３８．４゜）から非線形光
学素子１１０に入力する光路を設定するミラー３１１お
よびミラー３１２と、この光路中に配置された基本周波
数光の偏光方向は偏光せずに第２次高調波光のみの偏光
方向を９０゜回転する第２高調波光に関する１／２波長
板４１０と、非線形光学素子１１０から出力される第３
次高調波光とこの第３次高調波光と同一光路で出力され
る基本周波数光および第２次高調波光とについて第３次
高調波光のみを反射するミラー３１５と、ミラー３１５
を透過した基本周波数光と第２次高調波光とについて第
２次高調波光のみを反射するミラー３１６と、から構成
される。FIG. 1 shows the configuration of the apparatus of this embodiment. This device includes a nonlinear optical element 110 and a nonlinear optical element 1.
A laser beam having a polarization direction parallel to the z axis of 10 (that is, the axis indicating the direction of the highest refractive index in the optical principal axis system) and having a wavelength of 1064 nm is phased with respect to the generation of the second harmonic light of type I. Nd: YAG for output in the matching direction (optical spindle system, θ = 90 °, φ = 12 °)
Type I is applied to the light source 210 including a laser, the second harmonic light output from the nonlinear optical element 110, and the transmitted fundamental frequency light output in the same optical path as the second harmonic light.
, A mirror 311 and a mirror 312 that set an optical path to be input to the nonlinear optical element 110 from the phase matching direction (θ = 90 °, φ = 38.4 °) related to the generation of the third harmonic light by the sum frequency mixing, and this optical path. The polarization direction of the fundamental frequency light disposed therein is not polarized, but is output from the half-wave plate 410 for the second harmonic light that rotates the polarization direction of only the second harmonic light by 90 ° and the nonlinear optical element 110. 3rd
A mirror 315 that reflects only the third harmonic light of the fundamental harmonic light and the second harmonic light that is output in the same optical path as the third harmonic light and the third harmonic light, and a mirror 315.
Of the fundamental frequency light that has passed through the second harmonic light and the mirror 316 that reflects only the second harmonic light.
【００３１】この装置では、まず、光源２１０から、Ｎ
ｄ：ＹＡＧレーザのレーザ発振による、波長＝１０６４
ｎｍのレーザ光の内、線形光学素子１１０のｚ軸方向に
平行な偏光方向を有する直線偏光成分を選択されて基本
周波数光として出力させる。この出力された基本周波数
光は、この基本周波数光の波長および偏光方向について
タイプＩで位相整合する方向（光学主軸系において、θ
＝９０゜、φ＝１２゜）から、非線形光学素子１１０で
あるＬＢＯ結晶へ入力される。非線形光学素子１１０に
おいて、基本周波数光の担った電界に応答して電界に関
して２次の成分を有する電気分極が生じる。この電気分
極を種として、位相整合条件に従い、基本周波数光と同
一方向に進行する第２次高調波が発生し、透過する基本
周波数光とともに非線形光学素子１１０から出力され
る。ここで、発生した第２次高調波の偏光方向は、透過
した基本周波数光の偏光方向とは垂直となっている。In this apparatus, first, from the light source 210,
Wavelength = 1064 by laser oscillation of d: YAG laser
A linearly polarized light component having a polarization direction parallel to the z-axis direction of the linear optical element 110 is selected from the laser light of nm and is output as the fundamental frequency light. The output fundamental frequency light has a type I phase-matching direction (θ in the optical main axis system) with respect to the wavelength and polarization direction of the fundamental frequency light.
= 90 °, φ = 12 °), and is input to the LBO crystal that is the nonlinear optical element 110. In the nonlinear optical element 110, electric polarization having a quadratic component with respect to the electric field occurs in response to the electric field carried by the fundamental frequency light. Using this electric polarization as a seed, according to the phase matching condition, a second harmonic that travels in the same direction as the fundamental frequency light is generated, and is output from the nonlinear optical element 110 together with the fundamental frequency light that is transmitted. Here, the polarization direction of the generated second harmonic is perpendicular to the polarization direction of the transmitted fundamental frequency light.
【００３２】次に、非線形光学素子１１０から同一方向
へ出力された、上記の基本周波数光と第２次高調波光と
に対して、ミラー３１１およびミラー３１２を使用し
て、タイプＩで和周波混合による第３次高調波光の発生
に関する位相整合方向（θ＝９０゜、φ＝３８．４゜）
から非線形光学素子１１０に入力する光路を設定すると
ともに、この光路中に配置された第２高調波光に関する
１／２波長板を使用して、基本周波数光の偏光方向は偏
光せずに第２次高調波光のみの偏光方向を９０゜回転し
て双方の偏光方向をｚ軸と平行とし、タイプＩの位相整
合条件を整える。こうして、非線形光学素子１１０に同
時に入力した基本周波数光と第２次高調波光とは、非線
形光学素子１１０の非線形光学応答（入力光の電界に対
する２次の電気分極成分の発生）によって、和周波混合
され第３次高調波光が生成され、透過する基本周波数光
および第２次高調波光とともに非線形光学素子１１０か
ら出力される。ここで、発生した第３次高調波の偏光方
向は、透過した基本周波数光および第２次高調波の偏光
方向とは垂直となっている。Next, with respect to the fundamental frequency light and the second harmonic light output in the same direction from the non-linear optical element 110, a mirror 311 and a mirror 312 are used to perform a sum frequency mixing of type I. Phase matching direction (θ = 90 °, φ = 38.4 °) for the generation of third harmonic light by
The optical path to be input to the nonlinear optical element 110 from the optical path is set, and the half-wave plate for the second harmonic light arranged in the optical path is used to polarize the polarization direction of the fundamental frequency light to the second order. The polarization direction of the harmonic light alone is rotated by 90 ° so that both polarization directions are parallel to the z axis, and the type I phase matching condition is adjusted. Thus, the fundamental-frequency light and the second-harmonic light that are simultaneously input to the nonlinear optical element 110 are sum-frequency mixed by the nonlinear optical response of the nonlinear optical element 110 (generation of a secondary electrical polarization component with respect to the electric field of the input light). The third-order harmonic light is generated and is output from the nonlinear optical element 110 together with the fundamental frequency light and the second-order harmonic light that are transmitted. Here, the polarization direction of the generated third-order harmonic wave is perpendicular to the polarization directions of the transmitted fundamental frequency light and the second-order harmonic wave.
【００３３】次いで、非線形光学素子１１０から同一方
向へ出力された、上記の基本周波数光と第２次高調波光
と第３次高調波とを、これらの光の光路上に配置された
ミラー３１５およびミラー３１６を使用して分離するこ
とにより、第２次高調波と第３次高調波を同時に得るこ
とができる。Next, the fundamental frequency light, the second harmonic light, and the third harmonic light, which are output from the nonlinear optical element 110 in the same direction, are reflected by the mirror 315 and the mirror 315 arranged on the optical paths of these lights. By using the mirror 316 to separate, the second harmonic and the third harmonic can be obtained at the same time.
【００３４】（第２実施例）本実施例は、第１実施例と
同様に、非線形光学素子としてＬｉＢ3 Ｏ5 結晶（結晶
構造：ｍｍ２、以後、ＬＢＯ結晶と呼ぶ）を、基本周波
数光としてＮｄ：ＹＡＧレーザの発生する波長＝１０６
４ｎｍのレーザ光を用い、第２次高調波光の生成および
第３高調波光の生成をタイプＩで行ったものである。(Second Embodiment) In the present embodiment, as in the first embodiment, LiB 3 O 5 crystal (crystal structure: mm2, hereinafter referred to as LBO crystal) is used as a fundamental frequency light as a nonlinear optical element. Wavelength generated by Nd: YAG laser = 106
The generation of the second harmonic light and the generation of the third harmonic light are performed by the type I using the laser light of 4 nm.
【００３５】図２は、本実施例の装置の構成を示す。こ
の装置は、第１実施例の装置について非線形光学素子で
あるＬＢＯ結晶の切り出し角度を変えて装置の小型化を
図ったものであり、非線形光学素子１２０と非線形光学
素子１２０のｚ軸（すなわち、光学主軸系において最も
屈折率の大きな方向を示す軸）に平行な偏光方向を有
し、波長＝１０６４ｎｍのレーザ光を、タイプＩによる
第２次高調波光の発生に関して位相整合する方向（光学
主軸系でθ＝９０゜、φ＝１２゜）へ出力するＮｄ：Ｙ
ＡＧレーザを含む光源２２０と、非線形光学素子１２０
から出力される第２次高調波光とこの第２高調波と同一
光路で出力される透過した基本周波数光とに対してタイ
プＩで和周波混合による第３次高調波光の発生に関する
位相整合方向 （θ＝９０゜、φ＝３８．４゜）から非
線形光学素子１２０に入力する光路を設定するミラー３
２１およびミラー３２２と、この光路中に配置された基
本周波数光の偏光方向は偏光せずに第２次高調波光のみ
の偏光方向を９０゜回転する第２高調波光に関する１／
２波長板４２０と、非線形光学素子１２０から出力され
る第３次高調波光とこの第３次高調波光と同一光路で出
力される基本周波数光および第２次高調波光とについて
第３次高調波光のみを反射するミラー３２５と、ミラー
３２５を透過した基本周波数光と第２次高調波光とにつ
いて第２次高調波光のみを反射するミラー３２６と、か
ら構成される。この装置の動作は、第１実施例の装置と
全く同一である。FIG. 2 shows the structure of the apparatus of this embodiment. This apparatus is an apparatus for reducing the size of the apparatus of the first embodiment by changing the cut-out angle of the LBO crystal which is the nonlinear optical element, and the nonlinear optical element 120 and the z-axis of the nonlinear optical element 120 (that is, A direction in which a laser beam having a wavelength of 1064 nm is phase-matched with respect to generation of second-harmonic light of type I (optical main axis system) having a polarization direction parallel to an axis having the largest refractive index in the optical main axis system. Output to θ = 90 °, φ = 12 °) Nd: Y
A light source 220 including an AG laser and a nonlinear optical element 120
Phase matching direction for the generation of third harmonic light by type I sum frequency mixing with respect to the second harmonic light output from and the transmitted fundamental frequency light output in the same optical path as this second harmonic ( Mirror 3 for setting an optical path for inputting to the nonlinear optical element 120 from θ = 90 °, φ = 38.4 °)
21 and the mirror 322, and the polarization direction of the fundamental frequency light disposed in this optical path is not polarized, and the polarization direction of only the second harmonic light is rotated by 90 °.
Regarding the third-order harmonic light output from the two-wave plate 420, the nonlinear optical element 120, and the fundamental frequency light and the second-order harmonic light output in the same optical path as the third-order harmonic light, only the third-order harmonic light And a mirror 326 that reflects only the second harmonic light of the fundamental frequency light and the second harmonic light transmitted through the mirror 325. The operation of this device is exactly the same as that of the device of the first embodiment.
【００３６】（第３実施例）本実施例は、非線形光学素
子として第１実施例と同様にＬｉＢ3 Ｏ5 結晶（結晶構
造：ｍｍ２、以後、ＬＢＯ結晶と呼ぶ）を、基本周波数
光としてＮｄ：ＹＡＧレーザの発生する波長＝１０６４
ｎｍのレーザ光を用い、第２次高調波光の生成および第
３高調波光の生成をタイプＩＩで行ったものである。(Third Embodiment) In this embodiment, as a nonlinear optical element, LiB 3 O 5 crystal (crystal structure: mm2, hereinafter referred to as LBO crystal) is used as Nd as a fundamental frequency light as in the first embodiment. : Wavelength generated by YAG laser = 1064
The second harmonic light and the third harmonic light are generated by the type II using the laser light of nm.
【００３７】図３は、本実施例の装置の構成を示す。こ
の装置は、非線形光学素子１３０と非線形光学素子１３
０のｘ軸（すなわち、光学主軸系において最小の屈折率
の大きな方向を示す軸）に平行な偏光方向を有し、波長
＝１０６４ｎｍのレーザ光を、タイプＩＩによる第２次
高調波光の発生に関して位相整合する方向（光学主軸系
でθ＝１５．５゜、φ＝９０゜）へ出力するＮｄ：ＹＡ
Ｇレーザを含む光源２３０と、この光源２３０から出力
された直線偏光の偏光方向を４５゜回転させる基本周波
数光に関する１／２波長板４３１と、非線形光学素子１
３０から出力される第２次高調波光とこの第２高調波と
同一光路で出力される透過した基本周波数光とに対して
タイプＩＩで和周波混合による第３次高調波光の発生に
関する位相整合方向（θ＝４１゜、φ＝９０゜）から非
線形光学素子１３０に入力する光路を設定するミラー３
３１およびミラー３３２と、この光路中に配置された基
本周波数光の偏光方向は偏光せずに第２次高調波光のみ
の偏光方向を９０゜回転する第２高調波光に関する１／
２波長板４３２と、やはりこの光路中に配置された第２
次高調波光の偏光方向は偏光せずに基本周波数光のみの
偏光方向を４５゜回転する基本周波数光に関する１／２
波長板４３３と、非線形光学素子１３０から出力される
第３次高調波光とこの第３次高調波光と同一光路で出力
される基本周波数光および第２次高調波光とについて第
３次高調波光のみを反射するミラー３３５と、ミラー３
３５を透過した基本周波数光と第２次高調波光とについ
て第２次高調波光のみを反射するミラー３３６と、から
構成される。FIG. 3 shows the configuration of the apparatus of this embodiment. This apparatus includes a nonlinear optical element 130 and a nonlinear optical element 13.
Regarding the generation of the second harmonic light by the type II, the laser light having the polarization direction parallel to the x axis of 0 (that is, the axis indicating the direction of the minimum refractive index in the optical principal axis system) and having the wavelength of 1064 nm is used. Nd: YA that outputs in the phase matching direction (θ = 15.5 °, φ = 90 ° in the optical spindle system)
A light source 230 including a G laser, a half-wave plate 431 for fundamental frequency light that rotates the polarization direction of the linearly polarized light output from the light source 230 by 45 °, and the nonlinear optical element 1
Phase matching direction for generation of third harmonic light by type II sum frequency mixing with respect to second harmonic light output from H.30 and transmitted fundamental frequency light output in the same optical path as the second harmonic Mirror 3 for setting the optical path from (θ = 41 °, φ = 90 °) to the nonlinear optical element 130
31 and the mirror 332, the polarization direction of the fundamental frequency light disposed in this optical path is not polarized, and the polarization direction of only the second harmonic light is rotated by 90 °.
A two-wave plate 432 and a second wave plate 432 also arranged in this optical path.
The polarization direction of the second-harmonic light is not polarized, and the polarization direction of only the fundamental frequency light is rotated by 45 °.
Regarding the third harmonic light output from the wave plate 433, the non-linear optical element 130, and the fundamental frequency light and the second harmonic light output in the same optical path as the third harmonic light, only the third harmonic light is output. Reflecting mirror 335 and mirror 3
And a mirror 336 that reflects only the second-harmonic light of the fundamental-frequency light and the second-harmonic light that have passed through 35.
【００３８】この装置では、まず、光源２３０から、Ｎ
ｄ：ＹＡＧレーザのレーザ発振による、波長＝１０６４
ｎｍのレーザ光の内、線形光学素子１３０のｘ軸方向に
平行な偏光方向を有する直線偏光成分を選択されて基本
周波数光として出力される。光源２３０から出力された
基本周波数光は、基本周波数光に関する１／２波長板４
３１を経由することにより偏光方向について４５゜回転
が施され、この基本周波数光の波長および偏光方向につ
いてタイプＩＩで位相整合する方向（光学主軸系におい
て、θ＝１５．５゜、φ＝９０゜から、非線形光学素子
１３０であるＬＢＯ結晶へ入力される。非線形光学素子
１３０において、基本周波数光の担った電界に応答して
電界に関して２次の成分を有する電気分極が生じる。こ
の電気分極を種として、位相整合条件に従い、基本周波
数光と同一方向に進行する第２次高調波が発生し、透過
する基本周波数光とともに非線形光学素子１３０から出
力される。ここで、発生した第２次高調波の偏光方向
は、ｘ軸に対して垂直となっている。In this device, first, from the light source 230,
Wavelength = 1064 by laser oscillation of d: YAG laser
The linearly polarized light component having a polarization direction parallel to the x-axis direction of the linear optical element 130 is selected from the laser light of nm and is output as the fundamental frequency light. The fundamental frequency light output from the light source 230 is the half-wave plate 4 relating to the fundamental frequency light.
The polarization direction is rotated by 45 ° by way of 31, and the direction and the type II phase matching are performed with respect to the wavelength and polarization direction of the fundamental frequency light (θ = 15.5 °, φ = 90 ° in the optical main axis system). Is input to the LBO crystal which is the non-linear optical element 130. In the non-linear optical element 130, electric polarization having a quadratic component with respect to the electric field occurs in response to the electric field carried by the fundamental frequency light. As a result, according to the phase matching condition, a second-order harmonic wave that travels in the same direction as the fundamental-frequency light is generated and is output from the nonlinear optical element 130 together with the transmitted fundamental-frequency light. The polarization direction of is perpendicular to the x-axis.
【００３９】次に、非線形光学素子１３０から同一方向
へ出力された、上記の基本周波数光と第２次高調波光と
に対して、ミラー３３１およびミラー３３２を使用し
て、タイプＩで和周波混合による第３次高調波光の発生
に関する位相整合方向（θ＝４１゜、φ＝９０゜）から
非線形光学素子１３０に入力する光路を設定するととも
に、この光路中に配置された第２高調波光に関する１／
２波長板４３２を使用して基本周波数光の偏光方向は変
化させずに第２次高調波光のみの偏光方向を９０゜回転
し、また、やはりこの光路中に配置された基本周波数光
に関する１／２波長板４３３を使用して第２次高調波光
の偏光方向は変化させずに基本周波数光のみの偏光方向
を４５゜回転させてｘ軸に平行とし、タイプＩＩの位相
整合条件を整える。こうして、非線形光学素子１３０に
同時に入力した基本周波数光と第２次高調波光とは、非
線形光学素子１３０の非線形光学応答（入力光の電界に
対する２次の電気分極成分の発生）によって、和周波混
合され第３次高調波光が生成され、透過する基本周波数
光および第２次高調波光とともに非線形光学素子１３０
から出力される。ここで、発生した第３次高調波の偏光
方向は、透過した基本周波数光の偏光方向と平行となっ
ている。Next, using the mirror 331 and the mirror 332 for the fundamental frequency light and the second harmonic light output from the non-linear optical element 130 in the same direction, the sum frequency mixing of type I is performed. The optical path for inputting to the nonlinear optical element 130 from the phase matching direction (θ = 41 °, φ = 90 °) related to the generation of the third harmonic light by /
By using the two-wave plate 432, the polarization direction of the fundamental frequency light is not changed and the polarization direction of only the second harmonic light is rotated by 90 °. By using the two-wave plate 433, the polarization direction of the second harmonic light is not changed and the polarization direction of only the fundamental frequency light is rotated by 45 ° so as to be parallel to the x-axis, and the phase matching condition of type II is prepared. Thus, the fundamental frequency light and the second-harmonic light that are simultaneously input to the nonlinear optical element 130 are mixed at a sum frequency due to the nonlinear optical response of the nonlinear optical element 130 (the generation of a secondary electrical polarization component with respect to the electric field of the input light). The non-linear optical element 130 is generated together with the fundamental frequency light and the second harmonic light that generate and transmit the third harmonic light.
Is output from. Here, the polarization direction of the generated third harmonic is parallel to the polarization direction of the transmitted fundamental frequency light.
【００４０】次いで、非線形光学素子１３０から同一方
向へ出力された、上記の基本周波数光と第２次高調波光
と第３次高調波とを、これらの光の光路上に配置された
ミラー３３５およびミラー３３６を使用して分離するこ
とにより、第２次高調波と第３次高調波を同時に得るこ
とができる。Then, the fundamental frequency light, the second harmonic light, and the third harmonic light, which are output from the nonlinear optical element 130 in the same direction, are reflected by the mirror 335 and the mirror 335 arranged on the optical paths of these lights. By using the mirror 336 for separation, the second harmonic and the third harmonic can be obtained at the same time.
【００４１】（第４実施例）本実施例は、非線形光学素
子としてＬｉＢ3 Ｏ5 結晶（結晶構造：ｍｍ２、以後、
ＬＢＯ結晶と呼ぶ）を、基本周波数光としてＮｄ：ＹＡ
Ｇレーザの発生する波長＝１０６４ｎｍのレーザ光を用
い、第２次高調波光の生成、第３高調波光の生成、およ
び第４高調波の生成をタイプＩで行ったものである。(Fourth Embodiment) In this embodiment, as a nonlinear optical element, a LiB 3 O 5 crystal (crystal structure: mm2, hereinafter,
LBO crystal) is used as the fundamental frequency light in Nd: YA
Using the laser light of the wavelength = 1064 nm generated by the G laser, the generation of the second harmonic light, the generation of the third harmonic light, and the generation of the fourth harmonic light are performed by type I.
【００４２】図４は、本実施例の装置の構成を示す。こ
の装置は、第１実施例の装置に対して更にタイプＩでの
基本周波数光と第３次高調波光との和周波混合を実施さ
せるようにしたものであり、非線形光学素子１１０と非
線形光学素子１１０のｚ軸（すなわち、光学主軸系にお
いて最も屈折率の大きな方向を示す軸）に平行な偏光方
向を有し、波長＝１０６４ｎｍのレーザ光を、タイプＩ
による第２次高調波光の発生に関して位相整合する方向
（光学主軸系でθ＝９０゜、φ＝１２゜）へ出力するＮ
ｄ：ＹＡＧレーザを含む光源２１０と、非線形光学素子
１１０から出力される第２次高調波光とこの第２高調波
と同一光路で出力される透過した基本周波数光とに対し
てタイプＩで和周波混合による第３次高調波光の発生に
関する位相整合方向（θ＝９０゜、φ＝３８．４゜）か
ら非線形光学素子１１０に入力する光路を設定するミラ
ー３１１およびミラー３１２と、この光路中に配置され
た基本周波数光の偏光方向は偏光せずに第２次高調波光
のみの偏光方向を９０゜回転する第２高調波光に関する
１／２波長板４１０と、非線形光学素子１１０から出力
される第３次高調波光とこの第３高調波と同一光路で出
力される透過した基本周波数光とに対してタイプＩで和
周波混合による第４次高調波光の発生に関する位相整合
方向（θ＝９０゜、φ＝５７゜）から非線形光学素子１
１０に入力する光路を設定するミラー３４１およびミラ
ー３４２と、この光路中に配置された基本周波数光の偏
光方向は偏光せずに第２次高調波光のみの偏光方向を９
０゜回転する第３次高調波光に関する１／２波長板４４
０と、非線形光学素子１１０から出力される第４次高調
波光と、この第４次高調波光と同一光路で出力される基
本周波数光、第２次高調波光および第３次高調波光とに
ついて第４次高調波光のみを反射するミラー３４４と、
基本周波数光、第２次高調波光および第３次高調波光と
について第３次高調波光のみを反射するミラー３４５
と、ミラー３４５を透過した基本周波数光と第２次高調
波光とについて第２次高調波光のみを反射するミラー３
４６と、から構成される。FIG. 4 shows the structure of the apparatus of this embodiment. This apparatus is configured to further perform sum frequency mixing of the fundamental frequency light and the third harmonic light of type I with respect to the apparatus of the first embodiment, and the nonlinear optical element 110 and the nonlinear optical element. A laser beam with a wavelength of 1064 nm having a polarization direction parallel to the z-axis of 110 (that is, the axis indicating the direction with the largest refractive index in the optical principal axis system) is emitted as
N in the direction of phase matching (θ = 90 °, φ = 12 ° in the optical spindle system) with respect to the generation of the second harmonic light by
A light source 210 including a d: YAG laser, a second harmonic light output from the non-linear optical element 110, and a transmitted fundamental frequency light output in the same optical path as the second harmonic, with a type I sum frequency. A mirror 311 and a mirror 312 for setting an optical path to be input to the nonlinear optical element 110 from a phase matching direction (θ = 90 °, φ = 38.4 °) related to generation of third-harmonic light by mixing, and arranged in this optical path. The polarization direction of the fundamental frequency light is not polarized, and the half-wave plate 410 for the second harmonic light that rotates the polarization direction of only the second harmonic light by 90 °, and the third output from the nonlinear optical element 110 Phase-matching direction (θ = 90 °, θ = 90 °, with respect to generation of fourth harmonic light by type I sum frequency mixing with respect to the second harmonic light and the transmitted fundamental frequency light output in the same optical path as the third harmonic = Non-linear optical element 1 from 57 °)
The mirror 341 and the mirror 342 for setting the optical path to be input to the optical path 10 and the polarization direction of the fundamental frequency light arranged in this optical path are not polarized, and the polarization direction of only the second harmonic light is set to 9
Half-wave plate 44 for third harmonic light that rotates 0 °
0, the fourth harmonic light output from the nonlinear optical element 110, and the fundamental frequency light, the second harmonic light, and the third harmonic light output in the same optical path as the fourth harmonic light. A mirror 344 that reflects only the next harmonic light,
Mirror 345 that reflects only the third harmonic light of the fundamental frequency light, the second harmonic light, and the third harmonic light
And a mirror 3 that reflects only the second harmonic light of the fundamental frequency light and the second harmonic light transmitted through the mirror 345.
And 46.
【００４３】この装置では、第３次高調波光の生成まで
は第１実施例と全く同一の動作で行われる。第３次高調
波光の生成に引き続き、非線形光学素子１１０から同一
方向へ出力された、上記の基本周波数光と第３次高調波
光とに対して、ミラー３４１およびミラー３４２を使用
して、タイプＩで和周波混合による第４次高調波光の発
生に関する位相整合方向（θ＝９０゜、φ＝５７゜）か
ら非線形光学素子１１０に入力する光路を設定するとと
もに、この光路中に配置された第３高調波光に関する１
／２波長板を使用して基本周波数光の偏光方向は変化さ
せずに第３次高調波光のみの偏光方向を９０゜回転して
双方の偏光方向をｚ軸と平行とし、タイプＩの位相整合
条件を整える。こうして、非線形光学素子１１０に同時
に入力した基本周波数光と第３次高調波光とは、非線形
光学素子１１０の非線形光学応答（入力光の電界に対す
る２次の電気分極成分の発生）によって、和周波混合さ
れ第４次高調波光が生成され、透過する基本周波数光、
第２次高調波光および第３次高調波光とともに非線形光
学素子１１０から出力される。ここで、発生した第３次
高調波の偏光方向は、透過した基本周波数光の偏光方向
とは垂直となっている。In this device, the same operation as in the first embodiment is performed until the generation of the third harmonic light. Subsequent to the generation of the third-order harmonic light, the mirror 341 and the mirror 342 are used for the type I light with respect to the fundamental frequency light and the third-order harmonic light output from the nonlinear optical element 110 in the same direction. Then, the optical path to be input to the non-linear optical element 110 from the phase matching direction (θ = 90 °, φ = 57 °) related to the generation of the fourth harmonic light by the sum frequency mixing is set, and the third optical path disposed in this optical path is set. 1 regarding harmonic light
Using a / 2 wavelength plate, the polarization direction of the fundamental frequency light is not changed and the polarization direction of only the third harmonic light is rotated by 90 degrees to make both polarization directions parallel to the z-axis and type I phase matching. Adjust the conditions. In this way, the fundamental frequency light and the third-order harmonic light that are simultaneously input to the nonlinear optical element 110 are sum frequency mixed due to the nonlinear optical response of the nonlinear optical element 110 (generation of a secondary electrical polarization component with respect to the electric field of the input light). The fourth-harmonic light is generated and transmitted through the fundamental frequency light,
It is output from the non-linear optical element 110 together with the second harmonic light and the third harmonic light. Here, the polarization direction of the generated third harmonic wave is perpendicular to the polarization direction of the transmitted fundamental frequency light.
【００４４】次いで、非線形光学素子１１０から同一方
向へ出力された、上記の基本周波数光と第２次高調波光
と第３次高調波光と第４次高調波光とを、これらの光の
光路上に配置されたミラー３４４、ミラー３４５および
ミラー３４６を使用して分離することにより、第２次高
調波光と第３次高調波光と第４次高調波光を同時にかつ
独立に得ることができる。Next, the fundamental frequency light, the second harmonic light, the third harmonic light, and the fourth harmonic light, which are output from the nonlinear optical element 110 in the same direction, are placed on the optical paths of these lights. Separation using the arranged mirror 344, mirror 345, and mirror 346 makes it possible to obtain the second harmonic light, the third harmonic light, and the fourth harmonic light simultaneously and independently.
【００４５】本発明は上記実施例に限定されるものでは
なく様々な変形が可能である。例えば、上記実施例１〜
４では第２次高調波光の生成、第３次高調波光の生成、
および第４次高調波光の生成は同一のタイプを用いて実
施し、光路の設定を同一の平面上で行ったが、夫々の高
調波光の生成は、タイプＩあるいはタイプＩＩのいずれ
で実施してもよく、一つの装置でタイプＩとタイプＩＩ
とを混在して使用しても光高調波発生器を構成すること
もできる。このように、タイプＩとタイプＩＩとを混在
させた場合には、全ての光路を同一平面上に設定するこ
とは不可能になる。The present invention is not limited to the above embodiment, but various modifications can be made. For example, the above Examples 1 to
In 4, the generation of the second harmonic light, the generation of the third harmonic light,
The generation of the fourth harmonic light was performed using the same type, and the optical path was set on the same plane. However, the generation of each harmonic light was performed using either type I or type II. Well, type I and type II in one device
It is also possible to construct an optical harmonic generator by mixing and using. In this way, when type I and type II are mixed, it is impossible to set all optical paths on the same plane.
【００４６】また、上記の実施例では、非線形光学素子
としてＬＢＯ結晶を使用したが、これ以外にβ−ＢａＢ
2 Ｏ4 （ＢＢＯ）結晶、ＫＨ2 ＰＯ4 （ＫＤＰ）結晶、
ＫＤ2 ＰＯ4 （ＫＤ* Ｐ）結晶、ＫＴｉＯＰＯ4 （ＫＴ
Ｐ）結晶、またはＬｉＩＯ3結晶などを使用してもよ
い。ただし、位相整合方向および高調波・和周波発生率
は夫々の結晶によって異なるので、上記実施例とは異な
る偏光方向・光路設定を実施する必要がある。たとえ
ば、ＢＢＯ結晶を使用した場合、上記実施例と同一波長
（１０６４ｎｍ）の基本周波数光を使用して第３次高調
波光までを発生させるにあったては、タイプＩではタイ
プＩＩの約２倍の高調波発生効率を有するので、タイプ
Ｉで高調波生成を実施することが望ましい。この、ＢＢ
Ｏ結晶でのタイプＩによる高調波発生の位相整合方向
は、第２次高調波発生で（θ＝２３゜、φ＝０゜）であ
り、第３次高調波発生で（θ＝３１゜、φ＝０゜）であ
る。In the above embodiment, the LBO crystal is used as the non-linear optical element, but in addition to this, β-BaB is used.
2 O 4 (BBO) crystal, KH 2 PO 4 (KDP) crystal,
KD 2 PO 4 (KD * P) crystal, KTiOPO 4 (KT
P) crystal, LiIO 3 crystal or the like may be used. However, since the phase matching direction and the harmonic / sum frequency generation rate differ depending on each crystal, it is necessary to set the polarization direction / optical path different from that in the above-mentioned embodiment. For example, when a BBO crystal is used, in the case of generating up to the third harmonic light using the fundamental frequency light of the same wavelength (1064 nm) as in the above embodiment, the type I is about twice as much as the type II. It is desirable to implement type I harmonic generation because it has a harmonic generation efficiency of This, BB
The phase matching direction of the type I harmonic generation in the O crystal is the second harmonic generation (θ = 23 °, φ = 0 °) and the third harmonic generation (θ = 31 °, φ = 0 °).
【００４７】[0047]
【発明の効果】以上、詳細に説明した通り、本発明の光
高調波発生器によれば、単一の非線形光学素子を使用し
て、まず、この非線形光学素子に入力する直線偏光の
偏光方向と非線形光学素子を形成する結晶の光学主軸の
方向に応じて、第２次高調波の発生に関する位相整合方
向から非線形光学素子へ直線偏光を入力して、第２次高
調波を生成し、更に、同一方向に出力される、基本周
波数光と第ｎ次高調波光とを、この非線形光学素子に夫
々の偏光方向を調整後、第（ｎ＋１）次高調波光の発生
に関する位相整合方向から入力して、第（ｎ＋１）次高
調波光を生成しているので、３次以上の高調波生成にあ
たって、非線形光学素子の動作安定化のための温度調節
の対象が一つの結晶のみで済み、単一の非線形光学素子
の簡単な構成で、かつ容易に安定動作制御可能な装置を
廉価に実現できる。As described above in detail, according to the optical harmonic generator of the present invention, a single nonlinear optical element is used, and first, the polarization direction of the linearly polarized light input to the nonlinear optical element is input. According to the direction of the optical principal axis of the crystal forming the nonlinear optical element, linearly polarized light is input to the nonlinear optical element from the phase matching direction related to the generation of the second harmonic, and the second harmonic is generated. , The fundamental frequency light and the nth harmonic light output in the same direction are input to the non-linear optical element from the phase matching direction related to the generation of the (n + 1) th harmonic light, after adjusting the respective polarization directions. , The (n + 1) th order harmonic light is generated, so when generating the 3rd or higher order harmonics, only one crystal needs to be temperature-controlled to stabilize the operation of the nonlinear optical element. With a simple optical element configuration, and It can be inexpensively realize stable operation controllable device to easily.
【図１】第１実施例の光高調波発生器の構成図である。FIG. 1 is a configuration diagram of an optical harmonic generator according to a first embodiment.
【図２】第２実施例の光高調波発生器の構成図である。FIG. 2 is a configuration diagram of an optical harmonic generator according to a second embodiment.
【図３】第３実施例の光高調波発生器の構成図である。FIG. 3 is a configuration diagram of an optical harmonic generator according to a third embodiment.
【図４】第４実施例の光高調波発生器の構成図である。FIG. 4 is a configuration diagram of an optical harmonic generator according to a fourth embodiment.
【図５】従来の光高調波発生器の構成図である。FIG. 5 is a configuration diagram of a conventional optical harmonic generator.
１１０，１２０，１３０…非線形光学素子、２１０，２
２０，２３０…光源、３…３１１，３１２，３２１，３
２２，３３１，３３２，３４１，３４２…ミラー、３１
５，３１６，３２５，３２６，３３５，３３６，３４
４，３４５，３４６…波長選択透過ミラー、４３１，４
３３…基本周波数光の１／２波長板、４１０，４２０，
４３２…第２次高調波の１／２波長板、４４０…第３次
高調波の１／２波長板。110, 120, 130 ... Nonlinear optical element, 210, 2
20, 230 ... Light source, 3 ... 311, 312, 321, 3
22, 331, 332, 341, 342 ... Mirror, 31
5,316,325,326,335,336,34
4,345,346 ... Wavelength selective transmission mirrors, 431, 4
33 ... Half-wave plate of fundamental frequency light, 410, 420,
432 ... 1/2 wave plate of second harmonic wave, 440 ... 1/2 wave plate of third harmonic wave.
Claims (20)
線形光学素子と、 前記非線形光学素子に同一方向から入射する２つの直線
偏光の偏光方向が互いに平行の場合に第２次高調波の発
生に関して位相整合する方向から、前記非線形素子へ入
射する直線偏光した基本周波数光を出射するレーザ光源
と、 前記非線形素子から同一方向に出射される基本周波数光
と第２次高調波光とについて、第３次高調波の発生に関
して位相整合する方向から前記非線形素子へ入射する光
路および偏光方向を設定する光路・偏光方向設定手段
と、 を含んで構成されることを特徴とする光高調波発生器。1. A single non-linear optical element having a second-order non-linear optical effect, and a second non-linear optical element when two linearly polarized light incident on the non-linear optical element from the same direction have mutually parallel polarization directions. A laser light source that emits linearly polarized fundamental frequency light that is incident on the nonlinear element from a direction in which the generation is phase-matched, and fundamental frequency light and second harmonic light that are emitted in the same direction from the nonlinear element, An optical harmonics generator comprising: an optical path / polarization direction setting means for setting an optical path and a polarization direction that are incident on the nonlinear element from the direction of phase matching with respect to generation of a third harmonic.
晶から成り、 前記非線形光学素子に入射する基本波長光の偏光方向
は、前記非線形光学素子をなす結晶における最も屈折率
の大きな光学主軸の方向である、 ことを特徴とする請求項１記載の光高調波発生器。2. The nonlinear optical element is made of a LiB 3 O 5 crystal, and the polarization direction of the fundamental wavelength light incident on the nonlinear optical element is the optical axis of the crystal having the largest refractive index in the crystal forming the nonlinear optical element. The optical harmonic generator according to claim 1, wherein the optical harmonic generator is directional.
を９０゜回転して前記基本波長光の偏光方向と平行とす
る、第２次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項１記載の光高調
波発生器。3. The optical path / polarization direction setting means is arranged in the optical path with one or more reflecting mirrors for forming the optical path, and rotates the polarization direction of the second harmonic light by 90 °. 2. The optical harmonic generator according to claim 1, further comprising: a half-wave plate for the second harmonic, which is parallel to the polarization direction of the fundamental wavelength light.
波発生器。4. The optical harmonic generator according to claim 1, wherein the optical path / polarization direction setting means is composed of one or more reflecting mirrors for forming the optical path.
線形光学素子と、 前記非線形光学素子に同一方向から入射する２つの直線
偏光の偏光方向が互いに平行の場合に第２次高調波の発
生が位相整合する第１の方向から、前記非線形素子へ入
射する直線偏光した基本周波数光を出射するレーザ光源
と、 前記非線形素子から同一方向に出射される基本周波数光
と第２次高調波とについて、第３次高調波の発生に関し
て位相整合する方向から前記非線形素子へ入射する光路
および偏光方向を設定する第１の光路・偏光方向設定手
段と、 前記非線形素子から同一方向に出射される基本周波数光
と第３次高調波とについて、第４次高調波の発生に関し
て位相整合する方向から前記非線形素子へ入射する光路
および偏光方向を設定する第２の光路・偏光方向設定手
段と、 を含んで構成されることを特徴とする光高調波発生器。5. A single non-linear optical element having a second-order non-linear optical effect, and a second harmonic wave when the polarization directions of two linearly polarized lights incident on the non-linear optical element from the same direction are parallel to each other. A laser light source that emits linearly polarized fundamental frequency light that is incident on the nonlinear element from a first direction in which the generation is phase-matched, and a fundamental frequency light and a second harmonic that are emitted from the nonlinear element in the same direction. With respect to, the first optical path / polarization direction setting means for setting the optical path and the polarization direction that are incident on the nonlinear element from the direction of phase matching with respect to the generation of the third harmonic, and the basic light emitted from the nonlinear element in the same direction A second optical path / polarization for setting the optical path and the polarization direction of the frequency light and the third harmonic that are incident on the nonlinear element from the phase-matching direction with respect to the generation of the fourth harmonic. An optical harmonic generator, characterized by comprising: direction setting means.
晶から成り、 前記非線形光学素子に入射する基本波長光の偏光方向
は、前記非線形光学素子をなす結晶における最も屈折率
の大きな光学主軸の方向である、 ことを特徴とする請求項５記載の光高調波発生器。6. The non-linear optical element is made of a LiB 3 O 5 crystal, and the polarization direction of the fundamental wavelength light incident on the non-linear optical element is the optical axis having the largest refractive index in the crystal forming the non-linear optical element. The optical harmonic generator according to claim 5, wherein the optical harmonic generator is directional.
光方向を９０゜回転して前記基本波長光の偏光方向と平
行とする第２次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項５記載の光高調
波発生器。7. The first optical path / polarization direction setting means includes one or more reflecting mirrors for forming the first optical path, and the second harmonic arranged in the first optical path. A half-wave plate for the second harmonic that rotates the polarization direction of the wave light by 90 ° and is parallel to the polarization direction of the fundamental wavelength light, and the optical harmonics according to claim 5. Wave generator.
波発生器。8. The optical harmonics according to claim 5, wherein the first optical path / polarization direction setting means includes one or more reflecting mirrors for forming the first optical path. Wave generator.
を９０゜回転して前記基本波長光の偏光方向と平行とす
る第３次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項７ないしは請求
項８のいずれかに記載の光高調波発生器。9. The second optical path / polarization direction setting means is arranged in the optical path with one or more reflecting mirrors for forming the optical path, and sets the polarization direction of the third-order harmonic light to 90 degrees. 9. A half-wave plate for third harmonics which is rotated by .degree. To be parallel to the polarization direction of the fundamental wavelength light, and a half-wave plate for rotating the fundamental wavelength light. Optical harmonic generator.
は、 前記光路を形成するための１つ以上の反射鏡、 から構成されることを特徴とする請求項７ないしは請求
項８のいずれかに記載の光高調波発生器。10. The method according to claim 7, wherein the second optical path / polarization direction setting means is composed of one or more reflecting mirrors for forming the optical path. An optical harmonic generator described in.
非線形光学素子と、 前記非線形光学素子に同一方向から入射する２つの直線
偏光の偏光方向が互いに垂直の場合に第２次高調波の発
生が位相整合する方向から入射する、直線偏光した基本
周波数光を出射するレーザ光源と、 前記レーザ光源の出射した直線偏光した基本周波数光の
偏光方向を４５゜回転させる基本周波数光に関する第１
の１／２波長板と、 前記非線形素子から同一方向に出射される基本周波数光
と第２次高調波とについて、第３次高調波の発生に関し
て位相整合する方向から前記非線形素子へ入射する光路
および偏光方向を設定する光路・偏光方向設定手段と、 を含んで構成されることを特徴とする光高調波発生器。11. A single non-linear optical element having a second-order non-linear optical effect and a second non-linear optical element when two linearly polarized light incident on the non-linear optical element from the same direction are perpendicular to each other in polarization direction. A laser light source that emits a linearly polarized fundamental frequency light that is incident from the direction in which the generation is phase-matched, and a first fundamental frequency light that rotates the polarization direction of the linearly polarized fundamental frequency light that is emitted by the laser light source by 45 °
Half-wave plate, and an optical path of the fundamental frequency light and the second-order harmonic emitted from the non-linear element in the same direction, which are incident on the non-linear element from the direction in which the third harmonic is phase-matched. And an optical path / polarization direction setting means for setting the polarization direction, and an optical harmonic generator.
結晶から成り、 前記基本周波数光に関する第１の１／２波長板に入射す
る基本波長光の偏光方向は、前記非線形光学素子をなす
結晶における最も屈折率の小さな光学主軸の方向であ
る、 ことを特徴とする請求項１１記載の光高調波発生器。12. The non-linear optical element comprises LiB 3 O 5
The polarization direction of the fundamental wavelength light made of a crystal and incident on the first half-wave plate with respect to the fundamental frequency light is the direction of the optical principal axis having the smallest refractive index in the crystal forming the nonlinear optical element. The optical harmonic generator according to claim 11, which is characterized in that.
を９０゜回転して前記基本波長光の偏光方向と平行とす
る、第２次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項１１記載の光高
調波発生器。13. The optical path / polarization direction setting means is arranged in the optical path with one or more reflecting mirrors for forming the optical path, and rotates the polarization direction of the second harmonic light by 90 °. 12. The optical harmonic generator according to claim 11, further comprising: a half-wave plate for the second harmonic that is parallel to the polarization direction of the fundamental wavelength light.
調波発生器。14. The optical harmonic generator according to claim 11, wherein the optical path / polarization direction setting means comprises one or more reflecting mirrors for forming the optical path.
非線形光学素子と、 前記非線形光学素子に同一方向から入射する２つの直線
偏光の偏光方向が互いに垂直の場合に第２次高調波の発
生が位相整合する方向から入射する、直線偏光した基本
周波数光を出射するレーザ光源と、 前記レーザ光源の出射した直線偏光した基本周波数光の
偏光方向を４５゜回転させる基本周波数光に関する第１
の１／２波長板と、 前記非線形素子から同一方向に出射される基本周波数光
と第２次高調波とについて、第３次高調波の発生に関し
て位相整合する方向から前記非線形素子へ入射する光路
および偏光方向を設定する第１の光路・偏光方向設定手
段と、 前記非線形素子から同一方向に出射される基本周波数光
と第３次高調波とについて、第４次高調波の発生に関し
て位相整合する方向から前記非線形素子へ入射する光路
および偏光方向を設定する第２の光路・偏光方向設定手
段と、 を含んで構成されることを特徴とする光高調波発生器。15. A single non-linear optical element having a second-order non-linear optical effect and a second non-linear optical element when two linearly polarized light beams incident on the non-linear optical element from the same direction are perpendicular to each other in polarization direction. A laser light source that emits a linearly polarized fundamental frequency light that is incident from the direction in which the generation is phase-matched, and a first fundamental frequency light that rotates the polarization direction of the linearly polarized fundamental frequency light that is emitted by the laser light source by 45 °
Half-wave plate, and an optical path of the fundamental frequency light and the second-order harmonic emitted from the non-linear element in the same direction, which are incident on the non-linear element from the direction in which the third harmonic is phase-matched. And a first optical path / polarization direction setting means for setting the polarization direction, and the fundamental frequency light and the third harmonic emitted from the nonlinear element in the same direction are phase-matched with respect to the generation of the fourth harmonic. And a second optical path / polarization direction setting means for setting an optical path and a polarization direction that are incident on the nonlinear element from a direction.
結晶から成り、 前記基本周波数光に関する第１の１／２波長板に入射す
る基本波長光の偏光方向は、前記非線形光学素子をなす
結晶における最も屈折率の小さな光学主軸の方向であ
る、 ことを特徴とする請求項１５記載の光高調波発生器。16. The non-linear optical element is LiB 3 O 5
The polarization direction of the fundamental wavelength light made of a crystal and incident on the first half-wave plate with respect to the fundamental frequency light is the direction of the optical principal axis having the smallest refractive index in the crystal forming the nonlinear optical element. The optical harmonic generator according to claim 15, which is characterized in that.
は、 前記第１の光路を形成するための１つ以上の反射鏡と、 前記第１の光路中に配置され、前記第２次高調波光の偏
光方向を９０゜回転して前記基本波長光の偏光方向と平
行とする、第２次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項１５記載の光高
調波発生器。17. The first optical path / polarization direction setting means includes one or more reflecting mirrors for forming the first optical path, and the second harmonic disposed in the first optical path. 16. The light according to claim 15, further comprising: a half-wave plate for the second harmonic, which rotates the polarization direction of the wave light by 90 degrees to be parallel to the polarization direction of the fundamental wavelength light. Harmonic generator.
は、 前記第１の光路を形成するための１つ以上の反射鏡、 から構成されることを特徴とする請求項１５記載の光高
調波発生器。18. The optical harmonics according to claim 15, wherein the first optical path / polarization direction setting means is composed of one or more reflecting mirrors for forming the first optical path. Wave generator.
は、 前記光路を形成するための１つ以上の反射鏡と、 前記光路中に配置され、前記第３次高調波光の偏光方向
を９０゜回転して前記基本波長光の偏光方向と平行とす
る、第３次高調波に関する１／２波長板と、 から構成されることを特徴とする請求項１７ないしは請
求項１８のいずれかに記載の光高調波発生器。19. The second optical path / polarization direction setting means is arranged in the optical path with one or more reflecting mirrors for forming the optical path, and sets the polarization direction of the third harmonic light to 90 degrees. 19. A half-wave plate for third harmonics, which is rotated by .degree. To be parallel to the polarization direction of the fundamental wavelength light, and a half-wave plate for the third harmonic wave. Optical harmonic generator.
は、 前記光路を形成するための１つ以上の反射鏡、 から構成されることを特徴とする請求項１７ないしは請
求項１８のいずれかに記載の光高調波発生器。20. The method according to claim 17, wherein the second optical path / polarization direction setting means is composed of one or more reflecting mirrors for forming the optical path. An optical harmonic generator described in.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34436392A JP3322708B2 (en) | 1992-12-24 | 1992-12-24 | Optical harmonic generator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34436392A JP3322708B2 (en) | 1992-12-24 | 1992-12-24 | Optical harmonic generator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06194705A true JPH06194705A (en) | 1994-07-15 |
| JP3322708B2 JP3322708B2 (en) | 2002-09-09 |
Family
ID=18368660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34436392A Expired - Fee Related JP3322708B2 (en) | 1992-12-24 | 1992-12-24 | Optical harmonic generator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3322708B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102545021A (en) * | 2012-02-29 | 2012-07-04 | 长春理工大学 | Laser device and method for improving temperature matching conversion efficiency |
| WO2012132866A1 (en) * | 2011-03-28 | 2012-10-04 | 三菱電機株式会社 | Wavelength conversion element and wavelength conversion laser device |
-
1992
- 1992-12-24 JP JP34436392A patent/JP3322708B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012132866A1 (en) * | 2011-03-28 | 2012-10-04 | 三菱電機株式会社 | Wavelength conversion element and wavelength conversion laser device |
| CN103460125A (en) * | 2011-03-28 | 2013-12-18 | 三菱电机株式会社 | Wavelength conversion element and wavelength conversion laser device |
| JP5721812B2 (en) * | 2011-03-28 | 2015-05-20 | 三菱電機株式会社 | Wavelength conversion crystal and wavelength conversion laser device |
| US9188834B2 (en) | 2011-03-28 | 2015-11-17 | Mitsubishi Electric Corporation | Wavelength conversion crystal and wavelength conversion laser device |
| DE112012001525B4 (en) | 2011-03-28 | 2024-07-18 | Mitsubishi Electric Corp. | Wavelength conversion crystal and wavelength conversion laser device |
| CN102545021A (en) * | 2012-02-29 | 2012-07-04 | 长春理工大学 | Laser device and method for improving temperature matching conversion efficiency |
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| Publication number | Publication date |
|---|---|
| JP3322708B2 (en) | 2002-09-09 |
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