WO2007015501A1 - Green solid laser light oscillation method and oscillation device - Google Patents
Green solid laser light oscillation method and oscillation device Download PDFInfo
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- WO2007015501A1 WO2007015501A1 PCT/JP2006/315268 JP2006315268W WO2007015501A1 WO 2007015501 A1 WO2007015501 A1 WO 2007015501A1 JP 2006315268 W JP2006315268 W JP 2006315268W WO 2007015501 A1 WO2007015501 A1 WO 2007015501A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
- H01S3/109—Frequency multiplication, e.g. harmonic generation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
- H01S3/09415—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08018—Mode suppression
- H01S3/08022—Longitudinal modes
- H01S3/08031—Single-mode emission
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/131—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/1317—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/16—Solid materials
- H01S3/1601—Solid materials characterised by an active (lasing) ion
- H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
- H01S3/1611—Solid materials characterised by an active (lasing) ion rare earth neodymium
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/16—Solid materials
- H01S3/163—Solid materials characterised by a crystal matrix
- H01S3/1671—Solid materials characterised by a crystal matrix vanadate, niobate, tantalate
- H01S3/1673—YVO4 [YVO]
Definitions
- the present invention relates to an oscillation method and an oscillation apparatus for a Darling solid-state laser beam that uses laser light emitted from a semiconductor laser device as excitation light, and particularly to Darling solid-state laser beam free from green noise with maximum efficiency.
- the present invention relates to a method for oscillating green solid-state laser light and an oscillation device.
- FIG. 5 is a diagram showing a configuration of a semiconductor laser-excited solid-state laser described in Japanese Patent Laid-Open No. 5-198870 (see Patent Document 1).
- the pumping laser beam L emitted from the pumping semiconductor laser device 1 is solid-stated in a laser resonator.
- the functional optical element 5 is mounted on the same thermal conductive substrate 7 and the temperature of the thermal conductive substrate 7 is set.
- the temperature control devices 7a and 7b for controlling the temperature are provided.
- Patent Document 2 Japanese Patent Laid-Open No. 2000-349370 (see Patent Document 2) or Japanese Patent Laid-Open No. 8-32160 (Patent Document 3). See).
- Patent Document 3 Japanese Patent Laid-Open No. 8-32160
- Patent Document 4 Japanese Patent Laid-Open No. 5-198870
- Patent Document 2 JP 2000-349370 A
- Patent Document 3 JP-A-8-32160
- Patent Document 4 JP-A-6-77560
- a solid-state laser medium 2 and A solid-state laser crystal (Nd: YVO crystal) disposed in the laser resonator, and
- KTP crystal A combined wavelength conversion crystal
- the pumping laser beam L emitted from the pumping semiconductor laser device 1 is fixed in a laser resonator as described above.
- the solid laser medium 2 is excited to obtain the output laser beam L.
- the temperature of the solid-state laser medium 2 is controlled by a temperature control device that controls the temperature of the heat conductive substrate 7 on which the solid-state laser medium 2 is mounted. Even if the solid-state laser medium 2 is excited and changes in temperature, the temperature of the solid-state laser light is kept constant within a predetermined range by keeping these temperatures constant. RU
- a medium for laser oscillation (fundamental wave generation) and nonlinear optics for wavelength conversion (second-harmonic generation).
- a medium solid-state laser crystal
- nonlinear optics for wavelength conversion (second-harmonic generation).
- crystals wavelength conversion crystals
- the fundamental wave oscillated from the solid-state laser crystal becomes multi-longitudinal mode oscillation, and the second output that is the laser output due to the interference effect between longitudinal modes. Harmonics change periodically with time, and stable output cannot be obtained. This is called green noise and is one of the causes of instability of laser output.
- an object of the present invention is to provide a green solid-state laser oscillation device and a green solid-state laser light oscillation method that take advantage of the small size of the green solid-state laser device and do not increase the cost.
- an excitation laser is incident on a first solid-state laser medium disposed in a laser resonator to oscillate a laser fundamental wave
- the laser fundamental wave is disposed in the laser resonator.
- the first solid-state laser medium is oscillated so that the laser fundamental wave oscillates in a single longitudinal mode.
- the temperature of the second solid-state laser medium wavelength conversion crystal is adjusted such that the temperature is adjusted and the oscillation efficiency of the green solid-state laser light is maximized.
- the temperature of the second solid laser medium wavelength conversion crystal is adjusted by adjusting the temperature at which the laser fundamental wave has a maximum efficiency within the temperature range of the first solid laser medium in which single longitudinal mode oscillation occurs. It is preferable that
- the present invention provides an excitation laser light source, a first solid-state laser medium that is disposed in a resonator, receives laser light from the excitation laser light source, and oscillates fundamental laser light, and in the resonator And a second solid-state laser medium wavelength conversion crystal that receives the fundamental laser beam and oscillates the green solid-state laser light, wherein the first solid-state laser medium oscillates the fundamental First temperature adjusting means for adjusting the temperature of the first solid-state laser medium so that the wave laser beam is in a single longitudinal mode, and the second solid-state laser beam so that the oscillation of the Darling solid-state laser beam has maximum efficiency. And a second temperature adjusting means for adjusting the temperature of the solid-state laser medium.
- the present invention provides an excitation laser light source, a first solid-state laser medium that is disposed in a resonator, receives laser light from the excitation laser light source, and oscillates fundamental laser light, and the resonance Placed in the chamber to receive the fundamental laser beam and oscillate green solid laser beam
- a green solid-state laser oscillation device including a second solid-state laser medium
- the fundamental laser beam oscillated by the first solid-single-body laser medium is set to a single longitudinal mode.
- Temperature adjusting means for adjusting the temperature of the first solid-state laser medium and adjusting the temperature of the second solid-state laser medium within the temperature range so that the oscillation of the green solid-state laser light has maximum efficiency. It is characterized by having.
- the present invention it is possible to obtain a green solid-state laser device in which green noise is greatly suppressed and stable green laser light is emitted. Further, according to the present invention, single longitudinal mode oscillation can be realized without inserting a new optical component or the like in the laser resonator, and a small and low-cost green solid-state laser oscillation device can be obtained.
- FIG. 1 is a schematic view showing one embodiment of a semiconductor laser-pumped green solid-state laser device that works on the first embodiment of the present invention.
- FIG. 2 is a graph showing the time distribution of the output power of green solid-state laser light.
- FIG. 3 is a graph showing an output mode.
- FIG. 4 is a graph showing a single longitudinal mode.
- FIG. 5 is a schematic view of a conventional semiconductor laser pumped solid-state laser device.
- the method for oscillating green solid laser light includes a pump laser beam emitted from a pumping semiconductor laser, a solid-state laser crystal arranged in a laser resonator, and a wavelength conversion crystal coupled and integrated therewith.
- the green laser light is obtained by making the solid laser medium incident through a ball lens and exciting the solid laser medium.
- a solid-state laser crystal disposed in the laser resonator and a wavelength conversion crystal coupled and integrated with the solid-state laser crystal are mounted on a thermally conductive support having a Peltier temperature control element force. The temperature is controlled to a predetermined temperature by a temperature control device.
- the refractive indexes of the solid-state laser crystal and the wavelength conversion crystal are sensitive to temperature, and the refractive index value changes as the temperature changes.
- N and N Refractive index of solid laser crystal and wavelength conversion crystal are solid laser crystal and
- the conversion efficiency of the second harmonic wave generated by the wavelength conversion crystal (green laser light), the function (sin (A kd / 2) / (A kd / 2)) is proportional to 2.
- a k is the phase mismatch factor and T
- Angular frequency of fundamental laser beam, n , n , n are extraordinary ray fundamental wave and ordinary ray fundamental wave, respectively Refractive index of wave, extraordinary ray second harmonic.
- the temperature control by the Peltier temperature control element is preferably controlled within the temperature range of ⁇ o.o e.
- FIG. 1 is a block diagram showing a configuration of a green solid state laser device 11 of the present invention.
- the Spotify solid-state laser device 11 includes an excitation semiconductor laser 12, a lens cap 14, a ball lens 13, a solid-state laser crystal 15-1, a wavelength conversion crystal 15-2, and a Peltier temperature control element 16.
- the solid-state laser medium 15 uses an Nd: YVO crystal as the solid-state laser crystal 15-1 having a thickness of 1 mm, and is integrally coupled with this.
- the converted wavelength conversion crystal 15-2 is composed of, for example, a KTP crystal that is a wavelength conversion crystal having a length of 3 mm.
- the diameter of the ball lens 13 is 1.5 mm, and the laser from the semiconductor laser 12 is configured to excite the solid-state laser medium 15 via the ball lens 13 and output green laser light.
- they can be joined together by bonding them with an epoxy adhesive, or they can be joined together by an optical contact method in which reinforcing glass is attached to the side surfaces of the two so that they are in contact with each other.
- epoxy adhesive a highly transparent epoxy adhesive, which is desired, is commercially available from a plurality of manufacturers, and may be appropriately selected and used.
- a large Nd: YVO crystal and KTP crystal of the order of cm can be easily aligned.
- the Nd: YVO crystal used as the solid-state laser crystal in this example is currently a semiconductor laser.
- Nd YVO crystals have high power, high stability, and cost-effectiveness because they have excellent physical, optical, and mechanical properties that can be achieved with high damage thresholds due to laser light.
- the temperature control device 17 connected to the Peltier temperature control element 16 has a built-in controller.
- the temperature sensor (thermistor, etc.) 18 attached to the Peltier temperature control element 16 is used in accordance with temperature data input from the temperature sensor 17. Temperature can be controlled.
- the temperature of the Peltier temperature control element 16 is not optimally controlled by the temperature control device 17 but is controlled at an optimum temperature at which the laser output of the solid laser medium 15 becomes a predetermined value. It is. Such temperature control of the solid-state laser medium 15 has never been performed conventionally.
- the temperature change data of the solid-state laser medium 15 is collected by the temperature sensor 18 or the like, and the temperature change and laser output are collected. It is necessary to analyze the relationship between the temperature and the optimum temperature. The obtained value of the optimum temperature is fed back to the controller, and the temperature of the Peltier temperature control element 16 is controlled according to the temperature change of the solid-state laser medium 15. Thereby, the temperature can be controlled so that the laser output of the solid-state laser medium 15 becomes a predetermined value.
- the green solid-state laser device shown in Fig. 1 has a solid-state laser crystal (Nd: YVO crystal).
- the excitation semiconductor layer It is preferable that the first device 11 and the solid-state laser medium 15 are guided and slid by a rail disposed on a pedestal. In addition, it is preferable that both are fixed in a large and small lens barrel and connected to each other so that they can slide and extend.
- a selective reflection film 21 made of an dielectric multilayer film is formed on one end face that intersects the optical axis of the solid-state laser medium 15, that is, on the left end face in the drawing.
- the other end face of the solid-state laser medium 15, that is, the right end face in the figure is not shown, but a non-reflective coating is applied to the green laser light L.
- the reflectance for the laser light L of the fundamental wavelength at the end face is also 99% or more.
- the laser beam L emitted from the solid state laser medium 15 is detected by a detector 22.
- the laser beam L emitted from the solid-state laser medium 15 is a beam beam installed at an angle of about 45 degrees between the solid-state laser medium 15 and the detector 22.
- the Fabry-Perot scanning interferometer 24 checks whether the force is in the single longitudinal mode. Then, the data obtained by the detector 22 and the interferometer 24 are fed back to the temperature control device 17, and the temperature of the Peltier temperature control element 16 is controlled to the optimum temperature using the temperature control device 17.
- the pumping semiconductor laser device 11 is a Ga As semiconductor laser having a center wavelength of oscillation of 808 nm and an output of 120 mW. Although not shown, in this embodiment, the semiconductor laser device 11 is provided with a temperature control device that maintains its temperature at 25 ° C., and the oscillation wavelength matches the absorption peak of the solid-state laser medium 15 described below. Yes It is set to 808nm.
- the ball lens 13 condenses the excitation laser beam L emitted from the excitation semiconductor laser device 11 to collect the solid-state laser beam from the end surface on which the selective reflection film 21 of the solid-state laser medium 15 is formed.
- ⁇ is the angle that the optical axis makes with the crystal Z axis
- ⁇ is the angle that the projection of the optical axis onto the crystal XY plane makes with the X axis, which is a condition that satisfies phase matching at room temperature.
- the laser beam L of 1064nm generated by the laser crystal 15-1 is incident and the wavelength of 532nm
- the excitation laser light L emitted from the excitation semiconductor laser device 11 is condensed by the ball lens 13 and is incident on the solid laser medium 15 to be solid.
- the laser medium 15 is excited. From this, a laser beam L having a fundamental wavelength is generated from the solid-state laser medium 15, and this laser beam L having a fundamental wavelength is generated by a solid-state laser crystal in the laser resonator.
- This confined fundamental wavelength laser beam L is converted into a wavelength conversion crystal (KTP crystal).
- the green light L generated in this way is extracted outside as green laser light.
- FIG. 2 is a graph showing the time distribution of the output power of the green solid laser light at different laser operating temperatures.
- the vertical axis is output in arbitrary units (power), and the horizontal axis is time.
- the condition of this experiment is that the injection current to the semiconductor laser is 140-160mA, Nd: YVO crystal
- the thickness of 4 is lmm
- the thickness of the KTP crystal is 3mm
- the diameter of the ball lens is 1.5mm.
- Nd YVO crystal and KTP crystal are bonded with an adhesive.
- the operating temperature of the laser is 7.5 ° C (Fig. 2 (a)), 10 ° C (Fig. 2 (b)), 15 ° C (Fig. 2 (e)) and 17
- the output of the green solid-state laser fluctuates periodically, and the shape of the time variation of the output power varies with temperature.
- the laser operating temperature reaches 12 ° C (Fig. 2 (c)) and 14 ° C (Fig. 2 (d)
- the output power of the green solid-state laser becomes stable. Under the conditions where the laser operating temperature is 14 ° C and the pumping power of the semiconductor laser is 120 mW, a green solid laser with a maximum of 15.4 mW can be obtained.
- FIG. 4 is a graph showing the single longitudinal mode. As shown in Fig. 4, when the vertical axis is the output signal (FP signal) of the Fabry-Perot interferometer and the horizontal axis is the scanning time, the oscillation of the stable green laser light in single longitudinal mode is observed. It became possible to realize.
- the green solid-state laser device of the present invention can be widely applied in the fields of processing, material process, spectroscopy, wafer inspection, light diagnosis, medical diagnosis, laser printing, and other information processing and optical measurement. There is industrial applicability.
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Abstract
There is provided a green solid laser oscillation device using semiconductor laser excitation capable of significantly stabilizing a green solid state laser light and solving the problem of the green noise by a comparatively simple configuration. The green solid laser oscillation device includes: an excitation laser light source, a first solid laser medium arranged in a resonator for receiving a laser light from the excitation laser light source and oscillating a basic wave laser, and a second solid laser medium arranged in the resonator for receiving the basic wave laser light and oscillating green solid laser light. The green solid laser oscillation device further includes: first temperature control means for controlling the temperature of the first solid laser medium so that the basic wave laser light is in a single longitudinal mode, and second temperature control means for controlling the temperature of the second solid laser medium so that the oscillation of the green solid laser light has a maximum efficiency.
Description
明 細 書 Specification
グリーン固体レーザ光の発振方法及び発振装置 Method and apparatus for oscillating green solid laser light
技術分野 Technical field
[0001] この発明は、半導体レーザ装置力 射出されたレーザ光を励起光として用いるダリ ーン固体レーザ光の発振方法及び発振装置に関し、特にグリーンノイズがなぐダリ ーン固体レーザ光を最大効率で発振するグリーン固体レーザ光の発振方法、及び 発振装置に関する。 TECHNICAL FIELD [0001] The present invention relates to an oscillation method and an oscillation apparatus for a Darling solid-state laser beam that uses laser light emitted from a semiconductor laser device as excitation light, and particularly to Darling solid-state laser beam free from green noise with maximum efficiency. The present invention relates to a method for oscillating green solid-state laser light and an oscillation device.
背景技術 Background art
[0002] 図 5は特開平 5— 198870号公報 (特許文献 1参照)に記載された半導体レーザ励 起固体レーザの構成を示す図である。 FIG. 5 is a diagram showing a configuration of a semiconductor laser-excited solid-state laser described in Japanese Patent Laid-Open No. 5-198870 (see Patent Document 1).
[0003] 図 5に示す従来の半導体レーザ励起固体レーザにおいては、励起用半導体レー ザ装置 1から射出された励起用のレーザ光 Lを、レーザ共振器内に配置された固体 In the conventional semiconductor laser pumped solid-state laser shown in FIG. 5, the pumping laser beam L emitted from the pumping semiconductor laser device 1 is solid-stated in a laser resonator.
0 0
レーザ媒体 2に入射し、該固体レーザ媒体を励起して出力レーザ光 Lを得るように Enter the laser medium 2 and excite the solid laser medium to obtain the output laser beam L
2 2
するとともに、固体レーザ媒体 2及びレーザ共振器 3, 4並びに機能光学素子 5を用 いるときはこの機能光学素子 5を同一の熱伝導性基板 7上に取り付けるとともに、この 熱伝導性基板 7の温度を制御する温度制御装置 7a, 7bを設けたものとなって ヽる。 At the same time, when the solid-state laser medium 2, the laser resonators 3 and 4, and the functional optical element 5 are used, the functional optical element 5 is mounted on the same thermal conductive substrate 7 and the temperature of the thermal conductive substrate 7 is set. The temperature control devices 7a and 7b for controlling the temperature are provided.
[0004] 同様に固体レーザ媒体 2を含むレーザ共振器をペルチェ素子を用いて冷却するも のとして、特開 2000— 349370公報 (特許文献 2参照)ゃ特開平 8— 32160号公報 (特許文献 3参照)がある。またこの発明で用いている集光用レンズとしてのボールレ ンズについては、特開平 6— 77560号公報 (特許文献 4参照)に記載されている。 特許文献 1:特開平 5— 198870号公報 Similarly, as a laser resonator including a solid-state laser medium 2 is cooled by using a Peltier element, Japanese Patent Laid-Open No. 2000-349370 (see Patent Document 2) or Japanese Patent Laid-Open No. 8-32160 (Patent Document 3). See). A ball lens as a condensing lens used in the present invention is described in JP-A-6-77560 (see Patent Document 4). Patent Document 1: Japanese Patent Laid-Open No. 5-198870
特許文献 2:特開 2000— 349370公報 Patent Document 2: JP 2000-349370 A
特許文献 3 :特開平 8— 32160号公報 Patent Document 3: JP-A-8-32160
特許文献 4:特開平 6 - 77560号公報 Patent Document 4: JP-A-6-77560
発明の開示 Disclosure of the invention
発明が解決しょうとする課題 Problems to be solved by the invention
[0005] 半導体レーザ励起によるグリーン固体レーザ装置においては、固体レーザ媒体 2と
して、レーザ共振器内に配置された固体レーザ結晶(Nd:YVO結晶)、及びこれと [0005] In a green solid-state laser device using semiconductor laser excitation, a solid-state laser medium 2 and A solid-state laser crystal (Nd: YVO crystal) disposed in the laser resonator, and
4 Four
結合一体化した波長変換結晶 (KTP結晶)が一般的に用いられている。 A combined wavelength conversion crystal (KTP crystal) is generally used.
[0006] このような半導体レーザ励起固体レーザにおいては、上述のように励起用半導体レ 一ザ装置 1から射出された励起用のレーザ光 Lを、レーザ共振器内に配置された固 In such a semiconductor laser pumped solid-state laser, the pumping laser beam L emitted from the pumping semiconductor laser device 1 is fixed in a laser resonator as described above.
0 0
体レーザ媒体 2に入射し、該固体レーザ媒体 2を励起して出力レーザ光 Lを得てお The solid laser medium 2 is excited to obtain the output laser beam L.
2 り、そのような固体レーザ媒体 2をこれを搭載した熱伝導性基板 7の温度を制御する 温度制御装置によって温度制御している。そして、該固体レーザ媒体 2が励起されて 温度の変化があってもこれらの温度を一定に維持することで、所定の範囲内でダリー ン固体レーザ光の出力が一定となるように構成されて 、る。 Therefore, the temperature of the solid-state laser medium 2 is controlled by a temperature control device that controls the temperature of the heat conductive substrate 7 on which the solid-state laser medium 2 is mounted. Even if the solid-state laser medium 2 is excited and changes in temperature, the temperature of the solid-state laser light is kept constant within a predetermined range by keeping these temperatures constant. RU
[0007] し力し近年、半導体レーザ励起によるグリーン固体レーザの用途がますます拡がつ てきており、それにつれて、グリーンレーザ光の強度、縦'横モード等、グリーンレー ザ光の特性にっ 、て、より安定した出力特性が要求されるようになってきて 、る。 [0007] However, in recent years, the use of green solid-state lasers excited by semiconductor lasers has further expanded, and along with this, the characteristics of green laser light such as the intensity of the green laser light and the longitudinal and transverse modes have increased. As a result, more stable output characteristics are required.
[0008] 半導体レーザ励起によるグリーン固体レーザ装置の共振器内には、レーザ発振 (基 本波発生)のための媒体(固体レーザ結晶)と波長変換 (第 2高調波発生)のための 非線形光学結晶(波長変換結晶)が入っている。しかし、グリーン固体レーザ装置の 基本構成を固体レーザ結晶と波長変換結晶とした場合、固体レーザ結晶から発振し た基本波はマルチ縦モード発振となり、縦モード間における干渉効果によってレーザ 出力である第 2高調波が時間と共に周期的に変化し、安定した出力を得ることができ ない。これはグリーンノイズと言われ、レーザ出力の不安定要因の一つとなっている。 [0008] In a resonator of a green solid-state laser device excited by a semiconductor laser, there is a medium (solid-state laser crystal) for laser oscillation (fundamental wave generation) and nonlinear optics for wavelength conversion (second-harmonic generation). Contains crystals (wavelength conversion crystals). However, if the basic structure of the green solid-state laser device is a solid-state laser crystal and a wavelength conversion crystal, the fundamental wave oscillated from the solid-state laser crystal becomes multi-longitudinal mode oscillation, and the second output that is the laser output due to the interference effect between longitudinal modes. Harmonics change periodically with time, and stable output cannot be obtained. This is called green noise and is one of the causes of instability of laser output.
[0009] 力かるグリーンノイズ問題の解決法として、共振器内に 1/4波長板を挿入しモード 間の結合をなくす方法、リング共振器で単一縦モード発振を得る方法、あるいはエタ ロンを固体レーザ結晶と波長変換結晶間に挿入し、強制的に単一縦モードを発振さ せる方法等が考えられている。しかし、これらは手段ではいずれもグリーン固体レー ザ装置の小型であるという特徴を生かすことが難しぐまた装置のコストが高くなるとい う問題がある。 [0009] As a solution to the strong green noise problem, a method of inserting a quarter-wave plate in the resonator to eliminate coupling between modes, a method of obtaining single longitudinal mode oscillation with a ring resonator, or an etalon is used. A method of inserting a single laser between a solid-state laser crystal and a wavelength conversion crystal to forcibly oscillate a single longitudinal mode has been considered. However, these methods have a problem that it is difficult to take advantage of the small size of the green solid laser device and the cost of the device is high.
[0010] そこで本発明の課題は、グリーン固体レーザ装置が小型であるという特徴を活かし つつ、コスト高とならないグリーン固体レーザ発振装置、およびグリーン固体レーザ光 の発振方法を提供することにある。
課題を解決するための手段 Accordingly, an object of the present invention is to provide a green solid-state laser oscillation device and a green solid-state laser light oscillation method that take advantage of the small size of the green solid-state laser device and do not increase the cost. Means for solving the problem
[0011] 発明者は長年の研究の結果、グリーンノイズを抑えるためには、基本波を単一縦モ ードの発振とすることが不可欠であると考え、これを実現するためにレーザ発振 (基本 波発生)のための媒体 (固体レーザ結晶)と波長変換 (第 2高調波発生)のための非 線形光学結晶 (波長変換結晶)の温度依存性に注目し、レーザ発振と第 2高調波発 生の温度条件を最適化することによって高効率で安定したグリーン固体レーザ光を 発振する方法を実現した。 [0011] As a result of many years of research, the inventor considers that it is indispensable to make the fundamental wave a single longitudinal mode oscillation in order to suppress green noise, and laser oscillation ( Focus on the temperature dependence of the medium (solid laser crystal) for fundamental wave generation (non-linear laser crystal) and the nonlinear optical crystal (wavelength conversion crystal) for wavelength conversion (second harmonic generation). By optimizing the temperature conditions for generation, we realized a method for oscillating highly efficient and stable green solid-state laser light.
[0012] 即ち、本発明は、励起用レーザをレーザ共振器内に配置された第 1の固体レーザ 媒体に入射させレーザ基本波を発振させ、前記レーザ基本波を前記レーザ共振器 内に配置された第 2の固体レーザ媒体に入射させグリーン固体レーザ光を発振させ るグリーン固体レーザ光の発振方法において、前記レーザ基本波が単一縦モードの 発振となるように前記第 1の固体レーザ媒体の温度を調整し、かつ前記グリーン固体 レーザ光の発振効率が最大となるように前記第 2の固体レーザ媒体波長変換結晶の 温度を調整することを特徴とする。 That is, according to the present invention, an excitation laser is incident on a first solid-state laser medium disposed in a laser resonator to oscillate a laser fundamental wave, and the laser fundamental wave is disposed in the laser resonator. In the method of oscillating green solid-state laser light that is incident on the second solid-state laser medium and oscillates the green solid-state laser light, the first solid-state laser medium is oscillated so that the laser fundamental wave oscillates in a single longitudinal mode. The temperature of the second solid-state laser medium wavelength conversion crystal is adjusted such that the temperature is adjusted and the oscillation efficiency of the green solid-state laser light is maximized.
[0013] 前記第 2の固レーザ媒体波長変換結晶の温度の調整は、前記レーザ基本波が単 一縦モードの発振となる前記第 1の固体レーザ媒体の温度範囲内において最大効 率となる温度であることは好適である。 The temperature of the second solid laser medium wavelength conversion crystal is adjusted by adjusting the temperature at which the laser fundamental wave has a maximum efficiency within the temperature range of the first solid laser medium in which single longitudinal mode oscillation occurs. It is preferable that
[0014] 本発明は、励起用レーザ光源と、共振器内に配置され前記励起用レーザ光源から のレーザ光を受光し基本波レーザ光を発振する第 1の固体レーザ媒体と、前記共振 器内に配置され前記基本波レーザ光を受光し、グリーン固体レーザ光を発振する第 2の固体レーザ媒体波長変換結晶とを含むグリーン固体レーザ発振装置において、 前記第 1の固体レーザ媒体が発振する前記基本波レーザ光が単一縦モードとなるよ うに前記第 1の固体レーザ媒体の温度を調整する第 1の温度調整手段と、前記ダリー ン固体レーザ光の発振が最大効率となるように前記第 2の固体レーザ媒体の温度を 調整する第 2の温度調整手段とを備えたことを特徴とする。 [0014] The present invention provides an excitation laser light source, a first solid-state laser medium that is disposed in a resonator, receives laser light from the excitation laser light source, and oscillates fundamental laser light, and in the resonator And a second solid-state laser medium wavelength conversion crystal that receives the fundamental laser beam and oscillates the green solid-state laser light, wherein the first solid-state laser medium oscillates the fundamental First temperature adjusting means for adjusting the temperature of the first solid-state laser medium so that the wave laser beam is in a single longitudinal mode, and the second solid-state laser beam so that the oscillation of the Darling solid-state laser beam has maximum efficiency. And a second temperature adjusting means for adjusting the temperature of the solid-state laser medium.
[0015] 本発明は、励起用レーザ光源と、共振器内に配置され前記励起用レーザ光源から のレーザ光を受光し、基本波レーザ光を発振する第 1の固体レーザ媒体と、前記共 振器内に配置され前記基本波レーザ光を受光し、グリーン固体レーザ光を発振する
第 2の固体レーザ媒体とを含むグリーン固体レーザ発振装置において、前記第 1の 固1—体レーザ媒体が発振する前記基本波レーザ光が単一縦モードとなるように前記第[0015] The present invention provides an excitation laser light source, a first solid-state laser medium that is disposed in a resonator, receives laser light from the excitation laser light source, and oscillates fundamental laser light, and the resonance Placed in the chamber to receive the fundamental laser beam and oscillate green solid laser beam In a green solid-state laser oscillation device including a second solid-state laser medium, the fundamental laser beam oscillated by the first solid-single-body laser medium is set to a single longitudinal mode.
1の固体レーザ媒体の温度を調整するとともに、該温度範囲内であって前記グリーン 固体レーザ光の発振が最大効率となるように第 2の固体レーザ媒体の温度を調整す る温度調整手段とを備えたことを特徴とする。 Temperature adjusting means for adjusting the temperature of the first solid-state laser medium and adjusting the temperature of the second solid-state laser medium within the temperature range so that the oscillation of the green solid-state laser light has maximum efficiency. It is characterized by having.
発明の効果 The invention's effect
[0016] 本発明によれば、グリーンノイズが大幅に抑制され、安定したグリーンレーザ光を発 振するグリーン固体レーザ装置を得ることができる。また、本発明によればレーザ共 振器内に新たな光学部品等を挿入せずに単一縦モードの発振が実現でき、小型- 低コストのグリーン固体レーザ発振装置を得ることができる。 According to the present invention, it is possible to obtain a green solid-state laser device in which green noise is greatly suppressed and stable green laser light is emitted. Further, according to the present invention, single longitudinal mode oscillation can be realized without inserting a new optical component or the like in the laser resonator, and a small and low-cost green solid-state laser oscillation device can be obtained.
図面の簡単な説明 Brief Description of Drawings
[0017] [図 1]この発明の第 1実施例に力かる半導体レーザ励起グリーン固体レーザ装置の 1 実施例を示す概略図である。 FIG. 1 is a schematic view showing one embodiment of a semiconductor laser-pumped green solid-state laser device that works on the first embodiment of the present invention.
[図 2]グリーン固体レーザ光の出力パワーの時間分布を示したグラフである。 FIG. 2 is a graph showing the time distribution of the output power of green solid-state laser light.
[図 3]出力モードを示すグラフである。 FIG. 3 is a graph showing an output mode.
[図 4]単一縦モードを示すグラフである。 FIG. 4 is a graph showing a single longitudinal mode.
[図 5]従来の半導体レーザ励起固体レーザ装置の概略図である。 FIG. 5 is a schematic view of a conventional semiconductor laser pumped solid-state laser device.
符号の説明 Explanation of symbols
12 励起用半導体レーザ 12 Pumping semiconductor laser
13 ボーノレレンズ 13 Bonorelens
14 レンズキャップ 14 Lens cap
15 固体レーザ媒体 15 Solid-state laser medium
15 - - 1 固体レーザ結晶 (第 1の固体レーザ媒体) 15--1 Solid state laser crystal (first solid state laser medium)
15 - - 2 波長変換結晶 (第 2の固体レーザ媒体) 15--2 wavelength conversion crystal (second solid-state laser medium)
16 ペルチ 温度制御素子 16 Peltier Temperature control element
17 温度制御装置 17 Temperature controller
18 温度センサ
21 選択反射膜 18 Temperature sensor 21 Selective reflective film
22 検出器 22 Detector
23 ビームスプリツター 23 Beam Splitter
24 Fabry- Perot走査干渉計 24 Fabry-Perot scanning interferometer
L 励起用レーザ光 L Excitation laser light
0 0
L 基本波長のレーザ光 L fundamental wavelength laser light
1 1
L グリーンレーザ光 L Green laser light
2 2
発明を実施するための最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
[0019] 以下、本発明の実施の形態について詳細に説明する。本発明のグリーン固体レー ザ光の発振方法は、励起用半導体レーザから射出された励起レーザ光を、レーザ共 振器内に配置された固体レーザ結晶、及びこれと結合一体化した波長変換結晶から なる固体レーザ媒体にボールレンズを介して入射させ、該固体レーザ媒体を励起す ることでグリーンレーザ光を得るものである。 Hereinafter, embodiments of the present invention will be described in detail. The method for oscillating green solid laser light according to the present invention includes a pump laser beam emitted from a pumping semiconductor laser, a solid-state laser crystal arranged in a laser resonator, and a wavelength conversion crystal coupled and integrated therewith. The green laser light is obtained by making the solid laser medium incident through a ball lens and exciting the solid laser medium.
[0020] レーザ共振器内に配置された固体レーザ結晶、及びこれと結合一体化した波長変 換結晶を、ペルチェ温度制御素子力もなる熱伝導性支持体上に取り付けるとともに、 このペルチェ温度制御素子の温度を温度制御装置で、所定の温度に制御する。 [0020] A solid-state laser crystal disposed in the laser resonator and a wavelength conversion crystal coupled and integrated with the solid-state laser crystal are mounted on a thermally conductive support having a Peltier temperature control element force. The temperature is controlled to a predetermined temperature by a temperature control device.
[0021] 固体レーザ結晶及び波長変換結晶の屈折率は温度に敏感であり、温度が変化す ると、屈折率の値も変化する。レーザ発振の縦モード Vは、関係式 V =mc/2(n d +n m m L L N d )で与えられる力 ここで、 mは縦モード数を表す正の整数、 cは光速、 n、 nはそれ The refractive indexes of the solid-state laser crystal and the wavelength conversion crystal are sensitive to temperature, and the refractive index value changes as the temperature changes. The longitudinal mode V of laser oscillation is the force given by the relation V = mc / 2 (n d + n m m L L N d), where m is a positive integer representing the number of longitudinal modes, c is the speed of light, n and n are
N し N ぞれ固体レーザ結晶と波長変換結晶の屈折率、 d、 dはそれぞれ固体レーザ結晶と N and N Refractive index of solid laser crystal and wavelength conversion crystal, d and d are solid laser crystal and
L N L N
波長変換結晶の長さである。温度が変化すると、 n、 nが変化し、発振周波数 Vもそ This is the length of the wavelength conversion crystal. When the temperature changes, n and n change, and the oscillation frequency V also changes.
L N m れに伴って変化する。そこで、レーザ利得の最大値に最も近いところにある縦モード を、最大利得にあわせることで、利得競合により単一縦モードの発振とすることができ る。 L N m Changes with this. Therefore, by adjusting the longitudinal mode closest to the maximum laser gain to the maximum gain, single longitudinal mode oscillation can be achieved by gain competition.
[0022] 一方、波長変換結晶により発生した第 2高調波 (グリーンレーザ光)の変換効率は、 関数 (sin( A kd /2)/( A kd /2))2に比例する。ここで、 A kは位相不整合ファクターで、 T [0022] On the other hand, the conversion efficiency of the second harmonic wave generated by the wavelength conversion crystal (green laser light), the function (sin (A kd / 2) / (A kd / 2)) is proportional to 2. Where A k is the phase mismatch factor and T
N N N N
ype IIの位相整合方式では、式 A k= co (n +n - 2n )/cで与えられる。ただし、 ωは le lo 2e In the phase matching method of ype II, it is given by the expression A k = co (n + n−2n) / c. Where ω is le lo 2e
基本波レーザ光の角周波数、 n 、 n 、 n はそれぞれ異常光線基本波、常光線基本
波、異常光線第 2高調波の屈折率である。高い変換効率を得るために位相整合条件 ( Δ k=0)を満たさなければならな 、。結晶の温度を変えることによって結晶の屈折率 も変わり、 n +n -2n =0、及び A k=0の条件に最も近い温度で波長変換結晶を恒 le lo 2e Angular frequency of fundamental laser beam, n , n , n are extraordinary ray fundamental wave and ordinary ray fundamental wave, respectively Refractive index of wave, extraordinary ray second harmonic. In order to obtain high conversion efficiency, the phase matching condition (Δ k = 0) must be satisfied. By changing the crystal temperature, the refractive index of the crystal also changes, and the wavelength conversion crystal is fixed at the temperature closest to the conditions of n + n -2n = 0 and A k = 0.
温させると、高効率で安定したグリーンレーザ光を得ることできる。なお、ペルチェ温 度制御素子による温度制御は、 ±o. o eの温度範囲で制御することは好適である When heated, a highly efficient and stable green laser beam can be obtained. The temperature control by the Peltier temperature control element is preferably controlled within the temperature range of ± o.o e.
。上述したように固体レーザ結晶、波長変換結晶の温度を制御することで、グリーンノ ィズを含まず、高効率のグリーン固体レーザ光を得ることができる。 . As described above, by controlling the temperature of the solid-state laser crystal and the wavelength conversion crystal, high-efficiency green solid-state laser light can be obtained without including green noise.
実施例 Example
[0023] 図 1は本発明のグリーン固体レーザ装置 11の構成を示したブロック図である。ダリ ーン固体レーザ装置 11は、励起用半導体レーザ 12、レンズキャップ 14、ボールレン ズ 13、固体レーザ結晶 15— 1、及び波長変換結晶 15— 2、並びにペルチェ温度制 御素子 16から構成される。 FIG. 1 is a block diagram showing a configuration of a green solid state laser device 11 of the present invention. The Darren solid-state laser device 11 includes an excitation semiconductor laser 12, a lens cap 14, a ball lens 13, a solid-state laser crystal 15-1, a wavelength conversion crystal 15-2, and a Peltier temperature control element 16.
[0024] 半導体レーザ 12からボールレンズ 13を介して、レーザ共振器内の固体レーザ媒体 15に励起用レーザが入射される。この固体レーザ媒体 15は、この実施例において は厚さ lmmの固体レーザ結晶 15— 1として Nd:YVO結晶を用い、これと結合一体 An excitation laser is incident on the solid-state laser medium 15 in the laser resonator from the semiconductor laser 12 through the ball lens 13. In this embodiment, the solid-state laser medium 15 uses an Nd: YVO crystal as the solid-state laser crystal 15-1 having a thickness of 1 mm, and is integrally coupled with this.
4 Four
化した波長変換結晶 15— 2として、例えば長さ 3mmの波長変換結晶である KTP結 晶で構成している。ここで、ボールレンズ 13の直径は 1. 5mmであり、半導体レーザ 12からのレーザはボールレンズ 13を介して固体レーザ媒体 15を励起しグリーンレー ザ光を出力するように構成されて 、る。 The converted wavelength conversion crystal 15-2 is composed of, for example, a KTP crystal that is a wavelength conversion crystal having a length of 3 mm. Here, the diameter of the ball lens 13 is 1.5 mm, and the laser from the semiconductor laser 12 is configured to excite the solid-state laser medium 15 via the ball lens 13 and output green laser light.
[0025] 固体レーザ結晶(Nd:YVO結晶) 15— 1と波長変換結晶 (KTP結晶) 15— 2とを [0025] Solid laser crystal (Nd: YVO crystal) 15-1 and wavelength conversion crystal (KTP crystal) 15-2
4 Four
結合一体ィ匕するには、両者の間をエポキシ系接着剤によって接着し一体ィ匕する、又 は両者の側面に補強ガラスを取り付けて両者を当接する光学コンタクト方式によって 一体ィ匕すればよい。 In order to join together, they can be joined together by bonding them with an epoxy adhesive, or they can be joined together by an optical contact method in which reinforcing glass is attached to the side surfaces of the two so that they are in contact with each other.
[0026] エポキシ系接着剤としては高透明エポキシ系接着剤が望ましぐそのような接着剤 は複数のメーカによって市販されているので適宜選択して使用すればよい。ちなみ に、光軸が簡単に合わせられる cmオーダーの大きな Nd:YVO結晶と KTP結晶とを [0026] As the epoxy adhesive, a highly transparent epoxy adhesive, which is desired, is commercially available from a plurality of manufacturers, and may be appropriately selected and used. By the way, a large Nd: YVO crystal and KTP crystal of the order of cm can be easily aligned.
4 Four
高透明エポキシ系接着剤で接着してから、数 mmまで切り分けることによって所望の サイズの結合一体ィ匕した結晶を得ることができる。
[0027] 光学コンタクト方式においては、両者の間に接着剤を介さないで接合するため、接 合面における光の吸収を低く抑えることができるが、その接合面の平滑性や密着度 にお 、て、非常に高 、精度が要求されることは 、うまでもな!/、。 After bonding with a highly transparent epoxy adhesive, a crystal with a desired size can be obtained by cutting to a few mm . [0027] In the optical contact method, since bonding is performed without using an adhesive between the two, light absorption at the bonding surface can be suppressed to a low level. However, in terms of smoothness and adhesion of the bonding surface, It is a matter of course that very high accuracy is required!
[0028] この実施例で固体レーザ結晶として用いた Nd:YVO結晶は、現在、半導体レー [0028] The Nd: YVO crystal used as the solid-state laser crystal in this example is currently a semiconductor laser.
4 Four
ザ励起固体レーザ用としては最も効率的な結晶の 1つであり、 レーザ発振波長にお ける誘導断面積が大きぐ励起波長にお 、て吸収係数が高 、上に吸収バンド幅が広 ぐさらに、レーザ光による損傷しきい値が高いば力りでなぐ物理的、光学的、機械 的特性にも優れているので、 Nd:YVO結晶は、高出力で高安定、費用効果の高い It is one of the most efficient crystals for the pumped solid-state laser, has a high absorption coefficient at the excitation wavelength where the induced cross section at the laser oscillation wavelength is large, and a wider absorption bandwidth. Nd: YVO crystals have high power, high stability, and cost-effectiveness because they have excellent physical, optical, and mechanical properties that can be achieved with high damage thresholds due to laser light.
4 Four
半導体レーザ励起固体レーザ用として優れた結晶である。 It is an excellent crystal for semiconductor laser pumped solid state lasers.
[0029] 図 1においてレーザ共振器内の固体レーザ結晶(Nd:YVO結晶) 15— 1、及びこ [0029] In FIG. 1, the solid-state laser crystal (Nd: YVO crystal) 15-1 in the laser resonator and this
4 Four
れと結合一体化した波長変換結晶 (KTP結晶) 15— 2をペルチ 温度制御素子 16 の上面に取り付ける。ペルチェ温度制御素子 16と接続した温度制御装置 17にはコ ントローラが内蔵されており、ペルチエ温度制御素子 16に付設した温度センサ (サー ミスタ等) 18から入力される温度データに応じて、細力べ温度制御することができる。 A wavelength conversion crystal (KTP crystal) 15-2, which is integrated with this, is attached to the upper surface of the Peltier temperature control element 16. The temperature control device 17 connected to the Peltier temperature control element 16 has a built-in controller. The temperature sensor (thermistor, etc.) 18 attached to the Peltier temperature control element 16 is used in accordance with temperature data input from the temperature sensor 17. Temperature can be controlled.
[0030] ペルチェ温度制御素子 16の温度は、温度制御装置 17を用いて固体レーザ媒体 1 5を恒温制御するのではなぐ固体レーザ媒体 15のレーザ出力が所定の値となる最 適温度制御するものである。このような固体レーザ媒体 15の温度制御は従来全く行 われてこなかったものである。 [0030] The temperature of the Peltier temperature control element 16 is not optimally controlled by the temperature control device 17 but is controlled at an optimum temperature at which the laser output of the solid laser medium 15 becomes a predetermined value. It is. Such temperature control of the solid-state laser medium 15 has never been performed conventionally.
[0031] 固体レーザ媒体 15のレーザ出力が所定の値となるように温度制御するには、固体 レーザ媒体 15の温度変化のデータを温度センサ 18等で収集し、その温度変化とレ 一ザ出力との関係を細力べ分析して最適温度を導き出す必要がある。そして、得た最 適温度の数値は上記コントローラにフィードバックして、固体レーザ媒体 15の温度変 化に応じてペルチェ温度制御素子 16の温度を温度制御する。これにより、固体レー ザ媒体 15のレーザ出力が所定の値となるように温度制御できる。 In order to control the temperature so that the laser output of the solid-state laser medium 15 becomes a predetermined value, the temperature change data of the solid-state laser medium 15 is collected by the temperature sensor 18 or the like, and the temperature change and laser output are collected. It is necessary to analyze the relationship between the temperature and the optimum temperature. The obtained value of the optimum temperature is fed back to the controller, and the temperature of the Peltier temperature control element 16 is controlled according to the temperature change of the solid-state laser medium 15. Thereby, the temperature can be controlled so that the laser output of the solid-state laser medium 15 becomes a predetermined value.
[0032] 図 1に示すグリーン固体レーザ装置は、固体レーザ結晶(Nd:YVO結晶) 15— 1 [0032] The green solid-state laser device shown in Fig. 1 has a solid-state laser crystal (Nd: YVO crystal).
4 Four
、及びこれと結合一体化した波長変換結晶 (KTP結晶) 15— 2からなる固体レーザ 媒体 15と、励起用半導体レーザ装置 11から射出された励起用のレーザ光との位置 関係を最適化する手段を備えている。力かる最適化手段としては、励起用半導体レ
一ザ装置 11と固体レーザ媒体 15とを台座上に配設したレールによりガイドしスライド させる手段であることは好ましい。また、両者をそれぞれ大小の鏡筒内に固定した上 で連結し、互いにスライドして伸縮できるようにすることは好適である。 And a means for optimizing the positional relationship between the solid-state laser medium 15 composed of a wavelength conversion crystal (KTP crystal) 15-2 integrated with this and the pumping laser beam emitted from the pumping semiconductor laser device 11 It has. As a powerful optimization means, the excitation semiconductor layer It is preferable that the first device 11 and the solid-state laser medium 15 are guided and slid by a rail disposed on a pedestal. In addition, it is preferable that both are fixed in a large and small lens barrel and connected to each other so that they can slide and extend.
[0033] この固体レーザ媒体 15の光軸と交わる一方の端面、すなわち、図中左端面には誘 電体多層膜からなる選択反射膜 21が形成されている。この選択反射膜 21は、固体 レーザ媒体 15によって生ずる基本波長のレーザ光(L = 1064nm)に対しては 99. A selective reflection film 21 made of an dielectric multilayer film is formed on one end face that intersects the optical axis of the solid-state laser medium 15, that is, on the left end face in the drawing. This selective reflection film 21 is 99.99 nm for the fundamental wavelength laser light (L = 1064 nm) generated by the solid-state laser medium 15.
1 1
9%以上の高い反射率をもち、一方、励起用レーザ光 (L =808nm)を 90%以上透 It has a high reflectance of 9% or more, while transmitting excitation laser light (L = 808nm) more than 90%.
0 0
過する性質を有する。なお、固体レーザ媒体 15の他方の端面、すなわち、図中右端 面には図示しないが、グリーンレーザ光 Lに対して無反射コートが施されており、この It has the property to have. The other end face of the solid-state laser medium 15, that is, the right end face in the figure is not shown, but a non-reflective coating is applied to the green laser light L.
2 2
端面での基本波長のレーザ光 L に対する反射率も 99%以上になるようになつている The reflectance for the laser light L of the fundamental wavelength at the end face is also 99% or more.
1 1
[0034] 固体レーザ媒体 15から出射されるレーザ光 Lは、検出器 (detector) 22によってそ The laser beam L emitted from the solid state laser medium 15 is detected by a detector 22.
2 2
の出力強度や安定性が検出される。また固体レーザ媒体 15から出射されるレーザ光 Lは、固体レーザ媒体 15と検出器 22との間に約 45度の角度に設置されたビームス Output intensity and stability are detected. The laser beam L emitted from the solid-state laser medium 15 is a beam beam installed at an angle of about 45 degrees between the solid-state laser medium 15 and the detector 22.
2 2
プリツター 23により 90度折り曲げられ、 Fabry-Perot走査干渉計 24で単一縦モードで ある力否かを確認するようになっている。そして、上記検出器 22や干渉計 24で得た データを温度制御装置 17にフィードバックして、ペルチェ温度制御素子 16の温度を 温度制御装置 17を用 、て最適温度になるよう温度制御する。 It is bent 90 degrees by the presetter 23, and the Fabry-Perot scanning interferometer 24 checks whether the force is in the single longitudinal mode. Then, the data obtained by the detector 22 and the interferometer 24 are fed back to the temperature control device 17, and the temperature of the Peltier temperature control element 16 is controlled to the optimum temperature using the temperature control device 17.
[0035] 励起用半導体レーザ装置 11は、発振の中心波長が 808nm、出力 120mWの Ga As系の半導体レーザである。図示しないが、この実施例では、この半導体レーザ装 置 11にはその温度を 25° Cに保持する温度制御装置が設けられており、発振波長 が次に述べる固体レーザ媒体 15の吸収ピークに一致する 808nmになるように設定 されている。 The pumping semiconductor laser device 11 is a Ga As semiconductor laser having a center wavelength of oscillation of 808 nm and an output of 120 mW. Although not shown, in this embodiment, the semiconductor laser device 11 is provided with a temperature control device that maintains its temperature at 25 ° C., and the oscillation wavelength matches the absorption peak of the solid-state laser medium 15 described below. Yes It is set to 808nm.
[0036] ボールレンズ 13は、励起用半導体レーザ装置 11から射出された励起用レーザ光 L を集光して固体レーザ媒体 15の選択反射膜 21が形成された端面から該固体レー The ball lens 13 condenses the excitation laser beam L emitted from the excitation semiconductor laser device 11 to collect the solid-state laser beam from the end surface on which the selective reflection film 21 of the solid-state laser medium 15 is formed.
0 0
ザ媒体 15内に入射させて励起するものである。ボールレンズの焦点における大きな 収差を利用することによって、励起光が固体レーザ結晶内に効率よく収束することが できる。
[0037] 波長変換結晶 15— 2は、長さ 3mmの Type IIの KTP結晶である。この KTP結晶は 、結晶カット面 Θ = 90. 0° 、 φ = 23° になるようにカットされている。ここで、 φは光 軸が結晶 Z軸となす角度、 Θは光軸の結晶 XY平面への射影が X軸となす角度であ り、室温で位相整合を満たす条件である。これにより、 Nd:YVO結晶を用いた固体 The light enters the medium 15 and is excited. By utilizing the large aberration at the focal point of the ball lens, the excitation light can be efficiently converged in the solid-state laser crystal. [0037] The wavelength conversion crystal 15-2 is a Type II KTP crystal having a length of 3 mm. This KTP crystal is cut so that the crystal cut plane is Θ = 90.0 ° and φ = 23 °. Here, φ is the angle that the optical axis makes with the crystal Z axis, and Θ is the angle that the projection of the optical axis onto the crystal XY plane makes with the X axis, which is a condition that satisfies phase matching at room temperature. This allows solids using Nd: YVO crystals
4 Four
レーザ結晶 15— 1で発生した波長 1064nmのレーザ光 Lを入射して波長 532nmの The laser beam L of 1064nm generated by the laser crystal 15-1 is incident and the wavelength of 532nm
1 1
グリーン光 Lを発生するものである。 Green light L is generated.
2 2
[0038] 上述の構成において、励起用半導体レーザ装置 11から射出された励起用レーザ 光 L はボールレンズ 13によって集光されて固体レーザ媒体 15内に入射され、固体 In the above-described configuration, the excitation laser light L emitted from the excitation semiconductor laser device 11 is condensed by the ball lens 13 and is incident on the solid laser medium 15 to be solid.
0 0
レーザ媒体 15を励起する。これ〖こより、固体レーザ媒体 15から基本波長のレーザ光 Lが発生するが、この基本波長のレーザ光 Lはレーザ共振器内の固体レーザ結晶 The laser medium 15 is excited. From this, a laser beam L having a fundamental wavelength is generated from the solid-state laser medium 15, and this laser beam L having a fundamental wavelength is generated by a solid-state laser crystal in the laser resonator.
1 1 1 1
(Nd:YVO結晶)、及びこれと結合一体化した波長変換結晶 (KTP結晶)内に閉じ Closed in (Nd: YVO crystal) and wavelength conversion crystal (KTP crystal) combined with this
4 Four
こめられる。この閉じこめられた基本波長のレーザ光 Lが波長変換結晶 (KTP結晶) It can be filled. This confined fundamental wavelength laser beam L is converted into a wavelength conversion crystal (KTP crystal).
1 1
を通過し、 2次の非線形光学効果である第 2高調波発生 (SHG)によってグリーン光 L Through the second harmonic generation (SHG), which is a second-order nonlinear optical effect.
2 を発生させる。こうして発生したグリーン光 Lは、グリーンレーザ光として外部に取り出 2 is generated. The green light L generated in this way is extracted outside as green laser light.
2 2
される。 Is done.
[0039] 図 2は、異なるレーザ動作温度でグリーン固体レーザ光の出力パワーの時間分布 を示したグラフである。縦軸は任意単位の出力(power)とし、横軸は時間 (time)であ る。この実験の条件は、半導体レーザへの注入電流が 140-160mA、 Nd:YVO結晶 FIG. 2 is a graph showing the time distribution of the output power of the green solid laser light at different laser operating temperatures. The vertical axis is output in arbitrary units (power), and the horizontal axis is time. The condition of this experiment is that the injection current to the semiconductor laser is 140-160mA, Nd: YVO crystal
4 の厚みは lmm、 KTP結晶の厚みは 3mm、ボールレンズの直径は 1.5mmである。 Nd : YVO結晶と KTP結晶は接着剤で接着している。 The thickness of 4 is lmm, the thickness of the KTP crystal is 3mm, and the diameter of the ball lens is 1.5mm. Nd: YVO crystal and KTP crystal are bonded with an adhesive.
4 Four
[0040] 図 2に示すようにレーザの動作温度が 7. 5°C (図 2 (a) )、 10°C (図 2 (b) )、 15°C (図 2 (e) )と 17. 5°C (図 2 (f) )のときに、グリーン固体レーザの出力は周期的に変動し、 温度によって出力パワーの時間変動の形も異なる。しかし、レーザの動作温度が 12 °C (図 2 (c) )及び 14°C (図 2 (d) )になると、グリーン固体レーザの出力パワーは安定 する。レーザの動作温度が 14°C、半導体レーザの励起パワーが 120mWの条件では 、最大で 15. 4mWのグリーン固体レーザを得ることができた。 [0040] As shown in Fig. 2, the operating temperature of the laser is 7.5 ° C (Fig. 2 (a)), 10 ° C (Fig. 2 (b)), 15 ° C (Fig. 2 (e)) and 17 At 5 ° C (Fig. 2 (f)), the output of the green solid-state laser fluctuates periodically, and the shape of the time variation of the output power varies with temperature. However, when the laser operating temperature reaches 12 ° C (Fig. 2 (c)) and 14 ° C (Fig. 2 (d)), the output power of the green solid-state laser becomes stable. Under the conditions where the laser operating temperature is 14 ° C and the pumping power of the semiconductor laser is 120 mW, a green solid laser with a maximum of 15.4 mW can be obtained.
[0041] これらの結果から、レーザの動作温度を最適化することによって、従来のようにレー ザ共振器を恒温する効果のみならず、レーザ出力の不安定要因であるグリーンノィ
ズ問題も解決できることが示された。 From these results, by optimizing the operating temperature of the laser, not only the effect of keeping the temperature of the laser resonator as in the conventional case, but also the green noise that is an unstable factor of the laser output. It was shown that the problem can be solved.
[0042] 上述した条件によりグリーン固体レーザ装置によってレーザ発振実験を行ったとこ ろ、図 3に示すようなレーザ出力のグラフが得られた。図 3に示すように縦軸を出力(p ower)とし、横軸を時間 (time)として見た場合、発振出力が約 6a.u. (任意単位)で、レ 一ザ出力のぶれが 0. 5%以下という、極めて安定したグリーンレーザ光が得られた。 [0042] When a laser oscillation experiment was performed with the green solid-state laser device under the above-described conditions, a graph of laser output as shown in Fig. 3 was obtained. As shown in Fig. 3, when the vertical axis is the output (power) and the horizontal axis is the time, the oscillation output is about 6 a.u. (arbitrary unit) and the laser output fluctuation is 0. An extremely stable green laser beam of 5% or less was obtained.
[0043] 図 4は単一縦モードを示すグラフである。図 4に示す通り、縦軸を Fabry-Perot干渉 計の出力信号 (F-P signal)とし、横軸を走査時間(scanning time)として見た場合、単 一縦モードの安定したグリーンレーザ光の発振を実現することが可能となった。 FIG. 4 is a graph showing the single longitudinal mode. As shown in Fig. 4, when the vertical axis is the output signal (FP signal) of the Fabry-Perot interferometer and the horizontal axis is the scanning time, the oscillation of the stable green laser light in single longitudinal mode is observed. It became possible to realize.
[0044] 本明糸田書 ίま、 2005年 8月 4日出願の特願 2005— 227312に基づく。この内容【ま すべてここに含めておく。 [0044] Based on Japanese Patent Application No. 2005-227312 filed on August 4, 2005. This content [all included here.
産業上の利用可能性 Industrial applicability
[0045] 本発明のグリーン固体レーザ装置は、加工、材料プロセス、分光、ウェハ検査、ライ トシヨウ、医療診断、レーザプリント、その他情報処理および光計測の分野で広く応用 することが可能であることから、産業上の利用可能性がある。
The green solid-state laser device of the present invention can be widely applied in the fields of processing, material process, spectroscopy, wafer inspection, light diagnosis, medical diagnosis, laser printing, and other information processing and optical measurement. There is industrial applicability.
Claims
[1] 励起用レーザ光をレーザ共振器内に配置された第 1の固体レーザ媒体に入射しレー ザ基本波を発振させ、前記レーザ基本波を前記レーザ共振器内に配置された第 2の 固体レーザ媒体に入射させグリーン固体レーザ光を発振させるグリーン固体レーザ 光の発振方法において、 [1] An excitation laser beam is incident on a first solid-state laser medium disposed in a laser resonator to oscillate a laser fundamental wave, and the laser fundamental wave is disposed in a second cavity disposed in the laser resonator. In an oscillation method of green solid laser light that is incident on a solid laser medium and oscillates green solid laser light,
前記レーザ基本波が単一縦モードの発振となるように前記第 1の固体レーザ媒体の 温度を制御し、かつ前記グリーン固体レーザ光の発振効率が最大となるように前記 第 2の固体レーザ媒体の温度を制御することを特徴とするグリーン固体レーザ光の発 振方法。 Controlling the temperature of the first solid-state laser medium so that the laser fundamental wave oscillates in a single longitudinal mode, and the second solid-state laser medium so that the oscillation efficiency of the green solid-state laser light is maximized. A method for oscillating green solid-state laser light, characterized by controlling the temperature of the laser.
[2] 前記第 2の固体レーザ媒体の制御温度は、前記レーザ基本波が単一縦モードの発 振となる前記第 1の固体レーザ媒体の温度範囲内で、グリーン固体レーザ光の発振 効率を最大とする温度であることを特徴とする請求項 1に記載のグリーン固体レーザ 光の発振方法。 [2] The control temperature of the second solid-state laser medium is set so that the oscillation efficiency of the green solid-state laser light is within the temperature range of the first solid-state laser medium in which the laser fundamental wave is oscillated in a single longitudinal mode. 2. The method for oscillating green solid laser light according to claim 1, wherein the temperature is a maximum temperature.
[3] 前記温度制御は、ペルチェ温度制御素子を複数の単位面で分割し、各単位面毎に 温度制御できるようにしたことを特徴とする請求項 1又は 2に記載のグリーン固体レー ザ光の発振方法。 [3] The green solid-state laser light according to claim 1 or 2, wherein the temperature control is performed by dividing a Peltier temperature control element into a plurality of unit surfaces so that the temperature can be controlled for each unit surface. Oscillation method.
[4] 励起用レーザ光源と、共振器内に配置され前記励起用レーザ光源からのレーザ光を 受光し基本波レーザを発振する第 1の固体レーザ媒体と、前記共振器内に配置され 前記基本波レーザ光を受光しグリーン固体レーザ光を発振する第 2の固体レーザ媒 体とを含むグリーン固体レーザ発振装置において、 [4] An excitation laser light source, a first solid-state laser medium that is disposed in a resonator and receives laser light from the excitation laser light source and oscillates a fundamental laser, and the basic laser beam that is disposed in the resonator A green solid-state laser oscillation device including a second solid-state laser medium that receives a wave laser beam and oscillates a green solid-state laser beam,
前記基本波レーザ光が単一縦モードとなるように前記第 1の固体レーザ媒体の温 度を制御する第 1の温度制御手段と、 First temperature control means for controlling the temperature of the first solid-state laser medium so that the fundamental laser beam is in a single longitudinal mode;
前記グリーン固体レーザ光の発振が最大効率となるように前記第 2の固体レーザ媒 体の温度を制御する第 2の温度制御手段とを備えたことを特徴とするグリーン固体レ 一ザ発振装置。 A green solid-state laser oscillation device, comprising: a second temperature control means for controlling the temperature of the second solid-state laser medium so that the oscillation of the green solid-state laser beam has maximum efficiency.
[5] 励起用レーザ光源と、共振器内に配置され前記励起用レーザ光源からのレーザ光を 受光し基本波レーザを発振する第 1の固体レーザ媒体と、前記共振器内に配置され 前記基本波レーザ光を受光しグリーン固体レーザを発振する第 2の固体レーザ媒体
とを含むグリーン固体レーザ発振装置において、 [5] An excitation laser light source, a first solid-state laser medium that is disposed in the resonator and receives laser light from the excitation laser light source and oscillates a fundamental laser, and the basic laser medium that is disposed in the resonator Second solid-state laser medium that receives a wave laser beam and oscillates a green solid-state laser In a green solid state laser oscillation device including
前記第 1の固体レーザ媒体が発振する前記基本波レーザ光が単一縦モードとなる ように前記第 1の固体レーザ媒体の温度を制御するとともに、該温度範囲内であって 前記グリーン固体レーザ光の発振が最大効率となるように第 2の固体レーザ媒体の 温度を制御する温度制御手段とを備えたことを特徴とするグリーン固体レーザ発振 装置。 The temperature of the first solid-state laser medium is controlled so that the fundamental laser light oscillated by the first solid-state laser medium is in a single longitudinal mode, and the green solid-state laser light is within the temperature range. And a temperature control means for controlling the temperature of the second solid-state laser medium so as to maximize the oscillation of the green solid-state laser oscillation device.
前記温度制御手段は、ペルチェ温度制御素子を複数の単位面で分割し、各単位面 毎に温度制御できる手段であることを特徴とする請求項 4に記載のグリーン固体レー ザ発振装置。
5. The green solid state laser oscillation device according to claim 4, wherein the temperature control means is a means capable of dividing the Peltier temperature control element into a plurality of unit surfaces and controlling the temperature for each unit surface.
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JPH1093182A (en) * | 1996-06-05 | 1998-04-10 | Jin Tianfeng | Frequency conversion solid-state laser, frequency-doubling solid-state laser device, and frequency conversion coupling resonance cavity |
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JPH07235721A (en) * | 1994-02-23 | 1995-09-05 | Sumitomo Metal Mining Co Ltd | Laser apparatus |
JPH1093182A (en) * | 1996-06-05 | 1998-04-10 | Jin Tianfeng | Frequency conversion solid-state laser, frequency-doubling solid-state laser device, and frequency conversion coupling resonance cavity |
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HARIMOTO T. ET AL.: "Efficient and stable 532 nm microchip laser pumped by single-longitudinal-mode laser-diode", ELECTRONICS LETTERS, vol. 41, no. 12, 9 June 2005 (2005-06-09), pages 702 - 704, XP006024180 * |
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