JP3339081B2 - Laser light generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam generator, and more particularly, to a laser medium which absorbs an excitation laser beam and causes a fundamental laser beam to resonate to perform wavelength conversion. The present invention relates to a laser light generator having a resonance block that emits laser light.

[0002]

2. Description of the Related Art It has been conventionally proposed to efficiently perform wavelength conversion using a high power density inside a resonator. For example, an external resonance type SHG (second harmonic generation) has been proposed.
Also, SHG using a nonlinear optical element inside a laser resonator has been attempted.

As an example of the second harmonic generation type in a laser resonator, there has been known a laser resonator and a nonlinear optical crystal element disposed between at least a pair of reflectors constituting a resonator. In the case of this type of laser light generator, the second harmonic laser light is phase-matched to the fundamental laser light emitted from the laser medium in the nonlinear optical crystal element inside the resonator, so that the laser light is efficiently emitted. Second
Harmonic laser light can be extracted.

As a method for realizing the above-mentioned phase matching, a type I or type II phase matching condition is established between the fundamental laser light and the second harmonic laser light. In other words, type I phase matching is based on the principle that the ordinary ray of the fundamental laser light is used to generate a phenomenon in which two photons deflected in the same direction produce one photon whose frequency is doubled. Is what you do. On the other hand, type II phase matching is such that two fundamental wave eigenpolarizations orthogonal to each other are incident on a nonlinear optical crystal element so that phase matching conditions are satisfied for the two eigenpolarizations, respectively. The fundamental wave laser light is divided into an ordinary ray and an extraordinary ray inside the nonlinear optical crystal element, and phase-matches to the extraordinary ray of the second harmonic laser beam.

FIG. 5 shows an example of a conventional laser light generating apparatus in which the second harmonic laser light is phase-matched to the fundamental laser light emitted from the laser medium by satisfying the type II phase matching condition. 1 shows the configuration.

In FIG. 5, a pumping semiconductor laser (hereinafter, referred to as a laser diode) 101 composed of, for example, a laser diode (LD) is driven by a laser diode driving circuit 108 to generate a pumping laser beam (hereinafter, a pumping laser beam). ) Is caused to be incident on the lens 102. The lens 102 converges the excitation laser light, and passes through the concave mirror 103 and the quarter-wave plate 104, for example, Nd: Y.
The light is incident on the laser medium 105 using AG. The laser medium 105 generates a fundamental laser light in a resonator formed by the reflection mirrors 103 and 107 when receiving the excitation laser light. This fundamental laser light reaches the plane mirror 107 via the nonlinear optical crystal element 106 made of, for example, KTP (KTiOPO ₄ ). This plane mirror 1
Reference numeral 07 denotes a reflecting mirror for the fundamental wave laser light. The fundamental wave laser light reflected by the plane mirror 107 is incident on the laser medium 105 again via the nonlinear optical crystal element 106.

The fundamental laser light emitted from the laser medium 105 in the Z direction in FIG.
The light reaches the concave mirror 103 and is reflected. The reflected fundamental laser light is incident on the laser medium 105 again via the quarter-wave plate 104. In this way, the fundamental laser light reciprocates between the concave mirror 103 and the plane mirror 107. That is, concave mirror 103, quarter-wave plate 104, laser medium 1
05, a resonator 109 is formed by the nonlinear optical crystal element 106 and the plane mirror 107.

While the light is reflected by the concave mirror 103 and the plane mirror 107, the reciprocating positions of the fundamental laser light are concentrated. As a result, the energy is increased, and the nonlinear optical crystal element 106 made of, for example, KTP, has a second harmonic laser of twice the frequency (the wavelength is 倍 times) of the fundamental laser light due to the type II phase matching condition. Generates light. Plane mirror 10
Numeral 7 reflects most of the fundamental laser light but transmits most of the second harmonic laser light. As a result, the resonator 109
Thus, the second harmonic laser light is output.

Here, the quarter-wave plate 104 is adjusted to have an azimuth angle of 45 ° with respect to the nonlinear optical crystal element 106. This is because when the fundamental laser light generated in the laser medium 105 is caused to resonate so as to pass through the nonlinear optical crystal element 106 to generate the second harmonic laser light of type II, the fundamental laser light is orthogonal to each other. This is to prevent the occurrence of the coupling phenomenon due to the generation of the sum frequency between the two natural deflection modes. In addition, by setting the amount of phase delay by the nonlinear optical crystal element 106 to ± π / 2, spatial hole burning in the laser medium 105 can be reduced, and a single polarization mode can be set. As a result, the second harmonic laser light can be stabilized.

This laser light generator can be further miniaturized as shown in FIG. 6, for example. In FIG. 6, the quarter-wave plate 104, the laser medium 105, and the nonlinear optical crystal element 106 are integrated, and the concave mirror 1
Numeral 03 indicates that the surface of the quarter-wave plate 104 in the Z direction in the drawing is convex toward the lens 102 (concave toward the laser medium 105) and formed on the surface by vapor deposition. Similarly, a plane mirror 107 is formed on the end surface of the nonlinear optical crystal element 106 in the Y direction in the drawing by vapor deposition.

The resonator 1 thus formed is
09, the lens 102 and the laser diode 101 are mounted on a base 112, and are housed in a package 111.

As the noise of the second harmonic laser light emitted from the resonator 109, the sum frequency noise occupies a large part. This sum frequency noise is 4 degrees with respect to the intrinsic polarization axis of the nonlinear optical crystal element 106.
The use of the quarter-wave plate 104 inclined at 5 degrees and the automatic temperature control (Automatic Temperature control) using the laser diode 101 and the resonator 109 at a constant temperature.
Control: ATC).

FIG. 7 shows a circuit configuration of a laser light generator capable of removing such a sum frequency noise. The laser light generating device whose circuit configuration is shown in FIG. 7 performs a second harmonic laser light by causing a fundamental wave laser light from a laser medium to resonate so as to pass through a nonlinear optical crystal element provided therein. , A laser diode for excitation (hereinafter referred to as a laser diode) 62 for irradiating a laser medium in the resonator block 61 with excitation laser light, and a temperature of the laser diode 62, the resonator block 61 and the like. For example, a temperature detector 63 such as a thermistor for performing detection, a temperature conversion circuit 64 for electrically converting the current temperature in consideration of the characteristics of the temperature detector 63, and this laser light generator is suitable for operation. A target temperature value supply circuit 65 for electrically supplying a target temperature value; a temperature value from the temperature conversion circuit 64; An error amplifier circuit 66 for generating an error signal relating to temperature from the difference from the temperature value, a phase compensation circuit 67 for compensating for the phase of the error signal from the error amplifier circuit 66, and an error signal from the phase compensation circuit 67 A current having different polarities is supplied to an electronic cooling element 69, which will be described later, and an electronic cooling element driving circuit 68 for driving the electronic cooling element 69, and the laser diode 62 and the resonator block are driven by the electronic cooling element driving circuit 68. An electronic cooling element 69 such as a Peltier element for cooling or heating
A temperature control system operation monitoring circuit 71 for outputting information as to whether or not a temperature control system 70 constituted by the temperature detector 63, the electronic cooling element 69 and the peripheral components thereof is operating, according to the error signal from 6; A laser diode (LD) drive control circuit 72 for controlling on / off of a laser diode (LD) constant current drive circuit 74 described later based on the presence or absence of temperature control system operation information from the temperature control system operation monitoring circuit 71; A laser diode (LD) constant current for driving the laser diode 62 at a constant current based on an ON signal from the drive control circuit 72 and a target current value from a target current value supply circuit 73 for giving a target current value for driving the laser diode 62 And a drive circuit 74. That is, the conventional laser light generating apparatus includes a second harmonic laser light generating system 60 including the resonator block 61 and the laser diode 62, the temperature control system 70, and the temperature control system operation monitoring circuit. 71, a constant current control system 75 including the LD drive control circuit 72, a target current value supply circuit 73, and an LD constant current drive circuit 74.

The laser light generating apparatus includes a wavelength adjusting unit that adjusts the wavelength of the excitation laser light generated by the laser diode 62 to a wavelength range in which the laser medium that generates the fundamental laser light can efficiently absorb the laser light.
, And the constant current drive of the laser diode by the constant current drive control system 75 suppresses the above-mentioned sum frequency noise.

[0015]

By the way, in the laser light generating apparatus for generating the second harmonic laser light, noise as shown in FIG. 8A is generated in addition to the above-mentioned sum frequency noise. . FIG. 8 shows that the noise of the second harmonic laser light is expressed as a relative noise intensity (RIN: Relative Intensity Noise).
e) A noise spectrum characteristic diagram shown by display, wherein the horizontal axis represents frequency and the vertical axis represents relative noise intensity.

Normally, the second harmonic laser beam is, for example, 20
In a relatively low band of 0 KHz or less, noise of, for example, about -110 dB / Hz is generated in RIN display as shown in FIG. 8A, and in this band, the noise characteristic is inferior to that of the semiconductor laser. There are often.

Therefore, an error signal is obtained from the laser light having a correlation with the second harmonic laser light, and the error signal is negatively fed back to the excitation light source drive current, so that the second harmonic laser light is relatively low. It is conceivable to reduce band noise.

In the case of this laser light generator, the laser light correlated with the second harmonic laser light is the excitation laser light, the fundamental laser light and the second harmonic laser light itself. The excitation laser light, the fundamental laser light, and the second harmonic laser light are irradiated onto an optical disk or the like, for example, and are taken out so as not to adversely affect the second harmonic laser light used. It is important to reduce light noise.

In the case of extracting the above-mentioned pump laser light, if the output of the laser diode has a negative correlation with the change of the output of the laser medium due to the wavelength fluctuation due to the mode hop of the laser diode, noise may be amplified instead. There is.

In the case where the fundamental wave laser is taken out, since the resonator is configured to reflect the fundamental wave laser light, it is necessary to rely on the leaked light and to make the resonator unstable. It will be taken out.

Further, when the second harmonic laser light is used, the output of emitted light that can be used in an optical system such as an optical disk is reduced.

The present invention has been made in view of the above circumstances, and has a wavelength used by irradiating an optical disc or the like when obtaining a noise signal from a wavelength-converted laser beam such as a second harmonic laser beam. It is an object of the present invention to provide a laser light generating device capable of stably emitting a wavelength-converted laser light without reducing the emission light amount of the converted laser light.

[0023]

According to the present invention, there is provided a laser beam generating apparatus which absorbs an exciting laser beam from an exciting light source to generate a fundamental laser beam, and a fundamental laser beam from the laser medium. A resonance block for generating a wavelength-converted laser beam by causing the laser beam to resonate, wherein the wavelength-converted laser beam and the fundamental laser beam emitted from the resonance block to the excitation light source side. And excluding the excitation laser light, obtaining an error signal from the extracted wavelength-converted laser light and the fundamental laser light, and negatively feeding back the excitation light source to control the driving of the excitation light source. The above problem is solved by the feature.

Here, the wavelength-converted laser light and the fundamental laser light emitted from the resonance block to the excitation light source side transmit the excitation laser light, and the wavelength-converted laser light and the basic laser light. It is reflected and extracted by a wavelength separation mirror that reflects the wave laser light.

Further, the wavelength-converted laser light generated by the resonance block may be a second harmonic laser light.

[0026]

The laser light generator according to the present invention takes out the wavelength-converted laser light and the fundamental wave laser light emitted from the resonance block to the excitation light source side by the wavelength separation mirror,
An error signal is obtained from the extracted wavelength-converted laser light and the fundamental laser light, and the error signal is negatively fed back to the excitation light source to control the driving of the excitation light source. And the wavelength conversion in the resonator block is not unstable.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser light generator according to the present invention
An embodiment in which the present invention is applied to a laser light generator that generates a harmonic laser light will be described with reference to FIG. FIG. 1 is a plan view of the present embodiment. In FIG. 1, in this embodiment, a terminal 22 is provided on a package 21 so that an electric signal can be transmitted and received between the inside and the outside. A thermoelectric cooler (not shown) is provided inside the package 21, and a base plate 23 is disposed thereon. A heat sink 24 and units (assemblies) 25, 26, 27 are arranged on the base plate 23.

An excitation laser diode (hereinafter, referred to as a laser diode) 1 is attached to the heat sink 24. The unit 25 includes a lens 2, a wavelength separation mirror 3, and a photodetector 4 mounted on a substrate 28 for detecting the second harmonic laser light reflected by the wavelength separation mirror 3.

The unit 26 is provided with a quarter-wave plate 5 having a concave mirror 5R formed on the surface thereof, for example, Nd: Y.
Laser medium 6 by AG and a plane mirror 7R on one surface
Is formed, and a resonator 8 composed of a nonlinear optical crystal element 7 made of, for example, KTP (KTiOPO ₄ ). The unit 27 is provided with a rising mirror (not shown) that reflects the second harmonic laser light input from the resonator 8 at an angle of 90 °.

FIG. 2 is a side view (side view) of the embodiment shown in FIG. 1 with the package omitted.
FIG. 2 shows a thermoelectric cooler 29 and a rising mirror 30 not shown in FIG.

In FIG. 1 and FIG.
Is driven by a laser drive circuit (not shown) to generate an excitation laser beam and make it incident on the lens 2. The lens 2 focuses this excitation laser light and makes it incident on the laser medium 6 using, for example, Nd: YAG via the quarter-wave plate 5.
The laser medium 6 generates a fundamental laser beam in a resonator 8 formed by the concave mirror 5R of the quarter-wave plate 5 and the plane mirror 7R of the nonlinear optical crystal element 7 when receiving the excitation laser beam. I do. While the fundamental laser light is reflected by the concave mirror 5R and the plane mirror 7R, the reciprocating positions are concentrated. As a result, the energy is increased, and the nonlinear optical crystal element 7 operates at twice the frequency (wavelength is ２) of the fundamental laser light under the type II phase matching condition.
2nd harmonic laser light is generated. The flat mirror 7R reflects most of the fundamental laser light,
It transmits most of the second harmonic laser light. As a result, the second harmonic laser light is output by the resonator 8 and is irradiated by the rising mirror 30 in the direction of the optical disk, for example.

On the other hand, the second harmonic laser light is also output from the concave mirror 5R side of the laser light resonator 8. The second harmonic laser light output from the concave mirror 5R is defined as backward emission light. Conventionally, the backward emission light is reflected by the end face of the laser diode 1 and the heat sink 24 and returns to the resonator 8, thereby making the operation of the resonator 8 unstable. In the present embodiment, the backward emission light is guided to the photodetector 4 by the wavelength separation mirror 3 that transmits the excitation laser light and reflects the second harmonic laser light, and obtains an error signal.

This wavelength separating mirror 3 has a spectral characteristic as shown in FIG. The horizontal axis of FIG. 3 indicates the wavelength of light, and the vertical axis indicates the light transmittance. Since the wavelength of the pump laser light is 810 nm, the wavelength of the fundamental laser light is 1064 nm, and the second harmonic laser light is 532 nm, the wavelength separating mirror 3 almost transmits the pump laser light and outputs the second harmonic. Almost reflects laser light. In addition, the fundamental laser light is also almost reflected.

That is, the wavelength separating mirror 3 has a high reflectance with respect to the laser light excluding the excitation laser light, and outputs the backward emission light of the second harmonic laser light from the resonator 8 to the photodetector. It can be guided in four directions.

FIG. 4 is a block circuit diagram showing a circuit configuration of this embodiment. In this FIG.
d: a resonator 8 that generates a second harmonic laser light by causing a fundamental laser light from a laser medium made of YAG to resonate so as to pass through a nonlinear optical crystal element made of KTP provided therein; An excitation laser diode 1 that irradiates a laser medium in the resonator 8 with excitation laser light, and a backward emission light of the second harmonic laser light emitted from the resonator 8 is reflected by the wavelength separation mirror described above. A photodetector 4 such as a photodiode to be irradiated, a current-voltage conversion circuit 31 for converting a current output of the photodetector 4 into a voltage value, and a high-frequency component of, for example, 20 KHz or more of the current-voltage conversion circuit 31 An HPF (high-pass filter) 32 that passes only the reference voltage; a reference voltage generating circuit 33 that generates a reference voltage suitable for driving the laser diode 1; An error amplifier circuit 34 for generating an error signal in accordance with the difference between the detected high-frequency component and a reference voltage of the reference voltage generating circuit 33 at 32, the error amplifier circuit 34
, A high-frequency drive current generating circuit 36 for generating a high-frequency drive current according to the error signal from the phase compensation circuit 35, and a laser diode 1 and the like. A temperature detector 37 such as a thermistor for detecting a temperature, a temperature conversion circuit 38 for electrically converting the current temperature in consideration of the characteristics of the temperature detector 37, and the laser light generator of this embodiment operate. A target temperature value supply circuit 39 for electrically providing a target temperature value suitable for the above, and an error for generating an error signal from a difference between the temperature value from the temperature conversion circuit 38 and the temperature value from the target temperature value supply circuit 39. Amplifying circuit 40, a phase compensating circuit 41 for compensating the phase of the error signal from the error amplifying circuit 40, and a current having a polarity changed by the error signal from the phase compensating circuit 41. And an electronic cooling element driving circuit 42 for driving the electronic cooling element, an electronic cooling element 43 for cooling the laser diode 1, the resonator block 8 and the like by the electronic cooling element driving circuit 42, and an error amplifying circuit. The error signal from the temperature detector 3
7. a temperature control system operation monitoring circuit 45 that outputs information as to whether or not the temperature control system 44 constituted by the electronic cooling element 42 and its peripheral parts is operating;
A laser diode for controlling on / off of the high-range drive current generation circuit 36 and a laser diode (LD) constant current drive circuit 48 described later depending on whether or not temperature control system operation information is supplied from the temperature control system operation monitoring circuit 45. (LD) The laser diode 1 is controlled by an ON signal from the LD drive control circuit 46 and a target current value from a target current value supply circuit 47 for providing a target current value for driving the laser diode 1. An LD constant current drive circuit 48 for driving a constant current, and the high range drive current generating circuit 3
And an adder 49 for adding the currents of the high frequency range 6 so as to provide negative feedback and supplying the added output to the laser diode 1. That is, in the present embodiment, the second harmonic laser light generation system 50 including the resonator block 8 and the laser diode 1, the temperature control system 44, and the temperature control system operation monitoring circuit 4
5. LD drive control circuit 46, target current value supply circuit 4
7 and a constant current control system 51 composed of an LD constant current drive circuit 48, a photodetector 4, a current-voltage conversion circuit 31, an HPF 32, a reference voltage generation circuit 33, an error amplification circuit 34, and a phase compensation circuit 35. And a negative feedback loop system 52.

Next, the circuit operation of this embodiment having such a circuit configuration will be described. The second generated by the resonator 8
The backward emission light of the harmonic laser light is guided to the photodetector 4 by the wavelength separation mirror 3, and its high frequency component (for example, 20 KHz or more) is supplied to the error amplification circuit 34 via the current-voltage conversion circuit 31 and the HPF 32. ing. This error amplifier circuit 34
Is also supplied with a reference voltage from a reference voltage generation circuit 33, and generates an error signal therefrom. This error signal is phase-compensated by the phase compensation circuit 35 to add stability and high speed. Then, the error signal is supplied to the high frequency drive current generation circuit 36.

The temperature detector 37 provided on the heat sink 24 performs electrical detection for detecting the temperature of the laser diode 1 and the temperature of the entire laser light generator. The temperature conversion circuit 38 electrically converts the current temperature in consideration of the characteristics of the temperature detector 37. The temperature value from the temperature conversion circuit 38 is supplied to the error amplification circuit 40. The error amplifier circuit 38 is also supplied with a target value from a target temperature value supply circuit 39, and detects how much the temperature of the temperature detector 37 differs from the actual target temperature value. The temperature error signal from the error amplification circuit 40 is supplied to the phase compensation circuit 41 and also to the temperature control system operation monitoring circuit 51. The temperature error signal, which is phase-compensated by the phase compensation circuit 41 and has added stability and high speed, is supplied to the electronic cooling element drive circuit 42. The electronic cooling element drive circuit 42 supplies a current having a different polarity according to the temperature error signal to the electronic cooling element 43. Then, the electronic cooling element 43 cools the laser diode 1 and the like by a temperature error between the target temperature value for operating the apparatus originally provided by the target temperature value supply circuit 39 and the actual temperature value. Further, the temperature control system operation monitoring circuit 51 outputs information on whether the temperature control system 44 is operating. The temperature control system operation information from the temperature control system operation monitoring circuit 45 is
It is supplied to the drive control circuit 46. The LD drive control circuit 46 determines the timing for driving the laser diode 1 based on the temperature control system operation information, and generates an ON signal for driving the laser diode 1 and an OFF signal for not driving the laser diode 1 to generate the high-range drive current. Circuit 36 and LD
It is supplied to the constant current drive circuit 48. Therefore, the high-frequency drive current generating circuit 36 detects the backward emission light of the second harmonic laser light obtained through the wavelength separation mirror 3 with the photodetector 4 and obtains an error obtained from the high-frequency component. The high-frequency drive current by the signal is supplied to the adder 49 at the timing of the ON signal from the LD drive control circuit 46. Also,
The LD constant current drive circuit 48 includes the target current value supply circuit 4.
7 is supplied to the adder 49 at the timing of the ON signal from the LD drive control circuit 46 to drive the laser diode 1.

That is, the adder 49 supplies the laser diode 1 with a constant current to which the high-frequency component for driving the laser diode 1 is negatively fed back at the timing when the temperature control system 44 operates.

As described above, in the present embodiment, the wavelength separation mirror 3 which transmits the backward emission light of the second harmonic laser light generated by the resonator 8 and transmits the excitation laser light and reflects the second harmonic laser light. The signal is reflected and taken out by the photodetector 4, and an error signal between the signal obtained from the high frequency component and the reference voltage is negatively fed back and added to the LD constant current drive circuit 48 at the timing when the temperature control system 44 is operating. Then, the laser diode 1 is driven. Since the pump laser light generated by the laser diode 1 and the second harmonic laser light generated by the resonator 8 have a correlation, by controlling the drive current of the laser diode 1, the second harmonic The generation of the laser beam can be controlled, so that the noise level of the second harmonic laser beam on the low-frequency side can be reduced as shown in FIG.
As shown in FIG. At this time, as described above, from the forward emission light applied to the optical disc or the like,
Since no error signal is taken out, the light quantity of the forward emission light does not decrease. Also, the backward emission light of the second harmonic laser light transmitted through the wavelength separation mirror 3 is small, and the small amount of the backward emission light reflected from the laser diode 1 and the heat sink is again reflected by this wavelength separation plate. Since the light is reflected, it does not return to the resonator 8. Therefore, the resonator 8 does not perform an unstable operation.

The laser light generator according to the present invention is
It is not limited only to the above embodiment. For example, the wavelength-converted laser light generated by the resonance block is not limited to the second harmonic laser light. Further, the phase matching method is not limited to the type II, but also includes a type I and an element for quasi-phase matching.

[0041]

According to the laser light generating apparatus of the present invention, the resonance block resonates the fundamental laser light from the laser medium that absorbs the excitation laser light from the excitation light source and generates the fundamental laser light. A wavelength separating mirror extracts the backward emission light of the generated laser light having the converted wavelength and the fundamental laser light, and outputs an error signal from the extracted wavelength-converted laser light and the fundamental laser light. Since the drive of the excitation light source is controlled by negative feedback to the excitation light source, and the noise of the wavelength-converted laser light is reduced, the emission light amount of the wavelength-converted laser light that should be originally used is not reduced, and the wavelength is converted. Laser light can be emitted stably.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an embodiment of a laser light generator according to the present invention.

FIG. 2 is a side view of the embodiment shown in FIG.

FIG. 3 is a characteristic diagram illustrating spectral characteristics of a wavelength separation mirror used in the present embodiment.

FIG. 4 is a block circuit diagram showing a circuit configuration of the present embodiment.

FIG. 5 is a diagram showing a configuration of a conventional laser light generator.

FIG. 6 is a diagram showing a configuration in which a conventional laser light generator is miniaturized.

FIG. 7 is a block diagram showing a circuit configuration of a conventional laser light generator.

FIG. 8 is a characteristic diagram showing noise characteristics of the second harmonic laser light.

[Explanation of symbols]

 1 ····· Laser diode 2 ····· Lens 3 ····· Wavelength separation mirror 4 ····· Photodetector 5 ··· 1/4 wavelength plate 6 ····· Laser medium 7 Non-linear optical crystal element 8 Resonator

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-130437 (JP, A) JP-A-4-324688 (JP, A) JP-A-2-239238 (JP, A) JP-A-4- 29383 (JP, A) JP-A-62-189783 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/00-3/30

Claims (3)

(57) [Claims] 1. A laser medium that absorbs an excitation laser beam from an excitation light source to generate a fundamental laser beam, and causes the fundamental laser beam from the laser medium to resonate to generate a wavelength-converted laser beam. In the laser light generation device having a resonance block, the wavelength-converted laser light and the fundamental laser light emitted from the resonance block to the excitation light source side are extracted except for the excitation laser light, and are extracted. Above wavelength change
A laser light generator, wherein an error signal is obtained from the converted laser light and the fundamental laser light, and the error signal is negatively fed back to the excitation light source to control the driving of the excitation light source. 2. The wavelength-converted laser light emitted from the resonance block to the excitation light source side and the fundamental wave laser.
Light and is claimed in claim characterized in that it is taken out is reflected Ri by the wavelength separation mirror for reflecting the wavelength-converted laser light and the fundamental wave laser beam causes over-permeable to excitation laser beam 1 The laser light generator according to any one of the preceding claims. 3. The laser light generator according to claim 1, wherein the wavelength-converted laser light generated by the resonance block is a second harmonic laser light.