JP2501694B2 - Second harmonic generator in solid-state laser equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a second harmonic generation device in a solid-state laser device using a semiconductor laser as an excitation light source.

[0002]

2. Description of the Related Art In a conventional lamp-pumped solid-state laser device, in order to generate a second harmonic, a solid-state laser crystal is placed in a resonator consisting of two laser mirrors.
A method of arranging a nonlinear optical crystal between the solid laser crystal and one laser mirror, adjusting the laser mirror to oscillate a fundamental wave, and adjusting the nonlinear optical crystal so as to satisfy the phase matching condition is adopted. It had been.

[0003]

Since the lamp emits light in a wide wavelength range, a large amount of heat is generated in the solid laser crystal that absorbs the lamp light, and this heat induces birefringence. Becomes This thermally induced birefringence disturbs the polarization of the fundamental wave, and the deviation from the phase matching condition becomes large,
There is a problem that it is difficult to efficiently generate the second harmonic. Further, since the laser mirror, the solid-state laser crystal, and the nonlinear optical crystal are individually adjusted, a fine adjustment function is required for their supporting devices, and as a result, the entire apparatus becomes large in size and a high level of knowledge about laser is required. And skill was needed.

In the semiconductor laser pumped solid-state laser, since the wavelength range of the emitted light of the semiconductor laser is very narrow, the rate of heat generation in the solid-state laser crystal is small, and the effect of birefringence due to heat induction is small. Although there is an advantage that harmonics can be obtained, in order to obtain the second harmonic, it is necessary to precisely adjust the laser mirror, the solid-state laser crystal, and the nonlinear optical crystal as compared with the case of the solid-state laser device of the lamp excitation. Is the same.

The present invention provides a second harmonic generation in a semiconductor laser pumped solid-state laser in which a second harmonic can be obtained in an extremely short time without adjusting each of a laser mirror, a solid-state laser crystal and a nonlinear optical crystal. The purpose is to provide a device.

[0006]

In order to achieve the above object, the second harmonic generation device of the present invention comprises a groove having an arcuate cross section and a groove having a right angle cross section, which are formed adjacently on the same line. A base that also functions as a heat sink, a cylindrical holder fitted in the arcuate groove and holding a solid laser crystal inside the center, and fitted in the right-angled groove close to the cylindrical holder A nonlinear optical crystal and a laser mirror fitted in the arcuate groove close to the nonlinear optical crystal are provided.

[0007]

The cylinder holder is moved so that the end face of the solid-state laser crystal is adjusted so as to coincide with the focal position of the laser light from the semiconductor laser placed outside. An optical resonator is formed between the laser mirror and the end face on which the highly reflective coating of the solid laser crystal is applied. Laser oscillation of the fundamental wave is obtained by this optical resonator, and the fundamental wave of the laser is converted into the second harmonic by the nonlinear optical crystal. The cylindrical holder is rotated and fixed to a position where the intensity of the second harmonic is maximized.

[0008]

The present invention will be described in detail below based on the illustrated embodiments. In the figure, 1 is a base that also serves as a heat sink having a groove 1a having an arcuate cross-section, a groove 1b having a right-angled cross-section, and a groove 1c having an arcuate cross-section, which are sequentially formed adjacent to each other on the same line. A cylindrical holder 5 fitted in the groove 1a and having a solid-state laser crystal 4 fixedly held by a pressing member 3 in the center is a rectangular parallelepiped shape fitted in the right-angled groove 1b close to the cylindrical holder 2. Non-linear optical crystal, 6 is a disc-shaped laser mirror fitted in the arcuate groove 1c close to the non-linear optical crystal 5, 7 is a semiconductor laser, and 8 is a solid-state laser crystal that emits laser light emitted from the semiconductor laser 7. 4 is a condensing system for condensing light on the end face of No. 4. The cylindrical holder 2, the nonlinear optical crystal 5 and the laser mirror 6 are fixed to the base 1 with an adhesive having good thermal conductivity.

Although the apparatus is constructed as described above,
Next, the operation will be described. First, when assembling the device,
The non-linear optical crystal 2 and the laser mirror 6 are fitted and fixed to the respective grooves on the base 1 by the above adhesive, and the cylindrical holder 2 incorporating the solid-state laser crystal 4 is movably fitted in the arc-shaped groove 1a. To be dressed. In this state, outside the base 1,
As shown in FIG. 2, the semiconductor laser 7 and the focusing system 8 are placed,
The cylindrical holder 2 is moved and adjusted so that the focal position of the semiconductor laser light thus formed and the position of the incident end face of the solid-state laser crystal 4 coincide with each other. Thus,
An optical resonator is formed between the above-mentioned incident end face of the solid-state laser crystal 4 on which the high-reflection coating is applied and the laser mirror 6, and when the laser light is made incident on the solid-state laser crystal 4 from the semiconductor laser 7, laser oscillation occurs. Begins. In this case, since the length of the optical resonator is short, laser oscillation can be easily obtained. And the fundamental wave of the laser is
It is converted into the second harmonic by the non-linear optical crystal 5 arranged close to the cylindrical holder 2. The cylindrical holder 2 is rotated to satisfy the phase matching condition, and the cylindrical holder 2 is bonded to the base 1 at a position where the intensity of the second harmonic is maximized.
Fixed to. The solid-state laser crystal 4 and the rectangular parallelepiped nonlinear optical crystal 5 generate heat by absorbing light, but there is no problem because the base 1 also functions as a heat sink.

[0010]

As described above, according to the present invention, it is possible to provide a second harmonic generation device which can generate a second harmonic extremely easily and which is simple in structure and assembly, and is widely used. A visible green laser beam can be easily obtained by using a solid-state laser crystal having Nd as an active ion and KTiOPO ₄ (KTP) as a nonlinear optical crystal. Since this has a shorter wavelength than a semiconductor laser that oscillates in near-infrared light that is conventionally used, it is useful because it can increase the recording density when used as a light source of an optical memory.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a second harmonic generation device according to the present invention.

FIG. 2 is a partially cutaway plan view showing a state in which the second harmonic generation device shown in FIG. 1, a semiconductor laser as an excitation light source, and a focusing system are combined.

[Explanation of symbols]

 1 Base that also functions as a heat sink 1a, 1c Arc-shaped groove 1b Right-angled groove 2 Cylindrical holder 3 Holding member 4 Solid-state laser crystal 5 Non-linear optical crystal 6 Laser mirror 7 Semiconductor laser 8 Condensing system

Claims (1)

(57) [Claims] 1. In a solid-state laser device using a semiconductor laser as an excitation light source, a base that doubles as a heat sink and has a groove having an arc-shaped cross section and a groove having a right-angled cross section, which are formed adjacently on the same line, A cylindrical holder fitted in the arc-shaped groove and holding a solid-state laser crystal inside the center,
A second harmonic comprising a nonlinear optical crystal fitted in the right-angled groove close to the cylindrical holder, and a laser mirror fitted in the arc-shaped groove close to the nonlinear optical crystal. Wave generator.