JPH02146784A - Laser diode excitation solid laser - Google Patents

Abstract

PURPOSE:To make it possible to further compact an LD excitation solid laser while obtaining a high conversion efficiency to second harmonics by providing a temperature control means on a laser oscillation beam outgoing side end part of a laser rod of a solid laser. CONSTITUTION:In a laser diode excitation solid laser device, a temperature control means such as a temperature control element 12 is provided on a laser oscillation beam outgoing side edge part 9 of a laser rod 3 of a solid laser 1. And, when the laser rod 3 is warmed by a temperature control element 12, a thermal lens effect is generated to function just like a laser rod end face 9 works as a convex lens. As a result, a resonator mode 11 in a resonator makes a beam waist a nonlinear optical crystal 4 to raise power density so as to obtain high conversion efficiency.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a laser diode-pumped solid-state laser, and in particular, the present invention relates to a laser diode-pumped solid-state laser, and in particular, to suppress the thermal lens effect of the laser medium by maintaining the laser medium of the solid-state laser at an appropriate temperature. This invention relates to a laser diode-pumped solid-state laser that utilizes a laser diode to obtain focused laser oscillation light.

[Prior Art] In recent years, research and development of laser diode (LD) pumped solid-state laser devices have been actively conducted.

Compared to conventional lamp pumping, LD-pumped solid-state lasers have a longer excitation light source life, and there is almost no thermal effect on the laser medium, so there is no need for water cooling. It is attracting attention as In addition, the above-mentioned LD is currently well known as an all-solid-state laser, but LDs have problems such as an elliptical spatial output shape and instantaneous edge destruction, but LD-pumped solid-state lasers do not have these problems. This problem has been solved, and since the lifetime at the excited level is long, energy can be stored, and high peak output can be obtained through Q-switch operation. Therefore, LD-pumped solid-state lasers are expected to be used in various fields. It is also known to generate second harmonics by providing a nonlinear optical crystal inside the resonator.

[Problems to be Solved by the Invention] When such second harmonics are generated using a nonlinear optical crystal, the ratio of the second harmonics to the fundamental light, that is, the conversion efficiency, becomes important. -For boat fishing, the conversion efficiency increases in proportion to the square of the power density of the fundamental wave. Therefore, in order to increase the conversion efficiency, in addition to increasing the power of the fundamental wave, various efforts have been made to narrow down the beam and make it incident on the nonlinear optical crystal.

Conventionally, the conventional method of narrowing down this beam was to insert a convex lens into the resonator, but as the number of optical components in the laser head increases, alignment becomes difficult and the shape becomes larger. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a new laser diode pumped solid-state laser having high second harmonic conversion efficiency.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and in a one-nozzle diode-pumped solid-state laser device, the laser oscillation light emitting side end of the laser rod of the solid-state laser In a laser diode-pumped solid-state laser and a laser diode-pumped solid-state laser characterized in that a temperature control means is provided in the laser rod, the refractive index is adjusted within the laser rod by heating the end of the laser rod of the solid-state laser on the laser oscillation light output side. The object of the present invention is to provide a laser diode-pumped solid-state laser characterized by causing a change in laser oscillation light and converging the laser oscillation light.

[Function] In FIG. 1, the laser crystal 3 is heated by the temperature control element 12 to produce a thermal lens effect, as if the laser rod end face 9
functions as a convex lens. As a result, the resonator mode within the resonator creates a beam waist within the nonlinear optical crystal 4, and by increasing the power density there, it becomes possible to obtain high conversion efficiency.

FIG. 2 shows a conventional example in which a convex lens 12 is inserted into the nonlinear optical crystal 4 so that the beam waist is located. In this case, as the number of optical components of the laser head 10 increases, alignment becomes difficult and the overall shape becomes larger.

[Example] Embodiments of the present invention will be explained below.

FIG. 1 shows an example of the basic configuration of the present invention.

1 is a laser diode (LD), 2 is a coupling optical system, 3 is a laser rod, 4 is a nonlinear optical crystal, 5 is an output mirror,
6 is an excitation LD beam, 7 is an emitted laser beam, 8 and 9 are end faces of a laser rod, 10 is a laser head, 11 is a resonator mode, and 12 is a temperature control element.

Although the coupling optical system 2 only shows one convex lens component in FIG. 1, it may be a combination of a plurality of lenses. The resonator is composed of a laser rod end face 8 and a mirror 5, and another mirror is connected to a coupling optical system 2 and a laser rod end face 8.
The mirror and the mirror 5 may be provided between the two mirrors. The laser rod 3 is YAG or YLF.

Many laser crystals and laser glasses can be used, such as YAP, GGG, etc. As the nonlinear optical crystal 4, KTP, BB
O, KDP, KD”P.

KNbO, LiNbO3, etc. are used. Although FIG. 1 shows a directly coupled LD-excited solid-state laser that includes an LDI in the laser head 10, it may also be a fiber-coupled LD-excited solid-state laser that guides LD light through an optical fiber. As the temperature control element 12, a Bertier element, a heater using a heating wire, or the like is used. When the laser rod is a YAG crystal, the upper limit temperature that can be heated is approximately 300°C, and in this example, a crystal with a diameter of 3 mm and a length of 10 mm is used, and the laser oscillation light emitting end 3 mm is heated and maintained at approximately 70°C. , the other end was at about room temperature, and a sufficient thermal lens effect was observed. When using other laser media, the temperature of the laser rod is adjusted as appropriate, taking into consideration the thermal lens effect.

[Effects of the Invention] The present invention makes it possible to make the originally compact LD-pumped solid-state laser even more compact, and the alignment of each built-in component is almost the same as conventional ones, and moreover, it has a high conversion rate to the second harmonic. This has the effect of increasing efficiency.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, and is a basic configuration diagram of a laser diode-excited solid-state laser, and FIG. 2 is a basic configuration diagram of a conventional example. 1. Laser diode 3: Laser rod 4: Nonlinear optical crystal

Claims (2)

[Claims] (1) A laser diode-pumped solid-state laser, characterized in that a temperature control means is provided at the end of the laser rod of the solid-state laser on the laser oscillation light output side. (2) In a laser diode-pumped solid-state laser, the laser oscillation light is focused by heating the end of the laser rod of the solid-state laser on the laser oscillation light output side to cause a refractive index change in the laser rod. A laser diode-pumped solid-state laser.