JPH09266338A - Laser diode excitation solid laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fluctuations in output attributable to change in the length of a resonator or oscillation wave length by employing a simple and low cost structure in a laser diode excitation solid laser. SOLUTION: In a laser diode excitation solid laser which is provided with a solid laser crystal 13, a laser diode 11 which emits an excitation light which excites this solid laser crystal 13, and a resonator (for example, comprising the solid laser crystal 13 and a resonator mirror 14), the solid laser crystal 13, the laser diode 11 and the resonator are housed inside a vessel which consists of a package cover 30 and a package mount 31, for example and keeps both the inside and outside in air tightness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode pumped solid-state laser in which a solid-state laser crystal is pumped by a laser diode (semiconductor laser), and more specifically, it prevents fluctuations in output and oscillation wavelength due to changes in cavity length. The present invention relates to a solid-state laser pumped by a laser diode.

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Patent Application Laid-Open No. 62-189783, a laser diode pumped solid-state laser is known in which a solid laser crystal doped with a rare earth element such as neodymium is pumped by light emitted from a laser diode. Has become.

In this type of laser diode pumped solid-state laser, a resonator such as a Fabry-Perot resonator or a ring resonator is adopted, but the resonator length changes when the humidity or atmospheric pressure of the operating environment changes, Therefore, the problem that the oscillation wavelength fluctuates is recognized.

Japanese Unexamined Patent Publication (Kokai) No. 6-140706 discloses a solid-state laser device in which a resonator is housed in a container and the pressure in the container is adjusted by a pressure adjusting means to stabilize the oscillation wavelength. There is.

Further, as disclosed in the above publication as a prior art, a pair of resonator mirrors are supported by an electrostrictive element, and the position of the resonator mirrors is adjusted so that the resonator length is changed by the electrostrictive element. A solid-state laser device that stabilizes the oscillation wavelength is also known.

[0006]

However, if the means for adjusting the pressure in the container and the position of the resonator mirror are provided as described above, the structure of the laser device becomes complicated and the reliability is lowered. Also, it will lead to a significant cost increase.

The present invention has been made in view of the above circumstances, and provides a laser diode pumped solid-state laser capable of reliably preventing fluctuations in output and oscillation wavelength due to changes in resonator length, with a simple and inexpensive structure. The purpose is to

[0008]

A laser diode-pumped solid-state laser according to the present invention comprises a solid-state laser crystal, a laser diode that emits pumping light for exciting the solid-state laser crystal, and a resonator, as described above. A laser diode pumped solid-state laser is characterized in that a solid-state laser crystal, a laser diode and a resonator are housed inside a container that keeps the inside and outside airtight.

In the above construction, more preferably, an inert gas such as N ₂ gas is sealed in the container.

[0010]

As described above, when the solid-state laser crystal, the laser diode, and the resonator are housed inside a container that keeps the inside and outside airtight, these elements have a change in humidity or atmospheric pressure in the operating environment. Will not be affected. Therefore, it is possible to reliably prevent the output of the solid-state laser and the fluctuation of the oscillation wavelength by eliminating the change of the cavity length due to the change of the humidity and the atmospheric pressure.

If an inert gas such as N ₂ gas is enclosed in the container, deterioration of laser components such as a coat film, metal, adhesive and the like can be prevented.

The laser diode-pumped solid-state laser according to the present invention has a simple structure in which the solid-state laser crystal, the laser diode, and the resonator are simply housed in a hermetically sealed container as described above. It is also expensive and can be manufactured at a relatively low cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 respectively show a plane shape and a side shape of a laser diode pumped solid-state laser which is one embodiment of the present invention. This laser diode-pumped solid-state laser is a condenser lens composed of a laser diode 11 that emits a laser beam 10 as excitation light, and, for example, a gradient index rod lens that condenses the laser beam 10 that is divergent light.
12, a YAG crystal (hereinafter referred to as an Nd: YAG crystal) 13 which is a solid-state laser medium doped with neodymium (Nd), and a front side (right side in the figure) of the Nd: YAG crystal 13. A resonator mirror 14, a LiNbO ₃ crystal (hereinafter referred to as an LN crystal) 15 having a periodic domain inversion structure disposed between the resonator mirror 14 and the Nd: YAG crystal 13, and the LN crystal 15. It has a calcite etalon 16 disposed between it and a resonator mirror 14.

The laser diode 11 and the condenser lens 12 are enclosed in an LD package 17. Also,
Each element described above is fixed to a common reference plate 18, and the temperature is adjusted to a predetermined constant temperature by a Peltier element 19 via the reference plate 18.

Then, each of the above-mentioned elements, together with the reference plate 18 and the Peltier element 19, are contained in a container constituted by a package cover 30 and a package base 31. This container is constructed by fixing the Peltier device 19 to the package base 31 and then welding the package cover 30 to the package base 31. This welding is continuous welding,
The inside of the container is kept airtight with respect to the outside. It is desirable that this welding is performed intermittently in terms of time so that thermal strain does not occur.

A window hole 30a is formed in the package cover 30, and a transparent window plate 32 is attached to the window hole 30a. The window plate 32 is brazed to the package cover 30 so as to keep the container airtight. Further, the package cover 30 is provided with a plurality of connector pins 33 for connecting the laser diode 11, the Peltier element 19, and a thermistor (not shown) for detecting the temperature inside the resonator for the temperature adjustment to an external circuit. There is.

Further, in this embodiment, in particular, the welding of the package base 31 and the package cover 30 is performed in a dry N ₂ gas atmosphere which is one of the inert gases. As a result, the dry N ₂ gas is enclosed in the container.

The laser diode 11 has a wavelength of 89
A laser emitting a 0 nm laser beam 10 is used. The Nd: YAG crystal 13 emits light when neodymium ions are excited by the incident laser beam 10. This light resonates between the end surface 13a of the Nd: YAG crystal 13 and the mirror surface 14a of the resonator mirror 14, and has a wavelength of 94
A 6 nm solid state laser beam 20 is obtained. At this time, the laser oscillation mode is changed to a single longitudinal mode by the action of the etalon 16, and a stable output without mode competition noise can be obtained. As is clear from the above description, in this example, Nd: YA
The G crystal 13 and the resonator mirror 14 constitute a Fabry-Perot type resonator.

The solid laser beam 20 is transmitted by the LN crystal 15 to the second harmonic wave 21 having a wavelength of ½, that is, 473 nm.
The wavelength is converted to. This second harmonic 21 is generated by the resonator mirror 14
To the front, passes through the window hole 30a and the window plate 32, and is emitted to the outside of the container.

The Nd: YAG crystal end face 13a has a characteristic that the laser beam 10 having a wavelength of 890 nm is satisfactorily transmitted while the solid-state laser beam 20 having a wavelength of 946 nm and the second harmonic wave 21 having a wavelength of 473 nm are well reflected. Has been applied. Further, the resonator mirror surface 14a is coated with a characteristic that the solid-state laser beam 20 having a wavelength of 946 nm is well reflected, while the second harmonic wave 21 having a wavelength of 473 nm is well transmitted.

In this device, the laser diode 11, the Nd: YAG crystal 13 and the resonator are housed in a container which is hermetically sealed from the outside. The effect of changes in humidity and atmospheric pressure will not be affected. Therefore, it is possible to eliminate the change in the resonator length due to the change in the humidity and the atmospheric pressure, and reliably prevent the change in the output and the oscillation wavelength.

Further, in this example, since N ₂ gas, which is an inert gas, is sealed in the container, deterioration of laser components such as the coat film, metal and adhesive is prevented.

In this example, the laser diode 11 is L
Since the laser diode 11 is enclosed in the D package 17 and then housed in the container, the durability of the laser diode 11 is improved.

Needless to say, the solid-state laser crystal and the nonlinear optical crystal are not limited to the Nd: YAG crystal and the LN crystal 15 having the periodic domain inversion structure used in the above embodiment. Further, the resonator is not limited to the one composed of the solid-state laser crystal and the resonator mirror as mentioned above, and a Fabry
Perot type resonators, ring resonators, etc. can also be adopted.

Further, the laser diode-pumped solid-state laser described above converts the wavelength of the solid-state laser beam 20 into the second harmonic 21, but the present invention does not perform such wavelength conversion. It is also applicable to and has the same effect.

However, in a laser diode pumped solid-state laser that performs wavelength conversion, there is a problem that phase matching cannot be achieved when the oscillation wavelength changes, and the present invention is applied to a laser diode-pumped solid-state laser that performs wavelength conversion. Then, such a problem can be prevented from occurring, which is particularly preferable.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a laser diode pumped solid-state laser according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the laser diode pumped solid-state laser.

[Explanation of symbols]

 10 Laser Beam (Excitation Light) 11 Laser Diode 12 Condenser Lens 13 Nd: YAG Crystal 14 Resonator Mirror 15 LN Crystal with Periodic Domain Inversion Structure 16 Calcite Etalon 17 LD Package 18 Reference Plate 19 Peltier Device 20 Solid Laser Beam 21 Second harmonic 30 Package cover 30a Package cover window 31 Package stand 32 Window plate 33 Connector pin

Claims (3)

[Claims] 1. A solid-state laser crystal, and a laser diode that emits excitation light for exciting the solid-state laser crystal,
A laser diode pumped solid-state laser comprising a resonator, wherein the solid-state laser crystal, the laser diode and the resonator are housed inside a container that keeps the inside and outside airtight. . 2. The laser diode pumped solid-state laser according to claim 1, wherein an inert gas is sealed in the container. 3. The laser diode pumped solid-state laser according to claim 1, wherein a non-linear optical crystal for wavelength-converting the solid-state laser beam is arranged in the resonator.