JPH05160480A - Laser diode pumping solid-state laser - Google Patents

Abstract

PURPOSE:To obtain solid-state laser beam in TEM00 mode as well as to prevent a laser diode from generating return light induction noise in a laser diode pumping solid-state laser for pumping a solid-state laser medium with the laser diode. CONSTITUTION:In the case where 'd' is a distance between an Nd: YVO4 rod 16 as a solid-state laser medium and a laser diode chip 14, 'dM' the minimum value of the 'd' oscillating in higher-order horizontal mode, and 'dN' the maximum value of the 'd' generating return light noise of a laser diode, respectively, the distance 'd' is set so as to satisfy the relationship dN<d<dM.

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, and more particularly to a laser diode pumped solid-state laser in which a laser diode chip is disposed close to a solid-state laser medium.

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 62-189783, a laser diode pumping solid-state laser is known in which a solid-state laser medium doped with a rare earth element such as neodymium is pumped by a semiconductor laser (laser diode). ing. In this type of laser diode pumped solid-state laser, a laser diode chip is also placed close to the solid-state laser medium in order to improve oscillation efficiency.

[0003]

However, in such a laser diode pumped solid-state laser in which the laser diode chip is arranged close to the solid-state laser medium, the optical output is unstable due to the return light noise of the laser diode. The problem was recognized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser diode pumping solid-state laser in which the generation of return light noise of the laser diode is suppressed and the output is stable. is there.

[0005]

A laser diode pumped solid-state laser according to the present invention is a laser diode pumped solid-state laser in which a solid-state laser medium is pumped by a laser diode as described above. d, the minimum value of d for high-order transverse mode oscillation is d _M ,
The distance d is set to a value satisfying d _N <d <d _M , where d _N is the maximum value of d _at which the return light noise of the laser diode is generated.

[0006]

According to the research conducted by the present inventors,
In the laser diode pumping solid-state laser, return light noise occurs when the distance d between the solid-state laser medium and the laser diode chip becomes a certain value d _N or less, and on the other hand, when this distance d becomes a certain value d _M or more, the higher-order transverse mode Oscillates and d is between these values d _M and d _N
It turns out that there is a relationship of _N <d _M. Therefore, if the distance d is set to be larger than d _N , the return light noise of the laser diode is suppressed and the output is stabilized.

Even if the generation of return light noise can be prevented in this way, if the solid-state laser oscillates in the higher-order transverse mode, the laser beam obtained therefrom has a low utility value. I will end up. However, since there is a relationship of d _N <d _M as described above, there always exists a value of d satisfying d _N <d <d _M, and thus the distance d
By setting, the high-order transverse mode oscillation can be suppressed and a high-quality TEM ₀₀ mode laser beam can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 shows a laser diode pumped solid state laser according to a first embodiment of the present invention. This laser diode pumped solid-state laser is a solid-state laser medium doped with neodymium (Nd) and a laser diode chip 14 fixed to a mount 12 integrated with a housing 11 to emit a laser beam 13 as pumping light. YVO ₄ rod (hereinafter,
Nd: YVO ₄ rod) 16 and this Nd: YV 4
The resonator mirror 17 is disposed on the front side (right side in the figure) of the O ₄ rod 16.

As the laser diode chip 14, a broad area type which emits a laser beam 13 having a wavelength λ ₁ = 809 nm is used. On the other hand, Nd: YV
The O ₄ rod 16 is doped with Nd, for example, at 1 at%, and is formed to have a thickness of 1 mm. This Nd: YVO
_{4 The} rod 16 emits a laser beam 18 having a wavelength λ ₂ = 1064 nm by exciting neodymium atoms by the laser beam 13.

Nd: YVO ₄ rod 16 light incident side end face 16
a and the light emitting end face 16b are coated 2
0 and 21 are given. On the other hand, coatings 22 and 23 are respectively applied to the light incident side end surface 17a and the light emitting end surface 17b which are concave surfaces of the resonator mirror 17. The reflectivities of these coatings 20, 21, 22, 23 for wavelengths λ ₁ = 809 nm and λ ₂ = 1064 nm are as follows.

[0011] Therefore, the laser beam 18 having a wavelength of 1064 nm is confined between the surfaces 16a and 17a to cause laser oscillation, and a part of the laser beam 18 passes through the resonator mirror 17 and is emitted forward.

Here, the laser diode chip 14 and N
When the distance d to the d: YVO ₄ rod 16 is changed, the output of the solid-state laser changes as shown in FIG. The example of FIG. 2 is for a laser diode output of 180 mW. As shown in FIG. 2, the above distance d
As is shorter, the oscillation efficiency is improved and the laser output is increased. However, in this case, if the distance d is set to d _N = 50 μm or less, optical noise is generated in the laser diode chip 14, while if the distance d is d _M = 500 μm or more, higher-order transverse mode oscillation occurs. .. Therefore, in this embodiment, the distance d is set to 100 μm. That is, d _N <d <d _M.

By setting the value of d in this way,
A high-quality solid-state laser beam 18 in the TEM ₀₀ mode can be obtained, on the other hand, the generation of return light noise in the laser diode chip 14 is suppressed, and the solid-state laser output is stabilized.

Next, a second embodiment of the present invention will be described with reference to FIG. The laser diode pumped solid-state laser of FIG. 3 is basically different from that of FIG. 1 in that a KTP crystal 10 is arranged between an Nd: YVO ₄ rod 16 and a resonator mirror 17. Also this K
The entire apparatus including the TP crystal 10 is temperature controlled to a predetermined temperature by a Peltier element 40 and a temperature control circuit (not shown).

In the second embodiment, the wavelength λ ₂
= Laser beam 18 of 1064nm is incident on KTP crystal 10 which is a nonlinear optical material, a wavelength _{λ 3 = λ 2/2 =} 532 n
The wavelength is converted into the second harmonic wave 19 of m. Nd: YVO ₄ A coating 30 applied to both end surfaces 16a, 16b of the rod 16;
31, coatings 32 and 33 applied to both end surfaces 10a and 10b of the KTP crystal 10 and coatings 34 and 35 applied to end surfaces 17a and 17b of the resonator mirror 17, wavelength λ ₁ = 809 nm,
The reflectances for λ ₂ = 1064 nm and λ ₃ = 532 nm are as follows.

[0016] Therefore, the laser beam 18 oscillates between the end faces 16a and 17a, and the second harmonic wave 19 directly or
After being reflected by 16b, it enters the resonator mirror 17, passes through it, and is taken out of the housing 11.

Also in this apparatus, the distance d between the laser diode chip 14 and the Nd: YVO ₄ rod 16 is set to 100 so that the above-described relationship of d _N <d <d _M is satisfied.
It is set to μm. Thereby, also in this embodiment,
As in the case of the first embodiment, the second harmonic wave 19 of the TEM ₀₀ mode is obtained, the generation of the return light noise in the laser diode chip 14 is suppressed, and the output of the solid-state laser and thus the second harmonic wave 19 is stable. To do.

In the two embodiments described above, the distance d between the laser diode chip 14 and the Nd: YVO ₄ rod 16 is set to 100 μm.
The distance d in the present invention is not limited to this value as a matter of course, and may be appropriately set within a range satisfying the relationship of d _N <d <d _M described above.

The solid-state laser medium used in the present invention is Nd: YVO in the above-described embodiment.
Not limited to ₄ rods, other known ones, such as NYAB, LNP, Nd: YAG, Nd: Y
LF can be used as appropriate. The nonlinear optical material used for wavelength conversion is not limited to KTP, and other known materials such as BNNB and KN can be used.
bO ₃ , LiIO ₃ , Urea, disclosed in JP-A-2-77181 (3,5-dimethyl-1- (4-nitrophenyl) pyrazole, disclosed in JP-A-2-28 (3,5-dimethyl-1- (4-nitrophenyl) pyrazole).
5-dimethyl-1- (4-nitrophenyl) -1,2,
4-triazole or the like can be used as appropriate.

[Brief description of drawings]

FIG. 1 is a side view of a first embodiment device of the present invention.

FIG. 2 is a graph showing the relationship between the solid-state laser output, the return light noise occurrence state, and the transverse mode with respect to the distance between the laser diode chip and the solid-state laser medium.

FIG. 3 is a side view of a second embodiment device of the present invention.

[Explanation of symbols]

10 KTP crystal 13 Laser beam (pumping light) 14 Laser diode chip 16 Nd: YVO ₄ Rod 17 Resonator mirror 18 Laser beam 19 Second harmonic 20, 21, 22, 23, 30, 31, 32, 33, 34, 35 coating

Claims (1)

[Claims] 1. A laser diode pumped solid-state laser in which a solid-state laser medium doped with a rare earth element such as neodymium is pumped by a laser diode. Where d _{M is} the minimum value of d and the maximum value of d where the return light noise of the laser diode is generated is d _N , the distance d is set to a value satisfying d _N <d <d _M. Laser diode pumping solid state laser.