JPH0391978A - Semiconductor laser-excitated solid-state laser device - Google Patents

Abstract

PURPOSE:To obtain a subminiature harmonics conversion device by a method wherein a non-linear optical crystal, a solid laser medium, an aspherical lens, and a semiconductor laser chip are housed in the sam package in this order. CONSTITUTION:A nonlinear optical crystal 2, a solid laser medium 1, a lens 3, and a semiconductor laser chip 4 are housed in the same package in this sequence. That is, an optical resonator is composed of an end face 1A of the solid laser medium 1 closer to the semiconductor laser chip 4 and an end face 2B of the nonlinear optical crystal 2 on the further side from the semiconductor laser chip 4. Semiconductor laser rays are collected through the lens 3, and the end faces of the solid laser medium 1 are excited in an axial direction. By this setup, a subminiature stable semiconductor laser excitated solid laser formed in an integral structure can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultra-small semiconductor laser-excited solid-state laser device used for recording and reproducing optical discs, laser applied measurement, and the like.

Conventional technology Conventionally, arc lamps, flash lamps, etc. have been used to excite solid-state laser devices, but due to poor excitation efficiency, the overall efficiency of the laser is poor, and the device had to be large.

However, in recent years, with the increase in the output power of semiconductor lasers, attempts have been made to use them as an excitation source for solid-state lasers. When a semiconductor laser is used, the wavelength can be matched to the absorption band of a solid-state laser, resulting in extremely high excitation efficiency. Moreover, since there is no heat generated due to absorption of excess spectrum, heat dissipation is also easier, making it possible to create a compact and highly efficient solid-state laser.

On the other hand, a method of converting solid-state laser light into harmonics using a nonlinear optical crystal such as KTiOPO+ (KTP) crystal to obtain green or blue visible light is also known. Attempts have also been made to utilize harmonics of laser light.

Problems to be Solved by the Invention FIG. 2 shows a block diagram of a semiconductor laser pumped Nd:YAG laser. A Nd:YAG rod 1, a KTP crystal 2, a SELFOC lens 7, and a semiconductor laser chip 4 are housed in this order in the same package. In order to make the KTP crystal inserted into the resonator of the YAG laser, Y
The exit side end face 1-B of the AG rod 1 and the excitation side end face 2-A of the KTP crystal 2 are coated with HR coating for a wavelength of 1.06 μm. Furthermore, in order to reduce loss within the resonator, the end faces 1-A and 2-B of the YAG rod 1 and KTP crystal 2 inside the resonator are coated with an AR coating for a wavelength of 1.06 μm. . In addition, in order to efficiently focus the excitation semiconductor laser beam with a wavelength of 0.81 μm onto the YAG rod 1, both end surfaces 2-A, 2-B and Y
The excitation side end face 1-A of the AG rod 1 is AR coated for a wavelength of 0.81 μm. Furthermore, Nd:
In order to efficiently emit light with a wavelength of 0.53 μm, which is a harmonic of YAG laser light, the excitation side end face 2 of the KTP crystal 2
-A is HR coating for wavelength 0.53μm,
Other end faces 2-B, l-A. 1-B is AR coated. Table 1 summarizes the coatings for each wavelength.

As can be seen from Table 1, each end face is 3f! AR or HR coating must be applied to the lH wavelength, which proves to be extremely difficult to coat. Applying a complex multilayer coating is disadvantageous in terms of efficiency and yield, so it is desirable to simplify the coating as much as possible.

Means for Solving the Problems In order to simplify the end face coating of the YAG rod and the KTP crystal, the solid-state laser device of the present invention uses KTP crystal, N
d: Consists of a YAG rod, an aspherical lens, and a semiconductor laser chip arranged in this order.

The structure, which is more than functional, makes it possible to create an integrated ultra-small and stable semiconductor laser-excited solid-state laser.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a structural diagram of a semiconductor laser pumped solid-state laser device of the present invention. KTP crystal 2, Nd:YAG rod 1. An aspherical lens 3 and a semiconductor laser chip 4 are housed in this order. The YAG rod 1 has an Nda degree of 1.1%, a length of 5 m, and a diameter of 3 nm. The KTP crystal 2 has a length of 5 m and a diameter of 3 m. The resonator is formed between the excitation side end face 1-A of the YAG rod 1 and the output side end face 2-B of the KTP crystal, the former being a convex mirror with a curvature of 50 m, and the latter being a flat mirror. The structure is such that the KTP crystal 2 is inserted into the resonator of the Ncl:YAG laser, and the KTP crystal is placed where the beam diameter of the laser beam is the narrowest.
Exchange to harmonics is performed efficiently. The excitation side end face 1-A of the YAG rod 1 has a reflectance of 0425% or less for a wavelength of 0.81 ttm, a reflectance of 99.8% or more for a wavelength of 1.06 μm, and the other end face 1-B wavelength 0
．． Reflectance of 99% or more for 81μm, wavelength 1.06μ
A multilayer film coating is applied so that the amount of 0.25% or less of m is 0.25% or less. In addition, the excitation side end face 2- of the KTP crystal 2
A has a reflectance of 0.20% or less for a wavelength of 1.06 μm,
The reflectance for the wavelength of 0.53 μm is 99% or more, and the other end face 2-B has a reflectance of 99% for the wavelength of 1.06 μm.
A multilayer coating is applied so that the reflectance is 8% or more and the reflectance is 0.2% or less at a wavelength of 0.53 μm. Table 2 summarizes the coating state of each end face.

(Left below) Table 2 As can be seen from Table 2, each end face only needs to be coated with AR or HR coating for two types of wavelengths, making the coating simpler than that shown in Figure 3 and Table 1. It can be seen that it has been made possible. In addition, in the above order, Nd: Y
By arranging the AG rod 1 and the KTP crystal 2 and applying the above coating, the harmonic light of 0.53 μm is transmitted to the YAG
It can prevent the rod from being reabsorbed, and the efficiency is <0.
．． It can emit light of 53 μm.

The wavelength of the semiconductor laser light is adjusted to 0.809 μm, matching the absorption band of Nd:YAG. This semiconductor laser beam is passed through an aspherical lens 3 with a numerical aperture of 0.6 into a YAG
The light is focused near the center of the end face of the rod 1.

FIG. 3 shows the relationship between the Nd;YAG harmonic output and the semiconductor laser drive current. 16mW at 400mA drive current
of light output was obtained.

Effects of the Invention The semiconductor laser-excited solid-state laser device of the present invention is an ultra-compact harmonic conversion device, and has great effects in recording and reproducing optical discs, laser applied measurement, and the like.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of a semiconductor laser pumped solid-state laser device of the present invention, Fig. 2 is a diagram showing Nd:YAG harmonic output with respect to drive current, and Fig. 3 is a structural diagram of a conventional semiconductor laser pumped solid-state laser. . 1...Nd: YAG rod, 2...
・KTP crystal, 3...Aspherical lens, 4...
... Semiconductor laser chip, 5 ... PIN photodiode, 6 ... Song/base, 7 ... Selfoc lens.

Claims (1)

[Claims] Nonlinear optical crystal, solid-state laser medium,
A lens and a semiconductor laser chip are arranged and housed in this order, and an optical resonator is formed by an end face of the solid-state laser medium closer to the semiconductor laser chip and an end face of the nonlinear optical crystal farther from the semiconductor laser chip. and
A semiconductor laser-excited solid-state laser device, characterized in that the lens condenses semiconductor laser light to end-excite the solid-state laser medium in the axial direction.