JPH04268777A - Semiconductor laser excitation solid-state laser device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser excitation solid-state laser device which is able to emit green laser rays that focus at an optional point and adapted to the record reproducing device of an optical disc, a laser printer, laser applied measurement, or the like. CONSTITUTION:Laser rays emitted from a green laser which is composed of an Nd: YVO4 microchip 1 and a KTP crystal 2 and excited by a semiconductor laser chip 3 are converged by a lens 4 mounted in front of a package 7. The lens 4 is made to vary in focal length, whereby it is able to focus at an optional point. As the emitted light can be converged without providing a lens outside, a compact optical system adapted to the use of laser rays can be realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-small semiconductor laser-excited solid-state laser device used for recording and reproducing optical discs, laser printers, laser applied measurements, etc., and a method for manufacturing the same.

0002

[Prior Art] Conventionally, arc lamps and flash lamps have been used to excite solid-state laser media, but due to poor excitation efficiency, the efficiency of the laser as a whole is poor, and the device had to become larger. However, in recent years, with the increase in the output power of semiconductor lasers, attempts have been made to use semiconductor lasers as excitation light sources for solid-state lasers. When a semiconductor laser is used, the excitation wavelength can be matched to the absorption band of the solid-state laser, resulting in extremely high excitation efficiency. Furthermore, since no heat is generated due to absorption of excess spectrum, heat dissipation is facilitated, and a compact and highly efficient solid-state laser can be realized.

On the other hand, there has been a conventional method of converting infrared light from a solid-state laser into harmonics using a nonlinear optical crystal such as a KTiOPO4 (hereinafter referred to as KTP) crystal to obtain laser light in the visible range of green and blue. This is known, and attempts have also been made to utilize the harmonics of the solid-state laser light excited by the semiconductor laser described above.

FIG. 3 is a partially cutaway diagram of a conventional semiconductor laser pumped solid-state laser device. In FIG. 3, 1 is a yttrium vanadium oxide (hereinafter referred to as Nd:YVO4) microchip containing neodymium, which is a solid-state laser medium; 2 is a KTP crystal, which is a nonlinear optical crystal;
3 is a semiconductor laser chip that serves as an excitation light source, 5 is a PIN photodiode for adjusting output, 6 is a stem, and 7
8 is a storage container (hereinafter referred to as a package), and 8 is a glass window. In this way, Nd:YVO4 microchip 1, K
A TP crystal 2, a semiconductor laser chip 3, and a PIN photodiode 5 are housed in a package 7. Furthermore, a glass window 8 is attached to the front of the package 7 to seal the inside. The resonator of the Nd:YVO4 laser is connected to the excitation side end face of the Nd:YVO4 microchip 1 and KT.
It is formed between the output side end face of the P crystal 2 and the output side end face of the P crystal 2. The semiconductor laser chip 3 is closely attached to the end face of the Nd:YVO4 microchip 1, and the Nd:YVO4 microchip 1
d: The YVO4 microchip 1 can be sufficiently excited. Laser light with a wavelength of 1.064 μm is generated from the excited Nd:YVO4 microchip 1, and the laser light is converted by the KTP crystal 2 into green light with a wavelength of 0.53 μm, which is the second harmonic.

[0005]

However, the configuration of the conventional device described above has a problem in that the emitted green laser light is emitted with a spread angle of several mrad.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a semiconductor laser-excited solid-state laser device that emits laser light that is focused at an arbitrary distance, and a method for manufacturing the same.

[0007]

[Means for Solving the Problems] In order to achieve this object, the semiconductor laser pumped solid-state laser device of the present invention has a structure in which a lens is attached in place of the glass window on the front surface of the package.

[0008]

[Operation] With this configuration, the laser beam can be focused at any distance without providing a lens outside the laser device, so the number of parts can be reduced and it is convenient in terms of application.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway view of a semiconductor laser-excited solid-state laser device according to an embodiment of the present invention. The same parts as in the conventional example shown in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted. As shown in FIG. 1, a package 7 houses an Nd:YVO4 microchip 1, a KTP crystal 2, a semiconductor laser chip 3, and a PIN photodiode 5 for adjusting output. The semiconductor laser chip 3 is brought into close contact with the end face of the Nd:YVO4 microchip 1, so that the Nd:YVO4 microchip 1 can be sufficiently excited from the axial direction before the semiconductor laser light spreads. The resonator of the Nd:YVO4 laser is Nd:YVO4
It is formed between the excitation side end face of the microchip 1 and the output side end face of the KTP crystal 2 . Excited Nd:YVO4
A laser beam with a wavelength of 1.064 μm is generated from the microchip 1, and the laser beam is converted by the KTP crystal 2 into green light with a wavelength of 0.53 μm, which is the second harmonic. The converted green light is transmitted through lens 4 attached to the front.
The light can be focused at any distance.

FIG. 2 shows an example in which a convex lens 4a or a Fresnel lens 4b is attached as a lens. FIG. 2(a) is a cross-sectional view of the inside of a package with a convex lens 4a attached to the front surface, and FIG. 2(b) is a cross-sectional view of the package with a Fresnel lens 4b attached to the front surface.

Next, a method of manufacturing a semiconductor laser pumped solid-state laser device according to an embodiment of the present invention will be explained with reference to FIG. First, the semiconductor laser chip 3, the Nd:YVO4 microchip 1 and the K
A TP crystal 2 is attached, and then a cylindrical package 7 with a lens 4 attached to the front is attached to the stem 6. Nd:
YVO4 microchip 1 has a Nd concentration of 2 in YVO4.
%, and the chip size is 2 mm in diameter and 1 mm in thickness. The excitation side end face of this microchip 1 has a radius of curvature of 10 m.
It has a convex shape of m, and the end surface on the opposite side is a flat surface. The KTP crystal 2 has a cylindrical shape with a diameter of 2 mm and a length of 5 mm, and both end faces are flat. In addition, in order to form the resonator of the Nd:YVO4 laser, the excitation side end face of the microchip 1 and the K
A high reflection (HR) coating was applied to the output side end face of the TP crystal 2 for the fundamental wavelength of 1.06 μm of the Nd:YVO4 laser. In order to increase excitation efficiency, an anti-reflection (AR) coating was applied to the excitation side end face at an excitation wavelength of 0.808 μm. Further, in order to efficiently emit the second harmonic light converted within the KTP crystal 2 from the front surface, an AR coating was applied to the output side end face for a wavelength of 0.53 μm.

The beam shape of the green light emitted from the KTP crystal 2 is TEMOO, so it is circular and the wavelength is 0.
．． It is fixed at 532μm and the spread angle is YVO.
Since it is determined by the resonator length and curvature of the four lasers, the focal length of the lens 4 attached to the front surface of the package 7 can be arbitrarily designed according to the desired focal length. When the focal lengths are close, the convex lens 4a in FIG. 2(a) has a large thickness, but the Fresnel lens 4 as shown in FIG. 2(b)
It can be made thinner by using b. Further, it is convenient for the application if the emitted light is made to be parallel light.

As the semiconductor laser chip 3 for excitation, a single transverse mode high power semiconductor laser with a wavelength of 0.808 μm was used. Since this semiconductor laser operates in a stable mode up to an output of 300 mW, it has good coupling efficiency with the Nd:YVO4 laser in the axial direction, and high excitation efficiency can be obtained. Excitation input from semiconductor laser chip 3 is 250mW
At this time, 10 mW of green laser light was obtained. Also, the relative intensity noise (RIN) at this time is -145 dB/
It was Hz.

Note that in the present invention, the solid laser medium contains N.
Although d: YVO4 and KTP crystal were used as the nonlinear optical crystal, similar effects can be obtained by using other laser media and other nonlinear optical crystals. Further, a similar effect can be obtained by using a self-harmonic solid-state laser medium (for example, NYAB) that functions as both a solid-state laser medium and a nonlinear optical crystal.

[0016]

Effects of the Invention As described above, the present invention provides a compact optical system that can condense emitted light to an arbitrary distance without attaching an external lens by attaching a lens to the front surface of a storage container. This makes it possible to realize a semiconductor laser-excited solid-state laser device that is easy to adjust.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway diagram of a semiconductor laser pumped solid-state laser device according to an embodiment of the present invention.

[Figure 2] (a) is a cross-sectional view of the inside of the package with a convex lens attached to the front. (b) is a cross-sectional view of the package with a Fresnel lens attached to the front.

[Figure 3] Partial cutaway diagram of a conventional semiconductor laser pumped solid-state laser device

[Explanation of symbols]

1 Nd:YVO4 microchip (solid laser medium) 2 KTP crystal (nonlinear optical crystal) 3 semiconductor laser chip 4 lens 6 stem (storage container) 7 package (storage container)

Claims (4)

[Claims] Claim 1: At least a nonlinear optical crystal, a solid laser medium, and a semiconductor laser chip are housed in the same storage container,
and a semiconductor laser-excited solid-state laser device, wherein a lens is attached to the front surface of the storage container. 2. A semiconductor laser-excited solid-state laser device, wherein a solid-state laser medium having at least a self-harmonic function and a semiconductor laser chip are housed in the same container, and a lens is attached to the front surface of the container. 3. Semiconductor laser excitation, characterized in that at least a nonlinear optical crystal and a solid laser medium are attached to a stem to which a semiconductor laser chip is attached, and then the semiconductor laser chip is encapsulated with a cap having a lens attached to the front surface. A method for manufacturing a solid-state laser device. 4. A semiconductor laser characterized in that a solid laser medium having at least a self-harmonic function is attached to a stem to which a semiconductor laser chip is attached, and then the semiconductor laser chip is encapsulated with a cap having a lens attached to the front surface. A method for manufacturing a pumped solid-state laser device.