JP2008211232A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small, lightweight semiconductor laser device having a simple structure, capable of easily obtaining a high conversion efficiency and highly efficiently outputting short wavelength laser light of high power. <P>SOLUTION: One end face 11 of a laser diode chip 10 is made into a total reflection surface and the other end face 12 into a non-reflective surface. An optical oscillator is formed by the one end face 11 and a wavelength selective mirror 15, a nonlinear optical crystal 14 is arranged within the oscillator for wavelength conversion, and then only light subjected to wavelength conversion is allowed to pass through the wavelength selective mirror 15 for output to the outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a semiconductor laser device suitable for generating short-wavelength laser light used for various applications such as information equipment, semiconductor manufacturing equipment, biomedical equipment, and the like.

Conventionally, as a device for generating a short wavelength laser beam, a gas laser device represented by an Ar laser device, a wavelength conversion laser device for an LD-excited solid-state laser, and a laser device of a type that converts the wavelength of a semiconductor laser beam by an external resonator Etc. are known (see, for example, Patent Document 1) .
Japanese Patent Laid-Open No. 4-5880

However, any conventional laser apparatus that generates short-wavelength laser light has a problem. A gas laser device such as an Ar laser is large, has a short life, and consumes a large amount of power. In an LD-pumped solid-state laser wavelength conversion laser device, a laser device of a type that converts the wavelength of semiconductor laser light using an external resonator, the device is complicated, and adjustment and control are extremely difficult.

In view of the above, an object of the present invention is to provide a semiconductor laser device that is small in size, light in weight, simple in structure, and capable of outputting short-wavelength laser light with high efficiency.

In order to achieve the above object, in a semiconductor laser device according to the present invention, a semiconductor laser device in which one end surface is a total reflection surface and the other end surface is a non-reflection surface and emits a fundamental wave from the other end surface, and a resonator described later An optical resonator is formed between a wavelength conversion element that is disposed within and converts the fundamental wave into a second harmonic, and the one end face that is disposed outside the semiconductor laser element, and substantially A mirror that is totally reflected with respect to the fundamental wave and is not reflected with respect to the wavelength of the second harmonic, and a first Peltier element that controls the temperature of the semiconductor laser element so as to generate a laser beam with an appropriate wavelength A second Peltier element for controlling the temperature of the wavelength conversion element so as to perform the most efficient wavelength conversion, a heat sink for the first and second Peltier elements, and the mirror. It is connected, to have a third Peltier element for controlling so that the temperature of the whole is constant, the is the distinctive feature Te.

A laser resonator is formed by one end face of a semiconductor laser element and an external mirror, and a wavelength conversion element is arranged therein to output wavelength-converted light to the outside. The power density of the fundamental wave in the element can be increased, the structure is simple, high conversion efficiency can be easily obtained, and high-power laser light with a short wavelength can be obtained.

As described above, according to the semiconductor laser device of the present invention, a laser resonator is formed by one end face of a semiconductor laser element and an external mirror, and a nonlinear optical crystal that is a wavelength conversion element is disposed therein. Since the wavelength-converted light is output to the outside, the power density of the fundamental wave in the wavelength conversion element can be increased, the structure is simple, high conversion efficiency is easily obtained, and the size is small. Light weight and high output short wavelength laser light can be output with high efficiency.

Next, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, one end surface 11 of a laser diode chip (LD chip) 10 is provided with an HR coat that serves as a total reflection film for light having an oscillation wavelength, and the other end surface 12 has no effect on light having the same wavelength. An AR coat serving as a reflective film is applied. The laser beam emitted from the end face 12 is condensed on the nonlinear optical crystal 14 by the condensing lens 13 and further reflected by the wavelength selective mirror 15 which is a concave mirror. The light can enter the chip 10 again. As a result, a laser resonator is formed by the end face 11 and the mirror 15. Then, the laser beam having the wavelength transmitted through the mirror 15 is collimated by the collimating lens 16 and emitted.

The laser diode chip 10 is attached to the Peltier element 24 via the heat sink 25 and is temperature-controlled so as to generate a laser beam having an appropriate wavelength (for example, infrared light having a wavelength of about 860 nm, hereinafter referred to as a fundamental wave). It has been tuned.

The nonlinear optical crystal 14 converts the wavelength of light passing therethrough, and is attached to the Peltier element 26 via a heat sink 27 and controlled to a temperature at which the most efficient wavelength conversion is performed.

The mirror 15 totally reflects the wavelength of the fundamental wave that is emitted from the laser diode chip 10 and does not reflect the wavelength of the second harmonic converted by the nonlinear optical crystal 14. As a result, only the second harmonic converted by the nonlinear optical crystal 14 is emitted to the outside of the resonator. Thereby, the second harmonic obtained by wavelength conversion (for example, blue light having a wavelength of about 430 nm) can be emitted.

These laser diode chip 10, condensing lens 13, nonlinear optical crystal 14, wavelength selective mirror 15, and collimating lens 16 are directly connected to the base 21 via a Peltier element through or without a heat sink or Peltier element. It is fixed on the heat sink 23 attached via 22 and the whole is maintained at a constant temperature by the Peltier element 22.

In such a configuration, the resonator of the semiconductor laser device is constituted by the one end face 11 of the laser diode chip 10 and the external mirror 15, and the nonlinear optical crystal 14 is arranged in the resonator to perform wavelength conversion and conversion. Only the light of the specified wavelength is emitted to the outside. Therefore, the power density of the fundamental wave in the nonlinear optical crystal 14 can be easily increased without using a complicated structure such as an external resonator, and as a result, high conversion efficiency can be obtained. That is, the semiconductor laser device configured as described above is small and lightweight, and can generate short-wavelength laser light with high efficiency.

FIG. 2 shows another embodiment, in which a laser resonator is formed by one end face 11 of the laser diode chip 10 and a total reflection mirror 19. A nonlinear optical crystal 14 and a prism 18 are disposed in the resonator, and wavelength conversion is performed by the nonlinear optical crystal 14, and the fundamental wave and the second harmonic are subjected to wavelength selection using the spectral characteristics of the prism 18. Since the wavelength is selected by the prism 18, the mirror 19 is not a wavelength selectivity but a total reflection mirror. Further, the oscillation wavelength of the fundamental wave can be tuned by changing the angle of the mirror 19 and changing the wavelength of the light returned to the resonator as indicated by the arrow, and the result is converted by the nonlinear optical crystal 14. The wavelength of the generated second harmonic can be made variable.

Although not shown in FIG. 2, the laser diode chip 10 and the nonlinear optical crystal 14 are respectively controlled in temperature by being fixed via a heat sink and a Peltier element as in FIG. Other optical elements are preferably fixed to the base 21 via a heat sink 23 and a Peltier element 22 as shown in FIG.

The above description relates to one embodiment of the present invention. The present invention is not limited to the above, and it is needless to say that various modifications can be made without departing from the spirit of the present invention. For example, in FIG. 2, the wavelength can be tuned by using an etalon or a grating instead of the prism 18.

The schematic diagram which shows embodiment of this invention. The schematic diagram which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser diode chip 11 End surface 12 which is a total reflection surface End surfaces 13 and 17 which are non-reflection surfaces Condensing lens 14 Nonlinear optical crystal 15 Wavelength selective concave mirror 16 Collimating lens 18 Prism 19 Total reflection mirror 21 Base 22, 24, 26 Peltier element 23, 25, 27 Heat sink

Claims (2)

A semiconductor laser element that has one end surface as a total reflection surface and the other end surface as a non-reflection surface, and emits a fundamental wave from the other end surface ;
A wavelength conversion element that is arranged in an optical resonator to be described later and converts the fundamental wave into a second harmonic ;
An optical resonator is formed between the semiconductor laser element and the one end face, and is substantially totally reflected with respect to the fundamental wave and non-reflective with respect to the wavelength of the second harmonic wave. A mirror,
A first Peltier element that controls the temperature of the semiconductor laser element to generate a laser beam of an appropriate wavelength;
A second Peltier element that controls the temperature of the wavelength conversion element so that the most efficient wavelength conversion is performed;
A third Peltier element that is connected to the first and second Peltier elements and the mirror via a heat sink and controls the temperature of the entire optical resonator to be constant;
A semiconductor laser device comprising: A condensing lens disposed between the semiconductor laser element and the wavelength conversion element ;
A collimating lens disposed outside the resonator ;
2. The semiconductor laser device according to claim 1, wherein the condensing lens and the collimating lens are also connected to a third Peltier element via the heat sink .

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