JPH05145160A - Second harmonics generator in solid laser device - Google Patents

Abstract

PURPOSE:To provide a second harmonics generator where the processing of an optical element is easy, and the position adjustment of components is not molded and which is low-coat. CONSTITUTION:This is a laser diode excited solid laser which is equipped with a resonator 8 composed of a laser medium 5, where a curved mirror 3 is bonded through a UV hardening adhesive 4, and a nonlinear optical crystal KTP6 fitted with a plane mirror 7, and both the laser medium 5 and the nonlinear optical crystal 6 are made in rectangles easy to work and the light to be oscillated is the green laser by the second harmonics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a second harmonic generation device in a solid-state laser device using a laser diode as an excitation light source.

[0002]

2. Description of the Related Art Generally, when recording or reproducing information using light, the shorter the wavelength, the higher the recording density. In addition, when a light source is required as an element, it is indispensable for the generator to be small. For this reason, in particular, in the optical information industry, a small-sized light source that can obtain a short wavelength is desired. As a device for obtaining such a light source, a device for wavelength conversion by inserting a nonlinear optical crystal into a resonator of a solid-state laser using a laser diode as an excitation light source has been studied in recent years. Also,
Conventional examples of the resonator are as follows because they are easy to adjust. There is an output mirror having a curvature and a structure in which a plane mirror is attached to the other laser medium (Nikkei New Material, June 10, 1991, p. 33). There is also a method in which the end face of the laser medium is processed into a curved surface and a mirror is vapor-deposited to serve as one of the mirrors of the resonator (Optical Letters P-137, Vol.13, February,
1988).

In order to efficiently perform wavelength conversion, it is necessary to dispose a nonlinear optical crystal at the position of the beam waist of the fundamental wave oscillating in the resonator. With the structure as described above, however, There is a beam waist in the laser medium and it is not possible to bring the nonlinear optical crystal to its optimum position. Further, in the above structure, although it is theoretically possible to dispose the nonlinear optical crystal at the position of the beam waist, the resonator length becomes large and the processing of the laser medium becomes difficult, which makes it unsuitable for mass production. Moreover, there is a drawback that the range of use is narrow and the utility value is low.

[0004]

DISCLOSURE OF THE INVENTION The present invention is capable of easily processing an optical element and does not require fine adjustment of each element such as a laser mirror, a solid-state laser crystal and a non-linear optical crystal. An object of the present invention is to provide a second harmonic generation device in a solid-state laser device that can obtain a second harmonic.

[0005]

In view of the above-mentioned circumstances, the present invention is a second harmonic generation device in a solid-state laser device capable of eliminating these drawbacks, which uses a laser diode as an excitation light source. The laser device is characterized by including a resonator composed of a curved mirror bonded to a laser medium and a plane mirror deposited on a nonlinear optical crystal.

[0006]

In summary, since the present invention is constructed as described above, wavelength conversion to a short wavelength can be performed with higher efficiency than the conventional one. In addition, for the adjustment of resonance, it is possible to adjust the mirror so that it oscillates and then fix it by using an adhesive that cures by a scientific reaction, so it is necessary to make fine adjustments each time. Absent.

[0007]

Embodiment An embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows the structure of a solid-state laser component excited by a laser diode according to the present invention. In the figure, 1 is a laser diode, 2 is a SELFOC lens, and 3 is a curved mirror having a predetermined curvature. The curved mirror 3 is formed by processing a transparent substance such as glass having a flat surface on one side and a concave curved surface 3a on the other side into a lens shape and depositing a mirror on the concave curved surface 3a side. It is adhered to the front surface via an adhesive 4. For example, YVO ₄ (yttrium vanadate) is used as the laser medium, and a UV (Ultra Violet) curable adhesive is used as the adhesive 4. The adhesive 4 is already on the market, and the UV curing agent is activated by the irradiation of ultraviolet rays to start the crosslinking curing reaction of the resin. Therefore, as will be described later, the resonance can be adjusted by adjusting the mirror to a position where the element oscillates, and then curing the adhesive to fix it. Reference numeral 6 is a non-linear optical crystal of KTP (KTiOPO ₄ ) single crystal, which can easily obtain a visible green laser beam. This KTP has a crystal plane cut out so that the phase of the second harmonic can be adjusted. Incidentally, the laser medium YVO ₄ 5
Both the KTP nonlinear optical crystal 6 with a mirror are formed in a rectangular shape so as to be easily processed, and the resonator 8 is constituted by both.

The light emitted from the laser diode 1 is condensed in the laser medium YVO ₄ 5 via the SELFOC lens 2. Mirror 3 and 810nm in the laser medium YVO ₄ 5
AR (Anti-Reflection) coating of HR (Higt-Reflecti) which reflects well at 1064nm on the nonlinear optical crystal with mirror KTP 6
on) Coated. For YVO ₄ 5, strong absorption of 810nm is can serve laser medium with a thin crystal. In this case, for example, 1mm thick YVO ₄ and 5mm thick YVO ₄
By using KTP, a cavity length of 15 mm thick YVO ₄ could be realized. In addition, laser diode output 800 mW 100 mW
Realized the second harmonic output of.

As described above, according to the present invention, the beam waist can be brought to the end surface of the nonlinear optical crystal without increasing the cavity length by this structure.
Therefore, the visible green laser light by the second harmonic can be obtained very easily without adjusting each of the laser mirror, the solid-state laser crystal, and the nonlinear optical crystal. Moreover, since both the laser medium and the nonlinear optical crystal are formed in a rectangular shape, it is easy to process the device, and the optical system is constructed by combining a thin laser medium and an extremely thin nonlinear optical crystal by using commercially available parts. Since it is small, it can be used in a wide range, such as being suitable for being incorporated in a head component such as a CD. Further, by combining these, it is possible to realize a low cost, a simple operation, and a highly efficient second harmonic generator.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a second harmonic generation device according to the present invention.

[Explanation of symbols]

1 Laser diode 2 Selfoc lens 3 Curved mirror 3a Concave curved surface 4 UV curable adhesive 5 Laser medium YVO ₄ 6 Non-linear optical crystal (KTP with mirror) 7 Plane mirror 8 Resonator

Claims (1)

[Claims] 1. A solid-state laser device using a laser diode as an excitation light source, comprising a resonator comprising a curved mirror adhered to a laser medium and a plane mirror deposited on a nonlinear optical crystal. Second harmonic generation device in laser device.