JP2727936B2 - Wavelength converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength converter for performing harmonic conversion of laser light by using a nonlinear optical crystal, and more particularly to a wavelength converter for controlling the temperature of a nonlinear optical crystal.

[0002]

2. Description of the Related Art In the harmonic conversion of laser light by a nonlinear optical crystal, in order to increase the efficiency by matching the phase of wavelength conversion, or to improve the laser damage resistance, for example, as shown in FIG. Thus, the temperature is controlled by housing the nonlinear optical crystal 1 in the heat insulating container 21.

In FIG. 2, a heat insulating container 21 is a box body having an entrance window 22 and an exit window 23 having predetermined wavelength transmission characteristics, and a heater 24 for heating the nonlinear optical crystal 1 is provided on the floor surface. A thermistor 25 for detecting the temperature of the nonlinear optical crystal 1 is provided on the ceiling side. Temperature controller 26
Controls on / off of the heater 24 based on the output of the thermistor 25 to maintain the temperature of the nonlinear optical crystal 1 at a predetermined value.

The wavelength of a laser beam (fundamental wave) 27 input to the entrance window 22 is converted by the nonlinear optical crystal 1.
The incident fundamental wave is not completely converted into a harmonic. Therefore, the emission window 23 outputs the laser light 28 including the fundamental wave and the harmonic.

[0005]

The above-described conventional wavelength converter requires a heat insulating container and a temperature controller, and thus has a problem that the configuration is complicated and the price is high. In particular, when damage due to laser light is a problem, strict temperature control is not required, and thus improvement is desired.

An object of the present invention is to provide a wavelength converter capable of controlling the temperature of a nonlinear optical crystal with a simple configuration without providing a heat insulating container or a temperature controller.

[0007]

In order to achieve the above object, a wavelength converter according to the present invention has the following configuration. That is, the wavelength converter of the present invention is a wavelength of light exiting the harmonics caused to rise to harmonic conversion in the laser beam as a fundamental wave light
And a non-linear optical crystal as a converting element; is bonded to the optical on the exit surface of the nonlinear optical crystal, said nonlinear optical
The crystal to a certain temperature to ensure phase matching for wavelength conversion
And a fundamental wave absorption filter for absorbing a non-converted fundamental wave component emitted together with the harmonics. Incidentally, the fundamental wave absorption filter, and if the selected ones of the absorption coefficient of the nonlinear optical crystal on the basis of the absorption of the fundamental wave component can be heated to the predetermined temperature, the non-linear based on the absorption of the fundamental wave component and a case where having a thickness of capable of heating the optical crystal to the predetermined temperature is selected.

[0008]

Next, the operation of the wavelength converter according to the present invention configured as described above will be described. As is well known, a nonlinear optical crystal does not completely convert an input fundamental wave into a higher harmonic, so the laser light output from the nonlinear optical crystal is a mixture of the fundamental wave and its harmonics. , The proportion of the fundamental wave is quite high. Therefore, in the present invention, the laser light output from the nonlinear optical crystal is passed through a fundamental wave absorption filter,
The filter absorbs the fundamental wave. The fundamental wave absorption filter generates heat by the absorbed fundamental wave and heats the nonlinear optical crystal.

Therefore, by adjusting the absorption coefficient and the thickness of the fundamental wave absorption filter, the amount of heat generated by the filter can be adjusted, so that the nonlinear optical crystal can be controlled to a desired temperature.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a wavelength converter according to one embodiment of the present invention. The wavelength converter of the present invention is obtained by optically attaching a fundamental wave absorption filter 2 to an emission surface of a nonlinear optical crystal 1.

As described above, the laser light (fundamental wave) 3 incident on the nonlinear optical crystal 1 is not completely converted into a harmonic, and the laser light output from the nonlinear optical crystal 1 is a fundamental wave and its harmonics. Waves are mixed.

Since the fundamental wave absorption filter 2 transmits the higher harmonic wave and absorbs only the fundamental wave, the filter 2 outputs the laser light 4 of the higher harmonic wave. Heat is generated by the wave, and the nonlinear optical crystal 1
Heat.

Therefore, by adjusting the absorption coefficient and the thickness of the fundamental wave absorption filter 2, the amount of heat generated by the filter 2 can be adjusted, so that the nonlinear optical crystal 1 can be controlled to a desired temperature.

[0014]

As described above, in the wavelength converter of the present invention, a filter that absorbs only the fundamental wave is optically attached to the exit surface of the nonlinear optical crystal, and the fundamental wave whose wavelength has not been converted is used as a heat source. Since the nonlinear optical crystal can be heated and the temperature can be controlled by using the wavelength converter, the structure can be simplified in the wavelength converter which causes the problem of the damage by the laser beam, and as a result, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an external view of a wavelength converter according to one embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional wavelength converter.

[Explanation of symbols]

 Reference Signs List 1 nonlinear optical crystal 2 fundamental wave absorption filter 3 laser light (fundamental wave) 4 laser light (harmonic wave)

Claims (3)

(57) [Claims] 1. A wavelength conversion element for generating harmonics in a laser beam as a fundamental wave to be received and emitting the harmonics.
A non-linear optical crystal, and optically bonded to an emission surface of the non-linear optical crystal,
The temperature should be maintained at the specified temperature to ensure phase matching
Ku, fundamental absorption filter and which absorbs the fundamental wave component of the non-converted fraction of the light exit together with the harmonic; wavelength converter, characterized in that configured in. Wherein said fundamental wave absorption filter is chosen with absorption coefficients which can heat the nonlinear optical crystal on the basis of the absorption of the fundamental wave component to the predetermined temperature; in claim 1, characterized in that The wavelength converter as described. Wherein the fundamental wave absorption filter are those of the nonlinear optical crystal on the basis of the absorption of the fundamental wave component of said predetermined thickness which can be heated to a temperature is selected; in claim 1, characterized in that The wavelength converter as described.