JPH0567030U - Tunable solid-state laser - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To realize a wavelength tunable solid-state laser that has a structure that does not require a mechanically movable part and that can improve miniaturization, cost reduction, and high reliability. [Structure] A cavity formed by applying highly efficient reflective films on both sides of an extremely thin wavelength tunable laser crystal, or an extremely thin wavelength tunable laser crystal and an extremely thin transparent material with a large optical path length change due to temperature In addition, a resonator formed by applying a high-efficiency reflective film on both sides, a thermostat for controlling the temperature of the resonator to enable wavelength selection, and a laser beam that has passed through the resonator are used as seed light. And a variable wavelength laser crystal as a laser amplifier.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

The present invention relates to a tunable solid-state laser using Ti: Al ₂ O ₃ (titanium: sapphire), alexandrite, or the like.

[0002]

[Prior Art]

A tunable laser is a device that can be said to be the key to future spectroscopic analysis. Among them, a tunable solid-state laser using Ti: Al ₂ O ₃ or alexandrite as a laser medium has the advantages of high reliability and easy handling. Have Here, FIG. 3 is a diagram showing a general configuration example of a wavelength tunable solid-state laser using Ti: Al ₂ O ₃ as a laser medium. In FIG. 3, the wavelength is selected by changing the angle of the prism in (a), and the angle of the plane mirror facing the diffraction grating is changed in (b). Therefore, the wavelength is selected.

However, in the case of such a configuration, it is difficult to adjust the resonator, and a mechanical movable portion for moving the prism or the plane mirror for selecting the wavelength is required, so that the device Is large, the wavelength selection speed is slow, and there are mechanical wavelength jumps.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above-mentioned problems of the prior art, and provides a wavelength tunable solid-state laser that has a configuration that does not require a mechanical moving part, and that has improved miniaturization, cost reduction, and high reliability. The purpose is to do.

[0005]

[Means for Solving the Problems]

 The configuration of the present invention for solving the above-mentioned problems is based on a resonator formed by applying highly efficient reflection films on both sides of a very thin wavelength tunable laser crystal, or an extremely thin wavelength tunable laser crystal and an extremely thin temperature. A resonator formed by superimposing a transparent material having a large change in optical path length on both surfaces and applying a highly efficient reflection film, a thermostatic chamber for controlling the temperature of the resonator to enable wavelength selection, and The laser light passing through the resonator is used as a seed light, and the wavelength tunable laser crystal is used as a laser amplifier.

[0006]

[Action]

 According to the present invention, the wavelength is tunable by changing the refractive index due to the temperature change, and the wavelength can be tuned with high efficiency even without a mechanically movable part.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a variable wavelength solid-state laser of the present invention. In FIG. 1, reference numeral 1 is a resonator formed by applying highly efficient reflection films on both surfaces of a wavelength tunable laser crystal having a very thin thickness of about 10 to several 100 μm, and 2 is a thermostatic chamber for controlling the temperature of the resonator 1. Reference numeral 3 is a lens for focusing the pumping laser light on the resonator 1 to improve the pumping efficiency, 4 is a wavelength tunable laser crystal used as a laser amplifier, 5 is again focusing the pumping light that has passed through the resonator 1. Is a lens for increasing the excitation efficiency of the wavelength tunable laser crystal 4. The excitation laser light is focused by the lens 3 on the resonator 1 held in the constant temperature bath 2, and the excitation light passing through the resonator 1 is The light is focused on the lens 5, is incident on the laser amplifier 4, is amplified, and is output. In this case, the wavelength is selected by changing the optical path length of the resonator 1 held in the constant temperature bath 2 depending on the temperature.

In such a configuration, for example, in FIG. 1, description will be made assuming that a Ti: Al ₂ O ₃ crystal is used as the wavelength tunable laser crystal. If the oscillation wavelength λ = 800 nm and the resonator length L = 20 μm, then the longitudinal mode interval Δλ = 16 nm from Δλ / λ = λ / 2L. Therefore, if the coating on both sides of the wavelength tunable laser crystal of the resonator 1 is made to have a highly efficient reflectance at about 800 ± 10 nm, this laser oscillates in a single mode. The oscillation wavelength can be controlled by controlling the temperature in the constant temperature bath 2 and changing the optical path length of the resonator 1. However, since this change is small only with the Ti: Al ₂ O ₃ crystal, as shown in FIG. 2, as the resonator 1, a tunable laser crystal and a transparent substance having a large optical path length change with temperature are superposed. A structure in which highly efficient reflective films are applied to both surfaces may be used. In this case, using a substance of dn / dT = 10 ⁻⁴ / ° C. and dL / dT = 10 ⁻⁴ / ° C., if the temperature is changed by about 100 ° C., Δλ / λ = ΔL / L yields Δλ = Although a variable width of about 16 nm can be obtained, such a thin laser crystal generally has a high threshold and is difficult to oscillate, but since it is thin, the pump light can be narrowed down to about 1/10 of the general wavelength and Oscillation is possible if the variable width is limited to several tens of nm, considering that the reflectivity of the mirror can be considerably increased. However, since the emission power is low, in actual use, the wavelength tunable laser crystal 4 shown in FIG. 1 is used for laser amplification as a laser amplifier that uses the laser light that has passed through the resonator 1 as seed light.

As described above, in the present invention, the wavelength can be tuned by changing the refractive index according to the temperature change, and the wavelength can be tuned with high efficiency even without a mechanically movable part.

Although the refractive index is changed with temperature in the above embodiment, it can be changed with a magnetic field or an electric field. In this case, a wider wavelength tunable range cannot be obtained as compared with the case where the temperature is changed, but since the change can be performed at a very high speed, FM modulation can be performed.

[0011]

[Effect of the device]

 As described above in detail with reference to the embodiments, according to the present invention, for wavelength selection, there is no need for a movable part for changing the angle of a plane mirror facing a prism or a diffraction grating, and a resonator is also used. Because it is simple, it is small and inexpensive. No adjustment of the resonator is required. It is highly reliable and there is no wavelength skip due to mechanical rattling. In the past, expensive gratings or etalons with high resolution were required. However, since the longitudinal mode of the resonator is used, it is possible to realize a tunable solid-state laser having effects such as obtaining a longitudinal single mode.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a wavelength tunable solid-state laser of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of a resonator used in the wavelength tunable solid-state laser of the present invention.

FIG. 3 is a configuration diagram showing a conventional example of a tunable solid-state laser.

[Explanation of symbols]

 1 Resonator 2 Constant temperature bath 3, 5 Lens 4 Amplifier

Claims (1)

[Scope of utility model registration request] 1. A resonator formed by applying a highly efficient reflection film on both sides of a very thin wavelength tunable laser crystal, or a very thin wavelength tunable laser crystal and a very thin transparent material which has a large optical path length change with temperature. A resonator formed by superimposing a high-efficiency reflective film on both sides, a thermostatic chamber for controlling the temperature of the resonator to enable wavelength selection, and a laser beam passing through the resonator. A tunable solid-state laser having a structure including a tunable laser crystal as a laser amplifier using seed light.