Solid-state blue laser device capable of producing a blue laser beam

Abstract

In a solid-state blue laser device for producing a blue laser beam having a waveband of blue spectral range that is represented by a specific wavelength of, for example, 0.45 .mu.m, the solid-state blue laser device comprises a semiconductor laser device for producing an excitation laser beam having an excitation wavelength of, for example, 0.8 .mu.m. Excited by the excitation laser beam, a self-frequency doubling crystal, such as Nd.sub.x Y.sub.1-x Al.sub.3 (BO.sub.3).sub.4 where x has a value selected between 0.005 and 0.04, both exclusive, produces a harmonic laser beam having a wavelength of a second harmonic thereof that is equal to the specific wavelength. The solid-state blue laser device thereby produces the harmonic laser beam as the blue laser beam. The solid-state blue laser device may further comprise a condensing lens for condensing, as a condensed laser beam, the excitation laser beam onto the self-frequency doubling crystal. In order to cool the self-frequency doubling crystal, a cooler may be mounted on the self-frequency doubling crystal. An outer mirror may be disposed adjacent to the self-frequency doubling crystal to produce the harmonic laser beam as the blue laser beam. A Q-switching element may be disposed between the self-frequency doubling crystal and the outer mirror. The self-frequency doubling crystal may be directly coupled to the semiconductor laser device to produce the blue laser beam having a single longitudinal mode of TEM.sub.00.