| 摘要 |
PROBLEM TO BE SOLVED: To provide a summed frequency laser of a structure, wherein the frequency conversion efficiency of the summed frequency laser is improved by bringing the mode of a solid laser into a single longitudinal mode and the fluctuations of the output of the summed frequency laser caused by a mode hopping are inhibited. SOLUTION: An optical resonator 25 is constituted of a laser medium 23 having double refraction properties, a nonlinear optical element 24 which generates a beam walk-off, and an output mirror 41 with a reflective surface which is a recess surface, and a laser oscillation beam in the resonator 25 is turned into a first fundamental wave. When a second laser beam 31 having a wavelength different from a laser oscillation wavelength is directed from the outside into the element 24 as a second fundamental wave and the first fundamental wave is mixed with the second fundamental wave in the element 24, a sum frequency beam is generate. The element 24 is an off-cut crystal and when the beams pass through this element 24, the beam walk-off is generated according to the polarization directions of the beams, whereby the optical axis of the resonator 25 is separated into two optical axes 1 and 1a of polarization and the mirror 41 is arranged so that the optical axis of the resonator 25 is constituted of the shifted optical axis 1a of polarization only. |
