Q switch laser device

When an excitation light is entered in a laser medium including a doped (containing rare earth element) YAG, the vicinity of the excitation light entry face is locally heated which generates a birefringence, causing degradation of linear polarization of emitted laser. To avoid such a phenomenon, it was necessary to make the excitation light pulsed and slow down the repetition rate of the pulse. In this device, an undoped YAG is bonded to a excitation light entry face of the laser medium made of a doped YAG. By arranging the YAG axis so as to extend along the optical axis of the laser oscillation system, a linearly polarized pulse laser can be obtained.