THERMAL EFFECTS IN LASER-DIODE-PUMPED SELF-FREQUENCY-DOUBLED NDXY1-XAL3(BO3)(4)(NYAB) MICROCHIP LASER

We present what is, to our knowledge, the first report of thermal effe cts in the laser diode (LD) pumped NYAB laser. By blocking the pump en ergy periodically, we investigated temporal behavior of second harmoni c (SH) intensity. During the laser oscillation, the SH power decreased and its beam pattern changed from a Gaussian shape to a bell one. Und er lasing conditions, the optical distortion in the NYAB crystal was a nalyzed using a Michelson's interferometer. At the center of the pumpe d region, the phase shift of the laser rod had attained 2.05 rad compa red with the edge of the rod. It was proved that these temporal behavi ors of the second harmonics were caused by the temperature rise of the NYAB laser rod due to the local heating of the laser crystal.