Influences of laser thermal effect on second harmonic generation in periodically poled lithium niobate crystal

Considering the influences of temperature on refractive index and grating period, the paper studies the relations between quasi-phase-matched second harmonic generation (SHG) conversion efficiency and temperature, and analyzes the influences of laser thermal effect on quasi-phase-matched SHG. The temperature distribution and SHG conversion efficiency under the influences of laser thermal effect inside periodically poled lithium niobate (PPLN) crystal are calculated by finite element method. The results show that, for fundamental wave of different power, the temperature distributions and the refractive index distributions on crystal sections along the direction of light are different, and so are the SHG conversion efficiency distributions on the exit facet of crystal. With the pow