Optics and Photonics Society of Iran

In this paper, by solving coupled equations of nonlinear propagation of waves and heat equation, the effects of thermal distribution and also the effects of Gaussian profiles on the second harmonic generation efficiency by continuous laser with a wavelength of 1064 nm inside a periodically poled quasi phase-mached MgO:PPLN crystal has been investigated and it has been proved that for the incident powers above 10 watts, the asymmetric thermal distributions along the crystal will result a phase mismatching and a significant reduction in the second harmonic efficiency. The proposed method for increasing the second harmonic efficiency and reducing the thermal distribution effect is the use of the continuously varying period along the crystal so that which by this method one can minimize the effect of thermal distribution and enhance the second harmonic efficiency is close to the value that the effects of thermal distribution has been discarded.