Study of thermal effects, considering birefringence, on phase distortion of beam in a side pumped Nd:YAG rod using BEM

The present study uses boundary element method (BEM) in linear approximation to solve heat transfer equation. Differential equations of displacement are numerically solved through BEM to obtain strain tensor in an Nd:YAG crystal diode transversely pumped in a three fold geometry. Variation of refractive index, due to the temperature distribution and induced birefringence, which arises from photo-elastic effect, is obtained in the volume of the rod. Then the phase shift imposed on emerging beam from the rod is calculated by solving the equation of path of ray along the laser rod. Using the obtained results, effective focal distance and astigmatism of the beam for different types of polarization are calculated.