Numerical simulation of thermal shock effect on germanium induced by out-of-band pulsed-laser

The germanium can be damaged when it irradiated by high power laser. The germanium irradiated by out-of-band pulsed-laser was theoretically investigated. And then the thermal-mechanical physical model was built.The heat conduction differential equation and stress-balance equation were solved by the finite elements method. The numerical simulation of the transient temperature field and thermal stress field in various energy density was presented.The material position where was most probably to be damaged, the damage threshold and the relationship between the damage threshold and laser parameters were obtained. The results show that the thermal stress damage dominates in the damage mechanism, thermal stress damage of laser energy density is smaller than fusion damage,and the stress damage is distributing in the center of facula as pressure stress.