Heat flow in substrates induced by a scanning laser beam

A general model is derived for computing the heat flow induced by a scanning continuous-wave laser beam with a Gaussian intensity distribution in a semi-infinite substrate. Temperature-dependent thermal conductivity, thermal diffusivity, and surface reflectivity are incorporated in the model. The model is then applied to different substrate materials such as silicon, GaAs, and Mn-Zn ferrite. The numerical results show that the heat flow intensity in the substrate depends on the incident laser power, substrate temperature, scan speed, and beam radius. This study is expected to be useful in investigating the distributions of the laser-induced thermal stresses and lattice damages.