Articles techniques et présentations

A two dimensional transient analysis of the conjugate optical-thermal fields induced in a multilayer thin film structure by a moving Gaussian laser source is carried out numerically in order to compare back and front laser treatment processes. Thermal and optical nonlinearity is induced during transient heating, since the response of weakly absorbing thin films depends on temperature. The heat source can directly impinge the film surface or the glass substrate. The optical field is considered locally one dimensional and Maxwell equations are solved in order to evaluate the absorption in thin film while the thermal field is two dimensional. Results are presented in terms of transient temperature profiles and fields for different Péclet numbers and a-Si thicknesses.