A model of ultrashort laser pulse absorption in solid targets

A model for ultrashort laser pulse absorption and solid target heating has been developed. It combines a description of laser light absorption in the skin layer with a simple model of plasma heating. Heat wave propagation into the cold target material is the only loss mechanism balancing energy deposition due to absorption. An absorption coefficient is derived from the plasma conductivity and includes a description of physical processes responsible for collisional and collisionless skin layer absorption mechanisms. Comparison with recent femtosecond laser pulse interaction experiment data show good agreement over a wide range of pulse intensities. For laser intensities above 10(16) W/cm(2) plasma hydrodynamical expansion, which is neglected in our model contributes to a discrepancy between the calculated absorption and experimental data. (C) 1996 American Institute of Physics.