Effects of a spatially inhomogeneous laser field in non-linear absorption in solids

We investigate the influence of a spatially inhomogeneous laser field on the multiphoton absorption processes occurring in direct-gap semiconductors. We adopt a “non-perturbative” approach to treat the single-mode spatially homogeneous case using a parabolic band model to describe the solid. We show that corrections due to inhomogeneity may change the results in a significant way and thus have to be considered when comparing the calculated multiphoton absorption coefficients with the experimental data.