Kinetics of Two-Photon Absorption from Metastable Defect Levels in Solids

Abstract

The results of two-photon absorption from metastable defect levels are presented in terms of a wide range of the characteristic trapping parameters of a simple model of a solid. The instantaneous photocurrent maxima and the luminescence brightness maxima as obtained from exact solutions of the coupled nonlinear kinetic equations are shown to depend on the square of the laser flux, provided that the intensity is a few orders of magnitude smaller than the laserdamage threshold. The square-law dependence is lost close to the threshold. These results are independent of surface recombination and diffusion.