Abstract

Vogel et al. recently presented a rate equation model of optical breakdown in transparent dielectrics that considers photoionization based on the Keldysh theory, avalanche ionization, recombination, and diffusion losses [1]. It contains also a simple approach to consider the time constraints for avalanche ionization in femtosecond breakdown that have been modeled in a more refined fashion by Rethfeld [2]. A weakness of this model and other state-of-the-art breakdown models is the neglect of heating during or after the laser pulse. However, a temperature rise will influence the kinetics of nanosecond breakdown and during sequences of ultra-short laser pulses that are separated by times in the order of the thermalization time of the free electron energies.

© 2009 IEEE