Abstract

At the present time, systenratic experimental studies of radiation-matter interactions at light pulse intensities as high as 10¹⁴-10¹⁷ W/cm² and durations as short as tens of femtoseconds are carried out in a number of laboratories. Observation of nonlinear effects such as supercontinuum generation, conversion of laser radiation into high-order harmonics, etc., indicates that, for these parameters, the medium can no longer be considered as weakly nonlinear and strongly dispersive. In intense fields, the number of terms in the expansion of the polarization in powers of the field becomes significant while the phase-matching can be satisfied simultaneously for all harmonies. Therefore, the method of slowly varying amplitudes and phases becomes ineffective in describing the processes, and one should use exact equations of evolution of the EM field and material variables of the medium.

© 1993 Optical Society of America