Multiple reflections: cascaded upshifting of laser pulses by semiconductors

By studying the detailed dynamics of ultrashort pulses at semiconductor-vac uum interfaces, we have shown that the interaction of these pulses with non stationary semiconductor plasmas can, under appropriate conditions, lead to a variety of interesting phenomena: controlled upshifting of the laser fre quency, possible cascading of upshifting, a trapped pulse bouncing back and forth in the sample, and a so-called machine gun of increasingly blueshift ed pulses. (C) 2001 Optical Society of America.