It is shown theoretically that ultrashort terahertz electromagnetic pulses
can be generated in resonant systems containing a quantum semiconductor sup
erlattice. This effect is due to the compression of radiation incident on a
cavity as a result of ultrafast self-modulation of the cavity Q factor upo
n cyclic switching of the superlattice from the screening to the transparen
t state in a pump field. (C) 2000 MAIK "Nauka/Interperiodica".