LO-PHONON INSTABILITY IN SEMICONDUCTORS IN THE PRESENCE OF 2 LASER FIELDS PLUS DC STRONG MAGNETIC-FIELD

Phonon scattering by electrons in a bulk semiconductor in two laser fi elds in the additional presence of a strong (quantizing) magnetic fiel d is discussed. A kinetic equation for the LO-phonon population is der ived, from which the damping rate is calculated. It is found that long itudinal optical lattice waves may be amplified over a relatively narr ow range of plasmon wave numbers in the direction perpendicular to the magnetic field direction. Furthermore, the joint action of the three external fields results in a very large amplification rate, in contras t to the zero magnetic field case.