Magneto-plasmon spectrum in a semiconductor under intense laser radiation

We study how a linearly polarised intense laser irradiation affects the magneto-plasmon (MP) modes in a semiconductor. We first evaluate the electron Green's function, the density-density correlation function, and the random-phase approximation (RPA) dielectric function in the (Q, t) representation in the presence of a laser field and a quantizing magnetic field. From these results, we obtain the electron density of states (DOS) and the plasmon spectrum in the (Q, Omega) representation and investigate the dependence of the MP excitations on the frequency and intensity of the laser field in GaAs. The results are pertinent to the application of free-electron lasers developed recently. (C) 1998 Elsevier Science B.V. All rights reserved.