FREE-CARRIER INDUCED SATURATION OF THE FARADAY-ROTATION IN SEMIMAGNETIC SEMICONDUCTORS

Large photoinduced Faraday rotations of the polarization direction of a probe beam traveling through a semimagnetic semiconductor are obtained at temperatures higher than that of liquid nitrogen when a pump pulse is sent through the material. These rotations are quasiproportional to the photoinduced free-carrier density and the applied magnetic field and are strongly resonant with the band-gap-probe frequency detuning. A model based on the free-carrier induced saturation of the refractive indices explains well the experimental observations. The high values obtained for the photoinduced polarization rotations (more than 1°pJ-1 μm2) make such a process attractive for the design of optical signal processing devices.© 1995 American Institute of Physics.