ULTRAFAST TIME-RESOLVED QUANTUM BEATS IN THE POLARIZATION STATE OF COHERENT EMISSION FROM QUANTUM-WELLS

Dual-channel spectral interferometry is used to measure the ellipticit y, the orientation of the polarization ellipse, and the sense of rotat ion of the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well. Each parameter is observed to oscillate dramatically at the hea vy-hole-light-hole quantum heat frequency. During each beat period (in the strong quantum beat regime), the ellipticity oscillates twice bet ween linear and almost-circular polarization, the orientation of the p olarization ellipse rotates through a complete 180 degrees, and the se nse of rotation changes from left- to right-circular polarization. (C) 1998 Optical Society of America.