Femtosecond spectroscopy of semiconductor microcavity polaritons

Dynamics of semiconductor microcavity modes in ZnSe-metal structure was investigated by femtosecond pump-supercontinuum probe spectroscopy in a wide spectral region of 300-800 nm. The powerful laser pump pulse excites electrons of metal (i.e., boundary of the microcavity) and of ZnSe layer (by two-photon absorption and absorption of second-harmonic generated photon). Nonequilibrium carriers of metal penetrate through Schottky electron barrier into the semiconductor and change its dielectric function. This leads to a shift of frequencies of cavity modes to red region of spectrum. Energy relaxation of charge carriers leads to the heating of the structure and to a shift of the cavity modes in the opposite direction. The generation of coherent phonon oscillations (LO-phonon mode 250 cm(-1) and TO-phonon made 200 cm(-1)) in ZnSe was detected.