Ultrafast photoinduced shift of cavity modes in semiconductor microcavity under femtosecond excitations

Abstract

Ultrafast photoinduced changes of interference (cavity) modes frequencies in ZnSe films on metal substrates were investigated by femtosecond pump-supercontinuum probe spectroscopy. For the pumping energy below the energy gap of ZnSe the laser pulse excites mainly electrons of the metal, i.e. the boundary of the cavity. Nonequilibrium carriers of the metal penetrate into ZnSe film through the Schottky electron barrier and change dielectric function of the semiconductor microcavity. Photoinduced changes in the boundary condition and in optical thickness of the microcavity lead to observable ultrafast shifts of cavity modes with time less the time for establishment of the Fabry-Perot cavity modes.