We perform time-resolved degenerate four-wave mixing measurements using a streak camera system, in order to study the dynamics of coherent biexciton states in CuCl.
Abstract Using a picosecond light source and a streak camera as detection system, the temporal evolution of the signal generated throughout degenerate four‐wave mixing (DFWM) experiments is analysed in CuCl at low temperature. The signal emission shows different temporal behaviour depending on whether the test pulse reaches the surface of the sample before, during, or after the pump pulse. This enables one to distinguish the light‐induced grating contribution from the induced decay of quasi‐particles. The latter process can then be used to determine their dephasing time.
Abstract Using nanosecond laser pulses the time behaviour is investigated of degenerate four‐wave mixing close to the biexcitonic resonance in CuCl. The signal emission presents different time evolutions depending on excitation conditions. Its generation rate shows intensity changes and retardation effects. These effects are explained by an attenuation of the pump pulse through a time‐dependent nonlinear absorption and, at the resonance, by a loss of coherence related to collisions with bi‐excitons.