Picosecond acoustics in semiconductor optoelectronic nanostructures.

We overview the results of three recently performed experiments, where the picosecond acoustic technique was applied to semiconductor devices with quantum wells or quantum dots embedded in an optical microcavity. In these experiments, high amplitude picosecond strain pulses are injected into such a device and the resulting changes in the response of the optical resonance are monitored. First, in quantum well devices we observe the generation of THz sidebands in optical reflectivity near the polariton resonance. Second, for certain conditions we detect the destruction and recurrence of excitons by acoustic shock waves on picosecond time scales. Third, in a vertical cavity surface emitting laser with a quantum dot layer the injection of the picosecond strain pulses induces the giant increase of the laser output. All these effects are governed by nonadiabatic processes in the interaction between a strain pulse and the electronic quantum confined states. Their observation became possible due to the possibility of generating very short strain pulses with sufficiently high amplitude.