The Terahertz Laboratories

Polariton THz lasers emitting at THz frequencies

Recent studies of strong coupling intersubband microcavities have shown possibility of stimulated scattering of intersubband polaritons. Here we  explore the possibility of generating THz radiation in semiconductor microcavities in the regime of exciton polariton lasing. The quantum efficiency of this source is governed by population of the final polariton state, which may be tuned over a large range by means of the optical pumping. Recently it was demonstrated, that rate of spontaneous emission for THz photons can be additionally increased by bosonic stimulation, when the radiative transition occurs into a condensate state. Such condensate can be formed in semiconductor microcavities with quantum wells, where Bose-Einstein condensation of exciton-polariton was recently demonstrated at room temperature. In the microcavity of specific design, THz radiative transition become allowed due to mixing of dark and bright exciton state. Enhancement of THz emission by Purcell effect and by bosonic stimulation will make the rate of THz emission comparable to decay rate, thus opening the way for development of room temperature solid state THz CW and short pulse emitter, detectors and switches. The candidate will work aims to produce a new THz spectrometer where polariton lasing is used and measured by a photoconductive antenna in a time domain experimental configuration.