THz electromagnetic wave radiation from coherent oscillation of exciton population in high-Q semiconductor microcavities

The radiation of THz electromagnetic waves (EMWs) induced by impulse excitation from dc-biased high-Q semiconductor microcavities was observed. The oscillation period corresponding to the polariton (normal) mode splitting and the dependence of the EMW intensity on the dc bias and the excitation wavelength indicate that the EMWs are radiated from the polarized excitons in the quantum well. Hence, the results manifest the oscillation of the exciton population, and in turn, the coherent energy exchange between the excitons and the cavity-mode photons, the heart of the polariton concept.