Terahertz emission from multiple-microcavity exciton-polariton lasers

Terahertz emission between exciton-polariton branches in semiconductor microcavities is expected to be strongly stimulated in the polariton laser regime due to the high density of particles in the lower state (final-state stimulation effect). However, nonradiative scattering processes depopulate the upper state and greatly hinder the efficiency of such terahertz sources. In this work, we suggest a scheme using multiple microcavities and exploiting the transition between two interband polariton branches located below the exciton level. We compare the nonradiative processes loss rates in single and double cavity devices and we show that a dramatic reduction can be achieved in the latter, enhancing the efficiency of the terahertz emission.