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, non-radiative scattering processes depopulate the upper state and greatly hinder the efficiency of such terahertz sources. In this work, we suggest a new scheme using multiple microcavities and exploiting the transition between two interband polariton branches located below the exciton level. We compare the non-radiative 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. 
Simon Huppert, Ombline Lafont, Emmanuel Baudin, J\'er\^ome Tignon and   Robson Ferreira
cond-mat.mes-hall