Double bosonic stimulation of THz emission in a polaritonic cascade   laser
  We have considered a system of equidistant polaritonic states, interacting with an electromagnetic field of a localized THz cavity mode. An accumulation of photons in a THz cavity mode together with bosonic stimulation of the transition between polariton levels induces intensive radiative scattering of polaritons. The concept of double bosonic stimulation of a radiative transition in a bosonic cascade laser (BCL) is formulated, and the possibility of the use of a BCL for the emission of THz radiation is investigated. The system demonstrates threshold-like behaviour and, above threshold, cascade radiative transitions of polaritons which leads to an increase of quantum efficiency, which can exceed unity. The interaction of polaritons with a reservoir leads to an increase in the threshold pumping rate and a decrease of quantum efficiency. 
M.A. Kaliteevski and K. A. Ivanov
physics.optics cond-mat.other