Bosonic Cascade Laser
  We propose a concept of a quantum cascade laser based on transitions of bosonic quasiparticles (excitons and exciton-polaritons) in a parabolic potential trap in a semiconductor microcavity. This laser would emit terahertz radiation due to bosonic stimulation of excitonic transitions. Dynamics of a bosonic cascade is strongly different from the dynamics of a conventional fermionic cascade laser. We show that populations of excitonic ladders are parity-dependent and quantized if the laser operates without an external terahertz cavity. 
T. C. H. Liew, M. M. Glazov, K. V. Kavokin, I. A. Shelykh, M. A.   Kaliteevski, and A. V. Kavokin
cond-mat.mes-hall physics.optics