Bose-Einstein condensation of THz photons in an optical microcavity with Landau-quantized electrons

We present a theoretical model for a coherent terahertz radiation source based on Bose-Einstein condensate of incoherently pumped microcavity photons. Energy relaxation is provided by inelastic photon scattering on a two-dimensional electron gas in magnetic field. The proposed setup evades the standard lasing mechanisms: neither population inversion nor light wave amplification is utilized. We study the kinetics of photon condensation and describe a semiconductor-crystal based device.