  We consider the nonlinear terahertz emission by the system of cavity
polaritons in the regime of polariton lasing. To account for the quantum nature
of terahertz-polariton coupling we use the Lindblad master equation approach
and demonstrate that quantum microcavities reveal rich variety of the nonlinear
phenomena in terahertz range, including bistability, short THz pulse generation
and THz switching.
