Generation of photoritons—parametrically coupled photons and polaritons

An analysis is made of the tuning of the polariton spectrum of a solid, particularly a semiconductor, exposed to the parametric action of high-power optical radiation. The tuning spectrum corresponds to an elementary excitation described as a photoriton, which is a coupled pair consisting of a photon and a polariton of differing frequencies. Photoritons have two branches of nonlinear dispersion that differ substantially in an optical parametric amplifier and a frequency converter. Specific calculations of the dispersion curves for both these cases are given for CuI and CuCl crystals.