Phonon-mediated splitting in the optical susceptibility of polymers

Under the radiation of pump and probe laser fields, the nonlinear optical susceptibility of polymers in an optical cavity is investigated. Numerical calculations are made with parameters pertaining to polydiacetylene toluene sulfonate. The phenomenon of splitting in the susceptibility due to the phonon mediation is found, and sharp responses are obtained around the threshold of the pump-field intensity for the occurrence of optical tristability.