Efficient Parametric Decay in Dissipative Media

Three-wave-coupling interactions have been examined for a dissipative medium. It is shown that in the semicollisional regime, where the frequency of the low-frequency wave (${\omega }_3$) is smaller than the collision frequency $\nu$ that affects the weakly damped high-frequency waves (${\omega }_1$, ${\omega }_2$), i.e., ${\omega }_1,{\omega }_2\gg \nu >{\omega }_3$, the thermal nonlinearity predominates and decay efficiencies in excess of that expected from the Manley-Rowe relations can be achieved. In addition, the pump threshold power for complete decay is substantially reduced.