Stability of steady-state stimulated scattering in a nonlinear ring resonator

A theoretical investigation is made of the stability of the fundamental scattering mode in a nonlinear ring resonator under conditions of stimulated light scattering by transmission and reflection gratings. A system of this kind is stable until the stimulated scattering threshold is exceeded by a factor of 3–6. Oscillations of the intensity of the scattered radiation appear above the instability threshold: the period of these oscillations is of the order of the relaxation time of the refractive index grating. It is shown that an increase of the length of a feedback loop can reduce the instability threshold considerably. Moreover, it is demonstrated that the stability range for a transmission grating is narrower than for a reflection grating.