530.182+535.8+539.2As part of the program of developing perspective incoherent optics systems in which synergy phenomena are realizable, a complex of models of processes in a nonlinear ring interferometer with an optically active medium whose rotary power depends on the incoherent radiation intensity in the nonlinear ring interferometer is constructed. The light intensity depends nonlinearly on the angle of polarization plane rotation. The analogy of the constructed models with the well-known model of the nonlinear ring interferometer with the Kerr medium and laser radiation is established. The (non)linearity of the models and the application of the corresponding nonlinear ring interferometers are discussed. The results obtained are important for improvement in methods of natural light field processing.