Transverse structure of a field in nonlinear bistable interferometers. III. Dependence of the beam profile on the Fresnel number

A study is made of the influence of a change in the Fresnel number N on hysteresis in nonlinear interferometers. It is shown that at low values of N and for a limited power of the incident radiation there is no hysteresis. An increase in N first gives rise to hysteresis of the power of the transmitted radiation and then to hysteresis of the beam profile. The latter can then be used for multichannel operation.