Nonlinear fabry-perot action and optical bistability of a dielectric cladded thin film near the total internal reflection state

A nonlinear thin film bounded by two dielectric media could act as an optical switching and bistability device, owing to two physical mechanisms at work near the total internal reflection state. One is the simple intensity-dependent index change induced by the finite optical field in the film before transmission occurs, and the other is the nonlinear Fabry-Perot interference associated with the high reflectivities at the two interfaces when transmission takes place. We present a detailed theory for these two mechanisms and for the case in which the nonlinearity is also nonlocal (e.g., in a liquid-crystal film). The results for multiple switchings and hysteresis hold in general for any nonlinear thin film.