Photothermal displacement in an interference fringe

The photothermal displacement of the selfstanding film in an interference fringe is investigated theoretically and experimentally. It is found that the bistability of the displacement and the selfexcited vibration of the film are generated when the film is placed in the standing wave produced by the continuous wave laser light reflected from a mirror. In the selfexcited vibration, some nonlinear effects such as light intensity threshold for excitation, vibrational amplitude saturation etc., are obtained from the theoretical consideration. The theoretical results explain well the experimental results. The obtained results are useful for the optical activation of the resonator sensor and mechanoptical bistable switch.