OBSERVATION OF INTRINSIC OPTICAL BISTABILITY ARISING FROM LASER-INDUCED STRUCTURAL TRANSITION IN A NEMATIC FILM

Abstract

It is now well known that in a proper, geometry, a laser beam with intensity I ≥ Ith can induce a Freederiekscz transition in a nematic liquid crystal film.1 In the transition, molecules in the bulk of the film are reoriented by the laser field, leading to a very large induced birefringence. The transition is of second-order and exhibits critical behavior. With a sufficiently strong applied magnetic field, however, it is predicted that the optical-field-induced Freederickscz transition can become first-order.2 In this paper, we demonstrate experimentally that this is indeed the case. Laser-induced first-order transition is characterized by a hysteresis loop in the plot of induced birefringence versus laser intensity. It is a display of an intrinsic optical bistability with no external feedback. © 1985 Optical Society of America