LASER BEAM SELF-FOCUSING IN PHOTOREFRACTIVE MATERIALS: OPTICAL LIMITING APPLICATION

This paper presents a way to achieve optical limiting using the self-focusing of a laser beam in a photorefractive medium. In this view, the protection is not based on the absorption of the beam energy in the limiting system but on a global defocusing of the light in the optical system. We have studied experimentally and theoretically the self-focusing of a single laser beam in electrically biased Bi₁₂TiO₂₀ from the continuous to the pulsed regime. We show that photorefractive materials are, for given conditions, efficient against laser radiation on these two different time scales at a low energy level (nJ).