SINGLE-BEAM AND MULTIPLE-BEAM OPTICAL LIMITERS USING SEMICONDUCTORS

We report our investigations of single- and multiple-beam optical limiter configurations using GaAs and Si as the nonlinear optical materials. Three distinct multiple-beam geometries are discussed. One of these, in which two beams interfere within the semiconductor to produce a grating, takes advantage of transient energy transfer and photorefractive beam coupling to deplete the signal beam. The other two configurations exploit the whole-beam absorptive and refractive index changes induced in the semiconductor by a strong control beam that arrives at the sample before the signal. For one of the latter two configurations, nonlinear absorption and induced defocusing are used to attenuate the signal; in the other, nonlinear absorption and induced deflection are used. We discuss the relative merits of each configuration and compare them to single-beam results obtained under identical experimental conditions.