Two-photon absorption and nonlinear refraction of amorphous chalcogenide films

We present the characterization of nonlinear optical parameters of chalcogenide films (As2S3, AS(20)S(80), 2AS(2)S(3)/As2Se3, 3As(2)S(3)/As2Se3). We have measured their nonlinear refractive indices and two-photon absorption coefficients using the Z-scan method at the wavelengths of picosecond Nd:YAG laser radiation (1064 nm and 532 nm). We have analysed numerically the optical limiting of chalcogenide films due to the Kerr-induced nonlinearities, and in the case of 2As(2)S(3)/As2Se3 we found 12.5-fold limiting. We present the experimental results on optical limiting due to two-photon absorption. We obtained 25-fold optical limiting in the case of As2S3. We discuss the variations of nonlinear optical properties of chalcogenide films.