Investigation of Nonlinear Optical Characteristics of Colloidal Metals, Semiconductors, Fullerenes and Organic Dyes by Z-Scan Method and Third Harmonic Generation of Laser Radiation

Abstract

The nonlinear optical parameters of colloidal metal solutions, semiconductor chalcogenide films, dye vapors and solutions, and fullerene-doped polyimide films and solutions are investigated by Z-scan method and third harmonic generation (THG). We measure nonlinear refractive indices, nonlinear susceptibilities and nonlinear absorption coefficients of such materials at the wavelengths of Nd:YAG laser radiation and its second harmonic ( ; = 1064 nm and 532 nm, = 35 ps). We study the optical limiting of picosecond and nanosecond radiation in these media. We show that the appearance of long-wave wing of absorption at the final stages of colloidal metals aggregation leads to the nonlinear absorption of picosecond pulses. THG studies of picosecond Nd:YAG laser radiation in colloidal metals, fullerenes and dye vapors are presented. We measure their nonlinear optical susceptibilities ; (3) ( ; 3 , , , ) and discuss the influence of self-action processes on THG in these media.