Non Linear Optical Properties of Ferrofluids Investigated by Z Scan Technique

Abstract

This chapter gives a general outline of the optical nonlinearity shown by materials, and it also deals with the nonlinear optical properties of ferrofluids measured by open aperture Z-scan technique. Magnetite based ferrofluids were investigated for their non linear properties like induced scattering, multiphoton absorption etc and the observation were linked with the general non linear optical theories and the data were fitted for multiphoton absorption coefficients. The chapter gives the results of studies conducted on the non linear optical properties of ferrofluids. Surfactant coated ferrofluids based on magnetite and nickel doped magnetite have been synthesized by the co-precipitation process, with oleic acid as the surfactant and kerosene as the carrier. The colloidal suspensions contain nanosized particles of approximately 80 Å diameter, with a number density of the order of 1022/m3. Optical nonlinearities associated with the samples have been studied in the nanosecond and femtosecond excitation domains, employing the open aperture Z-scan technique. Excited state multi photon absorption and induced scattering are found to be responsible for the observed optical limiting in the nanosecond domain, while electronic nonlinearities dominate in the femtosecond regime, which were fitted for three photonabsorption. The wavelength and concentration dependence of the limiting also is investigated.