Characterization of solid state materials for use as optical spatial light modulators.

摘要

Scope and method of study. The nonlinear optical properties of several classes of materials were investigated for potential use as optical spatial light modulators. Focus was placed on (i) diluted magnetic semiconductors (DMS) (ii) fullerenes in toluene solution; (iii) photorefractive crystals; and (iv) Eu doped glasses. Light transmission, pump-probe and four-wave-mixing experiments were performed to investigate the role of the material composition on the magnitude of optical nonlinearities.; Findings and conclusions. Examples of optical switching using polarization rotation and four wave mixing were demonstrated for a CdTe sample. It was found that the response time of DMS and fullerenes make them suitable as the nonlinear medium for optical switching. On the other hand, photorefractive crystals and Eu doped glasses are best suited for optical memory storage. In DMS it was found that the nonlinear optical behavior are dictated by the optical properties of the free carriers. Furthermore, the carrier nonlinearities have a tendency to saturated in highly degenerate semiconductors. Two photon absorption and nonlinear refraction of fullerenes, studied with picosecond pulses at 532 nm, indicate that they possess a high degree of optical nonlinearity associated with their delocalized {dollar}pi{dollar}-electrons. Picosecond pulses were also used for the study of the photorefractive materials. The two photon absorption coefficient of these materials suggests that nonlinear absorption is the dominant mechanism for carrier generation in short pulse time regimes. The photorefractive behavior of the generated carriers was also studied for a number of crystals. Lastly, the dependence of the permanent index changes in Eu doped glasses of its chemical composition was studied using laser induced grating. The relevant parameters for the network former and modifier ions were found for each glass.