Polymer dispersed liquid crystals--New materials for nonlinear optics

Summary form only given. Several nonlinear optical effects observed in dye doped polymer dispersed liquid crystals (PDLC) are discussed. In one experiment, dye doped samples of PDLC were used to enhance the thermal nonlinearities induced by light absorption. The light scattering depends on the index mismatch δ = n_eff² - n_p², where n_eff is the effective refractive index of the droplet and n_p is the refractive index of the polymeric matrix. The absorption of radiation by the dye molecules and subsequent thermalization process heats the PDLC sample, thus changing the quantity δ through the thermal indexing effect. In a second experiment, thermal grating was induced in PDLC. The nonlinear light diffraction which shows a typical threshold behavior due to the self-transparency effect was studied. Phase and amplitude gratings were created under different experimental conditions. Finally, the coupling of the orientational and thermal properties of liquid crystals have been exploited to obtain all-optical switching and bistability in PDLC.