We present the results of nonlinear transmission in various ordered and disordered mesophases of liquid crystals,
and demonstrate that in bulk or guided wave geometry, they are capable of clamping the transmission of pulsed or cw
lasers to below the Maximum Permissible Exposure level of eyes and optical sensors in the entire visible - infrared
Metamaterials are of substantial current interest because they may exhibit unusual and/or configurable optical responses. We studied the optical properties of gold and silver nanoparticles dispersed in different organic liquids in the visible to near-IR. Calculation of the refractive indices of metallic nanospheres or metallic-coated silica spheres in liquid crystals show the possibility of tuning and varying the refractive index by reorientation of the liquid crystal molecules. Measurements of the refractive indices of gold nanoparticles in dodecane were experimentally studied by using spectroscopic ellipsometry and a reasonable agreement with the theoretical results based on Mie scattering was obtained. Finally, the effect of gold and silver nanospheres on the nonlinear absorption properties of an organic liquid (L34, a 4,4'-dialkyl phenyleneethynylene) was studied. The results suggest that metallic nanoparticles dispersed in a host organic fluids can be good materials for fabrication of low and tunable index materials in the visible to near-IR wavelength range, and for the enhancement of the nonlinear absorption of liquids used in switching applications.