Intensity-dependent optical nonlinearities of composite materials made of ionic liquid crystal glass and bimetallic nanoparticles

Although isotropic glass materials are ubiquitous in everyday life, the properties and applications of anisotropic liquid crystal glasses stable at room temperature are still insufficiently explored. In this paper, nonlinear-optical properties of unconventional glass nanocomposites made of mesogenic cadmium octanoate and bimetallic nanoparticles are reported. Two types of bimetallic nanoparticles (Ag/Au core - Au shell and Ag/Au homogeneous alloy) are synthesised utilising an ionic liquid crystal phase of cadmium octanoate as a nanoreactor. A nonlinear-optical characterisation of the studied samples is performed by means of a Z-scan technique and using nanosecond laser pulses at 1064 nm excitation wavelength. The studied nanocomposites exhibit a strong nonlinear-optical response with the magnitude of the third-order nonlinear optical susceptibility within a 2.81 x 10(-8) - 2.19 x 10(-7) esu range. The measured values of the effective nonlinear refractive indices and nonlinear absorption coefficients depend on the laser beam intensity. The physical mechanisms of the observed intensity-dependent optical nonlinearities are discussed.