Third-order nonlinear optical properties of an azobenzene-containing ionic liquid crystalline polymer

Abstract

The nonlinear optical properties of an azobenzene-containing ionic liquid crystalline polymer were investigated by a single beam Z-scan technique employing 38 ps and 6 ns laser pulses at 532 nm. The polymer film exhibited large nonlinear refraction and negligible nonlinear absorption under both ps and ns pulses excitation. The nonlinear refractive indices of the polymer were in the order of $$10^{-11} \hbox {cm}^{2}/\hbox {W}$$ under ps excitation and $$10^{-8}\hbox {cm}^{2}/\hbox {W}$$ under ns excitation, respectively. The mechanism accounting for the process of nonlinear refraction was discussed in terms of photoinduced trans-cis transformation and thermal effect.