Nonlinear optical refractive indices and absorption coefficients of α,β-unsaturated ketone derivatives

The nonlinear optical refractive indices and the nonlinear optical absorption coefficients of newly synthesized α,β-unsaturated ketone derivatives (USKDs) were investigated by use of the intensity-dependent transmittance method and the Z-scan technique with a pulsed Nd:YAG laser at 532-nm and 1064-nm wavelengths. Opposite changes of signs of the nonlinear refractive indices are observed at the two wavelengths and can be mainly attributed to the thermal effect and the two-photon absorption mechanism. The origins of the nonlinearity of USKDs are discussed, and by establishing a kinetic model for the USKDs, several other nonlinear optical parameters are obtained, such as the cross section of two-photon absorption, the absorption cross section of the excited state, and the real part of second-order hyperpolarizability of the ground state, The results indicate that USKDs are potential optical limiting materials.