Dynamic optical nonlinearities in di-furfuryl ether solution

Dynamic nonlinear refraction and absorption of di-furfuryl ether dissolved in dichloro-methane are investigated with a frequency-doubled Q-switched and mode-locked Nd:YAG laser. The nonlinear absorption presents a strong reverse saturation that seems promising for use in optical limiting devices. Three contributions are observed for the nonlinear refraction: one fast process related to the singlet population, and two slow accumulative contributions arising from the triplet population and thermal lensing. The time evolution of the optical nonlinearities, modeled by means of a five-energy-level diagram, allows the determination of excited state cross-sections as well as the intersystem crossing lifetime.