Measurement of the optical nonlinearities of water, ethanol and tetrahydrofuran (THF) at 355 nm

The nonlinear (NL) responses of liquid water, ethanol and tetrahydrofuran (THF) are investigated at 355 nm using a Nd:YAG laser delivering pulses of 10 ps. The experiments are performed using the D4σ method combined with the Z-scan technique. Third-order NL refractive indices are determined, as well as the two-photon absorption coefficient and the critical self-focus power. The NL refractive indices are found to be constant for intensity up to 150 GW/cm2 for the three considered solvents, revealing no higher order nonlinearities. Water appears to be a better solvent than ethanol and THF in the UV domain because of its lower NL index and absence of NL absorption. We expect the present study to be useful for NL index measurements in solutions and for numerous future fundamental interest or potential applications