Laguerre-Gaussian vortex beam for reduced thermal effects in nonlinear optical studies

Interaction of an intense laser beam with a material induces many thermal effects. In this work, thermo-optic effects induced by fundamental Gaussian and Laguerre-Gaussian vortex (LGV) laser beams in a sample in nonlinear optical (NLO) experiments are compared and their impact on the accuracy of determining the nonlinear susceptibility is examined. A solution of saturable absorber dye IR 26 in dichloroethane with the technique of z-scan to determine its third order nonlinear susceptibility was used as a model system. The LGV beams were generated by passing the Hermite-Gaussian beams from an Ar-ion laser through a cylindrical lens mode converter. Pump-probe setup was used to study the thermo-optic effects. Experiments and simulations suggest that the LGV beam is advantageous to reduce the thermal effects.