Simultaneous measurement of pure-optical and thermo-optical nonlinearitiesinduced by high-repetition-rate, femtosecond laser pulses: application to CS2

A simple experimental technique is presented capable of separating the cont ribution of purely optical Kerr effects from that of thermo-optical effects in the nonlinear response of materials under high-repetition-rate laser ir radiation. The technique has been realized by combining the single-beam Z-s can method with the single-beam thermal lens measurement method. We demonst rate this technique by analysing the nonlinear response at 770 nm of CS2 wh ich exhibits cumulative thermal effects when irradiated by very intense fem tosecond laser pulses at a 76-MHz repetition rate.