Nonlinear refraction in CS2

The nonlinear refractive index (gamma) of CS2 was measured using the Z-scan technique and laser radiation of various (femto-, pico-, and nano-second) pulse durations. We observed the growth of gamma with the increase of the pulse duration (from (3+/-0.6)x10(-15) cm(2) W-1 at 110 fs to (4+/-2)x10(-14) cm(2) W-1 at 75 ns) due to the additional influence of the molecular reorientational Kerr effect in the case of longer (picosecond and nanosecond) pulses. Acoustic wave induced negative nonlinear refraction was observed using wavefront analysis. We analyzed the simultaneous influence of both electronic and molecular processes leading to the positive nonlinear refraction and acoustic processes leading to the negative nonlinear refraction in carbon disulfide. Variations of the refractive index due to the thermal effect at high pulse repetition rates were also investigated.