Thermally induced and Kerr-induced optical nonlinearities of a pseudoisocyanine solution at 532 nm

The thermally induced and Kerr-induced nonlinearities of a pseudoisocyanine (PIC) aqueous solution were studied using 532 nm radiation. The thermally induced negative nonlinear refraction of 8 ns pulses was investigated by the pulse waveform analysis technique. The nonlinear refractive index of PIC was measured using the Z-scan technique to be gamma = -6 x 10(-12) cm(2) W-1. It was shown that saturated absorption dominates over nonlinear refraction in this spectral range. A comparison with previously reported data of nonlinear optical characteristics of PIC solution measured using femtosecond pulses has shown the influence of additional mechanisms responsible for the increase of gamma in the case of nanosecond pulses.