Fifth-order optical nonlinearity of pseudoisocyanine solution at 529 nm

Abstract

Evidence of the interference between third- and fifth-order nonlinear optical processes is shown in the studies of pseudoisocyanine (PIC) dye aqueous solution using 529 nm radiation (t = 475 fs) and the Z -scan technique. The third-order nonlinear refractive index of the PIC solution was measured to be −8 × 10 −14 cm 2 W −1 .W e have shown th at PIC solution changes from being self-defocusing to self-focusing at high laser intensity that was attributed to the influence of fifth-order nonlinearity. The fifth-order nonlinear refractive index was measured to be 4 × 10 −24 cm 4 W −2 .T he bleaching properties of PIC solution were analysed, and the imaginary part of third-order nonlinear susceptibility was measured to be Im χ (3) =− 2 × 10 −12 esu.