Laser induced self-diffraction from polyaniline/NMP solution

Laser induced concentric diffraction rings are observed in the far field when the 526nm TEMOO laser beam passes through the Polyaniline/N-Methyl-2- pyrrolidone (NMP) solution, which can be explained by the spatial self-phase modulation; of the Gaussian beam passing through the nonlinear medium. The theoretical analysis indicates, to thin sample, the transverse nonlinear phase shift distribution is similar to a Gaussian function. According to the number of the diffraction rings, the Kerr constant of the Polyaniline/NMP solution (absorption coefficient 0. 56cm ^-1 at 526nm) is evaluated to be 4. 4×10 ^-10m ²/W.