Femtosecond Studies on Third-Order Optical Nonlinearities of Polyanilines

The ultrafast dynamics of third order nonlinearities of polyaniline (PAn) and polyaniline doped in polymethyl mathacrylate (PAn-PMMA) films are investigated using femtosecond absorption spectroscopy. An ultrafast initial exciton deformation time of about 100fs is observed in PAn film. In PAn-PMMA film, the third-order nonlinearity results in an efficient two-photon absorption at about 2eV.