NONLINEAR REFRACTIVE-INDEXES OF POLYSTYRENE FILMS DOPED WITH AZOBENZENE DYE DISPERSE-RED-1

Nonlinear refractive indices of polystyrene films containing azobenzen e dye Disperse Red 1 (DR1) have been measured as a function of wavelen gth using the single beam Z-scan technique with a Fourier analysis of the transmittance time evolution. Although the C.W. excitation is carr ied out far from the absorption resonance region, the large nonlinear optical response has its origin in a thermal effect. We were able to f ind the thermal diffusivity coefficient of the sample.