Nonlinear-refractive-index measurement in As2S3 channel waveguides by asymmetric self-phase modulation

The nonlinear refractive index (n(2)) of an As2S3 channel waveguide at 1.55 mum has been measured. The n(2) was deduced when the spectral broadening and modulation due to self-phase modulation (SPM) were characterized. Owing to the temporal asymmetry of the injected pulse, a specific approach to asymmetric SPM is presented. The measurements have been performed for both photodarkened and nonphotodarkened etched thin films so that the effect of photodarkening on the n(2) could be assessed. (C) 2005 Optical Society of America.