Nonlinear-refractive-index measurement in As2S3 channel waveguides by asymmetric self-phase modulation
The nonlinear refractive index (n2) of an As2S3 channel waveguide at 1.55 µm has been measured. The n2 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 n2 could be assessed.