Optical switching in hydrogenated amorphous silicon–sulfur alloy prepared by glow discharge

The third-order optical non-linearity of hydrogenated amorphous silicon–sulfur alloys prepared by a plasma enhanced chemical vapor deposition process has been measured using the z-scan technique. Intensity absorption dependence was observed and attributed to reverse saturation absorption (optical limiting). The origin of the effect was explained in term of defect states in the band gap. We demonstrate that the reverse saturation absorption is responsible for the observed non-linearity and can be utilized to generate all optical switching.