Large and ultrafast third-order optical nonlinearity of GeS2–Ga2S3–CdS chalcogenide glass

We report measurements of third-order optical nonlinearity of the 90GeS2–5Ga2S3–5CdS (in mol%) chalcogenide glass using the femtosecond time-resolved optical Kerr gate technique at 820 nm. The third-order nonlinear susceptibility was estimated to be as large as 1.0 × 10−12 esu. The full width at half maximum of the Kerr signal was 150 fs, implying that the sample had a response faster than 120 fs. Its response was dominantly assigned to the ultrafast distortion of the electron cloud. This glass sample is promising in future all-optical switching devices.