Ultrafast optical Kerr effect in amorphous chalcogenide films

Amorphous chalcogenide As 2 S 3 , As 2 Se 3 , GeS 2 , GeSe 2 , Ge 20 As 25 S 55 , Ge 20 As 25 Se 55 , Ge 10 As 40 S 20 Se 30 films were studied by femtosecond OHD-OKE. Ict was indicated that the third-order nonlinear susceptibility χ (3) was as large as 10 -12 esu, and they also exhibited a very fast response time shorter than 200 fs. Their nonlinear refractive indices and absorption were also calculated from the above results. The ultrafast response and large third-order nonlinearity in amorphous chalcogenide films are attributed to the ultrafast distortion of the electron cloud of atoms.