Optical properties of amorphous In-doped GeSe2 films for all-optical applications

• In addition can significantly increase linear refractive index of GeSe2 films.
• In-doping can decrease optical band gap of GeSe2 films from 2.04 eV to 1.66 eV.
• In-doping can effectively enhance third-order nonlinear properties of GeSe2 films.
• Nonlinear refractive index of In-doped GeSe2 films is up to 8.5 × 10−16 m2/W.

In-doped GeSe2 films were prepared by magnetron co-sputtering method. Amorphous behavior of as-deposited films was confirmed by the X-ray diffraction. The linear optical properties of the films have been derived by analyzing transmission spectra. The experimental results show that linear refractive index rises and optical band gap reduces from 2.04 eV to 1.66 eV with increasing In content. The proper In content of 13.18 at.% is obtained by optimizing the composition of the films. The nonlinear optical properties of the films were studied at 800 nm by using femto-second Z-scan measurement. Experimental results show that the third-order nonlinear refractive index and nonlinear susceptibility of In13.18(GeSe2)86.82 film are up to 8.50 × 10−16 m2/W and 1.41 × 10−9 esu, respectively, almost two orders larger than those of the GeSe2 film. These excellent properties indicate that In-doped GeSe2 films are perspective in the aspect of all-optical applications.