Investigation of third-order optical nonlinearities of copper doped germanium-gallium-sulfur chalcogenide glasses

A series of copper doped germanium‑gallium‑sulfur (GGS-Cu) chalcogenide glasses were synthesized by melt-quenching method. Raman spectra showed that the introduction of Cu could alter the main structure of GGS network, leading to modification of thermal, mechanical and optical properties of the GGS glasses, even at very low doping level. Femtosecond Z-scan measurements were employed to study the third-order optical nonlinearities (TONL) of the GGS-Cu glasses at wavelength of 1550 nm. Significant improvement of TONL performance due to the Cu doping was observed, and its possible mechanism was studied.