Third-order nonlinearity in Ge–Sb–Se glasses at mid-infrared wavelengths

•The nonlinearity properties of Ge–Sb–Se glasses at mid-IR were explored.•The third order nonlinearity increased with the refractive index at 1550 nm.•The highest n2 is found at 2000 nm.•FOM of Ge20Sb10Se70 glass is larger than 10 at mid-IR wavelengths.

The optical properties of Ge–Sb–Se glasses have been extensively studied at telecom wavelengths in recent years. However, the understanding of nonlinearity in Ge–Sb–Se glasses at mid-infrared wavelengths still remains limited. In this work, a series of Ge20SbxSe80−x (x = 0, 5, 10) glasses were prepared by conventional melt–quenching method. The absorption spectra and the refractive index of glasses were recorded. The third order nonlinearity, n2, and nonlinear absorption coefficient were measured for Ge–Sb–Se glass samples at the wavelengths of 1550, 2000 and 2500 nm by Z-scan technique, respectively. With the increasing of Sb contents, the linear refractive index of glass increased. Among the three operating wavelengths, all the three glass samples have a highest n2 at 2000 nm. By using the figure of merit (FOM) to evaluate the studied three glasses, the Ge20Sb10Se70 glass shows the greatest potential for mid-IR all optical switching devices.

Graphical abstractThe nonlinearity of Ge–Sb–Se glasses at mid-infrared wavelengths are researched by Z-Scan technique and the large FOM (>10) of Ge20Sb10Se70 glass shows the greatest potential for mid-IR all optical switching devices.Figure optionsDownload full-size imageDownload as PowerPoint slide