Mitigating waveguide loss in Ge–Sb–Se chalcogenide glass photonics

Minimizing propagation loss within waveguides remains a central objective across diverse photonic platforms, impacting both linear lightwave transmission and nonlinear wavelength conversion efficiencies. Here, we present a method to mitigate waveguide loss in Ge 28 Sb 12 Se 60 chalcogenide glass, a material known for its high nonlinearity, broad mid-infrared transparency, and significant potential for mid-IR photonics applications. By applying a sacrifical oxide layer to eliminate etching residues and a subsequent waveguide thermal reflow to smooth lithography-induced line edge roughness, we successfully reduced the waveguide loss down to 0.8 dB cm −1 at 1550 nm wavelength. This represents the best result in small-core and high-index-contrast Ge 28 Sb 12 Se 60 channel waveguides. Our approach paves the way for low-loss, on-chip chalcogenide photonic devices.