Optical Characterization of Chalcogenide Ge–Sb–Se Waveguides at Telecom Wavelengths

Nonlinear single-mode Ge₂₈Sb₁₂Se₆₀ strip waveguides were demonstrated at 1.53-1.55 μm. The waveguides were fabricated by photo-or e-beam lithography, followed by thermal evaporation and lift-off. The linear propagation loss, ranging from 4.0 to 6.1 dB/cm, is compared for waveguides under various fabrication conditions. Using measurements of the power-dependent transmission and spectral broadening, the nonlinear loss β and nonlinear refractive index n₂ of the waveguides fabricated with e-beam lithography are determined to be 0.014±0.003 cm/GW and 5±2×10^-19 m²/W, respectively, at 1.55 μm. Given the large measured figure of merit, n₂/(βλ) = 2.3±0.9, this platform holds promise for nonlinear applications at telecom wavelengths.