Ultralow loss chalcogenide waveguide platform for mid-IR on-chip spectrometer applications

A chalcogenide waveguide platform with the combination of GeAsSeTe (IG3)/GeAsSe (IG2) on wet-/dry-etched silicon pedestals is reported. Chalcogenide glasses offer high index contrast and compact footprints, while the post-processing challenges are addressed using Si pedestals. The integration of IG2/IG3 chalcogenides on Si demonstrates ultralow loss of 0.08 ± 0.02 dB/cm at a wavelength of 10 μm. We have measured a thermo-optic coefficient of 1.1x10⁻⁴ K⁻¹, which is comparable to Si and GaAs. The combination of simplified fabrication, minimal propagation losses and a strong thermooptic coefficient, positions this waveguide platform as a promising candidate for on-chip tunable long-wave IR spectrometers for practical applications in biomedical diagnostics and environmental sensing.