Record-high-Q AMTIR-1 microresonators for mid- to long-wave infrared nonlinear photonics

AMTIR-1 chalcogenide glass has shown its potential for use in thermal imaging systems owing to its low refractive index, thermal resistance, and high transparency across the infrared wavelength regime. Here, we report a millimeter-scale high-Q whispering gallery mode microresonator made of AMTIR-1. The recorded Q-factor has reached 1.2×10⁷ at 1550 nm, which is almost two orders of magnitude higher than previously reported values. We characterize the thermal properties, where low thermal conductivity plays an important role in thermal resonance tuning. We further show that AMTIR-1 resonators support anomalous dispersion as well as a low absorption coefficient near the 7 µm wavelength band, thus offering the possibility of providing suitable platforms for mid-infrared, long-wave infrared nonlinear optics, including microresonator frequency comb generation.