High-Q mid-infrared chalcogenide glass resonators

TL;DR

This paper reports the fabrication of high-Q mid-infrared chalcogenide glass resonators on CaF2 substrates, demonstrating their potential for sensitive on-chip spectroscopy with improved performance and environmental stability.

Contribution

The work introduces the highest Q-factor achieved in planar mid-infrared resonators and explores environmental effects and recovery methods for device performance.

Findings

Intrinsic Q-factor of 4E5 at 5.2 microns

Moisture significantly affects device performance

Annealing restores high-Q characteristics

Abstract

In this letter, we fabricated and characterized chalcogenide glass resonators monolithically integrated on mid-infrared transparent CaF2 substrates. The devices feature an intrinsic Q-factor of 4E5 at 5.2 micron wavelength, which represents the highest Q-factor reported in planar mid-infrared resonators. It is found that moisture can significantly impact the device performance when the device was exposed to an ambient environment, although the high-Q characteristics can be restored after undergoing an annealing treatment. Using these devices, we further demonstrated on-chip cavity-enhanced spectroscopy to quantify mid-IR absorption of ethanol solutions around 5.2 micron wavelength.