Tunable mid-infrared optical resonator on nanopatterned chalcogenide glasses

摘要

We present the incorporation into the chalcogenide glasses of two-dimensional periodic nanopatterns to realize the first of a kind chalcogenide-based planar optical mid-infrared tunable resonant structure. Chalcogenide (ChG) glasses are promising for infrared photonics owing to their transparency in visible to far infrared, where various biomolecules and gases have their characteristic absorption lines, arising from rotational-vibrational transitions. The region of the electromagnetic spectrum in which this absorption occurs, the amount of absorption, and the specific characteristics of the absorption curve are unique to each gas. Thus, gases can be fingerprinted using their absorption characteristics. Utilizing the mid-IR resonance feature of our nanopatterned ChG glass, an innovative approach is proposed to achieve selective gas sensing through the tuning of the sensor resonance, providing an inbuilt selectivity. As an illustration, the presented chalcogenide-based nanostructure is customized to match its resonance wavelength with the absorption band of gaseous methanol, a key plant health indicator. The highly concentrated electromagnetic field at the nanostructure surface allows highly sensitive detection of the target analyte methanol.