Near-infrared on-chip hollow-core waveguide C2H2 sensing using hybrid chalcogenide/PDMS anti-resonant reflecting structure.

To increase the operating bandwidth and enhance gas absorption, we developed a hybrid chalcogenide glass (ChG)/polydimethylsiloxane (PDMS) anti-resonant reflecting hollow-core waveguide for C2H2 detection based on near-infrared absorption spectroscopy. ChG/SiO2 and RN-218/air anti-resonant bilayers combined with PDMS upper cladding are used to enhance light-gas interaction and broaden anti-resonant bandwidth. The simplified fabrication process includes plasma-enhanced chemical vapor deposition (PECVD), thermal evaporation, and one-step lithography. The proposed hybrid hollow-core ARROW achieves external confinement factors of 101.9% and a limit of detection of 25.13 parts-per-million (ppm) at an averaging time of 178 s using intensity modulation spectroscopy (IMS) techniques, with an anti-resonant bandwidth exceeding 200 nm, highlighting its potential for miniaturized on-chip gas sensing applications.