On-chip near-infrared multi-gas sensing using chalcogenide anti-resonant hollow-core waveguides

Abstract

On-chip infrared spectroscopic gas sensing using hollow-core anti-resonant reflecting optical waveguide (ARROW) with large external confinement factor (ECF) was rarely reported due to complex fabrication process and polarization dependence. Alternatively, we proposed ARROW gas sensors using chalcogenide (ChG) anti-resonant layers which require thermal evaporation and epoxy resin bonding for fabrication instead of complicated wafer bonding process. Polarization characteristics and ethylene (C2H2) sensing performance at 1.532 μm were measured for two ARROW sensors with four-side (WG_A) and three-side (WG_B) anti-resonant layers around the hollow-core. Due to a symmetric structure, the 1cm-long WG_A exhibits polarization-insensitive characteristics, which does not require an additional polarization controller for integrated on-chip sensors and enhances the stability and reliability of the sensor under fluctuating polarization states. A high ECF of 71% and a 1σ limit of detection (LoD) of ~ 23 parts-per-million (ppm) for WG_A were achieved at an averaging time of 100 s. Broadband multi-gas detection capability of WG_A was verified through C2H2 detection at 1.532 μm and CH4 at 1.654 μm, highlighting the potential of ARROWs for on-chip multi-gas sensing.