title: On-chip methane sensing by near-IR absorption signatures in a photonic crystal slot waveguide.
abstract: We demonstrate a 300 μm long silicon photonic crystal (PC) slot waveguide device for on-chip near-infrared absorption spectroscopy, based on the Beer-Lambert law for the detection of methane gas. The device combines slow light in a PC waveguide with high electric field intensity in a low-index 90 nm wide slot, which effectively increases the optical absorption path length. A methane concentration of 100 ppm (parts per million) in nitrogen was measured.
authors.affiliation: Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Wei-Cheng
authors.initials: WC
authors.lastname: Lai
authors.forename: Swapnajit
authors.initials: S
authors.lastname: Chakravarty
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Wang
authors.forename: Cheyun
authors.initials: C
authors.lastname: Lin
authors.forename: Ray T
authors.initials: RT
authors.lastname: Chen