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Photonic crystal slot waveguide absorption spectrometer for on-chip near-infrared spectroscopy of xylene in water

TitlePhotonic crystal slot waveguide absorption spectrometer for on-chip near-infrared spectroscopy of xylene in water
Publication TypeJournal Article
Year of Publication2011
AuthorsLai, W-C., S. Chakravarty, A. X. Wang, C. Lin, and R. T. Chen
JournalApplied Physics Letters
Volume98
Issue2
Pagination023304
Date Published01/2011
ISSN00036951
Keywordsabsorption coefficients, elemental semiconductors, infrared spectra, organic compounds, photonic crystals, silicon
Abstract

We experimentally demonstrate a 300 μm long silicon photonic crystal slot waveguide near-infrared absorption spectrometer. Based on Beer–Lambert absorption law, our on-chip absorption spectrometer combines slow light in a photonic crystal waveguide with a high electric field intensity in a low-index 75 nm wide slot, which effectively increases the optical absorption path length of the analyte. We demonstrate near-infrared absorption spectroscopy of xylene in water, with a polydimethyl siloxane sensing phase for xylene extraction from water. Xylene concentrations up to 100 ppb (parts per billion) (86 μg/l) in water were measured.

DOI10.1063/1.3531560
Short TitleAppl. Phys. Lett.