Photonic crystal slot waveguide absorption spectrometer for on-chip near-infrared spectroscopy

Over the last two decades, near-infrared spectroscopy (NIRS) has established itself as a non-destructive analytical technique in a variety of disciplines. Radiation losses occurring in photonic crystals etched into planar waveguides are analyzed using a first-order perturbation approximation. We experimentally demonstrate a 13.94 um long InP 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. which effectively increases the optical absorption path length of the analyte. We demonstrate near-infrared absorption spectroscopy.