Authors Joseph, S. ; Sarkar, S. ; Joseph, J.
Title High-sensitivity resonant cavity modes excited in a low contrast grating layer with large aspect-ratio
Date 01.09.2022
Number 60807
Abstract The resonant modes in a low contrast grating-waveguide structure with a larger aspect ratio possesses unique characteristics, observed under theoretical investigations. Subsequently, a photoresist grating with similar dimensions is realized over a dielectric waveguide to experimentally observe the resonant guided modes (GMR) and cavity modes (CM). In particular, the cavity mode exhibits remarkable characteristics of high sensitivity towards cover index variation, thus with a probable application for environmental index monitoring. In addition, the waveguide-supported GMR mode is negligibly sensitive and may serve as a reference line for such sensing experiments. The spectral responses analyzed in sugar solution with different concentrations as analytes demonstrate a high bulk sensitivity of ~300 nm/RIU in the visible spectrum. Thus, the study opens up possibilities of using optimized grating-based geometry for designing simple yet highly-sensitive handheld sensor devices.
Publisher IEEE Sensors Journal
Citation IEEE Sensors Journal 22 (2022) 16856-16861

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