Resonant grating filters as refractive index sensors for chemical and biological detections

Abstract

A chemical and biological sensor based on a free-space waveguide resonant grating optical filter has been developed. Different from the conventional surface plasmon resonance sensors and the conventional waveguide mode sensors, which require either prism coupling or grating coupling, the proposed free-space optical sensor device does not require special separate coupling. The inherent 100% coupling efficiency at resonance can significantly boost probe efficiency. Both simulation and experimental results have demonstrated that the sensor could deliver a resolution of better than 0.001–0.0001 for refractive index sensing, which is enough for detecting various chemical and biological materials. More importantly, under an angular detection scheme, the proposed waveguide resonant grating sensor could be one order’s more sensitive than the conventional surface plasmon resonance sensor.

Wavelength interrogation of grating-based optical biosensors in the input coupler configuration

“…The grating coupler has been implemented in a variety of configurations: input, output, and reflective modes [4][5][6][7] as well as various resonance approaches [8][9][10]. The operating principle of the input grating coupler is shown in Fig.…”

Silicon-on-insulator guided mode resonant grating for evanescent field molecular sensing

“…A similar configuration has been used in guided mode resonance filters to achieve very narrow spectral response [5]. When used as a molecular sensor, the transduction signal may again be either the angle or wavelength shift of the guided mode resonance in response to a refractive index change at the surface [6]. By the same arguments used for the PWEF sensors, choosing the TM mode of a thin SOI slab waveguide maximizes the sensitivity of guided mode resonance grating sensors.…”

Plasmonic Notch Filter Design Based on Long-range Surface Plasmon Excitation Along Metal Grating

“…The excitation condition of SPR is highly sensitive to the refractive indices and thicknesses of the metallic and dielectric materials near the metal-dielectric interface. This characteristic has been applied in many device designs and applications including electro-optics modulators [2][3][4][5][6][7], plasmonic filters [8][9][10][11], ultrahigh sensitivity chemical and biological sensing [12][13][14], ultrathin film deposition monitoring [15], temperature [16], angular measurements, etc. [17].…”