Abstract
Terahertz surface plasmon resonance (SPR) sensors have been regarded as a promising technology in biomedicine due to their real-time, label-free, and ultrasensitive monitoring features. Different authors have suggested a lot of SPR sensors, including those based on 2D and 3D metamaterials, subwavelength gratings, graphene, and graphene nanotube, as well as others. However, one of the traditional approaches to realize high sensitivity SPR sensors based on metal diffraction gratings has been studied poorly in the terahertz frequency range. In this article, a linear metal rectangular diffraction grating with high aspect ratio is studied. The influence of the grating structure parameters on the sensor sensitivity is simulated. Effects arising from different ratios of depth and width were discovered and explained. The results show that the sensitivity can be increased to 2.26 THz/RIU when the refractive index range of the gas to measure is between 1 and 1.002 with the resolution .
Highlights
Fast and ultrasensitive surface plasmon resonance (SPR) sensors are a well-proven technology of refractive index and spectra substance measurement in the optical frequency range [1]
One of the traditional approaches to realize high sensitivity SPR sensors based on metal diffraction gratings has been studied poorly in the terahertz frequency range
We investigate a one-dimensional periodic metal rectangular diffraction grating with high aspect ratio for terahertz SPR sensing
Summary
Fast and ultrasensitive surface plasmon resonance (SPR) sensors are a well-proven technology of refractive index and spectra substance measurement in the optical frequency range [1] It is based on the electron surface wave excitation in the Kretschman scheme on thin metallic films. In 2004, O’Hara et al was the first to experimentally investigate the excitation of terahertz surface plasmon polariton (SPP) wave with a metal grating and TDS spectroscopy [21] They determined that the coupling process was efficient, but the lifetime of SPP was very short. In 2020, Sathukarn et al used the rigorous coupled-wave analysis (RCWA) method to design terahertz SPR diffraction linear rectangular gratings providing as a refractive index sensor [26] They parametrically analyzed the gratings and found optimal parameters for surface plasmon resonance. Terahertz SPR sensors with different grating configurations are examined via characterization of analytes with different refractive indices for gas sensing
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