Abstract
We propose a terahertz surface plasmon resonance sensor based on dielectric metagrating coupling to the spoof surface plasmon (SSP) mode on periodically grooved metal films. The well-designed silicon metagrating converts the normal incident to the necessary angle in the dielectric substrate exciting SSP with the transmission coupling between couplers and SSP metasurfaces. Using an all-dielectric metagrating as an external coupler, the tightly confined SSP mode can be excited within a small resonant cavity, causing the strong light–matter interaction. The proposed SSP dielectric meta-couplers will pave new routes for ultra-thin and compact sensing devices. The dielectric substrate thickness, the air gap distance between the substrate and the metal groove array, and metal groove gaps have remarkable influences on the characteristics of SSP sensing. The SSP sensing by metagrating coupling with the resonance frequency around 0.404 THz provides a high sensitivity of up to 335 GHz/RIU and a detection limit less than 0.0001 RIU with a frequency resolution of 33.5 MHz. Dielectric metagrating coupling SSP provides enormous potential for constructing ultra-sensitive and compact SSP sensors in the terahertz frequency region.
Highlights
With extraordinary properties such as subwavelength resolution and a strongly enhanced near field, a surface plasmon polariton (SPP) on dielectric/plasmonic metal interfaces at near infrared and optical frequencies has drawn intensive interest in physics, chemistry, and biology1 and has been widely studied in super-resolution imaging,2 biosensing and chemical sensing,3 enhanced Raman4 and nonlinear effects,5 solar cells,6 and so on
We propose a terahertz surface plasmon resonance sensor based on dielectric metagrating coupling to the spoof surface plasmon (SSP) mode on periodically grooved metal films
Metamaterials characterized by micro-structures provide lower effective plasma frequencies, which can generate confined surface waves known as spoof surface plasmon polariton (SSP)
Summary
With extraordinary properties such as subwavelength resolution and a strongly enhanced near field, a surface plasmon polariton (SPP) on dielectric/plasmonic metal interfaces at near infrared and optical frequencies has drawn intensive interest in physics, chemistry, and biology1 and has been widely studied in super-resolution imaging,2 biosensing and chemical sensing,3 enhanced Raman4 and nonlinear effects,5 solar cells,6 and so on. We propose a terahertz surface plasmon resonance sensor based on dielectric metagrating coupling to the spoof surface plasmon (SSP) mode on periodically grooved metal films.
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