Probing Composite Vibrational Fingerprints in the Terahertz Range With Graphene Split Ring Resonator

Abstract

Sensors with single resonant mode often produce false positive when detecting the composite vibrational fingerprints of molecules in the terahertz (THz) range. In this study, a multi-resonant plasmonic structure, consisting of periodic graphene split ring resonator (SRR) arrays, is proposed for THz sensing. The effective detection of ultrathin (0.1 μm) lactose layer is given as an example to demonstrate the detection sensitivity. The vibrational fingerprints of lactose at 0.53 THz and 1.37 THz are enhanced in transmission spectra. Besides, resonant frequencies could be actively adjusted with the gate voltage applied on the SRR array. The physical mechanism of multi-resonance can be explained by a combination of LC resonance and dipole resonance of the structure, which can be observed in the electric field distributions. Moreover, the sensing performance can be further optimized by varying geometric parameters. Furthermore, the refractive index sensing performance of the sensor is also investigated by altering the surrounding medium on the surface. The designed sensor can work under an oblique incidence, which provides potential applications in biological analysis and medical diagnostics.

A pixelated frequency-agile metasurface for broadband terahertz molecular fingerprint sensing

“…The electromagnetic properties of graphene have a large impact on the electric field response of the rings, and strongly affect the resonance of the meta-atoms since it is placed in the near-field, thereby achieving more precise tunability. 12 The surface conductivity σ of the infinitely thin graphene monolayer related to the Fermi level, consisting of intraband σ intra and interband σ inter transition, can be expressed as: 36–40 σ = σ inter + σ intra .…”

Terahertz Vibrational Fingerprints Detection of Molecules with Particularly Designed Graphene Biosensors

“…Therefore, the single resonance biosensor often produces incorrect positives when detecting objects with multiple vibration fingerprints [29]. To overcome this phenomenon, Cai and Mao reported the use of graphene plasmons for realizing multi-resonance sensing [30,31]. However, there are still shortcomings in polarization dependence, and the resonance peaks cannot precisely overlap with the molecular fingerprints.…”

Tunable and polarization-sensitive graphene-based terahertz absorber with eight absorption bands

“…Terahertz (THz) technology is widely used in imaging, communications and sensing applications [1][2][3]. In recent years, THz metamaterial absorbers have received tremendous attention since the first metamaterial absorber was demonstrated in 2008 [4].…”