High Q-factor plasmonic resonators in continuous graphene excited by insulator-covered silicon gratings

Abstract

We propose a structure to excite plasmons in large-area continuous graphene films with insulator-covered sub-wavelength silicon gratings (ICSWSG). By numerical simulations we have demonstrated that, after adding a low-permittivity insulator underneath graphene, the graphene/gratings hybrid structure has a high Q-factor ($66) and a sharp notch (with the full width at half maximum of $122 nm) in the transmission spectra at mid-infrared resonant wavelength. Furthermore, the plasmonic properties, e.g.the resonant wavelength, magnitude and Q-factor, can be tuned over a wide range via structure modulation and/or gating of graphene. The transmission dip is achieved over a wide angle range. Finally we demonstrate that such highly confined graphene plasmons could also be excited in graphene sandwiched between silicon gratings and a SiO 2 substrate.

Tunable Ultra‐High Q‐Factor and Figure of Merit based on Fano Resonance in Graphene–Dielectric Multilayer Corrugated Structure

“…[13][14][15] For etched insulator silicon grating structure covered by monolayer graphene, the excitation of highly confined plasmonic waves was studied by Gao et al [16] However, the Q-factor of such structure is only about 40. For the similar graphene-dielectric structure, Zhao et al [17] introduced an insulator between the silicon grating and graphene film, and noticed that the graphenegrating hybrid structure has a Q-factor (≈66) and a sharp notch in mid-infrared region of its transmission spectra. These designs usually suffer a relatively low Q-factor which possibly restricts the practical applications.…”

Conformal Graphene-Decorated Nanofluidic Sensors Based on Surface Plasmons at Infrared Frequencies

“…One noticeable feature is that the narrow bandwidth and large resonance depth of the reflection spectrum are maintained until the incident angle is larger than 60°. This indicates that the proposed sensor possesses excellent angle-insensitive property, which is attributed to the deep sub-wavelength nature of graphene plasmons and the effects of Bragg scattering at the Brillouin zone center [ 16 ]. Such a feature contributes to the superior sensing performance of the device in a wide angle range, as plotted in Figure 6 b.…”

“…These superior features render graphene a promising candidate for engineering infrared SPR sensors. Up to now, graphene-based SPR sensors have mainly employed the localized plasmons in patterned graphene [ 14 , 15 ] or surface plasmons in continuous graphene [ 16 , 17 ]. In these devices, the sample solution (fluidic biomolecules or liquid chemical reagent) would be dropped on the sensor surface for detection.…”

Gold nanoparticle mediated graphene plasmon for broadband enhanced infrared spectroscopy

“…Therefore, metal nanoparticles could be an excellent choice to be introduced into graphene platform. The advantages are two fold: they are not only additionally employed as infrared absorption enhancer [18], but also changing the electrostatic environment around graphene [19]. Moreover, metal nanoparticles could be good doping source for graphene [20,21], which will result in stronger resonances to offer larger near-field enhancement and stronger infrared absorption [22].…”