Highly tunable hybrid metamaterials employing split-ring resonators strongly coupled to graphene surface plasmons

Abstract

Metamaterials and plasmonics are powerful tools for unconventional manipulation and harnessing of light. Metamaterials can be engineered to possess intriguing properties lacking in natural materials, such as negative refractive index. Plasmonics offers capabilities of confining light in subwavelength dimensions and enhancing light–matter interactions. Recently, the technological potential of graphene-based plasmonics has been recognized as the latter features large tunability, higher field-confinement and lower loss compared with metal-based plasmonics. Here, we introduce hybrid structures comprising graphene plasmonic resonators coupled to conventional split-ring resonators, thus demonstrating a type of highly tunable metamaterial, where the interaction between the two resonances reaches the strong-coupling regime. Such hybrid metamaterials are employed as high-speed THz modulators, exhibiting ∼60% transmission modulation and operating speed in excess of 40 MHz. This device concept also provides a platform for exploring cavity-enhanced light–matter interactions and optical processes in graphene plasmonic structures for applications including sensing, photo-detection and nonlinear frequency generation.

Coherent absorption of light by graphene and other optically conducting surfaces in realistic on-substrate configurations

“…[4][5][6][7][8] In addition, the conjunction of the two concepts above is expected to further boost the research field, thanks to the huge potential offered by 2D materials patterned as a metasurface [9][10][11] and by hybrid devices where a metallic metasurface is coupled to 2D conductors. [12][13][14] Whether based on 2D materials, traditional metals, or innovative alloys, 15 a (structured) optically conducting surface (OCS) shows a certain degree of energy loss, due to the very nature of the conductors which constitute the device. Such losses may be either detrimental or functional, depending on the intended application.…”

All-integrated terahertz modulators

“…Another novel and promising approach for frequency tuning has been recently proposed in Ref. [72]. The device architecture is based on complementary SRR (C-SRR) arrays strongly coupled to graphene ribbons, supporting surface plasmon resonances with frequencies close to the C-SRR resonances.…”

Graphene–Metamaterial Photodetectors for Integrated Infrared Sensing

“…The plasmon-phonon mode at 1250cm -1 , labelled P 4 , overlaps in frequency with the CSRR mode centered at 1170cm -1 , which concentrates the field within the capacitor gap, thus coupling to the graphene plasmon-phonon resonance 13 and the enhanced absorption associated with this resonance is observed as a peak in the thermoelectric voltage 20 . This observation is supported by the linewidth of the plasmon-phonon mode, which is ~110cm -1 , in close agreement with the ~105cm -1 measured linewidth of the photo-response peak.…”

“…Importantly, this would also enable high responsivity at high carrier density in the absorption region 21,25 and therefore be compatible with enhanced absorption due to plasmonic resonances 10,18,19 and strong 13 coupling of the hybrid metamaterial 13 . The tunability of the hybrid modes 13 , also provides a route towards spectrometer free sensing 26 , which combined with the integrated detector opens up the possibility of highly sensitive, low cost and miniaturized sensors for point-of-care medical applications. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 15 ASSOCIATED CONTENT …”