Active plasmonic switching at mid-infrared wavelengths with graphene ribbon arrays

Abstract

An active plasmonic switch based on single-and few-layer doped graphene ribbon array operating in the mid-infrared spectrum is investigated with theoretical and numerical calculations. It is shown that significant resonance wavelength shifts and modulation depths can be achieved with a slight variation of the doping concentration of the graphene ribbon. The few-layer graphene ribbon array device outperforms the single-layer one in terms of the achievable modulation depth. Our simulations reveal that, by modulating the Fermi-energy level between 0.2 eV and 0.25 eV, a fourlayer graphene ribbon array device can achieve a modulation depth and resonance wavelength shift of ∼13 dB and 0.94 µm respectively, compared to ∼2.8 dB and 1.85 µm for a single-layer device. Additionally, simple fitting models to predict the modulation depth and the resonance wavelength shift are proposed. These prospects pave the way towards ultrafast active graphene-based plasmonic devices for infrared and THz applications. a) Electronic mail: chuhs@ihpc.a-star.edu.sgRecently, there is tremendous scientific and technological interest in the mid-infrared spectral range of 2-20 µm. This range provides many potential applications for optics/photonics such as spectroscopy, materials processing, chemical and biomolecular sensing, remote explosive detection and covert communication systems 1,2 . Thanks to the integration with electronic devices and possibility to design devices with active control over the surface plasmon resonance 3 at metal/dielectric interfaces, the mid-infrared spectral region is also attractive for the study of plasmonic devices 4,5 . However, due to a relatively weak refractive index change with electrical-bias, mechanical force or temperature, the active plasmonic devices typically exhibit low optical performance such as high power consumption or slow response time. Graphene, a single layer of carbon atoms gathered in a honeycomb lattice, exhibits many unique physical features and has been recently investigated for nanoscale optoelectronic integrated circuits. Graphene-based plasmonic nanostructures support highly confined plasmonic modes that can be tuned via chemical or eletrostatic doping, and are promising to serve as future platforms for highly integrated active plasmonic devices ranged from the infrared to THz frequencies 6-14 . Therefore, it is important to develop broadly tunable plasmonic devices, either as an enabling technology or to add functionality to current plasmonic technologies. In this paper, we demonstrate with numerical simulations that an effective active plasmonic switch operating in the mid-infrared wavelength range can be real-

Review of mid-infrared plasmonic materials

“…The significant tuning of the graphene optical conductivity by electrostatic gating allows for the design and demonstration of broadly tunable active mid-IR plasmonic devices. [117][118][119][120] While such tuning has been demonstrated experimentally and shows tremendous promise, the field of graphene plasmonics has much room to grow and is expected to constitute a significant fraction of the larger field of mid-IR plasmonics moving forward.…”

Strong Coupling in the Far-Infrared between Graphene Plasmons and the Surface Optical Phonons of Silicon Dioxide

“…The ability to electrostatically gate the charge density in graphene to in excess of 1×10 13 cm -2 predicates tunable and switchable devices 1,4,7,8 and, coupled with an effective mass which is small compared to that of two dimensional electron gases in conventional semiconductors, results in significantly enhanced light-plasmon coupling and the observation of plasmons at room temperature 1 .…”

Dynamically-Tunable Terahertz Band-Stop Filter Based on Multilayer Graphene Metamaterial

“…The resonance frequency of graphene can be interpreted from the quasistatic analysis. The resonance frequency has inversely proportional to graphene length, And expressed as [18]:…”

“…These unique properties are a suitable candidate to be used in tunable and compact plasmonic devices. Recently, many devices have been theoretically and experimentally studied such as active plasmonic switching with graphene ribbon arrays [18], Fano metamaterial with tuning of the electrical properties of graphene for switching and sensing applications [19], tunable infrared plasmonic devices with graphene/insulator stacks [20], switching terahertz waves with gate-controlled graphene metamaterials and electromagnetic response [21] and broadband ultrafast dynamics of few-layer epitaxial graphene [22]. In this paper, a tunable band-stop filter with periodic structure consists of nanostrip and nanodisk graphenes.…”

“…[12][13][14][15]. Plasmonic devices based on graphene guide surface plasmon modes with low loss which can be dynamically tuned by changing the electrostatic doping [16,17]. These unique properties are a suitable candidate to be used in tunable and compact plasmonic devices.…”