We study optical coefficients that characterize wave propagation through layered structures called plasmonic crystals. These consist of a finite number of stacked metallic sheets embedded in dielectric hosts with a subwavelength spacing. By adjustment of the frequency, spacing, number as well as geometry of the layers, these structures may exhibit appealing transmission properties in a range of frequencies from the terahertz to the mid-infrared regime. Our approach uses a blend of analytical and numerical methods for the distinct geometries with infinite, translation invariant, flat sheets and nanoribbons. We describe the transmission of plane waves through a plasmonic crystal in comparison to an effective dielectric slab of equal total thickness that emerges from homogenization, in the limit of zero interlayer spacing. We demonstrate numerically that the replacement of the discrete plasmonic crystal by its homogenized counterpart can accurately capture a transmission coefficient akin to the extinction spectrum, even for a relatively small number of layers. We point out the role of a geometry-dependent corrector field, which expresses the effect of subwavelength surface plasmons. In particular, by use of the corrector we describe lateral resonances inherent to the nanoribbon geometry.
A theory of light reflection and transmission by an optically thin nanocomposite slab which contains randomly distributed metal nanoparticles (NPs) is developed. The underlying model takes into account the reflection of light scattered by NPs from the slab boundaries, enhanced decay of localized surface plasmons in dense NP arrays and light scattering at the slab surface -- the factors which are beyond the scope of the Maxwell Garnett approximation. It is demonstrated that the first two effects lead to broadband perfect absorption observed in such nanocomposites, whereas the last one is respon…
A plasmonic coupled-cavity system, which consists of a quarter-wave coupler cavity, a resonant Fabry-Perot detector nanocavity, and an off-resonant reflector cavity, is used to enhance the localization of surface plasmons in a plasmonic detector. The coupler cavity is designed based on transmission line theory and wavelength scaling rules in the optical regime, while the reflector cavity is derived from off-resonant resonator structures to attenuate transmission of plasmonic waves. We observed strong coupling of the cavities in simulation results, with an 86% improvement of surface plasmon loc…
This work is focussed on the role of the angle of incidence of an incoming electromagnetic wave in its transmission through a subwavelength nano-hole in a thin semiconductor plasmonic layer. Fully detailed calculations and results are exhibited for $ p$- and $s$-polarizations of the incident wave for a variety of incident angles in the near, middle and far zones of the transmitted radiation. Our dyadic Green's function formulation includes both (1) the electromagnetic field transmitted directly through the $ 2D $ plasmonic layer superposed with (2) the radiation emanating from the nano-hole. I…
We present a comprehensive theory of the one-dimensional plasmonic crystal formed in the grating gated two-dimensional electron gas (2DEG) in semiconductor heterostructures. To describe collective plasma excitations in the 2DEG, we develop a generalized transmission line theoretical formalism consistent with the plasma hydrodynamic model. We then apply this formalism to analyze the plasmonic spectra of 2DEG systems with step-like periodic changes of electron density and/or gate screening. We show that in a periodically modulated 2DEG, a plasmonic crystal is formed and derive closed-form analyt…
The concept, analysis, and design of series switches for graphene-strip plasmonic waveguides at near infrared frequencies are presented. Switching is achieved by using graphene's field effect to selectively enable or forbid propagation on a section of the graphene strip waveguide, thereby allowing good transmission or high isolation, respectively. The electromagnetic modeling of the proposed structure is performed using full-wave simulations and a transmission line model combined with a matrix-transfer approach, which takes into account the characteristics of the plasmons supported by the diff…
Optical nanosensors are promising for hydrogen sensing because they are small, free from spark generation, and feasible for remote optical readout. Conventional optical nanosensors require broadband excitation and spectrometers, rendering the devices bulky and complex. An alternative is spatial intensity-based optical sensing, which only requires an imaging system and a smartly designed platform to report the spatial distribution of analytical optical signals. Here, we present a spatial intensity-based hydrogen sensing platform based on Fano-like spatial distribution of the transmission in a P…
The characteristic impedance of a microwave transmission line is typically constrained to a value $Z_0$ = 50 $ Ω$, in-part because of the low impedance of free space and the limited range of permittivity and permeability realizable with conventional materials. Here we suggest the possibility of constructing high-impedance transmission lines by exploiting the plasmonic response of edge states associated with the quantum Hall effect in gated devices. We analyze various implementations of quantum Hall transmission lines based on distributed networks and lumped-element circuits, including a detail…
We measured a change in the current transport of an antenna-coupled, multi-gate, GaAs/AlGaAs field-effect transistor when terahertz electromagnetic waves irradiated the transistor and attribute the change to bolometric heating of the electrons in the two-dimensional electron channel. The observed terahertz absorption spectrum indicates coherence between plasmons excited under adjacent biased device gates. The experimental results agree quantitatively with a theoretical model we developed that is based on a generalized plasmonic transmission line formalism and describes an evolution of the plas…
We have theoretically studied a graphene-based plasmonic waveguide, which can gate the transmission of a surface plasmon polariton (SPP) localized at the graphene-semiconductor interface. When a gate voltage is applied above a certain critical value, the charge density modulation in the quasi two-dimensional electron gas formed in the inversion layer can induce a local plasma resonance. Since the local plasma resonance is strongly coupled to the SPP, it can suppress the transmission of the SPP. By calculating the propagation length of the SPP with varying gate voltage, we have obtained the sha…
Metal-coated microsphere monolayers as surface plasmon resonance sensors operating in both transmission and reflection modes
National Institute for Research and Development of Isotopic and Molecular Technologies（同位素和分子技术研究发展中心）；Institute for Interdisciplinary Research in Bio-Nano-Sciences, Babes-Bolyai University（巴比什-博约伊大学生物纳米科学交叉研究所）
A detailed numerical study of the Helmholtz Green's function for the description of scalar wave propagation through a nano-hole on a plasmonic layer is presented here. In conjunction with this, we briefly review the analytic formulation taking the nano-hole radius as the smallest length parameter of the system. Figures exhibiting the numerical results for this Green's function in various ranges of the transmission region are presented.
The performance of plasmonic nanoantenna structures on top of SOI wire waveguides as coherent perfect absorbers for modulators and all-optical switches is explored. The absorption, scattering, reflection and transmission spectra of gold and aluminum nanoantenna-loaded waveguides were calculated by means of 3D finite-difference time-domain simulations for single waves propagating along the waveguide, as well as for standing wave scenarios composed from two counterpropagating waves. The investigated configurations showed losses of roughly 1% and extinction ratios greater than 25 dB for modulator…
We study theoretically optical response of WS2 monolayer located near periodic metal nanostructured arrays in two and three dimensions. The emphasis of simulations is on the strong coupling regime of excitons supported by WS2 and surface plasmon-polaritons supported by various periodic plasmonic interfaces. It is demonstrated that a monolayer of WS2 placed in a close proximity of periodic arrays of either slits or holes results in a Rabi splitting of the corresponding surface plasmon-polariton resonance as revealed in calculated transmission and reflection spectra. The nonlinear regime, at whi…
We study plasmon propagation on a metallic two-dimensional surface partially coated with a thin film of anomalous-Hall material. The resulting three regions, separated by two sharp interfaces, are characterised by different Hall conductivities but identical normal conductivities. A single bound mode is found, which can localise to either interface and has an asymmetric potential profile across the region. For propagating modes, we calculate the reflection and transmission coefficients through the magnetic region. We find Airy transmission patterns with sharp maxima and minima as a function of …
The plasma wave instabilities in ballistic Field Effect Transistors (FETs) have a promise of developing sensitive THz detectors and efficient THz sources. One of the difficulties in achieving efficient resonant plasmonic detection and generation is assuring proper boundary conditions at the contacts and at the heterointerfaces and tuning the plasma velocity. We propose using the tunable narrow channel regions of an increased width, which we call "stubs" for optimizing the boundary conditions and for controlling the plasma velocity. We developed a compact model for THz plasmonic devices using t…
A plasmonic modulator is a device that controls the amplitude or phase of propagating plasmons. In a pure plasmonic modulator, the presence or absence of a pump plasmonic wave controls the amplitude of a probe plasmonic wave through a channel. This control has to be mediated by an interaction between disparate plasmonic waves, typically requiring the integration of a nonlinear material. In this work, we demonstrate the first 2D semiconductor nonlinear plasmonic modulator based on a WSe2 monolayer integrated on top of a lithographically defined metallic waveguide. We utilize the strong coupling…
Quantum Hall edge states have some characteristic features that can prove useful to measure and control solid state qubits. For example, their high voltage to current ratio and their dissipationless nature can be exploited to manufacture low-loss microwave transmission lines and resonators with a characteristic impedance of the order of the quantum of resistance $h/e^2\sim 25\mathrm{kΩ}$. The high value of the impedance guarantees that the voltage per photon is high and for this reason high impedance resonators can be exploited to obtain larger values of coupling to systems with a small charge…
Understanding of fundamental physics of plasmonic instabilities is the key issue for the design of a new generation of compact electronic devices required for numerous THz applications. Variable width plasmonic devices have emerged as potential candidates for such an application. The analysis of the variable width plasmonic devices presented in this paper shows that these structures enable both the Dyakonov-Shur instability (when the electron drift velocity everywhere in the device remains smaller than the plasma velocity) and the "plasmonic boom" instability that requires drift velocity excee…
We show that a graphene sheet perforated with micro- or nano-size antidots have prominent absorption resonances in the microwave and terahertz regions. These resonances correspond to surface plasmons of a continuous sheet "perturbed" by a lattice. They are excited in different diffraction orders, in contrast to cavity surface plasmon modes existing in disconnected graphene structures. The resonant absorption by the antidot array can essentially exceed the absorption by a continuous graphene sheet, even for high antidot diameter-to-period aspect ratios. Surface plasmon-enhanced absorption and s…
