Hybrid Surface Plasmon Polariton Research Articles

An electro-optic half subtractor from a silicon-based hybrid surface plasmon polariton waveguide

Abstract In order to solve the problems of low transmission rate and large device size of electro-optical modulator, an electro-optic half subtractor based on silicon-based hybrid surface plasmon polariton waveguide is proposed in this study. The proposed device utilizes three units metal-oxide-semiconductor capacitor structure to achieve the half subtractor logic function of electro-optic control, improving the transmission rate of the electro-optic half subtractor while also reducing the device size using surface plasmon polariton technology, with a size of only 32 μm × 4.3 μm. At the same time, the use of hybrid silicon waveguides reduces the sharp Ohmic attenuation caused by surface plasmon polaritons and reduces optical insertion losses (ILs). The simulation results show that when the electro-optic half subtractor operates at the wavelength of 1,550 nm, the IL difference is 1.0 dB in each state, the transmission rate of the device is 0.75 Tbit/s, and the energy consumption is 12.69 fj/bit.

Strong plasmon-mechanical coupling through standing acoustic waves and antenna enhancement, toward mass transduction

Plasmon-mechanical resonators are frequently employed in sensor development. Here, I report the coupling of plasmon and mechanical modes in a multilayer architecture. In the experiment, the multilayer comprised indium tin oxide (ITO) and silver (Ag) mirrors placed on the top and bottom of a SiO2 substrate. By activating a Fabry–Pérot hybrid mode and surface plasmon polariton in a Kretschmann configuration, I demonstrated the generation of a hybrid plasmon-mechanical mode by plasmonic dispersion and through strong coupling, which resulted in mechanical distortion at multiple frequencies. Adsorption of rhodamine G6 on Ag modifies the optomechanical spectrum; it causes eigenmodes to split, resulting in a coupling rate greater than the optical decay rate (κ∗<g). Besides, the excitonic modes were observed to interact with plasmon-mechanical modes, especially on-resonance, where the plasmon-mechanical modes exhibited the higher intensity. For example, the out-of-phase flexural mode (iii, g0=427×2πkHz) became active because of the coupling of the dye. Meanwhile, after dye absorption, the strong in-phase compressional mode (iv, g0=560×2πkHz) exhibited the widest splitting and an increase in the side peaks, which merged when the pump power was raised. The system was then analyzed to determine the ideal experimental settings for detecting mass by the oscillator in a controlled experiment. The mass sensor responsivity was evaluated to be F=1017Hzg−1. Advantages and disadvantages of this approach are presented.

Amplified hybrid surface plasmon polaritons in partially reduced graphene oxide supported on gold

We experimentally investigated the surface plasmon polaritons' (SPPs) localisation, resonance, and propagation in three plasmonic waveguides: graphene oxide (GO), partially reduced graphene oxide (PRGO), and reduced graphene oxide (RGO) in two configurations; as stand-alone structures and when deposited on gold films. Our experiments measuring the nonlinear absorption/refraction and leakage radiation microscopy (LRM) reveal that the intense Lorenz/Fano resonance of surface plasmon polaritons can occur in the PRGO-based waveguide. We also observe an increasing surface plasmon polaritons generation rate in PRGO-supported Au waveguide, a procedure similar to the spaser (surface plasmon nanolaser) mechanism. This, in turn, leads to increasing the propagation length. Furthermore, our analytical simulation results also suggest the suitability of PRGO as a superior optical material for spaser application. Our density functional calculations confirm that oxidised graphene has a more robust absorption spectrum in infrared wavelengths than pure graphene. Additionally, through van der Waals interaction, PRGO forms a more consistent and uniform bond with gold substrate than pristine graphene, reinforcing the suitability of PRGO as plasmonic waveguides.

Ultracompact Waveguide for an Optical Network-on-Chip with a Vacuum Gap Based on Surface Plasmon Polaritons

In an optical network-on-chip, optical waveguides play a crucial role in transmitting optical signals. Therefore, it is essential for optical waveguides to have a compact size and low insertion loss. This paper proposes a new type of optical waveguide with a vacuum gap based on surface plasmon polaritons. By utilizing surface plasmon polariton technology, the proposed waveguide reduces scattering attenuation caused by hybrid surface plasmon polaritons, saves space in the network-on-chip, and enables the integration of more devices on the chip while maintaining an ultracompact size requirement. Finite-Difference Time-Domain (FDTD) simulations and comparisons are performed between a conventional Si waveguide and two types of surface plasmon polariton waveguides. The results demonstrate that the designed waveguide exhibits excellent confinement capabilities even when the waveguide width is only 100 nm, with an insertion loss of 0.32 dB/μm. The relevant waveguide parameters are studied and optimized, providing a theoretical basis for the development of ultracompact gap surface plasmon polariton waveguides.

Theoretical analysis of hybrid surface plasmon polaritons in plasma-based elliptical structures with graphene layers for THz applications

Theoretical analysis of hybrid surface plasmon polaritons in plasma-based elliptical structures with graphene layers for THz applications

Ultra-short bilayer graphene optical fiber intensity modulator based on silver-semicircular hybrid plasmonic waveguide

The intensity modulator is a key component in optical fiber communication. In this paper, an ultra-short graphene light intensity modulator based on hybrid plasmonic waveguide (HPW) array is proposed. Al2O3 embedded with double-layer graphene at a certain interval is placed on the side polishing surface of the microfiber Mach–Zehnder modulator (MZM), and the silver-semicircular array is placed on the surface of the transition material as hybrid plasmonic waveguide for the first time in all-fiber modulator. Analyzing by building a 3D model in finite difference time domain software, the hybrid surface plasmon polariton (HSPP) between silver-semicircles significantly enhances the subwavelength confinement and the light–graphene interaction. The modulation range of the real part of effective refractive index (Neff) can reach to 0.01984 by adjusting the Fermi level of graphene. Therefore, π phase change can be achieved only in a modulation length of 45 μm, and the insert loss can be controlled below 0.0159 dB/μm through the analysis of the imaginary part of the Neff, which also leads to a low total loss of 0.7155 dB. Owing to the excellent phase modulation efficiency, high extinction ratios of 39.39 dB and 47.77 dB can be reached for port 1 and port 2, respectively. Double-layer graphene forms the flat capacitor, which brings high modulation efficiency while achieving a high modulation bandwidth of 59.945 GHz. The application of HPW in graphene optical fiber modulator greatly improves the working efficiency, reduces the difficulty of integration, overcomes high insert loss, improves the extinction ratio, this modulator can be widely used in the future optical fiber communication system.

Novel biosensors based on Weyl semimetals

We introduce two novel optical biosensors based on the combination of a Weyl semimetal and a finite one-dimensional photonic crystal to diagnose different analytes such as Jurkat cancer cells. Weyl semimetals are new emerging topological materials recently purposed for employment in optical devices due to their intriguing properties. We demonstrate that hybrid Tamm and surface plasmon polaritons can be excited in these structures under the circumstance of attenuated total reflection. In particular, we find that adjusting parameters of the first biosensor to excite Tamm plasmon polaritons leads to higher sensing performance, while in the second biosensor excitation of the surface plasmon polaritons provides higher functionality of this biosensor. According to our results, biosensors based on the Weyl semimetals can be used for sensitive and accurate recognition of different analytes, and they may form a new platform for high-performance biosensors.

Enhanced graphene surface plasmonics through incorporation into metallic nanostructures.

A methodology for enhancing the surface plasmon polariton (SPP) resonance associated with graphene, through nanoscale metal-dielectric-metal (MDM) gaps, is proposed. The modulation of the resonances, in the range of 0.7 µm to 1 µm was done through tuning the carrier density in graphene and has been shown to be of potential utility for surface analyte sensing. It was shown, from finite element simulations in the frequency domain, that the related hybrid SPP modes could be clearly delineated in far field spectroscopy.

Electro-Optic Hybrid Logic Gate Derived from a Silicon-Based Hybrid Surface Plasmon Polariton Waveguide

Electro-optic hybrid computing is a key research topic in high-performance computing. AND, OR and NON are the most basic computing units. Logic units, which are composed of a Mach Zehnder interferometer (MZI) and a micro ring resonator (MRR), have the issues of large size and poor thermal stability. To solve these problems, this paper discusses the design of AND, OR and NON basic logic units in compact electro-optic logics based on the principle of silicon-based hybrid surface plasmon polariton waveguides. By optimizing the parameters with the Finite Difference-Time Domain (FDTD), the simulation results show that the maximum insertion loss (IL) of the AND, OR and NON logic units is 5.1 dB, and the extinction ratio (ER) is at least 14.3 dB. The experimental simulation results provide a theoretical basis for the design of an electro-optic logic gate derived from a silicon-based hybrid surface plasmon polariton waveguide.

Broadband high-efficiency near-infrared graphene phase modulators enabled by metal–nanoribbon integrated hybrid plasmonic waveguides

Abstract The phase modulator is a key component in optical communications for its phase modulation functions. In this paper, we numerically demonstrate a variety of ultra-compact high-efficiency graphene phase modulators (GPMs) based on metal–nanoribbon integrated hybrid plasmonic waveguides in the near-infrared region. Benefiting from the good in-plane mode polarization matching and strong hybrid surface plasmon polariton and graphene interaction, the 20 μm-length GPM can achieve excellent phase modulation performance with a good phase and amplitude decoupling effect, a low insertion loss around 0.3 dB/μm, a high modulation efficiency with V π L π of 118.67 V μm at 1.55 μm, which is 1–3 orders improvement compared to the state-of-the-art graphene modulators. Furthermore, it has a wide modulation bandwidth of 67.96 GHz, a low energy consumption of 157.49 fJ/bit, and a wide operating wavelength ranging from 1.3 to 1.8 μm. By reducing the overlap width of the graphene–Al2O3–graphene capacitor, the modulation bandwidth and energy consumption of the modulator can be further improved to 370.36 GHz and 30.22 fJ/bit, respectively. These compact and energy-efficient GPMs may hold a key to various high-speed telecommunications, interconnects, and other graphene-based integrated photonics applications.

Subwavelength-scale lasing perovskite with ultrahigh Purcell enhancement

<h2>Summary</h2> The remarkable photophysical properties of halide perovskites have led to high-performance lasers. The slow emission dynamics and diffraction-limited device, however, impose an intrinsic barrier on realizing ultrafast and compact lasers for integrated optoelectronic applications. Plasmonic cavities have been employed to reduce laser size. Yet the emission dynamics is fundamentally limited due to the dilemma between ever-reduced cavity size and the increase of losses. Here, we show a subwavelength-scale lasing perovskite with ultrahigh Purcell enhancement of 209 that greatly enhances emission dynamics under ambient conditions. The hybrid surface plasmon polaritons (SPPs) coupled with perovskites significantly reduce plasmonic and trap state loss channels and promote a strong Purcell effect. Moreover, the realization of SPPs confinement away from the perovskite region mitigates gain degradations that enables superior long-term device stability and reliability. Our study opens a new avenue for on-chip ultrafast optoelectronics and fundamental studies of light-matter interactions at the strongly confined field.

Hybrid surface plasmon polariton (SPPs) modes between metal and anisotropic plasma interface

This manuscript investigates the properties of surface plasmon polaritons (SPPs) at anisotropic plasma metal interface. It has been shown that magnetized plasma surface plasmon waves have unique features such as hybridization nature, the existence of cutoff frequency and the dependence of normalized prorogation constant and prorogation length on plasma parameters such as cyclotron frequencies (𝜔𝑐) and plasma frequency (𝜔𝑝). The influence of plasma features on normalized propagation constant and propagation as the function of frequency under different values of plasma frequency and cyclotron frequencies are studied. This suggest SPPs at magnetized plasma metal interface may be exploited for Plasma-on-Chip for cancer treatment.

Characteristics of hybrid surface plasmon polaritons at a chiral graphene metal interface in cylindrical waveguides

A detailed theoretical analysis of the hybrid surface plasmon mode generation and propagation at a chiral graphene metal (CGM) interface for a cylindrical structure is presented. The conductivity of graphene is modeled using the Kubo formalism and the dispersion relation for the hybrid surface waves is computed on the basis of the Kubo formalism and impedance matching boundary conditions. The hybrid mode consisting of lower and upper plasmon modes is witnessed due to the presence of the chiral medium. The frequency band gap between the lower and upper plasmon modes is found to be sensitive and tunable with respect to the chiral strength, radial distance of the waveguide, and chemical potential of graphene. The propagation length and effective refractive index can also be modulated by varying the chiral strength and chemical potential. For very high values of chirality and biasing voltage, the Goos–Hänchen effect is observed at the CGM interface. The cutoff values of chiral strength as a function of normalized frequency make the proposed structure applicable for chiroptical and chemical sensing and enantiomeric detection in the THz frequency regime.

Hybrid surface plasmon polaritons in graphene coupled anisotropic van der Waals material waveguides

Polaritons in anisotropic van der Waals materials (AvdWMs), with either hyperbolic or elliptical topologies, have garnered significant attention due to their ability of field confinement and many useful applications in in-plane polariton nanophotonics, including directional guiding, canalization, and hyperlensing. Here, we obtain the dispersion relation of hybrid surface plasmon polaritons (SPPs) supported by a parallel-plate waveguide composed of an AvdWM, as an example tungsten ditelluride, that is coupled with a graphene layer. Through analytical calculations and numerical simulations, we first investigate the impact of losses on the modal characteristics of SPPs supported by the AvdWM. We then show that the coupling of the anisotropic layer to a graphene sheet in a parallel-plate waveguide heterostructure allows one to control the in-plane propagation and dispersion topology of the hybrid SPPs by changing the spacer thickness and the graphene chemical potential. Moreover, it is found that owing to the different coupling regimes, this anisotropic-isotropic SPPs hybridization can enhance the propagation length and spatial localization of the guided modes. We believe this approach can lead to the realization of vdW heterostructures with improved functionalities for in-plane and out-of-plane infrared nanophotonics.

Dispersion characteristics of surface plasmon polaritons (SPPs) in graphene–chiral–graphene waveguide

The theoretical analysis of hybrid surface plasmon polaritons in a planar waveguide filled with chiral material surrounded by graphene layers is presented in this manuscript. The Kobo formula is used to calculate the graphene’s conductivity and Maxwell’s equation in differential form is used to solve the analytical problem. It is demonstrated that graphene’s parameters relaxation time as well as chemical potential and chirality strength can be used to modulate the resonance surface plasmon frequencies for the proposed structure. The characteristic curve, normalized propagation constant, attenuation phase constant or propagation loss, propagation length, and normalized field distribution for graphene–chiral–graphene interfaces are examined numerically. The presented work based on plasmonics theory provides new possibilities for the design of more compact nanophotonic devices due to graphene’s extra degree of freedom compared to other metals.

Highly efficient and controllable photoluminescence emission on a suspended MoS2-based plasmonic grating

Being a new class of materials, transition metal dichalcogenides are paving the way for applications in atomically thin optoelectronics. However, the intrinsically weak light–matter interaction and the lack of manipulation ability has lead to poor light emission and tunable behavior. Here, we investigate the fluorescence characteristic of monolayer molybdenum disulfide on a metal narrow-slit grating, where a highly efficient, 471 times photoluminescence enhancement are realized, based on the hybrid surface plasmon polaritons resonances and the decreased influence of substrate. Moreover, the emitted intensity and polarization are controllable due to the polarization-dependent characteristic and anisotropy of grating. The manipulations of light-matter interactions in this special system provide a new insight into the fluorescent emission process and open a new avenue for high-performance low dimensional materials devices designs.

Analytical study of hybrid surface plasmon polaritons in a grounded chiral slab waveguide covered with graphene sheet

In this paper, we propose a new analytical model for grounded chiral slab waveguides covered with graphene sheets. The general waveguide is constructed of a graphene sheet sandwiched between two different chiral layers (as substrate and cover layers), each one has the permittivity, the permeability and the chirality of $$ \varepsilon_{c} ,\mu_{c} ,\gamma_{c}$$ , respectively. The substrate is supposed to be a perfect electromagnetic conductor, which is able to easily convert to a perfect electric conductor or a perfect magnetic conductor. A novel matrix representation is obtained for the general structure to find its dispersion relation and other propagating parameters. To show the richness of the proposed waveguide, two new structures have been introduced and investigated. It has been shown that the modal properties of these exemplary structures are tunable by changing the chemical potential of the graphene and the chirality. The proposed general structure and its analytical model can be utilized for designing tunable plasmonic devices in THz frequencies.

Self-Organized Nanogratings for Large-Area Surface Plasmon Polariton Excitation and Surface-Enhanced Raman Spectroscopy Sensing

Surface plasmon polaritons (SPP) are exploited due to their intriguing properties for the fabrication and miniaturization of photonic circuits, for surface-enhanced spectroscopy and imaging beyond the diffraction limit. However, excitation of these plasmonic modes by direct illumination is forbidden by energy/momentum conservation rules. One strategy to overcome this limitation relies on diffraction gratings to match the wavevector of the incoming photons with that of propagating SPP excitations. The main limit of the approaches so far reported in the literature is that they rely on highly ordered diffraction gratings fabricated by means of demanding nanolithographic processes. In this work, we demonstrate that an innovative, fully self-organized method based on wrinkling-assisted ion-beam sputtering can be exploited to fabricate large-area (cm2 scale) nanorippled soda lime templates, which conformally support ultrathin Au films deposited by physical deposition. The self-organized patterns act as quasi-one-dimensional (1D) gratings characterized by a remarkably high spatial order, which properly matches the transverse photon coherence length. The gratings can thus enable the excitation of hybrid SPP modes confined at the Au/dielectric interfaces, with a resonant wavelength that can be tuned by modifying the grating period, photon incidence angle, or, potentially, the choice of the thin-film conductive material. Surface-enhanced Raman scattering experiments show promising gains in the range of 103, which are competitive, even before a systematic optimization of the sample fabrication parameters, with state-of-the art lithographic systems, demonstrating the potential of such templates for a broad range of optoelectronic applications aiming at plasmon-enhanced photon harvesting for molecular or biosensing.

Hybrid Tamm and surface plasmon polaritons in resonant photonic structure

Hybrid modes originating from the coupling of the Tamm and surface plasmon polaritons excited in a one-dimensional resonant photonic structure are demonstrated. The structure represents a photonic crystal bounded by a nanocomposite film consisting of a transparent matrix and silver nanoparticles uniformly distributed over its volume. In comparison with structures on planar metal films the volume concentration and shape of nanoparticles are of great help in configuring the hybrid mode properties, including their wavelength and splitting. Also the radiation incidence angle variation opens the possibility of fine-tuning the energy spectra of the structure. We demonstrate the high-sensitivity of optical sensors based on the resonant photonic structure.

Negative asymmetry parameter in plasmonic core-shell nanoparticles.

Plasmonic nanoparticles with a dielectric-metal core-shell morphology exhibit hybridized modes where the surface plasmon polaritons at the outer and inner surfaces of the shell couple. We demonstrate that suitably tailoring the interference of such hybrid surface plasmon polariton modes leads to composite subwavelength nanospheres with negative asymmetry parameters and strong scattering in the optical frequency range. As a result, for a low density collection of scatterers an anomalous regime occurs, where the extinction mean free path is longer than the transport mean free path. Explicit results for silver-coated nanospheres are presented.