The Tunability of Surface Plasmon Polaritons in Graphene Waveguide Structures

The tunability of propagation properties of surface plasmon polariton (SPP) modes in a waveguide formed by two parallel graphene layers separated by a dielectric layer is studied. For this purpose, the dispersion equation of the structure is numerically solved and the effects of applied bias voltage, the role of effective structural parameters, and electron–phonon scattering rate on the propagation of symmetric and antisymmetric SPP waves are investigated. The results of calculations show that considering the electron–phonon scattering rate as a function of Fermi energy and temperature leads to a considerable decrease in the propagation length of SPPs. As the main result of this work, tuning the propagation characteristics of SPPs is possible by varying any of the parameters such as applied voltage, thickness of insulating layer between two graphene layers and permittivities of dielectric layers, and finally the temperature. It is found that antisymmetric mode benefits from a larger propagation length in comparison with that of the symmetric mode.

     

Surface Plasmon Polariton Waveguide by Bottom and Top of Graphene

Semiconductor surface plasmon polariton (SPP) waveguide has unique optical properties and compatibility with existing integrated circuit manufacturing technology; thus, SPP devices of semiconductor materials have wide application potential. In this study, a new integrated graphene SPP waveguide is designed using the bottom and top roles of graphene. Moreover, a T waveguide structure is designed by InGaAs of semiconductor gain, with rectangular GaAs material on both sides. The structure adopts light to stimulate the SPP, where its local area is enhanced by the interaction between two interface layers and a semiconductor gain and where its frequency can be adjusted by the thickness of the graphene. Characteristic analysis reveals the coupling between the T semiconductor gain and the SPP mode. The propagation distance of the waveguide can reach 75 cm, the effective mode field is approximately 0.0951λ ², the minimum of gain threshold is approximately 2992.7 cm^?1, and the quality factor (FOM) can reach 180. The waveguide structure which provides stronger localization can be compatible with several optical and electronic nanoscale components. That means, it can provide light for surface plasmon circuit and also can provide a great development in the low-threshold nanolaser.     

Ultra-Subwavelength and Low Loss in V-Shaped Hybrid Plasmonic Waveguide

A new kind of hybrid plasmonic waveguide is proposed, and its propagation properties are investigated using the finite-element method. This waveguide consists of a V-shaped silver nanowire embedded in a low-index dielectric cladding above a semiconductor substrate, which can confine light in the subwavelength region with a long propagation length. The field distribution, the mode effective index, the propagation length, and the normalized mode area of the hybrid mode supported by the waveguide are investigated at the wavelength of 1550 nm, which are dependent on the geometric parameters.     

Tunable Hybrid Gap Surface Plasmon Polariton Waveguides with Ultralow Loss Deep-Subwavelength Propagation

Exploring hybrid gap surface plasmon polariton waveguides (HGSPPWs) is an important milestone in developing the next-generation, nanoscale integrated photonic circuit technology. To advance their potential applications, HGSPPWs are required to have tunable capability, highly reliable, simple fabrication process, and feasible integration. In this paper, we propose two tunable HGSPPWs fulfilling the requirements. The proposed HGSPPWs consist of a metallic wedge laterally coupled with a dielectric waveguide. The modal characteristics of HGSPPWs are investigated at the optical telecommunication wavelength, which shows the modal characteristics could be effectively controlled by tuning the key geometry parameters and structure of HGSPPWs. The propagation length could achieve the centimeter scale while maintaining the propagation mode size at the deep-subwavelength scale (~ λ²/10⁵). The studies on fabrication tolerance and waveguide crosstalk show their robust property for practical implementations. The effective tunable mechanism is also proposed and studied, which shows remarkable feasibility to realize multifunctional plasmon-based photonic components. Compared with the conventional HGSPPWs, the proposed HGSPPWs exhibit superior features in ultralow loss deep-subwavelength light guiding, are highly reliable, and are easy to integrate.

     

Analysis of Mid-Infrared Surface Plasmon Modes in a Graphene-Based Cylindrical Hybrid Waveguide

A graphene-based cylindrical hybrid surface plasmon polariton waveguide, composed of a silicon nanowire core surrounded by a silica layer and then a graphene layer, is investigated using the finite-difference time-domain method. The analytical solutions and the numerical simulation show that an ultra-small mode area and a large propagation length can be achieved with this waveguide. Utilizing the perturbation theory of coupled mode, we demonstrate that the six lowest-order coupling modes originate from the coupling of the three lowest-order single-waveguide modes, and the m?=?1 order yy-coupling mode possesses the maximum coupling length and the minimum crosstalk. This waveguide can be used for photonic integrated circuits in the mid-infrared range.     

Graphene/Graphene Oxide-Based Ultrasensitive Surface Plasmon Resonance Biosensor

Plasmonics - Surface plasmon resonance (SPR)-based biosensing is an accurate and sensitive technique used to evaluate the biomolecular interactions in real time in a label-free environment. Several...     

Short-Range Surface Plasmon Polaritons for Extraordinary Low Transmission Through Ultra-Thin Metal Films with Nanopatterns

We provide both experimental and theoretical investigation on extraordinary low transmission through one-dimensional nanoslit and two-dimensional nanohole arrays on ultra-thin metal films. Unambiguous proofs demonstrate that short-range surface plasmon polaritons play a key role leading to this novel phenomenon, which could be useful for creating new polarization filters and other integrated plasmonic components.     

Novel Dielectric-Loaded Plasmonic Waveguide for Tight-Confined Hybrid Plasmon Mode

In this paper, a novel metal-dielectric waveguide structure is proposed to support hybrid long range surface plasmon polaritons (LRSPPs) with a highly confined mode field. The simulation results showed that our proposed structure has better mode confinement and propagation length compared to that of conventional dielectric-loaded surface plasmon polaritons (DLSPPs) waveguides. This structure offers greater flexibility for the design of surface plasmon polaritons (SPPs) waveguides by altering the trade-off between mode confinement and propagation length. The proposed structure has significant potential for application in highly integrated photonic circuits.     

Tunable Properties of Surface Plasmon Resonance of Metal Nanospheroid: Graphene Plasmon Interaction

Plasmonics - Graphene plasmonic resonances play a significant role for enhancing the photon absorption inside thin film solar devices. We investigate the field rising at the intersection of...     

Lifetime of Enhanced Graphene Surface Plasmon and Superstrate Sensitivity

Plasmonics - We investigated the field enhancement and lifetime of tuning surface plasmon in zero-thickness nanostructured graphene patches. The graphene surface plasmon (GSP) resonance mechanism...     

Novel Ridge-Type Gold Film Waveguide for Surface Plasmon Polariton Laser

Plasmonics - Surface plasmon polariton lasers are the basis for photonic circuits, but their losses, thresholds, and some other problems remain thorny issues. In this study, we put forward a novel...     

Coherent Controllable Transport of a Surface Plasmon Coupled to a Plasmonic Waveguide with a Metal Nanoparticle-Semiconductor Quantum Dot Hybrid System

Plasmonics - By using the real-space method, the switching of a single plasmon interacting with a hybrid nanosystem composed of a semiconductor quantum dot (SQD) and a metallic nanoparticle (MNP)...     

A Dielectric-Thickness-Adjusting Method for Manipulating Graphene Surface Plasmon Polariton

We propose and numerically investigate a dielectric-thickness-adjusting method to manipulate the graphene surface plasmon polariton (SPP). The dispersion relationships of graphene SPP at different dielectric thickness are derived by solving the analytic equations. In addition, the SPP effective index at cutoff dielectric thickness is obtained according to different dielectric permittivity and working frequencies. As a typical application, a plasmonic Bragg reflector is designed by alternately depositing dielectric gratings along the transverse direction of the SPP propagation. The performance of the Bragg reflector is analyzed at different grating thickness, and the effective index at cutoff thickness is verified by numerical simulation. The proposed method will have important potential prospects in designing graphene-based wave trapping and slow wave devices in future.     

Low Loss Plasmonic Bragg Gratings with a Trench Plasmonic Waveguide

Plasmonics - We designed plasmonic Bragg gratings based on a plasmonic trench waveguide and calculated the characteristics of the designed structure. Conventional plasmonic Bragg gratings are...     

A Novel Dual-Band Conformal Surface Plasmon Waveguide with Tunable Frequency Response in Large Scale

Plasmonics - A novel dual-band conformal surface plasmon (CSP) waveguide is designed and well studied in this paper. In earlier research studies, we have recognized that electromagnetic field of...     

Resonant Mode Analysis of the Nanoscale Surface Plasmon Polariton Waveguide Filter with Rectangle Cavity

The resonant mode characteristics of the nanoscale surface plasmon polaritons (SPP) waveguide filter with rectangle cavity are studied theoretically. By using the finite difference time domain method, both the band-stop- and band-pass-type rectangle SPP filters are analyzed. The results show that the whispering gallery mode (WGM) and the Fabry–Perot (FP) mode can be supported by the rectangle SPP resonator. Furthermore, both traveling-wave mode and standing-wave mode can be realized by the WGM, while only standing-wave mode can be introduced by the FP mode. The traveling-wave mode can only be realized by the square-shaped SPP resonator, and the traveling-wave mode is splitted into two standing-wave modes by transforming the cavity shape from square to rectangle. Also, the effects of the cavity shape, cavity size, and coupling gap size on the transmission spectra of the SPP resonators are analyzed in detail. This simple SPP waveguide filter is very promising for the high-density SPP waveguide integrations.