This work reports a graphene cylindrical hybrid plasmonic waveguide (GCHPW) consisting of a high-index dielectric core, a sandwiched low-index dielectric layer and a single layer graphene. Unlike traditional metallic cylindrical hybrid plasmonic waveguide (CHPW), GCHPW’s advance is that the nano-thickness light field can be significantly enhanced in the sandwiched low-index dielectric layer and the graphene interface, and a superior performance is achieved. Furthermore, the electromagnetic parameters of graphene is tunable, and the mode properties of the waveguide depend on the structural parameters, so the mode area and transmission distance can be flexibly optimized by adjusting these parameters. TM01 mode with radially polarized transverse component is supported in the novel GCHPW, and a more compact confinement of light field is achieved. Additionally, the GCHPW has a smaller size compared with the CHPW. This study provides a valuable reference for design of graphene plasmonic waveguides and offers a new way for the limited transmission of radially polarized light.
A conical hybrid plasmonic probe (CHPP) for ultrahigh field enhanced nanofocusing with lower loss is demonstrated. The CHPP consists of two different low-index dielectric layers sandwiched between a high-index conical core and a silver cladding. Properties of nanofocusing are analyzed by finite element method, under illumination of a radially polarized beam at a wavelength of 632.8 nm. The numerical results prove that, by introducing the additional lower-index layer, the whole low-index dielectric region is broadened to collect more energy efficiently, and the energy is converged on the apex of the CHPP to form the ultrahigh field enhancement. Compared with the traditional hybrid plasmonic probe, the optimized CHPP exhibits lower loss and higher field enhancement of 1771 times. The thickness and refractive index of the lower-index layer are discussed for optimizing the structure. The results indicate that the CHPP has a simple structure with excellent performance, which has important potential applications in relevant fields, particularly in nanotechnology of field enhancement. This work also provides a convenient way for designing and optimizing hybrid plasmonic structure.
Hybrid plasmonic waveguide (HPW) has received extensive attention recently due to its excellent performance of tight field confinement and low propagation loss. In this work, the transmission spectra of hybrid plasmonic waveguide Bragg gratings (HPWBGs) composed of two alternately arranged low refractive index dielectric materials are studied, combining the finite element method (FEM) and transfer matrix method (TMM). Meanwhile, by changing the width of the outermost layer of the waveguide, the influence on transmission spectra under different optical admittance matching conditions are discussed through admittance matching theory. Theoretical calculations and simulation results show that a specific thickness of the matching layer has a specific influence on the pass band or the forbidden band of a specific frequency range on the transmission spectrum. The transmission characteristics of the low-frequency or high-frequency pass band and the band gap can be optimized by adjusting the thickness of matching layer to obtain the admittance match or mismatch conditions. This result provides a good theoretical basis and design method for preparing photonic devices for requirements in different wavebands.
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