Hybrid plasmonic waveguides (HPWs) have attracted wide attention in recent years, because it makes a better compromise between the low loss of dielectric waveguide and the constraint capability of surface plasmonic waveguide. In this work, a hollow HPW with slat metal layer is analyzed to further reduce the loss and maintain constraint capability, then Bragg grating is designed and studied. By changing the waveguide width to further analyze the mode. The results show that normalized mode area is around 0.01, and propagation length (Lp) is up to 3500 μm, for TM polarized mode at operating wavelength of 1550 nm. For TE mode, Lp keeps millimeter level. Based on hollow HPW, Bragg grating is constructed by alternating the waveguides with different widths. Since the effective index of waveguide mode is quite sensitive to the change of the width and the trends of TM and TE modes are different from each other, Bragg gratings with different filtering characteristics and polarization properties can be designed by choosing combinations with different width. Simulations prove the validity of the design. HPW and Bragg structure proposed in this work would provide a reference for designing related photonic devices and have the potential applied value in the field of optical communication and integrated optics.
This work reports a graphene hyperbolic metamaterial hybrid plasmonic waveguides (GHMMHPW), and unlike traditional hybrid plasmonic waveguide (HPW), the GHMMHPW consists of a plasmonic cladding constructed by graphene hyperbolic metamaterial. Thanks to the particular structural arrangement, EM field can be localized and significantly enhanced in the low-index dielectric layer with nano-thickness. Thus, a superior performance is achieved. Meanwhile, electromagnetic parameters of graphene are tunable, and the mode properties also depend on the structural parameters, so the mode area and propagation distance can be optimized by adjusting these parameters flexibly. TM mode is supported in the GHMHPW, and improved performance is obtained. This study provides a novel and valuable reference for design of graphene plasmonic waveguides and prepares for the further development of micro-nano optics and integrated optoelectronic devices.
We theoretically investigate the characteristics of the multilayered hyperbolic metamaterial (HMM) composed of graphene and discuss the transmission properties from another angle of Fabry–Perot (F–P) resonance analysis. Dispersion characteristics of graphene-dielectric multilayered hyperbolic metamaterials (GDM HMMs) can be adjusted by changing the chemical potential of graphene. Transfer matrix method is improved to adapt the condition of large tangential vectors, and transmission properties are analyzed numerically. Calculated results indicate that dielectric material and graphene codetermine the dispersion properties of the HMMs, and the optical properties can be dynamically adjusted due to the introduction of graphene. Transmission spectra exhibit F–P resonance properties and discussions prove the validity of the F–P cavity theory. However, the transmission characteristics of GDM HMMs are different from the phenomena and laws of the traditional F–P cavity. Further analysis reveals that the mechanism originates from the contribution of graphene and high-k waves in HMMs. We present an innovative perspective for investigating and understanding transmission properties of GDM HMMs and provide references for design of HMMs and other related photonic devices.
Hybrid plasmonic waveguides (HPWs) have become a hot topic in nanophotonic due to their excellent optical field constraints and low propagation loss. Based on the polarization dependence of surface plasmon polariton (SPP) excitation the symmetry of cylindrical vector beams, a cylindrical hybrid plasmonic waveguide (CHPW) realizing limited propagation and two tapered hybrid plasmonic waveguides (THPWs) achieving nanofocusing are presented. CHPW supports radial polarization mode and well compensate mode propagation loss by adjusting the structural parameters of the waveguide. Splendid mode limitation and long transmission distance with low loss can be achieved simultaneously. On the basis of CHPW, the structure is tapered to realize nanofocusing. And periodic grooves are constructed on the metallic surface of the tapered hybrid plasmonic waveguide (THPW) to meet the phase matching condition and maximize the coupling of light energy from inside to outside. Meanwhile, the low index layer of THPW is replaced with two different index layers, which is broadened to gather more energy efficiently and the energy is converged on the apex of the waveguide to form the ultrahigh field enhancement, which is another optional way to improve the performance of THPW. The results offer vital reference value for designing and manufacture related photonic devices.
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.
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