scholarly journals Analytic modelling of a planar Goubau line with circular conductor

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tobias Schaich ◽  
Daniel Molnar ◽  
Anas Al Rawi ◽  
Mike Payne
Keyword(s):  
Numerical Simulations ◽  
Propagation Constant ◽  
Finite Thickness ◽  
Approximate Equation ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Wave Mode ◽  
Velocity Measurements ◽  
Low Loss ◽  
Transverse Magnetic Mode

AbstractPlanar Goubau lines show promise as high frequency, low-loss waveguides on a substrate. However, to date only numerical simulations and experimental measurements have been performed. This paper analytically investigates the surface wave mode propagating along a planar Goubau line consisting of a perfectly conducting circular wire on top of a dielectric substrate of finite thickness but infinite width. An approximate equation for the propagation constant is derived and solved through numerical integration. The dependence of the propagation constant on various system parameters is calculated and the results agree well with full numerical simulations. In addition, the spatial distribution of the longitudinal electric field is reported and excellent agreement with a numerical simulation and previous studies is found. Moreover, validation against experimental phase velocity measurements is also reported. Finally, insights gained from the model are considered for a Goubau line with a rectangular conductor. The analytic model reveals that the propagating mode of a planar Goubau line is hybrid in contrast to the transverse magnetic mode of a classic Goubau line.

Loss Compensation in Surface Plasmonic Waveguides with Low Polarization Dependence

2014 ◽  
Vol 602-605 ◽  
pp. 2726-2731
Author(s):  
Hui Fang He ◽  
Yu Min Liu ◽  
Zhong Yuan Yu ◽  
Tie Sheng Wu
Keyword(s):  
Polarization State ◽  
Transverse Magnetic ◽  
Polarization Dependence ◽  
Propagation Loss ◽  
Integrated Optics Devices ◽  
Plasmonic Waveguides ◽  
Low Loss ◽  
Transverse Magnetic Mode ◽  
Tm Mode ◽  
Loss Compensation

Surface plasmonic waveguides usually only support one mode called TM (transverse magnetic) mode. Recently, one waveguide structure that can propagate both TE (transverse electric) and TM mode was proposed. However, the large propagation loss of the plasmonic waveguides with low polarization dependence is still a problem. In order to make loss compensation to solve the problem, this paper makes improvements to decrease the loss of this kind of waveguide. Simulations have been made to prove the feasibility; as respected, low loss or even 0dB can be reached at both modes when low and high index materials are added. The improved plasmonic waveguide has a potential application in guiding and processing of light from a fiber with a random polarization state in low-loss condition and also can be applied to integrated optics devices.

Single-peak-regulation and wide-angle dual-band metamaterial absorber based on hollow-cross and solid-cross resonators

2020 ◽  
Vol 91 (3) ◽  
pp. 30901
Author(s):  
Yibo Tang ◽  
Longhui He ◽  
Jianming Xu ◽  
Hailang He ◽  
Yuhan Li ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Surface Current ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Peak ◽  
Dual Band ◽  
Single Peak ◽  
Wide Angle ◽  
Surface Current Density

A dual-band microwave metamaterial absorber with single-peak regulation and wide-angle absorption has been proposed and illustrated. The designed metamaterial absorber is consisted of hollow-cross resonators, solid-cross resonators, dielectric substrate and metallic background plane. Strong absorption peak coefficients of 99.92% and 99.55% are achieved at 8.42 and 11.31 GHz, respectively, which is basically consistent with the experimental results. Surface current density and changing material properties are employed to illustrate the absorptive mechanism. More importantly, the proposed dual-band metamaterial absorber has the adjustable property of single absorption peak and could operate well at wide incidence angles for both transverse electric (TE) and transverse magnetic (TM) waves. Research results could provide and enrich instructive guidances for realizing a single-peak-regulation and wide-angle dual-band metamaterial absorber.

scholarly journals Broadband Plasmonic Nanopolarizer Based on Different Surface Plasmon Resonance Modes in a Silver Nanorod

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 447
Author(s):  
Junxi Zhang ◽  
Lei Hu ◽  
Zhijia Hu ◽  
Yongqing Wei ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Electric Fields ◽  
Near Infrared ◽  
Near Field ◽  
Resonant Cavity ◽  
Transverse Magnetic ◽  
Wave Mode ◽  
Fdtd Simulation ◽  
Nanophotonic Devices ◽  
Resonance Modes ◽  
Polarization Characteristics

Conventional polarizers including sheet, wire-grid, prism, and Brewster-angle type polarizers are not easily integrated with photonic circuits. Polarizing elements on the nanoscale are indispensable for integrated all-optical nanophotonic devices. Here, we propose a plasmonic nanopolarizer based on a silver nanorod. The polarization characteristics result from the excitation of different resonance modes of localized surface plasmons (LSPs) at different wavelengths. Furthermore, the polarization characteristics in near field regions have been demonstrated by the electric field distribution of the nanorod based on finite-difference time-domain (FDTD) simulation, indicating a strong local resonant cavity with a standing wave mode for transverse electric (TE) polarization and weak electric fields distributed for transverse magnetic (TM) polarization. The nanopolarizer can efficiently work in the near field region, exhibiting a nanopolarization effect. In addition, very high extinction ratios and extremely low insertion losses can be achieved. Particularly, the nanopolarizer can work in a broadband from visible to near-infrared wavelengths, which can be tuned by changing the aspect ratio of the nanorod. The plasmonic nanopolarizer is a promising candidate for potential applications in the integration of nanophotonic devices and circuits.

scholarly journals Phenomenon of Electromagnetic Field Resonance in Metal and Dielectric Gratings and Its Possible Practical Applications

2020 ◽  
Vol 5 (3) ◽  
pp. 49
Author(s):  
Stefano Bellucci ◽  
Andrii Bendziak ◽  
Oleksandr Vernyhor ◽  
Volodymyr M. Fitio
Keyword(s):  
Refractive Index ◽  
Buffer Layer ◽  
Propagation Constant ◽  
Refractive Index Change ◽  
Dielectric Substrate ◽  
Angular Sensitivity ◽  
Practical Applications ◽  
Dielectric Gratings ◽  
Constant Change ◽  
Dielectric Grating

Calculations of the field distribution in the structure of the dielectric substrate/buffer layer/volume phase grating/analyzed medium were performed. It is shown that in the presence of a buffer layer with a low refractive index in the dielectric waveguide leads to a shift of the maximum field at the waveguide resonance into analyzed medium. As a result, the spectral and angular sensitivity of the corresponding sensor increases. Based on the waveguide equation, analytical expressions are obtained that connect the spectral and angular sensitivity of the sensor to the sensitivity of the propagation constant change due to the refractive index change of the analyzed medium. The conditions for the excitation of the resonance of surface plasmon–polariton waves in the structure with a metal or dielectric grating on a metal substrate are also given. The fields that occur at resonance for silver and gold gratings are calculated.

scholarly journals Electromagnetic surface waves supported by a resistive metasurface-covered metamaterial structure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Z. Yaqoob ◽  
A. Ghaffar ◽  
Majeed A. S. Alkanhal ◽  
M. Y. Naz ◽  
Ali H. Alqahtani ◽  
...  
Keyword(s):  
Surface Waves ◽  
Propagation Constant ◽  
Effective Permittivity ◽  
Phase Speed ◽  
Transverse Magnetic ◽  
Geometrical Parameters ◽  
Causality Principle ◽  
Metamaterial Structure ◽  
Impedance Boundary ◽  
Mode Index

Abstract This study examines the analytical and numerical solution of electromagnetic surface waves supported by a resistive metasurface-covered grounded metamaterial structure. To simulate the metamaterial, the Kramers–Kronig relation based on the causality principle is used, while the modeling of the resistive metasurface has been done by implementing the impedance boundary conditions. The analytical expressions for the field phasors of surface waves are developed for the transverse magnetic (TM) polarized mode and transverse electric (TE) polarized mode. The characteristic equations are computed for both modes, and the unknown propagation constant is evaluated numerically in the kernel. After computation, the dispersion curves, electric field profiles, effective mode index ($$N_{eff}$$ N eff ), and phase speeds ($$v_{p}$$ v p ) are presented for both the TM and TE polarized modes. To study the tunability of surface waves, the influence of the thickness of the metamaterial slab ($$d$$ d ), effective permittivity of the metamaterial ($$\varepsilon_{1}$$ ε 1 ), thickness of the resistive metasurface ($$t$$ t ), and effective permittivity of the metasurface ($$\varepsilon_{r}$$ ε r ) on all the numerical results has been studied. However, the geometrical parameters are found to be more sensitive to the effective mode index ($$N_{eff}$$ N eff ) and phase speed ($$v_{p}$$ v p ) of the surface waves. The results are consistent with the published results, which reflects the accuracy of the work. It is concluded that the appropriate choice of parameters can be used to achieve surface waves with the desired characteristics in the GHz range. The present work may have potential applications in surface waveguide design, surface wave speed controllers, surface communication devices, and light trapping configurations.

FINITE ELEMENT ANALYSIS OF TE AND TM MODES IN NONLINEAR PLANAR WAVEGUIDES

1994 ◽  
Vol 03 (01) ◽  
pp. 101-116 ◽  
Author(s):  
M. ZOBOLI ◽  
S. SELLERI
Keyword(s):  
Finite Element ◽  
Refractive Index ◽  
Transverse Magnetic ◽  
Planar Waveguides ◽  
Mode Analysis ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Transverse Magnetic Mode ◽  
Solution Convergence ◽  
Index Distribution

A general approach based on the finite element method for analyzing optical waves guided by dielectric planar waveguides with arbitrary nonlinear media and with arbitrary refractive index distribution is considered. A complete transverse-electric and transverse-magnetic mode analysis is presented and TM polarization solutions are obtained without approximations on the biaxial nature of the nonlinear refractive index. Solution convergence and stability is discussed and both film-guided and surface-guided modes are presented for symmetrical and asymmetrical structures. Bistability and hysteresis phenomena have been investigated for TE as well as for TM modes.

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