Excitation Of Hybrid Mode Research Articles

Excitation of hybrid modes in plasmonic nanoantennas coupled with GeSiSn/Si multiple quantum wells for the photoresponse enhancement in the short-wave infrared range

Hybrid structures represented by a plasmonic nanoantenna array located on the surface of GeSiSn/Si multiple quantum wells (MQWs) grown on a silicon-on-insulator (SOI) substrate by molecular-beam epitaxy were developed for applications in the short-wave infrared range. Using numerical modeling methods, the electromagnetic characteristics of metasurfaces based on aluminum nanoantennas located on the surface of GeSiSn/Si nanoheterostructures were studied. It is shown that the spectral and spatial overlap of localized plasmons in nanoantennas and waveguide modes in the semiconductor film leads to the formation of hybrid modes with a Fano-type resonance profile. The possibility of significant photoluminescence (PL) enhancement of GeSiSn/Si MQWs through the use of hybrid plasmonic structures is demonstrated. The PL enhancement reached to 250 % at the wavelength of 1.9 μm, coinciding with the maximum of the reflectance spectrum for the hybrid structure. Based on the hybrid system, represented by the plasmonic nanoantenna array on the top part of GeSiSn/Si MQWs, p-i-n photodiodes were fabricated. The photocurrent enhancement was approximately 7 times at wavelengths of 1.73 µm and 1.8 µm. The excitation of separately localized plasmons and waveguide modes is demonstrated, and their hybridization is also studied.

Broadband Tunable Infrared Light Emission from Metal-Oxide-Semiconductor Tunnel Junctions in Silicon Photonics.

Broadband near-infrared light emitting tunnel junctions are demonstrated with efficient coupling to a silicon photonic waveguide. The metal oxide semiconductor devices show long hybrid photonic-plasmonic mode propagation lengths of approximately 10 μm and thus can be integrated into an overcoupled resonant cavity with quality factor Q ≈ 49, allowing for tens of picowatt near-infrared light emission coupled directly into a waveguide. The electron inelastic tunneling transition rate and the cavity mode density are modeled, and the transverse magnetic (TM) hybrid mode excitation rate is derived. The results coincide well with polarization resolved experiments. Additionally, current-stressed devices are shown to emit unpolarized light due to radiative recombination inside the silicon electrode.

Theory and measurement of the single and hybrid-mode excitation and evolution in a lossy-dielectric-loaded waveguide

ABSTRACT This paper investigates the mode excited, evolved, and propagating properties of the lossy dielectric-loaded waveguide (DLW) used in a Ku-band TE11-mode gyrotron traveling wave tube (gyro-TWT). Theoretical calculation and numerical simulation show that different DLW eigenmodes can be excited by the hollow circular waveguide as a single or hybrid-mode. This study clearly reveals the transformation conditions of the single and hybrid-mode, and the mechanism of the resulting specific dispersion, loss, and electromagnetic field distribution. According to the mode excitation principle and its evolution laws, the propagating properties can be accurately controlled by adjusting the dielectric thickness, which can effectively suppress the potential oscillations and improve the electron bunching phase in the gyro-TWT. As a result, the dielectric loading scheme can be optimized by properly arranging the DLWs, thus enhancing the stability and gain of the gyro-TWT. The theory and simulation are verified by the vector network analyzer measurement at Ku-band, and the results show a good agreement.

Photon tunneling reconstitution in black phosphorus/ hBN heterostructure

Excitation of hybrid modes constituted by different material-supported polaritons is a common way to enhance the near-field radiative energy transport, which has fascinating promise in applications of thermal photonics. Here, we investigate near--field thermal radiation mechanisms in heterostructure composed of $h\mathrm{BN}$ film and black phosphorus single layer. The results show that this heterostructured system can give rise to a remarkable enhancement for photon tunneling, outperforming the near-field thermal radiation properties of its building blocks, as well as some other representative heterostructures. Moreover, we find that the anisotropic hybrid effect can induce a remarkable topological reconstitution of polaritons for $h\mathrm{BN}$ film and black phosphorus, forming a novel anisotropic hybrid polaritons. Notably, such hybrid modes show significant topological differences compared to $h\mathrm{BN}$ film and black phosphorus in the type-I Reststrahlen band due to the anisotropic anticrossing hybridization effect. Lastly, we systematically analyze the evolution of such hybrid polariton modes as a function of $h\mathrm{BN}$ film thickness and the corresponding influence on radiative properties of the heterostructure. This work may benefit the applications of near-field energy harvesting and radiative cooling based on hybrid polaritons in anisotropic two-dimensional material and hyperbolic film.

Elliptical and circular annular solid electron beam for excitation of hybrid modes in the plasma combined circular and elliptical waveguides

For two new configurations presented and by considering annular solid electron beam with background plasma the growth rates of the hybrid modes and the dispersion relation of electromagnetic waves propagating are studied. The interaction of elliptical and circular annular solid electron beams with plasma is investigated that it occurs microwave radiation generation dependent of configuration dimensions. The structures are including metallic elliptical(circular) waveguide with elliptical(circular) dielectric cladding and a core having a circular(elliptical) dielectric rod in center that it is surround by circular(elliptical)annular plasma and a circular(elliptical)annular relativistic electron beam is injected in to plasma. The electromagnetic fields components in each of regions in the considered configurations are calculated. By applying the boundary conditions dispersion relation and operating frequency are obtained. Furthermore for another case that it is applied an infinite magnetic field to considered structures,the problem is investigated. Numerical computations are made and results are graphically presented.

Tailoring Third-Harmonic Diffraction Efficiency by Hybrid Modes in High-Q Metasurfaces.

Metasurfaces are versatile tools for manipulating light; however, they have received little attention as devices for the efficient control of nonlinearly diffracted light. Here, we demonstrate nonlinear wavefront control through third-harmonic generation (THG) beaming into diffraction orders with efficiency tuned by excitation of hybrid Mie-quasi-bound states in the continuum (BIC) modes in a silicon metasurface. Simultaneous excitation of the high-Q collective Mie-type modes and quasi-BIC modes leads to their hybridization and results in a local electric field redistribution. We probe the hybrid mode by measuring far-field patterns of THG and observe the strong switching between (0,-1) and (-1,0) THG diffraction orders from 1:6 for off-resonant excitation to 129:1 for the hybrid mode excitation, showing tremendous contrast in controlling the nonlinear diffraction patterns. Our results pave the way to the realization of metasurfaces for novel light sources, telecommunications, and quantum photonics.

Efficient excitation of hybrid modes on a double-layer graphene with metallic slit grating.

The excitation of double-layer hybrid plasmonic modes is investigated by the finite element method. The hybrid modes, verified as the standing even order of both symmetric and anti-symmetric modes, are effectively generated. There are several advances in comparison with using the Si grating: the metallic grating not only compensates phase mismatch, but also acts as a magnetic polariton. The dependences of each hybrid mode on the geometric parameters are analyzed respectively. Interestingly, a second spectra splitting occurs at each hybrid resonant mode with an obliquely incident light. At last, the excitation efficiency can be further enhanced to 90% using the Salisbury screen. The proposed hybrid system can be utilized to design various double-layer graphene-based plasmonic devices, including tunable optical switches, thermal emitters, multiband absorbers, sensors, etc.

Tri-band composite cylindrical dielectric resonator antenna with hybrid mode excitation and cross-polarization suppression

This communication investigates composite cylindrical dielectric resonator antenna (CDRA) for various wireless applications. Three important features of proposed antenna design are (i) realization of two different hybrid modes, that is, HEM11δ and HEM12δ mode in CDRA with the help of modified annular ring printed line (work as both magnetic dipole and electric dipole), both the hybrid modes support broadside radiation characteristics (ii) suppression of HEM21δ mode, in order to reduce the cross-polarization level in H-plane of other hybrid modes (HEM11δ and HEM12δ mode) by an amount of 8-10 dB (iii) creation of triple-band attribute using the concept of composite antenna. The proposed antenna design has been fabricated and practically tested. Simulated outcomes show good agreement with measured outcomes. It works in three frequency bands, that is, 2.25-2.79 GHz, 3.1-4.0 GHz, and 5.05-5.6 GHz. The designed antenna structure is appropriate for WLAN and WiMAX applications.

Modified annular ring patch fed cylindrical dielectric resonator antenna for WLAN/WIMAX applications

ABSTRACTThis article investigates modified annular ring patch fed cylindrical dielectric resonator antenna (CDRA) with hybrid mode excitation. The present article comprises of two main aims (i) generation of HE11δ and HE12δ mode in CDRA with the support of modified annular ring patch, both the hybrid modes radiates in broadside direction and (ii) achieve triple band characteristics by using the concept of hybrid antenna. The proposed antenna design is functioning in three different frequency bands, i.e. 1.92–2.3 GHz, 3.13–4.6 GHz, and 5.4–6.5 GHz. The simulated outcomes are verified by using archetype of proposed antenna. The practical outcomes indicate good settlement with simulated outcomes. The proposed antenna structure is appropriate for WLAN/WiMAX applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:120–125, 2017

Substrate Integrated Waveguide Cavity-Backed Dumbbell-Shaped Slot Antenna for Dual-Frequency Applications

In this letter, a novel dumbbell-shaped slot along with thin substrate integrated waveguide (SIW) cavity backing ( ${\rm height} ) is used to design dual-frequency slot antenna. The proposed design exhibits unidirectional radiation characteristics, high gain, high front to back ratio (FTBR) at each resonant frequency while maintaining low profile, planar configuration. The unique slot shape helps to introduce complex current distribution at different frequencies that results in simultaneous excitation of hybrid mode at higher frequency along with conventional ${{\rm TE}_{120}}$ mode in the cavity. Both conventional mode and the hybrid mode helps the modified slot to radiate at the corresponding resonant frequencies resulting in compact, dual-frequency antenna. A fabricated prototype is also presented which resonates at 9.5 GHz and 13.85 GHz with impedance bandwidth more than 1.5% at both resonant frequencies and gain of 4.8 dBi and 3.74 dBi respectively. The front-to-back ratio of the antenna are above 10 dB at both operating frequencies.

Impedance Method for Investigation of Open Resonator Characteristics under Conditions of Hybrid Mode Excitation

Impedance Method for Investigation of Open Resonator Characteristics under Conditions of Hybrid Mode Excitation

Scattering matrices representing the transformations between modal bases in rectangular waveguide

The excitation of hybrid modes by discontinuities in rectangular waveguide can often be decomposed into separate LSE/LSM or TE/TM mechanisms, so that each component can be analyzed with the most suitable modal base. Correct interfacing, however, is required. We report the scattering matrices representing all the possible transformations of modal bases in rectangular waveguide. Such matrices provide an useful tool to simulate complex circuits made up of components strongly interacting, without requiring the use of a common modal base for the characterization of each element. Since the transformation matrices can easily include pieces of transmission lines, their use does not require any additional computation effort.

Symmetric and asymmetric mode interaction in high-power traveling wave amplifiers: experiments and theory

High-power microwave amplifier operation has been studied for use in a number of applications. The performance of the amplifiers has been marred, in some cases, by pulse shortening of the microwave signal. A possible source of the shortening is the loss of the beam due to hybrid HEM/sub 11/ mode interaction with the beam. In this paper, we describe experiments which investigate high-power operation and the effects of HEM modes on the amplifier performance. We report the high-output powers (>50 MW) with efficient (>54%) amplification of microwaves in an X-band traveling wave amplifier. In some experiments, peak power levels exceeding 120 MW were measured at an efficiency of 47%. The excitation of the asymmetric hybrid electromagnetic mode was monitored carefully, but does not seem to have a critical impact on the main interaction process in spite of the fact that its dispersion curve almost overlaps that of the symmetric interacting mode. Theoretical analysis of the interaction in a tapered traveling wave structure indicates that, even if the amount of power in the asymmetric modes at the input of the structure is comparable to that in the symmetric mode, the asymmetric modes cause no power reduction in the symmetric mode. For the case of off-axis beams the TM/sub 01/ output power may drop by about 30% and the power in the hybrid mode reach about one third of that in the symmetric mode. In order to avoid hybrid mode excitation it is necessary to suppress the reflections from both ends of the output structure several decibels below the gain level of the asymmetric mode.

Excitation of hybrid electrostatic-electromagnetic modes in a plasma-loaded sheath helix

A plasma-loaded sheath helix supports lower hybrid modes that extended to the outside vacuum region. The phase velocity of the mode is significantly retarded by the presence of the sheath helix, making it liable to excitation by a low-energy electron beam. The extent of the mode outside the plasma is also reduced by the helix. An analysis of lower hybrid mode excitation by a beam propagating in the vacuum region reveals that nonlocal effects significantly reduce the growth rate. If the instability is taken to saturate via particle trapping, it acquires a large amplitude, giving oscillatory velocity large enough to lead to nonlinear effects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>