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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Planar Optical Antennas as Efficient Single-Photon Sources for Free-Space and Fiber-Based Operation in Quantum Optics and Metrology
摘要： Practical implementations of quantum technologies, ranging from optical quantum computing to metrological measurements, suffer from the lack of high-rate, on-demand sources of indistinguishable single photons. We will discuss a simple and versatile planar optical antenna, showing both theoretical and experimental evidence of low-loss (< 20%) beaming of the radiation from a single quantum emitter into a narrow cone of solid angles in free space, which allows in principle up to 50% coupling into a single-mode fiber. In particular, we will first present an experimental implementation of the design operated at room temperature, exploiting Dibenzoterrylene molecules (DBT) hosted in a crystalline anthracene matrix (Ac) [1]. The DBT:Ac system is particularly suitable for this task, due to its outstanding photo-physical properties (i.e. long-term photostability both at room and cryogenic temperature, lifetime-limited emission at cryogenic temperatures, 780 nm operating wavelength) demonstrated in 50 nm-thick crystals [2] and recently also in nanocrystals [3]. Moreover, single photons from DBT molecules and similar [4] result very appealing concerning quantum communication and computation protocols which involve quantum memories, due to the unmatched stability and narrowness of their spectrum (below 100 MHz). Then we will report on our theoretical study to determine the ultimate performances attainable with such design in case of operation in cryogenic environment, exploring materials and fine tuning of geometrical parameters. We will finally discuss our recent results about a single-mirror antenna operating at cryogenic temperature. We demonstrate a photon flux in the Fourier-limited line higher than 1MHz at detectors, and coupling of fluorescence into single-mode fibers up to 46%. These results open to the deploiment of our system both in quantum optics experiments requiring deterministic single-photon sources and in metrology, in particular for a new operative definition of the candela, as recently proposed in the EMPIR project 'SIQUST' [5].
关键词： Quantum Optics,Single-Photon Sources,Dibenzoterrylene molecules,Metrology,Planar Optical Antennas,Crystalline anthracene matrix
更新于2025-09-12 10:27:22
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[IEEE 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - San Diego, CA, USA (2019.5.27-2019.5.31)] 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - Modeling Metamaterial Element in Dielectric-filled Waveguide-fed Metasurface Antennas
摘要： We study the modeling of metamaterial elements etched into planar, dielectric-filled waveguides for metasurface antennas. Metamaterial elements in these devices are subwavelength-sized, resonant openings embedded in waveguide walls—that can be modeled as the electric and magnetic dipoles—and couple to waveguide modes and radiate into free space. Due to a dielectric filling the waveguide, the dipole moments representing the element can contribute unequally to the scattered fields into the waveguide and the radiated fields into free space. Such different dipole strengths need to be considered for analytic modeling of metasurfaces. In this work, we present a retrieval of dipole moments of a metamaterial element by applying the law of power conservation and demonstrate its utility in the analytic model for the metasurface antennas.
关键词： dielectric-filled waveguides,dipole moments,power conservation,metamaterial elements,metasurface antennas
更新于2025-09-12 10:27:22
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Enhanced light-matter interaction in an atomically thin semiconductor coupled with dielectric nano-antennas
摘要： Unique structural and optical properties of atomically thin two-dimensional semiconducting transition metal dichalcogenides enable in principle their efficient coupling to photonic cavities having the optical mode volume close to or below the diffraction limit. Recently, it has become possible to make all-dielectric nano-cavities with reduced mode volumes and negligible non-radiative losses. Here, we realise low-loss high-refractive-index dielectric gallium phosphide (GaP) nano-antennas with small mode volumes coupled to atomic mono- and bilayers of WSe2. We observe a photoluminescence enhancement exceeding 104 compared with WSe2 placed on planar GaP, and trace its origin to a combination of enhancement of the spontaneous emission rate, favourable modification of the photoluminescence directionality and enhanced optical excitation efficiency. A further effect of the coupling is observed in the photoluminescence polarisation dependence and in the Raman scattering signal enhancement exceeding 103. Our findings reveal dielectric nano-antennas as a promising platform for engineering light-matter coupling in two-dimensional semiconductors.
关键词： atomically thin semiconductor,light-matter interaction,Raman scattering,dielectric nano-antennas,photoluminescence enhancement
更新于2025-09-12 10:27:22
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Glide-Symmetric Lens Antenna in Gap Waveguide Technology
摘要： In this paper, we propose a wideband fully-metallic impedance-matching horn lens antenna based on glide symmetry realized in the gap waveguide technology. A multiple iterative method is adopted, which overcomes the limitation of large phase deviations at the interface of traditional lens antennas, thus increases the directivity as a result. Moreover, the glide-symmetric configurations of inner metallic pins within the gap waveguide are employed to construct the artificial dielectric lens, with the advantage of the ultra-low dispersion, which is especially helpful to broaden the working bandwidth and improve the lens performance. The antenna is fed by a stepped double ridged gap waveguide which can easily excite the antenna working in a wide band. To reduce the undesired reflections at the antenna aperture, the antenna is ended with a tapered structure as an impedance transition. A prototype of the horn lens antenna is manufactured and measured, showing a broad operation bandwidth from 12 to 18.5 GHz with S11 less than -10 dB. The antenna can be further extended to the millimeter band due to the low losses of the gap waveguide at high frequencies and the iterative method can also be applied to other types of lens antenna designs.
关键词： glide symmetry,gap waveguide,Horn lens antennas
更新于2025-09-12 10:27:22
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A Low-Profile and High-Gain Frequency Beam Steering sub-THz Antenna Enabled by Silicon Micromachining
摘要： A very low-profile sub-THz high-gain frequency beam steering antenna, enabled by silicon micromachining, is reported for the first time in this paper. The operation bandwidth of the antenna spans from 220 GHz to 300 GHz providing a simulated field of view of 56?. The design is based on a dielectric filled parallel-plate waveguide (PPW) leaky-wave antenna fed by a pillbox. The pillbox, a two-level PPW structure, has an integrated parabolic reflector to generate a planar wave front. The device is enabled by two extreme aspect ratio, 16 mm x 16 mm large perforated membranes, which are only 30 μm thick, that provide the coupling between the two PPWs and form the LWA. The micromachined low-loss PPW structure results in a measured average radiation efficiency of ?1 dB and a maximum gain of 28.5 dBi with an input reflection coefficient below ?10 dB. The overall frequency beam steering frontend is extremely compact (24 mm x 24 mm x 0.9 mm) and can be directly mounted on a standard WM-864 waveguide flange. The design and fabrication challenges of such high performance antenna in the sub-THz frequency range are described and the measurement results of two fabricated prototypes are reported and discussed.
关键词： beam steering,leaky-wave antennas,silicon on insulator,terahertz radiation,silicon micromachining,quasi-optics,submillimeter-wave antennas
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Conference on Computational Electromagnetics (ICCEM) - Shanghai, China (2019.3.20-2019.3.22)] 2019 IEEE International Conference on Computational Electromagnetics (ICCEM) - A compact coplanar waveguide feed bow-tie slot antenna for WIMAX, C and X band applications
摘要： In this paper, a planar bow-tie slot antenna with coplanar waveguide fed for tri-band i.e. WIMAX, C and X band wireless communication applications is proposed. This antenna has been designed to meet the prerequisite of multiple resonant frequencies by setting up the proper dimensions of the bow-tie arm slots and feed line cutout slots. The dimensions corresponds to the tri-band resonant frequencies, are obtained by engraving slots of distinct length and width above the ground plane. The antenna is fed by 50? coplanar waveguide feed line. Physical size of the proposed antenna is 30×60 mm2 designed on thick substrate. The copper cladding ArlonCuClad217(tm) woven fiberglass laminate material with dielectric loss tangent 0.0009 and relative permittivity 2.17 is used. The gain, impedance bandwidths, return loss, and VSWR of proposed antenna has been analyzed and discussed. Moreover, the extensive parametric study has been carried out with dimensions of feed line cutout. The simulation results have shown that the designed prototype of an antenna exhibits the peak realized gain of 6.9dBi and average gain of 2.3dBi.The proposed antenna has three operating bands, which are suitable for WIMAX, C-band and X-band applications.
关键词： Tri-band,CPW-fed,Slot antennas,Gain,Bow-tie arm
更新于2025-09-11 14:15:04
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Well‐Controlled Decomposition of Copper Complex Inks Enabled by Metal Nanowire Networks for Highly Compact, Conductive, and Flexible Copper Films
摘要： Highly compact and conductive Cu films are successfully fabricated by introducing mechanically robust and highly conductive metal nanowires (NWs) as fillers and optimizing amine-based ligands in Cu complex inks. The metal NWs (AgNWs and CuNWs) dispersed in the complex inks provide networks of nucleation sites for the in situ formed Cu particles and thereby control the decomposition of Cu complex inks at low temperatures to realize Cu films with high uniformity and integrality. The high affinity between metal NWs and the in situ formed Cu element enables the growth of Cu particles along the metal NWs to create a compact structure. Besides, the amine-based ligands such as 2-amino-2-methyl-1-propanol (AMP), 2-ethylhexylamine (Ethy), and hexylamine (Hexy) are varied to adjust the size of Cu particles and further improve the microstructure and conductivity of the sintered Cu films. The Cu-Ethy complex/metal NW inks sintered at 140 °C exhibit the lowest resistivity of 14.9 μ? cm, which is about one-third that fabricated from the pure Cu-AMP complex inks. The flexible light-emitting diode circuits and V-shaped dipole antennas prepared from the Cu complex/metal NW inks have excellent performance due to their outstanding conductivity and flexibility, showing great potential in the fabrication of cost-effective, flexible printed electronic devices.
关键词： antennas,controllable decomposition,metal nanowires,Cu complex inks,amine-based ligands
更新于2025-09-11 14:15:04
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Plasmonic Trimers for Dual-Frequency Surface-Enhanced Two-dimensional Infrared Spectroscopy
摘要： Extension of surface-enhanced two-dimensional infrared spectroscopy (SE-2DIR) to dual-frequency experiments allows to study dynamics and energy transport in thin molecular films by tagging and probing vibrational modes on different sites of the molecule. Measurements of cross-peaks involving transitions largely separated in frequency by SE-2DIR require plasmonic nanostructures with resonant excitations at the corresponding frequencies, where the associated enhanced near-fields spatially overlap and different molecular transitions are simultaneously enhanced in the same molecule. Gold trimer infrared antennas localize enhanced fields within the gap formed by their arms. We exploit the symmetry of trimer antennas to individually tune frequencies of the in-plane plasmonic excitations to match molecular transitions of interest. Dual-frequency SE-2DIR measurements are demonstrated on 4-azidobutyrate-N-hydroxysuccinimide ester with the cross-peaks between the carbonyl and azido stretching vibrational modes, separated by 370 cm-1, and the carbonyl and C-N-C stretching modes, separated by 550 cm-1. Excitation with cross-polarized laser pulses allows to selectively access appropriate plasmon excitations in resonance with the relevant molecular transitions. Our approach, based on the rational plasmon mode engineering, achieves significant enhancement of the cross-peak signals involving largely-separated transition frequencies, which is not possible with single broadband plasmon modes.
关键词： Surface-Enhanced Two-dimensional Infrared Spectroscopy,Dual-frequency,Molecular transitions,Cross-peaks,Gold trimer infrared antennas,Plasmonics,Hybrid Materials,Optical,Magnetic
更新于2025-09-11 14:15:04
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Colloidal Plasmonic Nanostar Antennas with Wide Range Resonance Tunability
摘要： Gold nanostars display exceptional field enhancement properties and tunable resonant modes that can be leveraged to create effective imaging tags, phototherapeutic agents, and hot electron-based photocatalytic platforms. Despite having emerged as the cornerstone among plasmonic nanoparticles with respect to resonant strength and tunability, some well-known limitations have hampered their technological implementation. Herein we tackle these recognized intrinsic weaknesses, which stem from the complex, and thus computationally untreatable, morphology and the limited sample monodispersity, by proposing a novel 6-spike nanostar, which we have computationally studied and synthetically realized, as the epitome of 3D plasmonic nanoantenna with wide range plasmonic tunability. Our concerted computational and experimental effort shows that these nanostars combine the unique advantages of nanostructures fabricated from the top-down and those synthesized from the bottom-up, showcasing a unique plasmonic response that remains largely unaltered in going from the single particle to the ensemble. Furthermore, they display multiple, well-separated, narrow resonances, the most intense of which extends in space much farther than observed before for any plasmonic mode localized around a colloidal nanostructure. Importantly, the unique close correlation between morphology and plasmonic response leads the resonant modes of these particles to be tunable between 600 and 2000 nm, a unique feature that could find relevance in cutting edge technological applications.
关键词： 3D nano-antennas,colloidal nanostars,plasmon tunability,localized surface plasmon resonances,EELS
更新于2025-09-11 14:15:04
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Plasmonic Nano-antenna Optimization Using Characteristic Mode Analysis
摘要： Plasmonic nano-antennas are typically designed with RF-inspired rigorous parametric optimization processes that lack proper physical insights. In this study, we demonstrate a systematic optimization approach for nano-antennas based on characteristic mode analysis (CMA). A complex geometry, designated as split-ring two-wire antenna (SRA), is selected and optimized using the CMA technique. CMA identifies the dominant modes of the structure at the frequency of interest as well as explains the dependency of the modes on the structure’s shape, size and material properties. These insights from CMA have been used in the present study to efficiently optimize SRA shape, size, and material which yield more than 700 % near-field intensity enhancement (NFIE) at the desired operating frequency. This proposed CMA based optimization method can be adapted easily for many other nano-antenna applications, facilitating the development of improved nano-structures.
关键词： Split-ring Two-wire Antenna (SRA),Method of Moments (MOM),Plasmonic,Nano-structures / Nano-antennas,Near Field Intensity Enhancement (NFIE),Surface Integral Equation (SIE),Characteristic Mode Analysis (CMA)
更新于2025-09-11 14:15:04