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[IEEE 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Swat, Pakistan (2019.7.24-2019.7.25)] 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Nanoplasmonic Quasi Crystal Metascreen Optimized for Efficient Light Absorption
摘要： A metascreen absorber composed of plasmonic nanodisk array is used to absorb incident radiation at optical frequencies. The conventional Nobel metals such as gold and silver are considered as best plasmonic materials to couple incident light to surface plasmons modes. However, it is found that alternative plasmonic materials such as copper (Cu) offers optimized absorption characteristics. Copper nanodisk absorber offers a broad range of optical absorption ranging from 400 nm – 1500 nm wavelength. In addition, it is found that the light absorption bandwidth can be signi?cantly enhanced or near perfect absorption can be reached if plasmonic nanodisks are arranged in quasi-crystal con?guration. The proposed quasicrystal based metascreen absorber offers potential applications for light energy harvesting and optical sensing applications.
关键词： Salisbury screen absorber,polarization independent,metasurface,terahertz frequencies,broadband absorption
更新于2025-09-16 10:30:52
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Noninverse dynamics of a quantum emitter coupled to a fully anisotropic environment
摘要： Anisotropic nanophotonic structures can couple the levels of a quantum emitter through the quantum interference effect. In this paper we study the coupling of quantum emitter excited states through the modes of a fully anisotropic structure, a structure for which all directions are physically nonequivalent. We consider an anisotropic metasurface as an illustrative example of such a structure. We point out another degree of freedom in controlling the temporal dynamics and spectral pro?les of quantum emitters; namely, we show that a combination of the metasurface anisotropy and tilt of the emitter quantization axis with respect to the metasurface normal results in nonsymmetric dynamics between the transitions of electrons from the left-circular state to the right-circular state and in the inverse process. Our ?ndings give an additional mechanism for control over light emission by quantum systems and can be utilized for probing active transitions of quantum emitters.
关键词： metasurface,light emission control,anisotropic environment,quantum emitter,quantum interference
更新于2025-09-16 10:30:52
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Enhanced terahertz emission bandwidth from photoconductive antenna by manipulating carrier dynamics of semiconducting substrate with embedded plasmonic metasurface
摘要： In this article, we demonstrate a technique to enhance the Terahertz (THz) emission bandwidth from photo-conductive antenna (PCA) based on semiconducting substrates by manipulating the surface carrier dynamics of the semiconductor. Bandwidths in PCAs are limited by the decay of the photogenerated charge carriers, which in case of SI-GaAs is in the orders of 50 picoseconds. We show, with an embedded design of plasmonic meta-surface in the photoconductive gap of a PCA, it is possible to enhance the emission bandwidths by more than 50 percent. This is due to the fact that these nano-structures act as local recombination sites for the photogenerated carriers, effectively reducing the carriers’ lifetime. Additionally, the defect sites reduce the terminal current, thereby reducing the Joule heating in the device. Furthermore, the meta-surface also facilitates higher in-coupling of the exciting infrared light on to the PCA, thereby increasing the optical-to-THz conversion efficiency of the device.
关键词： carrier dynamics,plasmonic metasurface,bandwidth enhancement,photoconductive antenna,Terahertz
更新于2025-09-16 10:30:52
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Nanoplasmonics - Fundamentals and Applications || Magneto‐Plasmonics and Optical Activity in Graphene‐Based Nanowires
摘要： Nowadays, graphene plasmonics shows a great number of features unusual for traditional (metal-based) plasmonics from high localization and large propagation distance of surface plasmon-polaritons (SPPs) through the existence of both TE- and TM-polarized SPPs to the possibility of controlled SPPs by graphene chemical potential (or, equivalently, by gate voltage or chemical doping). Cylindrical graphene-based plasmonic structures have some advantages in contrast to planar geometry: absence of edge losses, existence of high-order azimuthal modes, etc. In this work, we discuss some ways to obtain an optical activity in cylindrical graphene-based plasmonic structures and its possible applications to SPPs manipulation.
关键词： surface plasmon-polaritons,metasurface,graphene,magneto-plasmonics,optical activity
更新于2025-09-16 10:30:52
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Broadband multi-resonant circular dichroism in metal-VO2 hybrid dagger-like plasmonic structure for switching application
摘要： Metallic and metal-VO2 hybrid dagger-like novel chiral plasmonic structure is proposed and demonstrated numerically using finite difference time domain (FDTD) computation to realize broadband multi-resonant circular dichroism (CD). CD switching is realized in the hybrid system that can be actively controlled externally. Dagger-like structure is considered where asymmetry is introduced in both the arms of a dagger structure to break in-plane rotational symmetry making the structure in-planar chiral. Multi-resonant broadband CD between visible to infrared frequencies is observed in pure asymmetric metallic dagger-like structure (MDLS) made of gold, as well as, in asymmetric metal-VO2 hybrid dagger-like structure (MVHDLS). Interestingly, multi-resonant CD in MVHDLS vanishes completely when VO2 phase changes from semiconducting to metallic phase. Dynamic control of VO2 phase externally enables us to realize CD switching action in MVHDLS. The proposed structure opens up the possibility of switching based plasmonic and photonic CD applications.
关键词： Modeling and simulation,Novel metal-VO2 hybrid dagger-like structure,Circular dichroism and its switching,Plasmonic metasurface
更新于2025-09-16 10:30:52
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Metasurface Enabled Advanced Short Backfire Antenna
摘要： Metasurfaces with independently tunable anisotropic dispersion characteristics have been designed to significantly improve the radiation efficiency of a short backfire antenna (SBFA) when placed within the antenna cavity walls. This advanced short backfire antenna (A-SBFA) features a hexagonal aperture, which typically results in much lower aperture efficiency and increased cross polarization. However, the addition of metasurfaces leads to a higher aperture efficiency than is achievable with a conventional circular SBFA. Through careful design and optimization of the metasurface dispersion, the A-SBFA achieves high aperture efficiency across two discrete frequency bands while maintaining a relatively low height and weight. A detailed design and optimization methodology is presented here, along with simulation studies that explore the design space and provide insight into how the antenna performance is affected as the metasurface parameters are adjusted. The A-SBFA is shown to be a promising candidate for future satellite-based antenna arrays due to its high aperture efficiency, hexagonal cavity, low weight, and low profile.
关键词： short backfire antenna,Metasurface,optimization
更新于2025-09-16 10:30:52
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Ultrathin Metasurface Wavelength-Selective Mirror for Millimeter/Terahertz Wave Fabry-Perot Cavities
摘要： We present an ultrathin metasurface working as both a highly reflective wavelength-selective mirror and a high transmittance output coupler for a semiconfocal Fabry-Perot cavity. The numerically optimized 2-μm-thick metasurface achieves a peak reflectivity of R = 99.35% at ω0 =94 GHz and peak transmittance of T ≈ 90% at the fourth harmonic (4ω0). Experimental results show that the metasurface FP cavity exhibits comparable quality factors to cavities enclosed by either a copper mirror or Bragg grating mirror. Our work highlights the potential for ultrathin metasurfaces to function as frequency selective mirrors in millimeter or terahertz wave cavities for various applications, such as nonlinear terahertz wave generation, material characterization, and imaging.
关键词： Fabry Perot,Terahertz,Metasurface
更新于2025-09-16 10:30:52
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Design principles for sensitivity optimization in plasmonic hydrogen sensors
摘要： Palladium nanoparticles have proven to be an exceptionally suitable material for the optical detection of hydrogen gas, due to the dielectric function that changes with the hydrogen concentration. The development of a reliable, low-cost, and widely applicable hydrogen detector requires a simple optical read-out mechanism and an optimization of the lowest detectable hydrogen concentration. So-called ‘perfect absorber’-type structures, consisting of a layer of plasmonic palladium nanoantennas suspended above a metallic mirror layer, are a promising approach to realizing such sensors. The absorption of hydrogen by palladium leads to a shift of the plasmon resonance and thus to a change in the far-?eld re?ectance spectrum. The spectral change can be analyzed in detail using spectroscopic measurements, while the re?ectance change at a speci?c wavelength can be detected with a simple photometric system of a photodiode and a monochromatic light source. Here, we systematically investigate the geometry of cavity-coupled palladium nanostructures as well as the optical system concept, which enables us to formulate a set of design rules for optimizing the hydrogen sensitivity. Employing these principles, we demonstrate the robust detection of hydrogen at concentrations down to 100 ppm. Our results are not limited to hydrogen sensing, but can be applied to any type of plasmonic sensor.
关键词： Hydrogen detection,Palladium,Tailored disorder,Plasmonic sensing,Microspectroscopy,Metasurface,Perfect absorber,Fourier-plane spectroscopy
更新于2025-09-16 10:30:52
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[IEEE 2018 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Beijing, China (2018.7.29-2018.8.1)] 2018 International Applied Computational Electromagnetics Society Symposium - China (ACES) - Terahertz metasurface for flexible band-pass filter
摘要： We present a coupled mode theory (CMT) to design terahertz flexible band-pass filter. Based on this theory, we designed three band-pass filters with passband 0.74-0.89, 0.72-0.91 and 0.72-0.95THz. The transmission in the passband is all above 80%. This method can be easily extended to other frequency regime.
关键词： band-pass filter,metasurface,terahertz,coupled-mode theory
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - All-Dielectric Metasurfaces: Optical Nonlinearities and Emission Control
摘要： In this work we show our results on the harmonic generation and nonlinear frequency mixing enhanced by Mie modes in GaAs metasurfaces. Moreover, we show enhancement and directionality control of the quantum dot emission embedded in the metasurface.
关键词： nonlinear frequency mixing,semiconductor metasurface,all-dielectric metasurface,second harmonic generation
更新于2025-09-12 10:27:22