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Dual-band asymmetric optical transmission of both linearly and circularly polarized waves using bilayer coupled complementary chiral metasurface
摘要： It is highly desirable to develop asymmetric transmission (AT) devices for both linearly and circularly polarized light. However, currently existing metamaterial-based AT devices require multi-step micro-nano fabrication processes and usually realize AT responses only for linearly or circularly polarized waves, not simultaneously for both. We here propose a dual-band AT device for both linearly and circularly polarized waves in the near-infrared region by using a bilayer coupled complementary chiral metasurface, which includes a half-gammadion-shape gold (Au) structural layer and its Babinet’s complimentary copy. Unlike other multilayer AT devices working at optical frequencies, it takes less micro-nano fabrication steps. Besides, with the help of chirality and the inherent near-?eld coupling e?ect between the two complementary Au layers, the maximal AT parameters for linearly and circularly polarized waves can reach up to 0.45 and 0.56, respectively. The underlying mechanisms of dual-band AT responses are also investigated in depth from the perspectives of chirality and coupling e?ect. Our work o?ers a new and simple approach to high-performance AT devices, helps to better understand near-?led coupling e?ect in coupled complementary metasurfaces, and also expands their application ?elds.
关键词： chiral metasurface,asymmetric transmission,polarization conversion,coupling effect,near-infrared
更新于2025-09-11 14:15:04
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SUBSTRATE INTEGRATED WAVEGUIDE FILTER WITH IMPROVED STOPBAND PERFORMANCE USING LTCC TECHNOLOGY
摘要： A novel multi-layer third-order substrate integrated waveguide (SIW) bandpass ?lter with improved lower stopband performance is proposed. TE201-mode in folded-SIW cavity is utilized to implement negative cross coupling, and the TE101-mode is taken as a non-resonating node (NRN) for implementing bypass coupling. A circular aperture etched on the middle metal layer is used to realize coupling between source and the second SIW cavity. Then, three transmission zeros located below the passband can be obtained to improve stopband attenuation. Meanwhile, better spurious suppression performance above passband is achieved. A ?lter sample is designed and fabricated with multi-layer low-temperature co-?red ceramic (LTCC) technology. The measured S-parameters agree well with the simulated ones, with its predicted good performance.
关键词： transmission zeros,low-temperature co-?red ceramic (LTCC),Substrate integrated waveguide (SIW),bandpass ?lter,stopband performance
更新于2025-09-11 14:15:04
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Resonant Tunneling Diode (RTD) Terahertz Active Transmission Line Oscillator with Graphene-Plasma Wave and Two Graphene Antennas
摘要： This study describes the design of a resonant tunneling diode (RTD) oscillator (RTD oscillator) with a RTD-gated-graphene-2DEF (two dimensional electron fluid) and demonstrates the functioning of this RTD oscillator through a transmission line simulation model. Impedance of the RTD oscillator changes periodically when physical dimension of the device is of considerable fraction of the electrical wavelength. As long as impedance matching is achieved, the oscillation frequency is not limited by the size of the device. An RTD oscillator with a graphene film and negative differential resistance (NDR) will produce power amplification. The positive electrode of the DC power supply is modified and designed as an antenna. So, the reflected power can also be radiated to increase RTD oscillator output power. The output analysis shows that through the optimization of the antenna structure, it is possible to increase the RTD oscillator output to 22 mW at 1.9 THz and 20 mW at 6.1 THz respectively. Furthermore, the RTD oscillator has the potential to oscillate at 50 THz with a matching antenna.
关键词： transmission line model,RTD-gated-graphene-2DEF,resonant tunneling diode (RTD),graphene-plasma,two-dimensional electron fluid (2DEF),resonant tunneling diode oscillator (RTD oscillator),terahertz
更新于2025-09-11 14:15:04
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Analysis of the Processing‐Pressure Dependent Refractive Index of Polycarbonate by Transmission Measurements of Glass‐Filled Specimen
摘要： In this study, the influence of pressure during processing on the refractive index (RI) of polycarbonate (PC) was investigated by transmission measurements on glass-filled samples with a spectrometer. In order to isolate the pressure dependence of the RI from other influencing parameters such as cooling rate, orientation and stress states, the samples were prepared in a pressure-specific volume-Temperature (pvT) instrument under constant cooling rate and temperature history and without shear effects. Subsequently, the RI was determined at the intersection of the dispersion curves of the glass and the polymer by evaluating the wavelength of the maximal transmission of the samples. The mean RI over the entire cross section of the sample is determined by the transmission measurements without complex sample preparation. The investigations show that the RI of PC increases by 3.26 E-6 per bar with increasing pressure.
关键词： glass-filled specimen,processing-pressure,refractive index,polycarbonate,transmission measurements
更新于2025-09-11 14:15:04
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Measurement and Evaluation of Local Surface Temperature Induced by Irradiation of Nanoscaled or Microscaled Electron Beams
摘要： Electron beams (e-beams) have been applied as detecting probes and clean energy sources in many applications. In this work, we investigated several approaches for measurement and estimation of the range and distribution of local temperatures on a subject surface under irradiation of nano-microscale e-beams. We showed that a high-intensity e-beam with current density of 105-6 A/cm2 could result in vaporization of solid Si and Au materials in seconds, with a local surface temperature higher than 3000 K. With a lower beam intensity to 103-4 A/cm2, e-beams could introduce local surface temperature in the range of 1000–2000 K shortly, causing local melting in metallic nanowires and Cr, Pt, and Pd thin films, and phase transition in metallic Mg-B films. We demonstrated that thin film thermocouples on a freestanding Si3N4 window were capable of detecting peaked local surface temperatures up to 2000 K and stable, and temperatures in a lower range with a high precision. We discussed the distribution of surface temperatures under e-beams, thermal dissipation of thick substrate, and a small converting ratio from the high kinetic energy of e-beam to the surface heat. The results may offer some clues for novel applications of e-beams.
关键词： Vaporization,Local temperature,Nanoscale thermometry,Transmission electron microscopy,Thin film thermocouple,Energy converting,Electron beam,Scanning electron microscopy,Melting point
更新于2025-09-11 14:15:04
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Quasi-Elliptic Waveguide Dual-Band Bandpass Filters
摘要： This article presents a novel folded configuration of dual-band filter employing TE11m dual-mode elliptical cavity resonators. The proposed side-coupled configuration leads to a significant reduction of filter footprint compared with previously reported in-line dual-band filter structures. Such configuration also facilitates cross couplings to realize advanced quasi-elliptic filter functions. The structure employs irises for both sequential and cross couplings. The limitations of bandwidth realization and spurious-free window are analyzed in detail, and new coupling structures are proposed to improve the overall in-band and out-of-band responses. All the proposed dual-band designs have low insertion loss and allow for independent control of each frequency and coupling parameter. To demonstrate the concept, two 8-pole C-band elliptical cavity dual-band filters are designed, manufactured, measured, and compared. To the best of the authors’ knowledge, this is the first reported folded dual-band filter configuration based on metallic waveguide cavities.
关键词： elliptical cavity,transmission zeros (TZs),waveguide,dual-band filter,dual-mode resonator,folded structure,Bandwidth
更新于2025-09-11 14:15:04
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Characteristics of Coplanar Waveguide of Small Cross Section on BCB with Coplanar Ground to Conductor-Backed Plane Interconnection
摘要： Conductor-backed coplanar waveguide on 30-μm-thick BCB polymer is fabricated. In order to eliminate unwanted propagation modes for these lines designed for frequencies up to 1 THz, electroplated vias interconnect each coplanar ground to the backed conductor. Transmission line properties are extracted here up to 67 GHz, showing a characteristic impedance of about 50 Ω, but with high conduction losses for this frequency range due to the thin metal layer used. Thru-reflect-line correction and a de-embedding with electrical circuit of accesses are applied to extract line properties. The comparison with a coplanar waveguide model leads to a relative permittivity of 2.676 for the BCB in this low-frequency range.
关键词： Transmission lines,Submillimeter wave waveguides,THz coplanar waveguides,Polymer dielectric
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - An Optimal Driving Strategy for Maximum Electro-optical Conversion Efficiency of Laser Diode in Laser Power Transmission System
摘要： Laser Power Transmission technique features high energy density, flexible devices and advantageous orientation ability, making itself extremely promising for realizing long-distance, high-power wireless power transmission. Laser diode (LD), a core component in LPT system’s transmitter, realizes power conversion from electricity to high-intensity laser beam. LD’s performance significantly affects the efficiency of LPT transmitter. Different driving current patterns lead to different electro-optical conversion efficiency (EOCE). The paper presents a novel LD driving strategy for optimal EOCE under different working conditions. To precisely estimate EOCE of LD, a simplified LD equivalent circuit model with only five parameters is proposed, which can readily be adopted to characterize any commercial LD using curves given in their datasheets. Though simplified, the model can still depict the its power-current-voltage (P-I-V) characteristics well, and accuracy is shown to be as close as its traditional counterparts. Based on the model, the optimal driving current strategy for maximum EOCE is derived for all optical power output conditions. A is constructed to verify the proposed driving strategy. As all experimental results indicate, the proposed method enjoys a fine performance in improving LD’s EOCE.
关键词： laser power transmission,optimal driving strategy,laser diode,maximum electro-optical conversion efficiency
更新于2025-09-11 14:15:04
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74.38 Tb/s Transmission Over 6300 km Single Mode Fibre Enabled by C+L Amplification and Geometrically Shaped PDM-64QAM
摘要： Ultrawide-bandwidth optical amplification over almost 90 nm, covering the C+L bands, is described. Complemented by system-tailored geometrical constellation shaping and nonlinearity compensation, it enabled a record capacity transmission of 74.38 Tb/s over 6,300 km of G.654 single-mode fibre. The hybrid scheme, combining backward Raman pre-amplification with EDFA, significantly improves the average effective noise figure across the entire bandwidth, allowing the use of span lengths of 70 km. The system-tailored GS-64QAM constellation was optimised to both linear link impairments and transceiver nonlinearities, improving the gap to the AWGN channel capacity relative to square 64QAM from 0.6 bit/symbol to 0.35 bit/symbol. We experimentally evaluated the system performance using the bit-wise achievable information rate (AIR) and signal-to-noise ratio (SNR) at the end of transmission, as well as post SD-FEC BER.
关键词： geometric constellation shaping,nonlinear compensation,Erbium-doped fibre amplifier,Raman amplification,Broadband C+L band transoceanic transmission
更新于2025-09-11 14:15:04
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Quantum photonic transistor controlled by an atom in a Floquet cavity-QED system
摘要： The photon transmission of a Floquet cavity quantum electrodynamic (QED) system containing three periodically modulated cavities interacting with a two-level atom is investigated. The input-output relations and the second-order correlation functions of the output fields are calculated. The system demonstrates the feature of a quantum photonic transistor, i.e., the photon transmission is controlled by the quantum states of the atom. This device can be used as a building block for various quantum information processing.
关键词： photon transmission,Quantum photonic transistor,Floquet cavity-QED system,quantum information processing
更新于2025-09-11 14:15:04