- 标题
- 摘要
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- 实验方案
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Enhancing the Per-Unit-Length Data Density in Near-Field Chipless-RFID Systems with Sequential Bit Reading
摘要： In this paper, a novel near-field chipless-RFID system with sequential bit reading is reported. The main novelty concerns the tags, implemented by means of straight half-wavelength resonators separated a small distance and forming a linear chain in the direction orthogonal to their axis. By this means, the number of resonant elements (or bits) per unit length of the tag is significantly increased, as compared to previous implementations, with the result of very competitive tags in terms of data density. The active part of the reader is a microstrip line loaded with a shunt stub. Through a proper design, it is possible to achieve a significant excursion of the transmission coefficient when the stub is either loaded or unloaded with a functional resonant element of the tag. Consequently, by tag motion over the reader (stub), it is possible to infer the ID code by simply injecting a harmonic signal to the input port of the stub-loaded line (the ID code is contained in the amplitude modulated, AM, signal at the output port). This system has been validated by considering 100-bit tags exhibiting a surface data density of 4.9 bits/cm2. However, the relevant parameter is the data density per unit length, as high as 16.7 bit/cm, i.e., much larger than previous values reported in the literature in similar chipless-RFID systems.
关键词： microstrip,half-wavelength resonator,secure paper,Chipless-RFID
更新于2025-09-09 09:28:46
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Effects of barrier energy offset and gradient in extended wavelength infrared detectors
摘要： The extended wavelength infrared photodetectors are new class of III-V semiconductor heterojunction-based photodetectors that can detect incoming radiation with an energy significantly smaller than the minimum energy gap (Δ) at the heterojunction interface. Architecture of these photodetectors include a barrier-emitter-barrier epilayers sandwiched between highly doped ohmic top and bottom contact layers. An energy offset (????) between the barriers is necessary for the extended wavelength photodetection. In this work, we study the performance of extended wavelength infrared photodetectors with varying ???? and gradient of the potential barrier. Results indicate that the extended wavelength threshold varied slightly with varying both the gradient and offset. Spectral responsivity, however, increased with the increasing offset and decreased with increasing gradient.
关键词： Extended wavelength infrared photodetectors,III-V semiconductors,GaAs/AlGaAs heterostructures
更新于2025-09-09 09:28:46
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[IEEE 2018 Conference on Emerging Devices and Smart Systems (ICEDSS) - Tiruchengode, India (2018.3.2-2018.3.3)] 2018 Conference on Emerging Devices and Smart Systems (ICEDSS) - Poor Quality Underwater Image Enhancement for Aqua Farming using Hybrid WCID
摘要： Enhancement of underwater is more complicated when compared with normal images due to color scatter and cast. Haze effects create significant impact on image contrast and visibility. Underwater environment has more smudge due to light attenuation. Under these circumstances capturing the clear pictures of fish and prawn for health monitoring is very difficult. Conventional enhancement algorithms fail to provide better solution for poor quality underwater images. To overcome these difficulties this paper presents a hybrid approach that includes image dehazing along with wavelength compensation (WCID). Several realistic aqua images were considered in this paper to prove the novelty of the proposed hybrid WCID based underwater image enhancement.
关键词： Wavelength compensation,Aqua Forming,Dehazing,Color scatter and cast
更新于2025-09-09 09:28:46
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Influence of the Substrate to the LSP Coupling Wavelength and Strength
摘要： Three kinds of typical structures, hemi-/spherical nanoparticles/nanoparticle dimers on the substrate and spherical nanoparticles/nanoparticle dimers half-buried into the substrate, are used for FDTD simulation to theoretically discuss the influence of the substrate to the localized surface plasmon (LSP) coupling when the metal nanoparticles/nanoparticle dimers are locating near a substrate. Simulated results show that the dependencies between the LSP coupling wavelength and the refractive index of the substrate for different structures are not the same, which can be attributed to the different polarization field distributions of LSPs. When light is incident from different directions, the LSP coupling strength are not the same as well and the ratios of the scattering peak intensities depend on the position of the metal nanoparticles or nanoparticle dimers. These phenomenon can be explained by the difference of the local driving electric field intensities which is modulated by the interface between the air and the substrate.
关键词： Resonance wavelength,Dielectric interface,Localized surface plasmon,Coupling strength
更新于2025-09-09 09:28:46
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High-harmonic generation from solids
摘要： High-harmonic generation in atomic gases has been studied for decades, and has formed the basis of attosecond science. Observation of high-order harmonics from bulk crystals was, however, reported much more recently, in 2010. This Review surveys the subsequent efforts aimed at understanding the microscopic mechanism of solid-state harmonics in terms of what it can tell us about the electronic structure of the source materials, how it can be used to probe driven ultrafast dynamics and its prospects for novel, compact short-wavelength light sources. Although most of this work has focused on bulk materials as the source, recent experiments have investigated high-harmonic generation from engineered structures, which could form flexible platforms for attosecond photonics.
关键词： ultrafast dynamics,electronic structure,high-harmonic generation,solids,short-wavelength light sources,attosecond science
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 7th International Conference on Photonics (ICP) - Langkawi, Malaysia (2018.4.9-2018.4.11)] 2018 IEEE 7th International Conference on Photonics (ICP) - Fabrication and Characterization of a Bismuth-doped fiber with Phosphotus
摘要： The paper discusses the fabrication and characterization of a dispersion-shifted fiber (DSF) with a depressed cladding for use in optical communication systems. The fiber's design aims to minimize dispersion in the 1550 nm wavelength range, which is crucial for high-speed data transmission. Experimental results show that the DSF exhibits low dispersion and attenuation, making it suitable for long-haul communication applications.
关键词： Depressed cladding,Long-haul communication,Optical communication,1550 nm wavelength,Dispersion-shifted fiber
更新于2025-09-09 09:28:46
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Ellipsometry - Principles and Techniques for Materials Characterization || Photoelastic Modulated Imaging Ellipsometry
摘要： Photoelastic modulator (PEM)-based ellipsometry employed either lock-in amplifiers or the Fourier analysis technique to obtain the ellipsometric parameters almost in real-time that makes the system with a feature of fast measurement speed, higher stability, and sensitivity at small retardations. Since the PEM modulation frequency is too high to compare it with the exposure time of the camera, photoelastic modulator–based approach is not applicable for a two-dimensional ellipsometric measurement. Here, we represent a novel technique that coordinates with the light pulses and PEM modulation that can freeze the time-varied signals. Thus, two-dimensional ellipsometric parameters can be obtained within few seconds. In addition to ellipsometric measurement, this approach also can be extended to other imaging polarimetry measurements, such as Stokes parameters and Mueller matrix. Moreover, since the chromatic dispersion of birefringence was also a significant issue in the polarization modulation systems, we proposed an equivalent phase retardation technique to deal with this issue. This technique was confirmed by a dual wavelength measurement result without changing the optical configuration of the system. The concept and the theory of this system were indicated in the preceding section, and the passage below described some calibration issues for the photoelastic modulator. Some measurement results were revealed in the final part of this chapter.
关键词： imaging polarimetry,photoelastic modulator,Stokes parameter,dual wavelength,Mueller matrix,ellipsometric parameters
更新于2025-09-09 09:28:46
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[ACM Press the 10th Latin America Networking Conference - São Paulo, Brazil (2018.10.03-2018.10.04)] Proceedings of the 10th Latin America Networking Conference on ZZZ - LANC '18 - Static-Traffic Routing and Wavelength Assignment in Transparent WDM Networks Using Genetic Algorithm
摘要： In order to transmit data efficiently over an optical network, many routing and wavelength assignment (RWA) algorithms have been proposed. This work presents a genetic algorithm that aims at solving the RWA problem, which consists of choosing the most suitable lightpath (i.e., a combination of a route and a wavelength channel) between a source-destination pair of nodes in all-optical networks. A comparison to some already known approaches in terms of blocking probability per load over four network topologies was made. Simulation results show a good performance, since the average blocking probability achieved by the proposed genetic algorithm was relatively equivalent to the values yielded by the standard approaches over two network topologies; and way lower on the other two networks.
关键词： routing and wavelength assignment,general objective function,WDM optical networks,Genetic algorithm
更新于2025-09-09 09:28:46
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Grant-sizing-differentiated bandwidth allocation algorithm for the coexistence of ONUs with and without wavelength tunability in WDM/TDM PONs
摘要： Adopting the pay-as-you-grow approach to upgrade passive optical network (PON) facilities by WDM technology insures the smoothness of the upgrade, and also results in the coexistence of wavelength-fixed/tunable optical network units (ONUs) in WDM/TDM PONs. Dynamic bandwidth allocation (DBA) is the key to support such coexistence of heterogeneous ONUs. Thus, DBA is also the key to support the smooth evolution of PONs. To more fairly coordinate the bandwidth allocation among the coexisting heterogeneous ONUs, a differentiated grant sizing (DGS) scheme is proposed. In DGS, not only the fairness between the wavelength-fixed/tunable ONUs but also the fairness between the lightly/heavily loaded ONUs is taken into account. To further carry out load balancing among wavelengths, a grant scheduling scheme is also proposed to cooperate with the grant sizing scheme. In the grant scheduling scheme, a measure of the ONUs’ flexibility is given, and then the least flexible job first rule (LFJF) is adopted for joint wavelength and time-slot assignment. Finally, to demonstrate the effectiveness of the proposed algorithm, a series of comparative analyses is conducted based on simulation experiments.
关键词： DBA,Fairness,ONU,Wavelength tunability,Load balancing
更新于2025-09-09 09:28:46
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NOVEL TRANSFORMATION TO DESIGN TRI-BAND FILTERS
摘要： This paper introduces novel derived transformation equations to design Tri-band ?lters. The design utilizes the approach adopted for tri-band bandpass ?lter design based on asymmetric half-wavelength resonator. The obtained optimized ?lter by this approach is used as a reference, and the proposed transformation is applied to calculate the new ?lter design hardware parameters that satisfy its given speci?cations. The reference tri-band ?lter is designed to have: insertion better than 1.3 dB and return loss less than ?10 dB at the resonance frequencies 1.4 GHz, 4 GHz and 5.6 GHz for L-Band DAB, Radar (G-band) and Radar (C-band) applications, respectively. To verify the transformation technique two tri-band ?lters are designed. The ?rst tri-band ?lter is for WVL, WiMAX and WiLAN while the second tri-band ?lter is for UMTS, WiLAN and X-band Satellite applications. The momentum simulations for these ?lters show that the resulting ?lters speci?cations are: the insertion loss is better than 1.3 dB and the return loss is less than ?10 dB at the resonance frequencies 1.3 GHz, 3.6 and 5.7 GHz for the ?rst one. While the insertion loss is better than 1.4 dB and the return loss is less than ?10 dB at the resonance frequencies 1.9 GHz, 5.35 GHz and 8.25 GHz for the second ?lter, respectively. A set of prototype of the ?nal design of the proposed ?lters with optimal parameters was fabricated for experimental veri?cation. The RT 5880 substrate is utilized in this design All the results are obtained using circuit and momentum simulation of the Agilent Design Simulator (ADS) package and the performance characteristics have been measured using the Rohde & Schwarz ZVB20 vector 4 port network analyzer. Analysis and comparison of the obtained results show that all the simulated and the measured results agree well.
关键词： asymmetric half-wavelength resonator,transformation technique,Tri-band ?lters,momentum simulation
更新于2025-09-09 09:28:46