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Integrated 25?GHz and 50?GHz spectral line width dense wavelength division demultiplexer on single photonic crystal chip
摘要： We propose a new integrated demultiplexer model using the two-dimensional photonic crystal (2D PC) through the hexagonal resonant cavity (HRC) for the International Telecommunication Union (ITU) standard. The integrated model of demultiplexer for both 25 GHz and 50 GHz has been designed for the ?rst time. The demultiplexer consists of bus input waveguide, drop waveguide, Hexagonal Resonant Cavity (HRC), 6 Air Hole Filter (6-AHF), 7 Air Hole Filter (7-AHF). The 7-AHF is used to ?lter 25GHz wavelength, and the 6-AHF ?lter is used to ?lter 50 GHz wavelength. The Q-factor on the designed demultiplexer is ?exible based on the idea of increasing the number of air holes between drop waveguide and resonant cavity. The demultiplexer is designed to drop maximum 8 resonant wavelengths. One side of demultiplexer is able to drop 50 GHz ITU standard wavelengths, which are of 1556.3 nm, 1556.7 nm, 1557.1 nm and 1557.5 nm, and further the other facet is able to drop 25 GHz wavelengths, which are of 1551.4 nm, 1551.6 nm, 1551.8 nm, and 1552.0 nm. The proposed demultiplexer may be carried out within the integrated dual system. This system is able to lessen the architecture cost and the size is miniaturized substantially.
关键词： Line width,Crosstalk,Cavity,Demultiplexer,Quality factor
更新于2025-09-23 15:21:01
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A High-Power-Factor Dimmable LED Driver with Integrated Boost Converter and Half-Bridge-Topology Converter
摘要： This paper proposes a dimmable light-emitting diode (LED) driver featuring a high power factor and zero-voltage switching on (ZVS). The circuit is obtained by integrating a boost converter and a dc-dc converter with half-bridge topology. The high power factor is achieved by operating the boost converter in discontinuous current mode (DCM). The LEDs are dimmed by the control scheme of asymmetrical pulse-width modulation (ASPWM). The developed circuit eliminates the inherited dc-o?set current of the transformer in a conventional asymmetrical half-bridge converter by introducing a balance capacitor. Both active switches can operate at ZVS by freewheeling the boost inductor current and the transformer magnetizing current to discharge the energy stored in their parasitic capacitance. The circuit operation is analyzed in detailed, and mathematical equations are derived. Finally, a 115-W prototype circuit for driving high brightness LEDs was built and tested. The experimental results verify the feasibility of the proposed LED driver with satisfactory performance. It can achieve a high power factor and ZVS operation.
关键词： power-factor correction,half-bridge converter,zero-voltage switching on (ZVS),asymmetrical pulse-width modulation (ASPWM),light-emitting diode (LED)
更新于2025-09-23 15:21:01
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Quantum Particle Swarm Optimization for Synthesis of Non-uniformly Spaced Linear Arrays with Broadband Frequency Invariant Pattern
摘要： This paper describes a method using Quantum Particle Swarm Optimization to obtain a broadband frequency invariant pattern for synthesis of nonuniformly spaced linear array of isotropic antennas. Two cases related to this work using QPSO have been studied, namely, in the first case, the generated frequency invariant far-field pattern is broadside in the vertical plane and in the second case, the far-field frequency invariant pattern is scanned in a particular direction. An effort is made such that the side lobe level and first null beam widths of the patterns are made similar to their related desired values. The two cases are presented in this paper to show the effectiveness of the proposed method in achieving the desired specifications. Even though, the developed method is utilized here for a linear array of isotropic antennas; it can be extended to other type of arrays. The performance of this algorithm is validated by duly comparing it with firefly algorithm.
关键词： firefly algorithm,quantum particle swarm optimization,frequency invariant pattern,side lobe level,first null beam width,Broadband array
更新于2025-09-23 15:21:01
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Acid(g)/base(g)-controlled reversible ????1/2 of absorption spectrum of a functional dye film
摘要： UV–Vis absorption full width at half maximum (FWHM) plays a significant role not only in describing spectral shapes but also in determining the use of organic dyes for a particular application. For example, organic dyes with a relatively wide absorption FWHM are beneficial with respect to enhancing photon absorption efficiency of solar cells, whereas, for improving color purity in optical filters, narrow FWHM is desirable. Despite such a critical role, studies examining the modulation of absorption FWHM from an organic dye in the solid state are relatively lacking. In this work, we suggest rapid, simple, and effective method to control the absorption FWHM of a squarylium-based dye (SQ) film using an organic solvent vapor. Alternative treatments of base/acid gas to the SQ film (2.0 s for each gas) resulted in reversible absorption FWHM (D FWHM: 121 nm). From the systematic optical and morphology characterizations, it was revealed that changes in FWHM originated from reversible molecular arrangements between monomer-type and H-aggregate-type of SQ by efficient base/acid vapor diffusion into the SQ film. Moreover, the modulation exhibited high fatigue resistance against repeated gas treatments, which secures its practical applications. These results suggest that the proposed simple gas-treatment process in this work is beneficial for the efficient modulation of absorption FWHM of various organic dyes.
关键词： gas treatment,aggregation,organic dyes,full width at half maximum,monomer,absorption spectrum
更新于2025-09-23 15:19:57
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Graphene Nanoribbons from Electrostatic-Force-Controlled Electric Unzipping of Single- and Multi-Walled Carbon Nanotubes
摘要： An electrostatic forces (EF) controlled electric unzipping method was developed for producing graphene nanoribbon (GNR) from both the single- (SWCNT) and multi-walled carbon nanotubes (MWCNT). Experimentally, an electrostatic generator was employed by taking its two electrodes with oppositely charges to alternatively link to the metal vessel and the CNT/water solution to form two oppositely electric cycles corresponding to the EF in enhancement or reduction, respectively. Transmission electron microscopy images showed that this applied method can unzip both the SWCNT and MWCNT into relative GNRs. During the EF-controlled electric unzipping process, the concentration increase and EF-controlled in reduction model can produce GNR with enhanced width and quality.
关键词： electrostatic forces control,graphene nanoribbon,Single- and multi-walled carbon nanotubes,electric unzipping,width and quality
更新于2025-09-23 15:19:57
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Virtual binocular vision sensing and control of molten pool width for GMA additive manufactured thin-walled components
摘要： Gas metal arc (GMA) additive manufacturing (AM) is one of the significant wire and arc AM processes with the ability to produce large-scale metal parts in a layer by layer fashion. Despite this fact, techniques to realize process sensing and geometry control have not been perfectly developed. This study aims at molten pool width control in GMA AM using a passive vision sensing technique. A virtual binocular vision sensing system consisting of a biprism and a camera is designed to monitor the molten pool geometry. The molten pool width in a captured image pair is extracted by a series of procedures, such as sensor calibration, image pair rectification, disparity calculation, and width reconstruction. A verification test is conducted and reveals that the detection error of the sensing system is less than 3%. To keep consistent layer width in each layer, the deviation of the molten pool width is compensated by designing a fuzzy intelligent controller to adjust the arc current in real time. The effectiveness of the controller is evaluated via the deposition of thin-walled parts. The results indicate that the consistency of the molten pool width in GMA AM can be improved when employing the fuzzy controller.
关键词： fuzzy control,GMA AM,thin-walled parts,virtual binocular vision sensing,molten pool width
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - New designed electrode patterns on rear side of bifacial PERC solar cells
摘要： Present-day smartphones and tablets demand high audio fidelity (e.g., total harmonic distortion + noise, THD + N < 0.01%), and high noise immunity (e.g., power supply rejection ratio, PSRR > 80 dB) to allow high integration in an SoC. The design of conventional closed-loop pulse width modulation (PWM) Class-D amplifiers (CDAs) typically involves undesirable trade-offs between fidelity (qualified by THD + N), PSRR and switching frequency. In this paper, we propose a fully integrated CMOS CDA that embodies a novel input-modulated carrier generator and a novel phase-error-free PWM modulator, collectively allowing the employment of high loop-gain to achieve high PSRR, yet without compromising linearity/dynamic-range or resorting to high switching frequency. The prototype CDA, realized in 65 nm CMOS, achieves a THD + N of 0.0027% and a power efficiency of 94% when delivering 500 mW to an 8 ? load from VDD = 3.6 V. The PSRR of the prototype CDA is very high, –101 dB @217 Hz and 90 dB @1 kHz, arguably the highest to-date. Furthermore, the switching frequency of the prototype CDA varies from 320 to 420 kHz, potentially reducing the EMI due to spread-spectrum. In addition, the prototype CDA is versatile with a large operating-voltage range, with VDD ranging from rechargeable 1.2 V single battery to standard 3.6 V smart-device supply voltages.
关键词： Audio power amplifiers,power supply rejection ratio (PSRR),total harmonic distortion (THD),pulse width modulation (PWM),class D amplifiers
更新于2025-09-23 15:19:57
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Communication Compact CRLH Leaky-wave Antenna using TE20 Mode Substrate Integrated Waveguide for Broad Space Radiation Coverage
摘要： This paper introduces a combinational modulation method to be used in classic full-bridge single phase inverters. The proposed method eliminates even-order harmonics at the pulse width modulation (PWM) stage in the control section, unlike the conventional method of even order harmonic cancelation in the power stage, and offers a cost-effective design by switching one leg at high frequency. Using a low-cost digital signal controller platform, a regular sampling technique based on real-time calculation was employed to verify the feasibility of the proposed method on a 500-W single phase voltage source inverter. Performance characteristics, such as switching losses and harmonic distortions, are presented for the new approach and compared with a classic inverter modulation method.
关键词： switching frequency,Combinational logic circuits,inverters,pulse width modulation (PWM),silicon carbide,harmonic distortion
更新于2025-09-23 15:19:57
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Selective laser ablation and patterning on Ag thin films with width and depth control
摘要： Silver (Ag) films were deposited on glass substrates by radio frequency (RF) magnetron sputtering and then ablated by a 532 nm nanosecond pulsed laser. The effects of laser fluence and defocusing amount on the width and depth of laser-ablated grooves on 100- and 600-nm-thick Ag films were systematically investigated under single- and multi-scan ablation. The results suggested that the Ag films could be successfully removed from the substrate owing to laser-induced thermoelastic force or vaporization. It was confirmed that laser fluence and defocusing amount played very important roles in controlling the width and depth of the laser-ablated grooves. In the present work, grooves with widths ranging from 53 to 196 μm and depths ranging from 56 to 196 nm were obtained on 100-nm-thick Ag films by single-scan laser ablation, and laser ablation or removal with controllable depths was realized on 600-nm-thick Ag films by adopting single- or multi-scan (i.e., scanning numbers of 1–6). Furthermore, square spiral Ag patterns were successfully obtained by single- and multi-scan laser ablation and showed good electrical conductivity in a simple circuit. This work may have great potential applications in various fields that demand width and depth control of laser ablation/removal.
关键词： Width and depth control,Laser ablation,Ag thin films,RF magnetron sputtering,Nanosecond pulsed laser
更新于2025-09-23 15:19:57
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Zinc Oxo Clusters Improve the Optoelectronic Properties on Indium Phosphide Quantum Dots
摘要： This study explored the effect of zinc precursors on the optical properties of InP quantum dots (QDs) by controlling the reactivity of zinc carboxylates via a simple thermal treatment. The formation of zinc oxo clusters, Zn4O(oleate)6 and Zn7O2(oleate)10, during the thermal decomposition of zinc oleate was confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. By using the zinc oxo clusters as reaction precursors, high-quality InP QDs with high photoluminescence quantum yield (PLQY) and narrow full width at half maximum (FWHM) were synthesized. (Green QDs: PLQY=95%, FWHM=37 nm. Red QDs: PLQY=84%, FWHM=40 nm) The analysis results showed that the improved optoelectronic properties were achieved by two important functions of the zinc oxo clusters: 1) suppressing the rapid depletion of the highly reactive phosphorus source and inducing size uniformity of the In(Zn)P core, and 2) facilitating the formation of an oxidized buffer layer, which effectively controls defects. Likewise, the use of reactivity-controlled species is an effective strategy for the synthesis of well-designed QDs.
关键词： full width at half maximum,InP quantum dots,optoelectronic properties,photoluminescence quantum yield,zinc oxo clusters
更新于2025-09-23 15:19:57