scholarly journals High efficiency half-wave retardation in diffracted light by coupled waves

2012 ◽  
Vol 20 (4) ◽  
pp. 4681 ◽  
Author(s):  
Kalle Ventola ◽  
Jani Tervo ◽  
Samuli Siitonen ◽  
Hemmo Tuovinen ◽  
Markku Kuittinen
Keyword(s):  
High Efficiency ◽  
Half Wave ◽  
Wave Retardation

scholarly journals Novel High-Efficiency High Step-Up DC–DC Converter with Soft Switching and Low Component Voltage Stress for Photovoltaic System

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1112
Author(s):  
Yu-En Wu ◽  
Jyun-Wei Wang
Keyword(s):  
High Voltage ◽  
Output Voltage ◽  
High Efficiency ◽  
Low Voltage ◽  
Leakage Inductance ◽  
Power Switch ◽  
Half Wave Voltage ◽  
Half Wave ◽  
Voltage Stress ◽  
Voltage Doubler

This study developed a novel, high-efficiency, high step-up DC–DC converter for photovoltaic (PV) systems. The converter can step-up the low output voltage of PV modules to the voltage level of the inverter and is used to feed into the grid. The converter can achieve a high step-up voltage through its architecture consisting of a three-winding coupled inductor common iron core on the low-voltage side and a half-wave voltage doubler circuit on the high-voltage side. The leakage inductance energy generated by the coupling inductor during the conversion process can be recovered by the capacitor on the low-voltage side to reduce the voltage surge on the power switch, which gives the power switch of the circuit a soft-switching effect. In addition, the half-wave voltage doubler circuit on the high-voltage side can recover the leakage inductance energy of the tertiary side and increase the output voltage. The advantages of the circuit are low loss, high efficiency, high conversion ratio, and low component voltage stress. Finally, a 500-W high step-up converter was experimentally tested to verify the feasibility and practicability of the proposed architecture. The results revealed that the highest efficiency of the circuit is 98%.

scholarly journals High-Efficiency All-Dielectric Metasurfaces for the Generation and Detection of Focused Optical Vortex for the Ultraviolet Domain

2020 ◽  
Vol 10 (16) ◽  
pp. 5716
Author(s):  
Ziheng Zhang ◽  
Tong Li ◽  
Xiaofei Jiao ◽  
Guofeng Song ◽  
Yun Xu
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Dielectric Material ◽  
Optical Vortex ◽  
Magnetic Dipoles ◽  
Half Wave ◽  
Potential Applications ◽  
On Chip ◽  
High Flexibility ◽  
Meta Atom

The optical vortex (OV) has drawn considerable attention owing to its tremendous advanced applications, such as optical communication, quantum entanglement, and on-chip detectors. However, traditional OV generators suffer from a bulky configuration and limited performance, especially in the ultraviolet range. In this paper, we utilize a large bandgap dielectric material, niobium pentoxide (Nb2O5), to construct ultra-thin and compact transmission-type metasurfaces to generate and detect the OV at a wavelength of 355 nm. The meta-atom, which operates as a miniature half-wave plate and demonstrates a large tolerance to fabrication error, manipulates the phase of an incident right-handed circular polarized wave with high cross-polarized conversion efficiency (around 86.9%). The phase delay of π between the orthogonal electric field component is attributed to the anti-parallel magnetic dipoles induced in the nanobar. Besides, focused vortex generation (topological charge l from 1 to 3) and multichannel detection (l from −2 to 2) are demonstrated with high efficiency, up to 79.2%. We envision that our devices of high flexibility may have potential applications in high-performance micron-scale integrated ultraviolet nanophotonics and meta-optics.

High‐efficiency TEM00continuous‐wave (Al,Ga)As epitaxial surface‐emitting lasers and effect of half‐wave periodic gain

1989 ◽  
Vol 54 (13) ◽  
pp. 1209-1211 ◽  
Author(s):  
P. L. Gourley ◽  
T. M. Brennan ◽  
B. E. Hammons ◽  
S. W. Corzine ◽  
R. S. Geels ◽  
...  
Keyword(s):  
High Efficiency ◽  
Half Wave ◽  
Surface Emitting Lasers ◽  
Emitting Lasers

scholarly journals Compact and High-Efficiency Rectenna for Wireless Power-Harvesting Applications

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Dalia H. Sadek ◽  
Heba A. Shawkey ◽  
Abdelhalim A. Zekry
Keyword(s):  
High Efficiency ◽  
Single Layer ◽  
Load Resistance ◽  
Center Frequency ◽  
Wireless Power ◽  
Power Harvesting ◽  
Rectifier Circuit ◽  
Half Wave ◽  
Voltage Doubler ◽  
Conversion Efficiencies

A compact, single-layer microstrip rectenna for dedicated far-field RF wireless power-harvesting applications is presented. The proposed rectenna circuit configurations including multiband triple L-Arms patch antenna with diamond slot ground are designed to resonate at 10, 13, 17, and 26 GHz with 10 dB impedance bandwidths of 0.67, 0.8, 2.45, and 4.3 GHz, respectively. Two rectifier designs have been fabricated and compared, a half wave rectifier with a shunted Schottky diode and a voltage doubler rectifier. The measured and simulated maximum conversion efficiencies of the rectifier using the shunted diode half-wave rectifier are 41%, and 34%, respectively, for 300 Ω load resistance, whereas they amount to 50% and 43%, respectively, for voltage doubler rectifier with 650 Ω load resistance. Compared to the shunted rectifier circuit, it is significant to note that the voltage doubler rectifier circuit has higher efficiency. Both rectifier’s circuits presented are tuned for a center frequency of 10 GHz and implemented using 0.81 mm thick Rogers (RO4003c) substrate. The overall size of the antenna is 16.5 × 16.5 mm2, and the shunted rectifier is only 13.3 × 8.2 mm2 and 19.7 × 7.4 mm2 for the voltage doubler rectifier. The antenna is designed and simulated using the CST Microwave Studio Suite (Computer Simulation Technology), while the complete rectenna is simulated using Agilent’s ADS tool with good agreement for both simulation and measurements.

scholarly journals A Compact Thévenin Model for a Rectenna and Its Application to an RF Harvester with MPPT

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1641 ◽  
Author(s):  
Manel Gasulla ◽  
Edgar Ripoll-Vercellone ◽  
Ferran Reverter
Keyword(s):  
Power Efficiency ◽  
High Efficiency ◽  
Maximum Efficiency ◽  
Maximum Power Point ◽  
Half Wave ◽  
Proposed Model ◽  
Current Voltage ◽  
Power Point ◽  
Transmitting Antenna ◽  
Current Voltage Relationship

This paper proposes a compact Thévenin model for a rectenna. This model is then applied to design a high-efficiency radio frequency harvester with a maximum power point tracker (MPPT). The rectenna under study consists of an L-matching network and a half-wave rectifier. The derived model is simpler and more compact than those suggested so far in the literature and includes explicit expressions of the Thévenin voltage (Voc) and resistance and of the power efficiency related with the parameters of the rectenna. The rectenna was implemented and characterized from −30 to −10 dBm at 808 MHz. Experimental results agree with the proposed model, showing a linear current–voltage relationship as well as a maximum efficiency at Voc/2, in particular 60% at −10 dBm, which is a remarkable value. An MPPT was also used at the rectenna output in order to automatically work at the maximum efficiency point, with an overall efficiency near 50% at −10 dBm. Further tests were performed using a nearby transmitting antenna for powering a sensor node with a power consumption of 4.2 µW.

Anisotropic Nano-Imprinting Technique for Fabricating a Patterned Optical Film of a Liquid Crystalline Polymer

2008 ◽  
Vol 8 (9) ◽  
pp. 4775-4778 ◽  
Author(s):  
Yong-Woon Lim ◽  
Chang-Hwan Kwak ◽  
Sin-Doo Lee
Keyword(s):  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Scale Level ◽  
Alignment Layer ◽  
Anisotropic Surface ◽  
Optical Film ◽  
Half Wave ◽  
Quarter Wave ◽  
Wave Retardation

We developed an anisotropic nano-imprinting technique, which combines the exposure of ultraviolet light, to fabricate a patterned optical film of a liquid crystalline polymer (LCP). The nano-imprinted LCP film has two-fold functionality of an in-cell retarder and an alignment layer of liquid crystal (LC) molecules. In addition to the geometrically generated microgrooves, the anisotropic surface interactions of the LCP acquired at a nano-scale level during the imprinting process results in the LC alignment on the patterned LCP film without any surface treatment. The nano-imprinted, quarter wave LCP was implemented into a LC cell which produces half-wave retardation under crossed polarizers.

scholarly journals High-Efficiency and Wide-Angle Versatile Polarization Controller Based on Metagratings

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 623 ◽  
Author(s):  
Kun Song ◽  
Ruonan Ji ◽  
Duman Shrestha ◽  
Changlin Ding ◽  
Yahong Liu ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
High Efficiency ◽  
Wide Angle ◽  
Polarization Control ◽  
Dielectric Gratings ◽  
Single Function ◽  
Half Wave ◽  
Single Structure ◽  
Quarter Wave

Metamaterials with their customized properties enable us to efficiently manipulate the polarization states of electromagnetic waves with flexible approaches, which is of great significance in various realms. However, most current metamaterial-based polarization controllers can only realize single function, which has extremely hindered the expansion of their applications. Here, we experimentally demonstrate highly efficient and multifunctional polarization conversion effects using metagrating by integrating single-structure metallic meta-atoms into the dielectric gratings. Benefiting from the combined advantages of the gratings and the metamaterials, the considered metagrating can operate in transmission and reflection modes simultaneously, acting as a high-performance and wide-angle quarter-wave or half-wave plate with distinct functions in different frequency bands. This metagrating structure is scalable to other frequency ranges and may provide opportunities to design compact multifunctional optical polarization control devices.

scholarly journals N, S, P-Codoped Graphene-Supported Ag-MnFe2O4 Heterojunction Nanoparticles as Bifunctional Oxygen Electrocatalyst with High Efficiency

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1550
Author(s):  
Hongzhou Dong ◽  
Yingjie Chen ◽  
Chong Gong ◽  
Lina Sui ◽  
Qiong Sun ◽  
...  
Keyword(s):  
Current Density ◽  
Oxygen Evolution Reaction ◽  
Precious Metal ◽  
High Efficiency ◽  
Reduction Reaction ◽  
Half Wave ◽  
Slow Kinetics ◽  
Alkaline Conditions ◽  
Doped Graphene ◽  
Kinetics Of

Due to slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharging and charging processes, it is essential to rationally design and synthesize non-precious metal bifunctional electrocatalysts with good performance for metal-air batteries. Herein, Ag-MnFe2O4 heterojunction nanoparticles supported on N, S, P-codoped graphene (NSPG) are developed with enhanced ORR and OER bifunctional electrocatalytic activities and stability. In contrast, S, P-doped graphene (SPG) and N, P-doped graphene (NPG) show less stabilization for the heterojunction particles. For example, under alkaline conditions, the ORR half-wave potential of Ag-MnFe2O4/NSPG can reach 0.831 V, and the over potential for OER is 0.56 V at the current density 10 mA·cm−2. Furthermore, Ag-MnFe2O4/NSPG shows better methanol resistance and durability than Pt/C catalysts.

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