scholarly journals High Efficient Metadevices for Terahertz Beam Shaping

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinan Li ◽  
Zhixiong Shen ◽  
Qinggui Tan ◽  
Wei Hu
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Berry Phase ◽  
Vortex Generator ◽  
Maximum Efficiency ◽  
Optical Elements ◽  
Target Frequency ◽  
High Efficient ◽  
Pillar Arrays ◽  
Silicon Pillars

Metasurfaces supply a planar approach for flexible wavefront manipulation, thus facilitating the integration and minimization of optical elements, especially in the terahertz (THz) range. High efficient THz metadevices are highly pursued at present. Here, we propose a bilayer design to improve the efficiency of metadevice. Two silicon pillar arrays with distinguishing geometries are integrated on single silicon substrate. On one side, elliptical silicon pillars, with geometry optimized for the target frequency, are spatially orientated to realize the desired Pancharatnam-Berry phase. On the other side, uniform circular silicon pillars are set to suppress the reflection. With this design, versatile metadevices such as lens, lens array, polarization fork grating, Bessel vortex generator, and Airy beam generator are demonstrated. Maximum efficiency up to 95% for the target frequency and excellent design flexibility are verified. It provides a practical strategy for the generation of compact and high-efficiency THz metadevices, which suit for high-performance THz imaging and communication apparatuses.

scholarly journals A High-Efficient Multi-Output Mixed Dynamic/Static Single-Bit Adder Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Shima Mehrabi ◽  
Reza Faghih Mirzaee ◽  
Keivan Navi ◽  
Omid Hashemipour
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
State Of The Art ◽  
Dynamic Logic ◽  
Full Adder ◽  
Digital Electronics ◽  
High Efficient ◽  
Static Part

Dynamic logic is a well-known logic style which is widely used in digital electronics. A mixed dynamic/static full adder cell is presented in this paper with the aim of reaching high efficiency. The midoutputs are obtained from a Multi-output dynamic module. Then, a multiplexer generates final outputs in the static part. Several conventional and state-of-the-art dynamic adders are also surveyed and compared in the paper. All circuits are simulated by HSPICE with 32 nm CNFET technology. The proposed design is the fastest dynamic adder cell. In addition, it has approximately 5% higher efficiency in terms of PDP than the second most high-performance cell, which is DDCVS.

scholarly journals Recent progress in Pancharatnam–Berry phase optical elements and the applications for virtual/augmented realities

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Yun-Han Lee ◽  
Guanjun Tan ◽  
Tao Zhan ◽  
Yishi Weng ◽  
Guigeng Liu ◽  
...  
Keyword(s):  
Recent Progress ◽  
High Efficiency ◽  
Berry Phase ◽  
Large Angle ◽  
Beam Deflection ◽  
Optical Elements ◽  
Display Devices ◽  
Head Mounted Display ◽  
Fast Switching ◽  
Display Systems

AbstractIn this review paper,we report recent progress on Pancharatnam-Berry (PB) phase optical elements, such as lens, grating, and deflector. PB lenses exhibit a fast switching time between two or more focal lengths with large diopter change and aperture size, which is particularly attractive for addressing the accommodation mismatch in head-mounted display devices. On the other hand, PB gratings and deflectors offer a large-angle beam deflection with wide acceptance cone and high efficiency, as compared to conventional volume gratings. Such merits provide great advantages for waveguide-coupling augmented reality headsets. Moreover, the thickness of PB optical elements is only a few micrometers, thus they can be conveniently integrated into modern wearable display systems.

Technological Assurance of High-Efficiency Machining of Internal Rope Threads on Computer Numerical Control Milling Machines

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Anna Neshta ◽  
Dmytro Kryvoruchko ◽  
Michal Hatala ◽  
Vitalii Ivanov ◽  
Frantisek Botko ◽  
...  
Keyword(s):  
High Efficiency ◽  
Dimensional Accuracy ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Maximum Efficiency ◽  
Internal Thread ◽  
Cnc Milling ◽  
High Efficient ◽  
Milling Machines ◽  
Machined Parts

The analysis of various methods of machining of rope internal thread ISO 10208, DIN 20317 has been carried out and the criteria of high-efficiency machining have been formulated. The concept of the method has been developed, which supposes the designing of the construction of noncore tool and the calculation of the parameters of mechanical trajectory with the purpose of ensuring the machining per one pass on the computer numerical control (CNC) milling machine. The compensation procedure of dimensional wear of insert has been developed. While machining the production batch of the parts in an experimental way, the optimum cutting conditions have been determined which allow ensuring the maximum efficiency on reaching the required roughness and the dimensional accuracy of the profile of rope thread. The performed statistical analysis of the machined parts allowed to establish that dispersions of the actual values of profiles' roughness follow Gauss' law. In an experimental way, it has been proved that the application of the proposed method increased the efficiency of machining of the internal rope thread by 2.5 times. On the basis of comparison of engineering-and-economical performance, the efficient fields of application of high-efficient method of machining of the rope threads have been determined.

scholarly journals Titanium dioxide metasurface manipulating high-efficiency and broadband photonic spin Hall effect in visible regime

Nanophotonics ◽  
2020 ◽  
Vol 9 (14) ◽  
pp. 4327-4335
Author(s):  
Wei Zhu ◽  
Ruisheng Yang ◽  
Guangzhou Geng ◽  
Yuancheng Fan ◽  
Xuyue Guo ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Angular Momentum ◽  
Hall Effect ◽  
High Efficiency ◽  
Berry Phase ◽  
Spin Hall Effect ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
High Efficient

AbstractThe interactions of photonic spin angular momentum and orbital angular momentum, i.e., the spin-orbit coupling in focused beams, evanescent waves or artificial photonic structures, have attracted intensive investigations for the unusual fundamental phenomena in physics and potential applications in optical and quantum systems. It is of fundamental importance to enhance performance of spin-orbit coupling in optics. Here, we demonstrate a titanium dioxide (TiO2)–based all-dielectric metasurface exhibiting a high efficient control of photonic spin Hall effect (PSHE) in a transmissive configuration. This metasurface can achieve high-efficiency symmetric spin-dependent trajectory propagation due to the spin-dependent Pancharatnam-Berry phase. The as-formed metadevices with high-aspect-ratio TiO2 nanofins are able to realize (86%, measured at 514 nm) and broadband PSHEs in visible regime. Our results provide useful insights on high-efficiency metasurfaces with versatile functionalities in visible regime.

scholarly journals High Efficient Resonant DC-DC Converter for Automotive LED Driver Applications using Phase Shift Control Strategy

2021 ◽  
Vol 7 (10) ◽  
pp. 1-7
Author(s):  
Syed Simran.K, Md.Anwar, Dr.Sharan Reddy and Santosh.B.M
Keyword(s):  
Phase Shift ◽  
High Performance ◽  
High Efficiency ◽  
Switching Frequency ◽  
Led Driver ◽  
Load Current ◽  
Shift Control ◽  
Wide Range ◽  
High Efficient ◽  
Overall Performance

A high frequency DC-DC converter operating in the MHz range is proposed, which can achieve unbiased load current even while maintaining high performance over a wide range of load voltages. Due to these functions, the provided transformer is suitable for LED driver applications, which require different types of LEDs to operate with controlled current. The proposed transformer satisfies the uncontrolled load current using the LCL-T resonance community and achieves high efficiency using a predetermined switching frequency. The LCL-T resonance transformer also works effectively in controlling its output to the required rating using phase shift control. The overall performance of the LCL-T Echo transducer was evaluated and compared with the LC3L controlled echo transducer. Simulation work is done using the MATLAB / Simulink program.

scholarly journals A Fast-Response and Helicity-Dependent Lens Enabled by Micro-Patterned Dual-Frequency Liquid Crystals

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 111 ◽  
Author(s):  
Wei Duan ◽  
Peng Chen ◽  
Shi-Jun Ge ◽  
Xiao Liang ◽  
Wei Hu
Keyword(s):  
Liquid Crystals ◽  
High Efficiency ◽  
Switching Time ◽  
Berry Phase ◽  
Fast Response ◽  
Dual Frequency ◽  
Optical Elements ◽  
New Strategy ◽  
Patterning Technique ◽  
Liquid Crystal Lens

Liquid crystals are excellent candidates for tunable optical elements due to their large birefringence and continuous tunability by external fields. A dual-frequency liquid crystal lens integrated with Pancharatnam–Berry phase was fabricated via a dynamic photo-patterning technique. The proposed lens exhibited distinctive polarization-dependent characteristics and ultra-high efficiency rates of up to 95%. Via merely alternating the frequency of the applied electric field, the switching time between unfocused and focused states was measured in submilliseconds. This work supplies a new strategy for fast-response, high-efficiency and helicity-dependent lens with merits of easy fabrication and low power consumption.

scholarly journals Broadband high-efficiency dielectric metasurfaces for the visible spectrum

2016 ◽  
Vol 113 (38) ◽  
pp. 10473-10478 ◽  
Author(s):  
Robert C. Devlin ◽  
Mohammadreza Khorasaninejad ◽  
Wei Ting Chen ◽  
Jaewon Oh ◽  
Federico Capasso
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Numerical Aperture ◽  
Optical Loss ◽  
Visible Spectrum ◽  
Optical Element ◽  
Atomic Layer ◽  
Optical Elements ◽  
Layer Deposition ◽  
Visible Wavelengths

Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Original dielectric metasurfaces are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Thus, it is critical that new materials and nanofabrication techniques be developed to extend dielectric metasurfaces across the visible spectrum and to enable applications such as high numerical aperture lenses, color holograms, and wearable optics. Here, we demonstrate high performance dielectric metasurfaces in the form of holograms for red, green, and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide with surface roughness less than 1 nm and negligible optical loss. We use a process for fabricating dielectric metasurfaces that allows us to produce anisotropic, subwavelength-spaced dielectric nanostructures with shape birefringence. This process is capable of realizing any high-efficiency metasurface optical element, e.g., metalenses and axicons.

scholarly journals Hydrogenated Cs2AgBiBr6 for High-Efficient Lead-Free Inorganic Double Perovskite Solar Cell

2021 ◽  
Author(s):  
Zeyu Zhang ◽  
Qingde Sun ◽  
Yue Lu ◽  
Feng Lu ◽  
Xulin Mu ◽  
...  
Keyword(s):  
Solar Cell ◽  
High Performance ◽  
High Efficiency ◽  
Energy Levels ◽  
Perovskite Solar Cells ◽  
Double Perovskite ◽  
Perovskite Solar Cell ◽  
Lead Free ◽  
High Efficient ◽  
New Strategy

Abstract Development of the stable, lead-free inorganic perovskite material is of greatly importance on fabricating the third-generation solar cell. Until now, double perovskite, such as Cs2AgBiBr6, has been proved to be one of the most potential candidates to solve the toxicity and stability issues of traditional lead halide perovskite solar cells (PSCs). However, due to a wide and indirect bandgap of Cs2AgBiBr6 film, its light absorption ability is largely limited and the photoelectronic conversion efficiency (PCE) is normally lower than 2.5%. In this text, by using a hydrogenation method, the bandgap (Eg) of Cs2AgBiBr6 films could be tunable from 2.14 eV to 1.61 eV. At the same time, the highest PCE of hydrogenated Cs2AgBiBr6 perovskite solar cell has been improved more than 150% up to 6.27%. To the best of our knowledge, this is a record high efficiency of Cs2AgBiBr6-based perovskite solar cell. Further investigations confirmed that the interstitial doping of atomic hydrogen (H*) in Cs2AgBiBr6 lattice could not only adjust its valence and conduction band energy levels, but also optimize the carrier mobility from 1.71 cm2V-1s-1 to 9.28 cm2V-1s-1 and enhance the carrier lifetime from 18.85 ns to 41.86 ns. All these works provide a new strategy to fabricate the high performance lead-free inorganic PSCs.

A vacuum flash–assisted solution process for high-efficiency large-area perovskite solar cells

Science ◽  
2016 ◽  
Vol 353 (6294) ◽  
pp. 58-62 ◽  
Author(s):  
Xiong Li ◽  
Dongqin Bi ◽  
Chenyi Yi ◽  
Jean-David Décoppet ◽  
Jingshan Luo ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Solution Process ◽  
Maximum Efficiency ◽  
Large Area ◽  
Large Size ◽  
Metal Halide Perovskite ◽  
Practical Development

Metal halide perovskite solar cells (PSCs) currently attract enormous research interest because of their high solar-to-electric power conversion efficiency (PCE) and low fabrication costs, but their practical development is hampered by difficulties in achieving high performance with large-size devices. We devised a simple vacuum flash–assisted solution processing method to obtain shiny, smooth, crystalline perovskite films of high electronic quality over large areas. This enabled us to fabricate solar cells with an aperture area exceeding 1 square centimeter, a maximum efficiency of 20.5%, and a certified PCE of 19.6%. By contrast, the best certified PCE to date is 15.6% for PSCs of similar size. We demonstrate that the reproducibility of the method is excellent and that the cells show virtually no hysteresis. Our approach enables the realization of highly efficient large-area PSCs for practical deployment.

scholarly journals High Efficiency Focusing and Vortex Generator Based on Polarization-Insensitive Gallium Nitride Metasurface

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2638
Author(s):  
Zhitong Sun ◽  
Bijun Xu ◽  
Bairui Wu ◽  
Xiaogang Wang ◽  
Hao Ying
Keyword(s):  
Gallium Nitride ◽  
Optical Communication ◽  
High Efficiency ◽  
Structural Parameters ◽  
Vortex Generator ◽  
Maximum Efficiency ◽  
Dynamic Phase ◽  
Linearly Polarized ◽  
Polarization Insensitive ◽  
Focused Beam

In this paper, two polarization-insensitive Gallium Nitride (GaN) metasurfaces based on a dynamic phase for adjusting the wavefront are proposed. Specifically, we obtained the target phase to satisfy some design conditions by changing the structural parameters at the nanoscales. Under the irradiation of linearly polarized (LP) light and circularly polarized (CP) light, respectively, one of the metasurfaces can generate a focused beam with an efficiency of 84.7%, and the other can generate a vortex beam with a maximum efficiency of 76.6%. Our designed metasurfaces will have important applications in optical communication, holographic projection, and particle capture.

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