scholarly journals Mid-infrared polarization-controlled broadband achromatic metadevice

2020 ◽  
Vol 6 (37) ◽  
pp. eabc0711 ◽  
Author(s):  
Kai Ou ◽  
Feilong Yu ◽  
Guanhai Li ◽  
Wenjuan Wang ◽  
Andrey E. Miroshnichenko ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
State Of The Art ◽  
Extinction Ratio ◽  
Chromatic Aberration ◽  
Cmos Technology ◽  
Practical Applications ◽  
Polarization Control ◽  
Large Size ◽  
Polarization Multiplexing

Metasurfaces provide a compact, flexible, and efficient platform to manipulate the electromagnetic waves. However, chromatic aberration imposes severe restrictions on their applications in broadband polarization control. Here, we propose a broadband achromatic methodology to implement polarization-controlled multifunctional metadevices in mid-wavelength infrared with birefringent meta-atoms. We demonstrate the generation of polarization-controlled and achromatically on-axis focused optical vortex beams with diffraction-limited focal spots and switchable topological charge (L∥ = 0 and L⊥ = 2). Besides, we further implement broadband achromatic polarization beamsplitter with high polarization isolation (extinction ratio up to 21). The adoption of all-silicon configuration not only facilitates the integration with CMOS technology but also endows the polarization multiplexing meta-atoms with broad phase dispersion coverage, ensuring the large size and high performance of the metadevices. Compared with the state-of-the-art chromatic aberration-restricted polarization-controlled metadevices, our work represents a substantial advance and a step toward practical applications.

scholarly journals Flux Method Growth of Large Size Group IV–V 2D GeP Single Crystals and Photoresponse Application

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 235
Author(s):  
Shuqi Zhao ◽  
Tongtong Yu ◽  
Ziming Wang ◽  
Shilei Wang ◽  
Limei Wei ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystals ◽  
High Performance ◽  
Group Iv ◽  
X Ray Diffraction ◽  
High Quality ◽  
Practical Applications ◽  
Large Size ◽  
Growth Method ◽  
Polarized Raman

Two-dimensional (2D) materials driven by their unique electronic and optoelectronic properties have opened up possibilities for their various applications. The large and high-quality single crystals are essential to fabricate high-performance 2D devices for practical applications. Herein, IV-V 2D GeP single crystals with high-quality and large size of 20 × 15 × 5 mm3 were successfully grown by the Bi flux growth method. The crystalline quality of GeP was confirmed by high-resolution X-ray diffraction (HRXRD), Laue diffraction, electron probe microanalysis (EPMA) and Raman spectroscopy. Additionally, intrinsic anisotropic optical properties were investigated by angle-resolved polarized Raman spectroscopy (ARPRS) and transmission spectra in detail. Furthermore, we fabricated high-performance photodetectors based on GeP, presenting a relatively large photocurrent over 3 mA. More generally, our results will significantly contribute the GeP crystal to the wide optoelectronic applications.

Integrated Optoelectronic Devices on Silicon

2012 ◽  
Vol 1396 ◽  
Author(s):  
Di Liang ◽  
John E. Bowers
Keyword(s):  
Output Power ◽  
Integrated Circuit ◽  
High Speed ◽  
High Performance ◽  
Continuous Wave ◽  
Light Emission ◽  
Extinction Ratio ◽  
Cmos Technology ◽  
Oxide Semiconductor ◽  
Pockels Effect

ABSTRACTSilicon (Si) has been the dominating material platform of microelectronics over half century. Continuous technological advances in circuit design and manufacturing enable complementary metal-oxide semiconductor (CMOS) chips with increasingly high integration complexity to be fabricated in an unprecedently scale and economical manner. Conventional Si-based planar lightwave circuits (PLCs) has benefited from advanced CMOS technology but only demonstrate passive functionalities in most circumstances due to poor light emission efficiency and weak major electro-optic effects (e.g., Pockels effect, the Kerr effect and the Franz–Keldysh effect) in Si. Recently, a new hybrid III-V-on-Si integration platform has been developed, aiming to bridge the gap between Si and III-V direct-bandgap materials for active Si photonic integrated circuit applications. Since then high-performance lasers, amplifiers, photodetectors and modulators, etc. have been demonstrated. Here we review the most recent progress on hybrid Si lasers and high-speed hybrid Si modulators. The former include distributed feedback (DFB) lasers showing over 10 mW output power and up to 85 oC continuous-wave (cw) operation, compact hybrid microring lasers with cw threshold less than 4 mA and over 3 mW output power, and 4-channel hybrid Si AWG lasers with channel space of 360 GHz. Recently fabricated traveling-wave electro-absorption modulators (EAMs) and Mach-Zehnder interferometer modulators (MZM) on this platform support 50 Gb/s and 40 Gb/s data transmission with over 10 dB extinction ratio, respectively.

scholarly journals Pitfalls and Best Practices in Algorithm Configuration

2019 ◽  
Vol 64 ◽  
pp. 861-893 ◽  
Author(s):  
Katharina Eggensperger ◽  
Marius Lindauer ◽  
Frank Hutter
Keyword(s):  
Best Practices ◽  
High Performance ◽  
State Of The Art ◽  
Parameter Tuning ◽  
Propositional Satisfiability ◽  
Ai Planning ◽  
Practical Applications ◽  
Automated Algorithm ◽  
Algorithm Configuration ◽  
Satisfiability Solving

Good parameter settings are crucial to achieve high performance in many areas of artificial intelligence (AI), such as propositional satisfiability solving, AI planning, scheduling, and machine learning (in particular deep learning). Automated algorithm configuration methods have recently received much attention in the AI community since they replace tedious, irreproducible and error-prone manual parameter tuning and can lead to new state-of-the-art performance. However, practical applications of algorithm configuration are prone to several (often subtle) pitfalls in the experimental design that can render the procedure ineffective. We identify several common issues and propose best practices for avoiding them. As one possibility for automatically handling as many of these as possible, we also propose a tool called GenericWrapper4AC.

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.

PRESENT STATUS AND FUTURE DIRECTIONS OF SiGe HBT TECHNOLOGY

2007 ◽  
Vol 17 (01) ◽  
pp. 61-80
Author(s):  
Marwan H. Khater ◽  
Thomas N. Adam ◽  
Rajendran Krishnasamy ◽  
Mattias E. Dahlstrom ◽  
Jae-Sung Rieh ◽  
...  
Keyword(s):  
High Performance ◽  
State Of The Art ◽  
Device Simulation ◽  
Cmos Technology ◽  
Advanced Materials ◽  
Vertical Scaling ◽  
Device Structure ◽  
Future Directions ◽  
Materials Development ◽  
Sige Hbt

The implementation of challenging novel materials and process techniques has led to remarkable device improvements in state-of-the-art high-performance SiGe HBTs, rivaling their III-V compound semiconductor counterparts. Vertical scaling, lateral scaling, and device structure innovations required to improve SiGe HBTs performance have benefited from advanced materials and process techniques developed for next generation CMOS technology. In this work, we present a review of recent process and materials development enabling operational speeds of SiGe HBTs approaching 400 GHz. In addition, we present device simulation results that show the extendibility of SiGe HBT technology performance towards half-terahertz and beyond with further scaling and device structure improvements.

scholarly journals Single-layer phase gradient mmWave metasurface for incident angle independent focusing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wonwoo Lee ◽  
Semin Jo ◽  
Kanghyeok Lee ◽  
Hong Soo Park ◽  
Junhyuk Yang ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
Phase Distribution ◽  
Focal Point ◽  
Incident Angle ◽  
Rapid Development ◽  
Single Layer ◽  
Phase Gradient ◽  
Wave Focusing ◽  
Practical Applications

AbstractMetasurfaces allow the rapid development of compact and flat electromagnetic devices owing to their capability in manipulating the wavefront of electromagnetic waves. Particularly, with respect to the metasurface lenses, wide operational bandwidth and wide incident angle behavior are critically required for practical applications. Herein, a single-layer phase gradient metasurface lens is presented to achieve millimeter-wave focusing at a focal point of 13 mm regardless of the incident angle. The proposed metasurface lens is fabricated by constructing subwavelength-thick (< λ/10) phase elements composed of two metallic layers separated by a single dielectric substrate that exhibits low-Q resonance properties and a wide phase modulation range with satisfactory transmissivity. By controlling the spatial phase distribution, the proposed metasurface lens successfully realises effective wavefront manipulation properties and high-performance electromagnetic-wave-focusing characteristics over a wide operating frequency range from 35 to 40 GHz with incident angle independency up to 30°.

scholarly journals Multiple objects tracking in the UAV system based on hierarchical deep high-resolution network

2021 ◽  
Author(s):  
Wei Huang ◽  
Xiaoshu Zhou ◽  
Mingchao Dong ◽  
Huaiyu Xu
Keyword(s):  
High Resolution ◽  
Object Tracking ◽  
High Performance ◽  
State Of The Art ◽  
Class Imbalance ◽  
Unified Framework ◽  
Multiple Objects ◽  
Tracking Process ◽  
Objects Tracking ◽  
Different Types

AbstractRobust and high-performance visual multi-object tracking is a big challenge in computer vision, especially in a drone scenario. In this paper, an online Multi-Object Tracking (MOT) approach in the UAV system is proposed to handle small target detections and class imbalance challenges, which integrates the merits of deep high-resolution representation network and data association method in a unified framework. Specifically, while applying tracking-by-detection architecture to our tracking framework, a Hierarchical Deep High-resolution network (HDHNet) is proposed, which encourages the model to handle different types and scales of targets, and extract more effective and comprehensive features during online learning. After that, the extracted features are fed into different prediction networks for interesting targets recognition. Besides, an adjustable fusion loss function is proposed by combining focal loss and GIoU loss to solve the problems of class imbalance and hard samples. During the tracking process, these detection results are applied to an improved DeepSORT MOT algorithm in each frame, which is available to make full use of the target appearance features to match one by one on a practical basis. The experimental results on the VisDrone2019 MOT benchmark show that the proposed UAV MOT system achieves the highest accuracy and the best robustness compared with state-of-the-art methods.

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