热点论文带您探究5G和未来通信材料技术领域 ——图书馆前沿文献专题推荐服务（6）
2020-04-10
在上一期推荐中，我们从不同的角度解读5G的发展以及对6G的展望，比如5G组网的安全性、边缘计算MEC的应用前景等。在本期推荐中，我们开始着眼于5G和未来通信系统中面临的一些基础性问题的研究讨论。
在B5G和6G系统广泛讨论的Massive MIMO阵列技术以及毫米波技术，需要使用大量的射频器件，如果沿用目前的材料和工艺，必然造成系统复杂度高，成本居高不下的局面。因而，在B5G和6G标准讨论的过程中，相关材料技术的研究也备受关注，本期选取了4篇文献，介绍与B5G和6G发展相关的材料研究热点文章以及研究成果，包括“超表面”操控电磁波的超材料技术，碳纳米管技术在毫米波中的应用，钙钛矿二极管实现相同器件间的双向光信号传输，以及小型化、可扩展的相控阵系统等领域，推送给相关领域的科研人员。
An optically driven digital metasurface for programming electromagnetic functions
Xin Ge Zhang, etc
Nature Electronics,2020,(3):165–171
Metasurfaces are engineered surfaces that consist of subwavelength periodic elements and can be used to manipulate electromagnetic waves. Multifunctional or reconfigurable electromagnetic meta-devices based on a direct-current biasing system can be built using lumped electronic components. However, such meta-devices require bulky power supplies, field-programmable gate arrays, electrical wires and complex control circuits. Here, we report a digital metasurface platform that can be programmed optically to implement electromagnetic functions. Our digital platform has 6 × 6 subarrays, each of which contains 4 × 4 metasurface elements based on electronic varactors integrated with an optical interrogation network based on photodiodes. The interrogation network can convert visible light illumination patterns to voltages and applies bias to the metasurface elements, generating specific microwave reflection phase distributions. To illustrate the capabilities of our approach, we use the optically driven digital metasurface for external cloaking, illusion and dynamic vortex beam generation.
Wafer-scalable, aligned carbon nanotube transistors operating at frequencies of over 100 GHz
Christopher Rutherglen, etc.
Nature Electronics,2020,3: 156–164
Wireless device technology operating in the millimetre-wave regime (30 to 300 GHz) increasingly needs to offer both high performance and a high level of integration with complementary metal–oxide–semiconductor (CMOS) technology. Aligned carbon nanotubes are proposed as an alternative to III–V technologies in such applications because of their highly linear signal amplification and compatibility with CMOS. Here we report the wafer-scalable fabrication of aligned carbon nanotube field-effect transistors operating at gigahertz frequencies. The devices have gate lengths of 110 nm and are capable, in distinct devices, of an extrinsic cutoff frequency and maximum frequency of oscillation of over 100 GHz, which surpasses the 90 GHz cutoff frequency of radio-frequency CMOS devices with gate lengths of 100 nm and is close to the performance of GaAs technology. Our devices also offer good linearity, with distinct devices capable of a peak output third-order intercept point of 26.5 dB when normalized to the 1 dB compression power, and 10.4 dB when normalized to d.c. power.
Bidirectional optical signal transmission between two identical devices using perovskite diodes
Chunxiong Bao, etc
Nature Electronics,2020,,(3):156–164 .
The integration of optical signal generation and reception into one device—thus allowing a bidirectional optical signal transmission between two identical devices—is of value in the development of miniaturized and integrated optoelectronic devices. However, conventional solution-processable semiconductors have intrinsic material and design limitations that prevent them from being used to create such devices with a high performance. Here we report an efficient solution-processed perovskite diode that is capable of working in both emission and detection modes. The device can be switched between modes by changing the bias direction, and it exhibits light emission with an external quantum efficiency of over 21% and a light detection limit on a subpicowatt scale. The operation speed for both functions can reach tens of megahertz. Benefiting from the small Stokes shift of perovskites, our diodes exhibit a high specific detectivity (more than 2 × 1012 Jones) at its peak emission (~804 nm), which allows an optical signal exchange between two identical diodes. To illustrate the potential of the dual-functional diode, we show that it can be used to create a monolithic pulse sensor and a bidirectional optical communication system.
A flexible phased array system with low areal mass density
Article
Published: 17 May 2019
Mohammed Reza M.Hashemi, etc.
Nature Electronics,2019,2:195-205
Phased arrays are multiple antenna systems capable of forming and steering beams electronically using constructive and destructive interference between sources. They are employed extensively in radar and communication systems but are typically rigid, bulky and heavy, which limits their use in compact or portable devices and systems. Here, we report a scalable phased array system that is both lightweight and flexible. The array architecture consists of a self-monitoring complementary metal–oxide–semiconductor-based integrated circuit, which is responsible for generating multiple independent phase- and amplitude-controlled signal channels, combined with flexible and collapsible radiating structures. The modular platform, which can be collapsed, rolled and folded, is capable of operating standalone or as a subarray in a larger-scale flexible phased array system. To illustrate the capabilities of the approach, we created a 4 × 4 flexible phased array tile operating at 9.4–10.4 GHz, with a low areal mass density of 0.1 g cm−2. We also created a flexible phased array prototype that is powered by photovoltaic cells and intended for use in a wireless space-based solar power transfer array.
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