分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yao Zhang
Hua-Ying Liu
Xiaoyi Liu
Peng Xu
Xiang Dong
Pengfei Fan
Hua Yu
Dong Pan
Zhijun Yin
Guilu Long
Shi-Ning Zhu
Zhenda Xie
摘要： Free-space optical communication (FSO) can achieve fast, secure and license-free communication without need for physical cables, making it a cost-effective, energy-efficient and flexible solution when the fiber connection is absent. To establish FSO connection on-demand, it is essential to build portable FSO devices with compact structure and light weight. Here, we develop a miniaturized FSO system and realize 9.16 Gbps FSO between two nodes that is 1 km apart, using a commercial fiber-coupled optical transceiver module with no optical amplification. Basing on the home-made compact 90 mm-diameter acquisition, pointing and tracking (APT) system with four-stage close-loop feedback, the link tracking error is controlled at 3 {\mu}rad and results an average coupling loss of 13.7 dB. Such loss is within the tolerance of the commercial optical communication modules, and without the need of optical amplifiers, which contributes to the low system weight and power consumption. As a result, a single FSO device weighs only about 12 kg, making it compact and portable for potential application in high-speed wireless communication. Our FSO link has been tested up to 4 km, with link loss of 18 dB in the foggy weather in Nanjing, that shows longer distances can be covered with optical amplification.
分类： 其他 >> 综合 提交时间： 2023-01-02 合作期刊: 《Art & Design Research》
摘要： In the past 30 years, the development of brownland into green land has become an important way for the sustainable development and management of urban land. Fully understanding the various application scenarios and values of this approach is helpful to explore its efforts in providing ecosystem services and meet the development needs of different types of cities. This paper reviews the practice and literature of brownfield redevelopment from the perspective of landscape architecture, and obtains the process of its theoretical development and its understanding deepening. Through sorting out the relevant discipline literature, the seven main green space types and their potential broad benefits are summarized, and we realize that the brownfield itself has many values that cannot be ignored in the development process. On this basis, it proposes that there is a new cognition of the relationship between brownfield and green space.
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