Increasing the spectral efficiency and per channel data rate have historically been shown to be the most cost-effective method to meet the need of ever growing capacity demand in the core network. In this paper we rev...Increasing the spectral efficiency and per channel data rate have historically been shown to be the most cost-effective method to meet the need of ever growing capacity demand in the core network. In this paper we review recent progress in high-speed and high-spectral-efficient optical transmission technology. We discuss spectrally efficient modulation and detection technologies that have been experimentally explored for future 100-Gb/s and above optical transmission system. Emerging methods aiming at extending system reach for noise and nonlinearity-stressed high spectral efficiency optical transmission systems have also been reviewed. We show that spectrallyefficient multilevel coding coupled with polarization multiplexing and digital coherent detection has the potential to enable 400Gb/s per channel WDM system operating with existing 50GHzspaced WDM infrastructure at a spectral efficiency of 8b/s/Hz.展开更多
This paper studies the capacity issues of a wireless communication system that implements single channel full duplex(SCFD) communication at the base station(BS), thereby the mobile stations share the channel via time ...This paper studies the capacity issues of a wireless communication system that implements single channel full duplex(SCFD) communication at the base station(BS), thereby the mobile stations share the channel via time division duplex(TDD). The system makes use of the same setup as has been used in previous studies of SCFD, but unlike these previous systems, the new system uses water-filling to maximize the spectral efficiency of the uplink channel. The concept of a free window is introduced to the duplex model for measuring, intuitively, the effective bandwidth of the bi-directional communication. The capacity gain is calculated and numerical results show the advantage of the proposed system over that of conventional TDD.展开更多
Due to distinctive lattice and electronic properties,the thiocyanate anion(SCN-)perovskite as an alluring two-dimensional(2D)material system,can be applied in optoelectronic devices.Herein,both photovoltaic and photod...Due to distinctive lattice and electronic properties,the thiocyanate anion(SCN-)perovskite as an alluring two-dimensional(2D)material system,can be applied in optoelectronic devices.Herein,both photovoltaic and photodetection performances of the 2D Cs2Pb(SCN)2I2 have been investigated.Compared with the conventional cationic 2D perovskites,Cs2Pb(SCN)2I2 possesses ultra-small interlayer spacing,additional interlayer nano channels,which is thus beneficial for charge transport ability.The planar heterojunction solar cell based on Cs2Pb(SCN)2I2 as the light absorber,has presented the highest power conversion efficiency among long-chain-cation-based 2D perovskite devices.Besides,the Cs2Pb(SCN)2I2-based photodetector also exhibits much higher photodetection performance(i.e.quantum efficiency,on/off ratio,responsivity,detectivity,response speed,polarization sensitivity and detection stability).It is thus suggested that these outstanding photoelectric characteristics of Cs2Pb(SCN)2I2 could bring huge opportunities for its more abundant optoelectronic applications,such as field-effect transistor and light-emitting diodes.展开更多
文摘Increasing the spectral efficiency and per channel data rate have historically been shown to be the most cost-effective method to meet the need of ever growing capacity demand in the core network. In this paper we review recent progress in high-speed and high-spectral-efficient optical transmission technology. We discuss spectrally efficient modulation and detection technologies that have been experimentally explored for future 100-Gb/s and above optical transmission system. Emerging methods aiming at extending system reach for noise and nonlinearity-stressed high spectral efficiency optical transmission systems have also been reviewed. We show that spectrallyefficient multilevel coding coupled with polarization multiplexing and digital coherent detection has the potential to enable 400Gb/s per channel WDM system operating with existing 50GHzspaced WDM infrastructure at a spectral efficiency of 8b/s/Hz.
基金supported by the HongKong, Macao and Taiwan Science & Technology Cooperation Program of China (Grant no. 2015DFT10170)the Beijing Higher Education Young Elite Teacher Project
文摘This paper studies the capacity issues of a wireless communication system that implements single channel full duplex(SCFD) communication at the base station(BS), thereby the mobile stations share the channel via time division duplex(TDD). The system makes use of the same setup as has been used in previous studies of SCFD, but unlike these previous systems, the new system uses water-filling to maximize the spectral efficiency of the uplink channel. The concept of a free window is introduced to the duplex model for measuring, intuitively, the effective bandwidth of the bi-directional communication. The capacity gain is calculated and numerical results show the advantage of the proposed system over that of conventional TDD.
基金supported by the National Key R&D Program of China(2018YFB1500101)the National Natural Science Foundation of China(11874402,51421002,51627803,91733301 and 51761145042)the International Partnership Program of Chinese Academy of Sciences(112111KYSB20170089)。
文摘Due to distinctive lattice and electronic properties,the thiocyanate anion(SCN-)perovskite as an alluring two-dimensional(2D)material system,can be applied in optoelectronic devices.Herein,both photovoltaic and photodetection performances of the 2D Cs2Pb(SCN)2I2 have been investigated.Compared with the conventional cationic 2D perovskites,Cs2Pb(SCN)2I2 possesses ultra-small interlayer spacing,additional interlayer nano channels,which is thus beneficial for charge transport ability.The planar heterojunction solar cell based on Cs2Pb(SCN)2I2 as the light absorber,has presented the highest power conversion efficiency among long-chain-cation-based 2D perovskite devices.Besides,the Cs2Pb(SCN)2I2-based photodetector also exhibits much higher photodetection performance(i.e.quantum efficiency,on/off ratio,responsivity,detectivity,response speed,polarization sensitivity and detection stability).It is thus suggested that these outstanding photoelectric characteristics of Cs2Pb(SCN)2I2 could bring huge opportunities for its more abundant optoelectronic applications,such as field-effect transistor and light-emitting diodes.
