We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is...We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is polarization independent due to its symmetrical unit structure. The full wave simulation results show that an absorber with three graphenebased layers can efficiently harvest an electromagnetic wave with random polarization from 17.9 GHz to 188.7 GHz（i.e.,covering frequency regimes from K to D bands and relative bandwidth of - 165%）. The physical absorption mechanism of ultra-broadband absorption has been elaborated upon using the destructive interference method and multiple resonances approach in a multilayered medium. The proposed absorber can be used in many applications such as medical treatment,electromagnetic compatibility, and stealth technique.展开更多
We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pum...We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum（center wavelength and linewidth） are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.展开更多
In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an...In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency,covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%.At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave.展开更多
Based on the designed As2Se3 and As2S3 chalcogenide glass photonic crystal fiber（PCF） and the scalar nonlinear Schrdinger equation,the effects of pump power and wavelength on modulation instability（MI） gain are co...Based on the designed As2Se3 and As2S3 chalcogenide glass photonic crystal fiber（PCF） and the scalar nonlinear Schrdinger equation,the effects of pump power and wavelength on modulation instability（MI） gain are comprehensively studied in the abnormal dispersion regime of chalcogenide glass PCF.Owing to high Raman effect and high nonlinearity,ultra-broadband MI gain is obtained in chalcogenide glass PCF.By choosing the appropriate pump parameter,the MI gain bandwidth reaches 2738 nm for the As2Se3 glass PCF in the abnormal-dispersion region,while it is 1961 nm for the As2S3 glass PCF.展开更多
In this paper, the design of a planar ultra-broadband sum-and-difference network is pre-sented. This network employs a novel power divider and anti-phase balun as a building block. An equivalent 180o coupler with a ba...In this paper, the design of a planar ultra-broadband sum-and-difference network is pre-sented. This network employs a novel power divider and anti-phase balun as a building block. An equivalent 180o coupler with a bandwidth of 6.2～14GHz is achieved by back-connecting the power divider and balun together. Four such couplers are connected to form an ultra-broadband sum-and-difference network which has a bandwidth of 91%. This network, with insertion loss less than 1.8dB in sum port and nulls less than -20dB in all delta ports, is verified to be excellent, resulting in the advantages of being compact, easy manufacturing and low cost.展开更多
To efficiently meet the increasing demands for mobile broadband, Ultra Mobile Broadband (UMB) is designed to complement 3G deployments. It is equipped with all the necessary features for optimal support of real-time a...To efficiently meet the increasing demands for mobile broadband, Ultra Mobile Broadband (UMB) is designed to complement 3G deployments. It is equipped with all the necessary features for optimal support of real-time and best-effort traffic with seamless mobility. This article overviews the UMB technology, and discusses its competitive advantages, which are fast time to market, flexible deployment options, inherently designed for real-time services and flexible IP-based network architecture. Moreover, the article analyzes key UMB design features, including Orthogonal Frequency Division Multiple Access (OFDMA), advanced antenna techniques, Reverse Link (RL) sector capacity optimization, adaptive interference management mechanisms, efficient RL control design, low-overhead signaling, fast seamless handoffs, multi-carrier support and beacons, enhanced terminal battery life, and flexible IP-based network architecture. UMB is well suited to be at the center of the future that melds broadband applications with faster, more capable mobile multimedia devices. UMB’s competitive advantages provide operators with continuous differentiation today and tomorrow.展开更多
为更好地使URLLC(Ultra-Reliable and Low Latency Communications)与增强型移动宽带业务(eMBB:enhanced Mobile Broad Band)在同一载波频段有效复用,进一步提升混合业务系统性能,提出一种基于可扩展传输时间间隔(TTI:Transmission Time...为更好地使URLLC(Ultra-Reliable and Low Latency Communications)与增强型移动宽带业务(eMBB:enhanced Mobile Broad Band)在同一载波频段有效复用,进一步提升混合业务系统性能,提出一种基于可扩展传输时间间隔(TTI:Transmission Time Interval)的动态带宽分配策略。系统根据业务类型进行带宽动态划分;时域上提升URLLC调度优先级;频域上采用不同长度的TTI进行以用户为中心的无线资源分配。动态系统级仿真表明,在不同程度的负载水平下,相比传统无线资源分配算法,该方案能在有效满足URLLC用户时延需求的前提下优化eMBB用户的吞吐量消耗,URLLC用户时延增益最高达到83.8%,提升了5G混合业务系统中不同类型业务的服务质量(QoS:Quality of Service)。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61661012,61461016,61361005,and 61561013)the Natural Science Foundation of Guangxi,China(Grant No.2017JJB160028)+1 种基金the Program for Innovation Research Team of Guilin University of Electronic Technology,Chinathe Dean Project of Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing,China
文摘We propose an ultra-broadband and polarization independent planar absorber comprising multilayered graphene. The bandwidth of the proposed absorber is extended by increasing the number of layers of graphene, and it is polarization independent due to its symmetrical unit structure. The full wave simulation results show that an absorber with three graphenebased layers can efficiently harvest an electromagnetic wave with random polarization from 17.9 GHz to 188.7 GHz（i.e.,covering frequency regimes from K to D bands and relative bandwidth of - 165%）. The physical absorption mechanism of ultra-broadband absorption has been elaborated upon using the destructive interference method and multiple resonances approach in a multilayered medium. The proposed absorber can be used in many applications such as medical treatment,electromagnetic compatibility, and stealth technique.
基金supported by the National Basic Research Program of China(Grant No.2013CB922404)the National Scientific Research Project of China(Grant No.61177047)the National Natural Science Foundation of China(Grant No.61575011)
文摘We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum（center wavelength and linewidth） are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.
基金supported by the National Natural Science Foundation of China(Grant Nos.61471292,61331005,61471388,51277012,41404095,and 61501365)the 111 Project,China(Grant No.B14040)+1 种基金the National Basic Research Program of China(Grant No.2015CB654602)the China Postdoctoral Science Foundation(Grant No.2015M580849)
文摘In this paper, we present a novel metasurface design that achieves a high-efficiency ultra-broadband cross polarization conversion. The metasurface is composed of an array of unit resonators, each of which combines an H-shaped structure and two rectangular metallic patches. Different plasmon resonance modes are excited in unit resonators and allow the polarization states to be manipulated. The bandwidth of the cross polarization converter is 82% of the central frequency,covering the range from 15.7 GHz to 37.5 GHz. The conversion efficiency of the innovative new design is higher than 90%.At 14.43 GHz and 40.95 GHz, the linearly polarized incident wave is converted into a circularly polarized wave.
基金Project supported by the National Natural Science Fundation of China(Grant No.11404286)the Natural Science Fundation of Zhejiang Province,China(Grant No.LY15F050010)the Scientific Research Foundation of Zhejiang University of Technology,China(Grant No.1401109012408)
文摘Based on the designed As2Se3 and As2S3 chalcogenide glass photonic crystal fiber（PCF） and the scalar nonlinear Schrdinger equation,the effects of pump power and wavelength on modulation instability（MI） gain are comprehensively studied in the abnormal dispersion regime of chalcogenide glass PCF.Owing to high Raman effect and high nonlinearity,ultra-broadband MI gain is obtained in chalcogenide glass PCF.By choosing the appropriate pump parameter,the MI gain bandwidth reaches 2738 nm for the As2Se3 glass PCF in the abnormal-dispersion region,while it is 1961 nm for the As2S3 glass PCF.
文摘In this paper, the design of a planar ultra-broadband sum-and-difference network is pre-sented. This network employs a novel power divider and anti-phase balun as a building block. An equivalent 180o coupler with a bandwidth of 6.2～14GHz is achieved by back-connecting the power divider and balun together. Four such couplers are connected to form an ultra-broadband sum-and-difference network which has a bandwidth of 91%. This network, with insertion loss less than 1.8dB in sum port and nulls less than -20dB in all delta ports, is verified to be excellent, resulting in the advantages of being compact, easy manufacturing and low cost.
文摘To efficiently meet the increasing demands for mobile broadband, Ultra Mobile Broadband (UMB) is designed to complement 3G deployments. It is equipped with all the necessary features for optimal support of real-time and best-effort traffic with seamless mobility. This article overviews the UMB technology, and discusses its competitive advantages, which are fast time to market, flexible deployment options, inherently designed for real-time services and flexible IP-based network architecture. Moreover, the article analyzes key UMB design features, including Orthogonal Frequency Division Multiple Access (OFDMA), advanced antenna techniques, Reverse Link (RL) sector capacity optimization, adaptive interference management mechanisms, efficient RL control design, low-overhead signaling, fast seamless handoffs, multi-carrier support and beacons, enhanced terminal battery life, and flexible IP-based network architecture. UMB is well suited to be at the center of the future that melds broadband applications with faster, more capable mobile multimedia devices. UMB’s competitive advantages provide operators with continuous differentiation today and tomorrow.
文摘为更好地使URLLC(Ultra-Reliable and Low Latency Communications)与增强型移动宽带业务(eMBB:enhanced Mobile Broad Band)在同一载波频段有效复用,进一步提升混合业务系统性能,提出一种基于可扩展传输时间间隔(TTI:Transmission Time Interval)的动态带宽分配策略。系统根据业务类型进行带宽动态划分;时域上提升URLLC调度优先级;频域上采用不同长度的TTI进行以用户为中心的无线资源分配。动态系统级仿真表明,在不同程度的负载水平下,相比传统无线资源分配算法,该方案能在有效满足URLLC用户时延需求的前提下优化eMBB用户的吞吐量消耗,URLLC用户时延增益最高达到83.8%,提升了5G混合业务系统中不同类型业务的服务质量(QoS:Quality of Service)。
