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Computationally Efficient Nonlinearity Compensation for Coherent Fiber-Optic Systems
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作者 likai Zhu guifang li 《ZTE Communications》 2012年第3期12-15,共4页
Split-step digital backward propagation (DBP) can be combined with coherent detection to compensate for fiber nonlinear impairments. A large number of DBP steps is usually needed for a long-haul fiber system, and th... Split-step digital backward propagation (DBP) can be combined with coherent detection to compensate for fiber nonlinear impairments. A large number of DBP steps is usually needed for a long-haul fiber system, and this creates a heavy computational load. In a trade-off between complexity and performance, interchannel nonlinearity can be disregarded in order to simplify the DBP algorithm. The number of steps can also be reduced at the expense of performance. In periodic dispersion-managed long-haul transmission systems, optical waveform distortion is dominated by chromatic dispersion. As a result, the nonlinearity of the optical signal repeats in every dispersion period. Because of this periodic behavior, DBP of many fiber spans can be folded into one span. Using this distance-folded DBP method, the required computation for a transoceanic transmission system with full inline dispersion compensation can be reduced by up to two orders of magnitude with negligible penalty. The folded DBP method can be modified to compensate for nonlinearity in fiber links with non-zero residua dispersion per span. 展开更多
关键词 coherent fiber communication nonlinearity compensation folded digital backward propagation
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Few-mode fibre-optic microwave photonic links 被引量:4
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作者 He Wen Hongjun Zheng +9 位作者 Qi Mo Amado Manuel Velázquez-Benítez Cen Xia Bin Huang Huiyuan liu Huang Yu Pierre Sillard Jose Enrique Antonio Lopez Rodrigo Amezcua Correa guifang li 《Light(Science & Applications)》 SCIE EI CAS CSCD 2017年第1期684-691,共8页
The fibre-optic microwave photonic link has become one of the basic building blocks for microwave photonics.Increasing the optical power at the receiver is the best way to improve all link performance metrics includin... The fibre-optic microwave photonic link has become one of the basic building blocks for microwave photonics.Increasing the optical power at the receiver is the best way to improve all link performance metrics including gain,noise figure and dynamic range.Even though lasers can produce and photodetectors can receive optical powers on the order of a Watt or more,the power-handling capability of optical fibres is orders-of-magnitude lower.In this paper,we propose and demonstrate the use of few-mode fibres to bridge this power-handling gap,exploiting their unique features of small acousto-optic effective area,large effective areas of optical modes,as well as orthogonality and walk-off among spatial modes.Using specially designed few-mode fibres,we demonstrate order-of-magnitude improvements in link performances for single-channel and multiplexed transmission.This work represents the first step in few-mode microwave photonics.The spatial degrees of freedom can also offer other functionalities such as large,tunable delays based on modal dispersion and wavelength-independent lossless signal combining,which are indispensable in microwave photonics. 展开更多
关键词 analogue optic-fibre link few-mode fibre fibre nonlinearity microwave photonics space-division multiplexing
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Scalable non-mode selective Hermite–Gaussian mode multiplexer based on multi-plane light conversion 被引量:4
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作者 HE WEN YUANHANG ZHANG +4 位作者 RACHEL SAMPSON NICOLAS K.FONTAINE NING WANG SHENGli FAN guifang li 《Photonics Research》 SCIE EI CAS CSCD 2021年第2期88-97,共10页
Non-mode-selective(NMS) multiplexers(muxes) are highly desirable for coherent power combining to produce a high-power beam with a shaped profile(wavefront synthesis) from discrete, phase-locked emitters. We propose a ... Non-mode-selective(NMS) multiplexers(muxes) are highly desirable for coherent power combining to produce a high-power beam with a shaped profile(wavefront synthesis) from discrete, phase-locked emitters. We propose a design for a multi-plane light conversion(MPLC)-based NMS mux, which requires only a few phase masks for coherently combining hundreds of discrete input beams into an output beam consisting of hundreds of Hermite–Gaussian(HG) modes. The combination of HG modes as a base can further construct a beam with arbitrary wavefront. The low number of phase masks is attributed to the identical zero-crossing structure of the Hadamard-coded input arrays and of the output HG modes, enabling the practicality of such devices. An NMS mux supporting 256 HG modes is designed using only seven phase masks, and achieves an insertion loss of-1.6 d B, mode-dependent loss of 4.7 d B, and average total mode crosstalk of-4.4 d B. Additionally, this design,featuring equal power for all input beams, enables phase-only control in coherent power combining, resulting in significant simplifications and fast convergence compared with phase-and-amplitude control. 展开更多
关键词 MODE coherent hundreds
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Applications of weakly-coupled few-mode fibers[Invited] 被引量:2
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作者 Huiyuan liu He Wen guifang li 《Chinese Optics Letters》 SCIE EI CAS CSCD 2020年第4期1-11,共11页
Space-division multiplexing(SDM)has attracted significant attention in recent years because larger transmission capacity is enabled by more degrees of freedom(DOFs)in few-mode fibers(FMFs)compared with singlemode fibe... Space-division multiplexing(SDM)has attracted significant attention in recent years because larger transmission capacity is enabled by more degrees of freedom(DOFs)in few-mode fibers(FMFs)compared with singlemode fibers(SMFs).To transmit independent information on spatial modes without or with minor digital signal processing(DSP),weakly-coupled FMFs are preferred in various applications.Several cases with different use of spatial DOFs in weakly-coupled FMFs are demonstrated in this work,including single-mode or mode-groupmultiplexed transmission,and spatial DOFs combined with time or frequency DOF to improve the system performance. 展开更多
关键词 MULTIPLEXING nonlinear optics fibers radio frequency photonics fiber optics links and subsystems few-mode fibers
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Optical fiber amplifiers for space-division multiplexing 被引量:3
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作者 Dagong JIA Haiwei ZHANG +2 位作者 Zhe JI Neng BAI guifang li 《Frontiers of Optoelectronics》 2012年第4期351-357,共7页
Recently, space-division multiplexing (SDM) techniques using multi-core fiber (MCF) and few-mode fiber (FMF) have been introduced into optical fiber communication to increase transmission capacity. Two main type... Recently, space-division multiplexing (SDM) techniques using multi-core fiber (MCF) and few-mode fiber (FMF) have been introduced into optical fiber communication to increase transmission capacity. Two main types of optical fiber amplifiers based on the Erbium- doped fiber (EDF) and the Raman effect have been developed to amplify signals in the MCF and FMF. In this paper, we reviewed the principles and configurations of these amplifiers. 展开更多
关键词 optical fiber amplifier space-division multi-plexing (SDM) multi-core fiber (MCF) few-mode fiber(FMF)
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Broadband athermal waveguides and resonators for datacom and telecom applications 被引量:2
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作者 liUQING HE YUHAO GUO +6 位作者 ZHAOHONG HAN KAZUMI WADA JURGEN MICHEL ANURADHA M.AGARWAL liONEL C.KIMERliNG guifang li liN ZHANG 《Photonics Research》 SCIE EI 2018年第11期987-990,共4页
The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-sh... The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-shift microring resonator, designing a broadband athermal waveguide becomes a significant task. In this work,we propose a broadband athermal waveguide that shows a low effective thermo-optical coefficient of1 × 10^(-6)∕K from 1400 to 1700 nm. The proposed waveguide shows a low-loss performance and stable broadband athermal property when it is applied to ring resonators, and the bending loss of ring resonators with a radius of >30 μm is 0.02 dB/cm. 展开更多
关键词 TOC TELECOM APPLICATIONS TiO SiO
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Robust cavity soliton formation with hybrid dispersion 被引量:1
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作者 JING WANG YUHAO GUO +5 位作者 HENAN liU liONEL C.KIMERliNG JURGEN MICHEL ANURADHA M.AGARWAL guifang li liN ZHANG 《Photonics Research》 SCIE EI 2018年第6期647-651,共5页
Microresonator-based Kerr frequency combs have attracted a great deal of attention in recent years, in which mode locking of the generated combs is associated with bright or dark cavity soliton formation. In this pape... Microresonator-based Kerr frequency combs have attracted a great deal of attention in recent years, in which mode locking of the generated combs is associated with bright or dark cavity soliton formation. In this paper, we show a unique that, different from soliton propagation along a waveguide, cavity solitons can be robustly formed under dispersion profile with four zero-dispersion wavelengths. More importantly, such a dispersion profile exhibits much smaller overall dispersion, thus making it possible to greatly reduce the pump power by five to six times. 展开更多
关键词 Nonlinear optics four-wave mixing Kerr effect
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Novel applications of space-division multiplexing
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作者 Christian CARBONI guifang li 《Frontiers of Optoelectronics》 EI CSCD 2016年第2期270-276,共7页
Space-division multiplexing (SDM) using multi-core fibers (MCFs) and few-mode fibers (FMFs) was proposed as a solution to increase capacity and/or reduce the cost per bit of fiber-optic transmission. Advances in... Space-division multiplexing (SDM) using multi-core fibers (MCFs) and few-mode fibers (FMFs) was proposed as a solution to increase capacity and/or reduce the cost per bit of fiber-optic transmission. Advances in passive and active SDM devices as well as digital signal processing have led to impressive SDM transmission demonstrations in the laboratory. Although the perceived advantages in terms of capacity and cost per bit that SDM offers over parallel SMF bundles are not universally accepted, SDM is beginning to emerge as an indispensable solution in major network segments. The introduction of the spatial degree of freedom allows optical networks to overcome fundamental limitations such as fiber nonlinearity as well practical limitations such as power delivery. We describe these application scenarios that the optical communications industry has already began to explore. From a fundamental science point of view, concepts such as the principal modes, generalized Stokes space, and multi-component solitons discovered in SDM research will likely have a broad impact in other areas of science and engineering. 展开更多
关键词 space-division multiplexing (SDM) few-mode fiber (FMF) multi-core fiber (MCF) wavelength-selective switch (WSS) passive optical network (PON)
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Single-ended characterization of the coherent transfer matrix of coupled multimode transmission channels
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作者 AliREZA FARDOOST FATEMEH GHAEDI VANANI +1 位作者 SETHUMADHAVAN CHANDRASEKHAR guifang li 《Photonics Research》 SCIE EI CAS CSCD 2023年第10期1627-1634,共8页
Light propagation in random media is a subject of interest to the optics community at large,with applications ranging from imaging to communication and sensing.However,real-time characterization of wavefront distortio... Light propagation in random media is a subject of interest to the optics community at large,with applications ranging from imaging to communication and sensing.However,real-time characterization of wavefront distortion in random media remains a major challenge.Compounding the difficulties,for many applications such as imaging(e.g.,endoscopy)and focusing through random media,we only have single-ended access.In this work,we propose to represent wavefronts as superpositions of spatial modes.Within this framework,random media can be represented as a coupled multimode transmission channel.Once the distributed coherent transfer matrix of the channel is characterized,wavefront distortions along the path can be obtained.Fortunately,backreflections almost always accompany mode coupling and wavefront distortions.Therefore,we further propose to utilize backreflections to perform single-ended characterization of the coherent transfer matrix.We first develop the general framework for single-ended characterization of the coherent transfer matrix of coupled multimode transmission channels.Then,we apply this framework to the case of a two-mode channel,a single-mode fiber,which supports two randomly coupled polarization modes,to provide a proof-of-concept demonstration.Furthermore,as one of the main applications of coherent channel estimation,a polarization imaging system through singlemode fibers is implemented.We envision that the proposed method can be applied to both guided and free-space channels with a multitude of applications. 展开更多
关键词 POLARIZATION COHERENT CHARACTERIZATION
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基于稳定同位素技术的塔里木河下游不同林龄胡杨的水分利用来源 被引量:17
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作者 张江 李桂芳 +3 位作者 贺亚玲 穆雨迪 庄丽 刘红玲 《生物多样性》 CAS CSCD 北大核心 2018年第6期564-571,共8页
水分是制约很多陆地生态系统植物生长和繁殖的重要因素,在干旱地区尤为明显。利用稳定同位素技术探究塔里木河下游不同林龄胡杨(Populus euphratica)的水分来源情况,了解生态输水背景下荒漠河岸林的水分利用循环与利用策略,可为生态输... 水分是制约很多陆地生态系统植物生长和繁殖的重要因素,在干旱地区尤为明显。利用稳定同位素技术探究塔里木河下游不同林龄胡杨(Populus euphratica)的水分来源情况,了解生态输水背景下荒漠河岸林的水分利用循环与利用策略,可为生态输水提供科学依据,同时也可对同类地区的生态恢复提供借鉴。本研究通过测定塔里木河下游胡杨茎干水和各潜在水源(土壤水、地下水)的稳定氢氧同位素值(δD、δ^(18)O),应用多源线性混合模型(Iso Source)分析了各潜在水源对不同林龄胡杨的贡献比例,并结合3种林龄胡杨不同土壤深度含水量的变化,分析了胡杨的主要吸水层位。结果表明:(1)不同林龄胡杨样地的不同深度区间上的土壤水δ^(18)O值存在显著差异(P<0.05):胡杨幼龄木、成熟木、过熟木木质部δ^(18)O分别为-7.83±0.07‰、-8.53±0.11‰、-9.36±0.21‰;而δD值不存在显著差异(P>0.05)。可据此来推断胡杨的主要吸水层位。(2)总体上,三种林龄胡杨土壤水δ^(18)O值随土壤深度增加而减小,并趋于接近地下水的δ^(18)O值。其中,0–60 cm土壤水受蒸发影响比较大,其同位素组成经历了强烈的蒸发分馏过程,土壤含水量极少,土壤水δ^(18)O值偏正。(3)不同林龄胡杨所利用的水分来源不同:胡杨幼龄木对于地表80 cm以下的土壤水以及地下水均有一定程度的利用,对80–140 cm、140–220 cm和220–340 cm的土壤水平均利用比率依次为16.2%、21.4%和24.6%,对地下水平均利用比率为24.5%;成熟木主要利用220–340 cm的土壤水及地下水,平均利用比率分别为36.9%和42.3%;过熟木主要利用140–340 cm的土壤水及地下水,平均利用比率分别为32.8%和49.3%。 展开更多
关键词 氢氧稳定同位素 水分利用来源 土壤水 林龄 胡杨 地下水
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Mode demultiplexing hybrids for mode-division multiplexing coherent receivers 被引量:5
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作者 HE WEN HUIYUAN liU +2 位作者 YUANHANG ZHANG PENG ZHANG guifang li 《Photonics Research》 SCIE EI CSCD 2019年第8期917-925,共9页
We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of... We propose a mode demultiplexing hybrid(MDH) that integrates mode demultiplexing, local oscillator power splitting, and optical 90-deg mixing using multi-plane light conversion(MPLC). We demonstrate the realization of a three-mode MDH using four phase plates, one more than what is required for an MPLC-based mode demultiplexer, via numerical simulations. The performance of the three-mode MDH is comparable to that of commercial single-mode 90-deg hybrids. This multiple-functionality device enables simplification of the coherent optical front end of mode-division multiplexing receivers. 展开更多
关键词 domain MODE DEMULTIPLEXING mode-division MULTIPLEXING coherent RECEIVERS
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Synthesis,crystal structure and photoluminescence properties of novel double perovskite La2CaSnO6:Eu3+red-emitting phosphors 被引量:3
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作者 Yangyi Xu guifang li +2 位作者 Xufeng Guan Yunge Wei Maolin Zhang 《Journal of Rare Earths》 SCIE EI CAS CSCD 2022年第11期1682-1690,I0001,共10页
A series of new double perovskite LaEuCaSnO(0≤x≤0.8)red phosphors were synthesized by traditional solid-state reaction.The phase,micro structure,photoluminescence(PL)properties,quantum efficiency,and thermal stabili... A series of new double perovskite LaEuCaSnO(0≤x≤0.8)red phosphors were synthesized by traditional solid-state reaction.The phase,micro structure,photoluminescence(PL)properties,quantum efficiency,and thermal stability of the phosphors were investigated.LaCaSnOmatrix has a monoclinic double perovskite structure with space group P2/n.Under near-ultraviolet(UV)light at395 nm,LaEuCaSnOphosphors exhibit the most typical red emission peak at 614 nm,which corresponds to~5 D→~7 Felectric dipole transition of Eu.The optimum Eudoping content is attained at x=0.5,and the LaEuCaSnOphosphor shows a moderate quantum efficiency(32.3%)and high color purity(92.2%).Besides,the temperature-dependent spectrum of the phosphor was studied.The emission intensity of Euat 423 K decreases to 70.94%of the initial intensity at 303 K,and the activation energyΔE is estimated to be 0.232 eV,suggesting that the phosphors possess good thermal stability.The fabricated w-LED based on the phosphors has higher Ra(89),lower CCT(4539 K),and better chromaticity coo rdinates(0.371,0.428).These results prove that the Eu-doped LaCaSnOred phosphor has great potential applications in w-LEDs. 展开更多
关键词 PHOSPHORS Double perovskite Luminescence properties La2CaSnO6 Rare earths
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Ultra-flat dispersion in an integrated waveguide with five and six zero-dispersion wavelengths for mid-infrared photonics 被引量:3
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作者 Yuhao Guo Zeinab Jafari +8 位作者 lijuan Xu Changjing Bao Peicheng liao guifang li Anuradha M.Agarwal lionel C.Kimerling Jurgen Michel Alan E.Willner lin Zhang 《Photonics Research》 SCIE EI CSCD 2019年第11期1279-1286,共8页
We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 ... We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 to 0.35 ps/(nm·km) from 4 to 8 μm, which to the best of our knowledge is the flattest one reported so far, and the dispersion flatness is improved by more than an order of magnitude. We explain the principle of producing six ZDWs. Mode distribution in this waveguide is made stable over a wide bandwidth. General guidelines to systematically control the dispersion value, sign, and slope are provided, and one can achieve the desired dispersion by properly adjusting the structural parameters. Fabrication tolerance of this waveguide is also examined. 展开更多
关键词 WAVEGUIDE dispersion FLAT
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A smart MXene-copolymeric molecularly imprinted hydrogel with dual-response and photothermal conversion performance for specific recognition of cis-diol compounds
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作者 Jingyang Zhao Yucheng li +7 位作者 Huatai Zhu guifang li lingling Kang Jing liu Jing He Jiandu Lei Luying Wang Qiong Yan 《Nano Research》 SCIE EI CSCD 2022年第3期2764-2772,共9页
In this work,a novel MXene-copolymeric molecularly imprinted hydrogel(FMMIH)with temperature/pH dual response and photothermal conversion performance for selective recognition of cis-diol compounds is successfully pre... In this work,a novel MXene-copolymeric molecularly imprinted hydrogel(FMMIH)with temperature/pH dual response and photothermal conversion performance for selective recognition of cis-diol compounds is successfully prepared.Functionalized MXene becomes an important part of the hydrogel’s skeleton by participating in the free radical polymerization reaction.Therefore,FMMIH exhibits improved mechanical properties and great photothermal conversion performance.Furthermore,based on the temperature/pH dual response,FMMIH can realize the controllable capture and release of ginsenoside Rb1 with cis diol structures through dual recognitions of functional groups and geometric space.Under the conditions of pH 8.5 and 25℃,the adsorption capacity of FMMIH is 26.3 mg·g^(-1) and the imprinting factor is 16.4,showing a good imprinting effect.It is worth noting that the volume shrinkage caused by photothermal conversion of the hydrogel is conducive to the elution of template molecules and greatly saves the time of desorption(the desorption efficiency is as high as 89.4%under light conditions for 30 min,which is 3.7 times in dark conditions).These excellent properties make it possible to have broad prospects in many fields such as separation of cis-diol compounds,drug delivery systems,and biosensors. 展开更多
关键词 functional MXene photothermal conversion molecular imprinting temperature/pH response specific recognition
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Robust generation of frequency combs in a microresonator with strong and narrowband loss
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作者 JING WANG ZHAOHONG HAN +5 位作者 YUHAO GUO liONEL C.KIMERliNG JURGEN MICHEL ANURADHA M.AGARWAL guifang li liN ZHANG 《Photonics Research》 SCIE EI 2017年第6期77-81,共5页
Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We e... Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We examine the impact of the spectral loss and propose robust comb generation with a loss of even 300 dB/cm.Cavity nonlinear dynamics show that a phase change associated with spectral losses can facilitate phase matching and Kerr comb generation. Given this unique capability, we propose a novel architecture of on-chip spectroscopy systems. 展开更多
关键词 Robust generation of frequency combs in a microresonator with strong and narrowband loss THz
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