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Chinese Physics B 2014年第9期23卷 387-393页

作者：慈雪婷吴伯涛宋敏陈耿旭刘岩武愕曾和平 State Key Laboratory of Precision spectroscopy East China Normal University

The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied using the finite difference time domain method. The extinction spectra and the electric field distribution profiles of the two dimers for various gap distances between two individual nanospheres are compared with those of the corresponding monomers to reveal the extent of plasmon coupling. It is found that with the interparticle distance decreasing, a strong plasmon coupling between two Al or Alcore/Al2O3shell nanospheres is observed accompanied by a significant red shift in the extinction spectra at the parallel polarization direction of the incident light related to the dimer axis, while for the case of the perpendicular polarization direction, a weak plasmon coupling arises characterized by a slight blue shift in the extinction spectra. The electric field distribution profiles show that benefiting from the dielectric Al2O3 shell, the gap distance of Alcore/Al2O3shell nanosphere dimers can be tailored to 〈 1 nm scale and results in a very high electric field enhancement. The estimated surface-enhanced Raman scattering enhancement factors suggests that the Alcore/Al2O3shell nanosphere dimers with the gap of 〈 1 nm gave rise to an enhancement as high as 8.1 × 10^7 for interparticle gap = 0.5 nm. Our studies reveal that the Alcore/Al2O3shell nanosphere dimers may be promising substrates for surface-enhanced spectroscopy in the deep-ultraviolet region.

关键词： localized surface plasmon resonance deep ultraviolet aluminum nanosphere dimers enhancedspectroscopy

Effect of radiative loss mechanisms on FIR thermometric parameters of Nd^(3+)-doped lithium tellurite glasses

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Journal of Rare Earths 2024年第7期42卷 1250-1257,I0002页

作者： C.Y.Morassuti A.P.L Silva L.A.O.Nunes S.M.Lima L.H.C.Andrade Optical and Photothermal spectroscopy Group(GEOF) Center for Studies in Natural Resources(CERNA)State University of Mato Grosso do Sul(UEMS)C.P.351DouradosMSBrazil Renato Archer Information Technology Center Dom Pedro I Highway(SP-65)Km 1436-Chácaras Campos dos AmaraisCampinasSPBrazil Institute of Physics of São Carlos University of São PauloSão CarlosSPBrazil

Nd^(3+)-doped tellurite glasses are promising materials for thermometers based on the fluorescence intensity ratio(FIR)***,at high Nd^(3+)concentrations,energy transfer(ET)processes such as optical reabsorption and cross-relaxation can affect the Nd^(3+)emission,which has been little explored in the ***,the present work investigated the use of Nd^(3+)-doped tellurite glass(samples doped with Nd^(3+)at 0.2 mol%,0.5 mol%,2.0 mol%,and 4.0 mol%)in fluorescence thermometers,in the temperature range from 299 to 371 *** results indicate a strong dependence of the FIR parameters on the Nd^(3+)concentration,due to changes in the emission band profiles caused by optical reabsorption of the Nd^(3+)emissions and cross-relaxation processes.A decrease of the relative sensitivity of the ratio^(4)F_(5/2)→^(4)I_(9/2)/^(4)F_(3/2)→^(4)I_(9/2)is observed for samples doped with higher amounts of Nd^(3+).The maximum relative sensitivity at 299 K is 3.00%/K,which is the highest value among the reported Nd^(3+)ions.

关键词： Nd^(3+)-doped tellurite glass Fluorescence intensity ratio Optical thermometry Judd-Ofelt Rare earths

Improving model performance in mapping cropland soil organic matter using time-series remote sensing data

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Journal of Integrative Agriculture 2024年第8期23卷 2820-2841页

作者： Xianglin Zhang Jie Xue Songchao Chen Zhiqing Zhuo Zheng Wang Xueyao Chen Yi Xiao Zhou Shi Institute of Applied Remote Sensing and Information Technology College of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China Department of Land Management Zhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311215China Institute of Digital Agriculture Zhejiang Academy of Agricultural SciencesHangzhou 310021China Key Laboratory of spectroscopy Sensing Ministry of Agriculture and Rural AffairsHangzhou 310058China

Faced with increasing global soil degradation,spatially explicit data on cropland soil organic matter(SOM)provides crucial data for soil carbon pool accounting,cropland quality assessment and the formulation of effective management *** a spatial information prediction technique,digital soil mapping(DSM)has been widely used to spatially map soil information at different ***,the accuracy of digital SOM maps for cropland is typically lower than for other land cover types due to the inherent difficulty in precisely quantifying human *** overcome this limitation,this study systematically assessed a framework of“information extractionfeature selection-model averaging”for improving model performance in mapping cropland SOM using 462 cropland soil samples collected in Guangzhou,China in *** results showed that using the framework of dynamic information extraction,feature selection and model averaging could efficiently improve the accuracy of the final predictions(R^(2):0.48 to 0.53)without having obviously negative impacts on *** the dynamic information of the environment was an efficient way to generate covariates that are linearly and nonlinearly related to SOM,which improved the R^(2)of random forest from 0.44 to 0.48 and the R^(2)of extreme gradient boosting from 0.37to *** recursive feature selection(FRFS)is recommended when there are relatively few environmental covariates(500).The Granger-Ramanathan model averaging approach could improve the prediction accuracy and average *** the structures of initial prediction models are similar,increasing in the number of averaging models did not have significantly positive effects on the final *** the advantages of these selected strategies over information extraction,feature selection and model averaging have a great potential for high-accuracy soil mapping

关键词： cropland soil organic matter digital soil mapping machine learning feature selection model averaging

Frequency stabilization of a 399-nm laser by modulation transfer spectroscopy in an ytterbium hollow cathode lamp

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Chinese Physics B 2011年第1期20卷 310-315页

作者：王文丽叶捷蒋海灵毕志毅马龙生徐信业 State Key Laboratory of Precision spectroscopy and Department of Physics East China Normal University

The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.

关键词： laser frequency stabilization modulation transfer spectroscopy ytterbium hollow cathode lamp

Valence Orbitals of Ethane by Electron Momentum spectroscopy

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Chinese Physics Letters 1998年第5期15卷 341-342页

作者： PANG Wen-ning GAO Nai-fei ZHANG Wen-xin SHANG Ren-cheng DENG Jing-kang CHEN Xue-jun Laboratory of Electron Momentum spectroscopy Department of PhysicsTsinghua UniversityBeijing 100084

The valence electron binding energy spectra and orbital electron momentum distributions of ethane(C2H6)have been measured by high resolution(ΔE=0.9eV,Δp=0.1 a.u.)symmetric non-coplanar electron momentum spectroscopy,at an impact energy of 1200eV+binding *** high energy resolution is adequate for us to be observe clearly the separated valence orbitals of C_(2)H_(6).

关键词： energy. momentum valence

Stochastic resonance of spinor condensates in optical cavity

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 80-87页

作者： Zheng-Chun Li Bixuan Fan Lu Zhou Weiping Zhang School of Physics and Astronomy and Tsung-Dao Lee InstituteShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Precision spectroscopy School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China College of Physics and Communication Electronics Jiangxi Normal UniversityNanchang 330022China Shanghai Branch Hefei National LaboratoryShanghai 201315China Shanghai Research Center for Quantum Sciences Shanghai 201315China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Stochastic resonance is a phenomenon in which adding random noise to a system enhances the detection or transmission of a weak signal. It occurs when the noise interacts with the system's nonlinearity, thus improving signal-to-noise ratio and increasing sensitivity. Although parametric resonances in an atomic spinor Bose-Einstein condensate have been investigated, the question of whether one can observe stochastic resonance in such a system persists. In this study we propose a scheme for generating stochastic resonance in a cavity-spinor Bose-Einstein condensate coupling system. We demonstrate stochastic resonance through numerical calculations using the mean-field theory and truncated Wigner approximation methods. Furthermore, the characteristics of the system's response to noise and periodic signals are studied in detail. This study unravels a new scheme for observing stochastic resonance via linking atomic many-body physics with cavity quantum electrodynamics.

关键词： spinor condensate stochastic resonance optical cavity

Ultrafast dynamics of femtosecond laser-induced high spatial frequency periodic structures on silicon surfaces

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Opto-Electronic Science 2024年第3期3卷 33-46页

作者： Ruozhong Han Yuchan Zhang Qilin Jiang Long Chen Kaiqiang Cao Shian Zhang Donghai Feng Zhenrong Sun Tianqing Jia State Key Laboratory of Precision spectroscopy School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Institute of Laser Manufacturing Henan Academy of SciencesZhengzhou 450046China Institute of Physics Chinese Acadamy of SciencesBeijing 100190China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few *** particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient ***,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily ***,the formation mechanism of HSFL is complex and has always been a research hotspot in this *** this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond *** ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging *** general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is *** results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.

关键词： laser-induced periodic surface structures(LIPSS) local field enhancement collinear pump-probe imaging silicon high spatial frequency periodic structures

High-resolution mid-infrared single-photon upconversion ranging

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Photonics Research 2024年第6期12卷 1294-1302页

作者： SHUHONG JIANG KUN HUANG TINGTING YU JIANAN FANG BEN SUN YAN LIANG QIANG HAO E.WU MING YAN HEPING ZENG State Key Laboratory of Precision spectroscopy East China Normal UniversityShanghai 200062China Chongqing Key Laboratory of Precision Optics Chongqing Institute of East China Normal UniversityChongqing 401121China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China School of Optical Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Research Center for Quantum Sciences Shanghai 201315China Guangyang Bay Laboratory Chongqing Institute for Brain and IntelligenceChongqing 400064China

Single-photon laser ranging has widespread applications in remote sensing and target ***,highly sensitive light detection and ranging(lidar)has long been restricted in the visible or near-infrared *** appealing quest is to extend the operation wavelength into the mid-infrared(MIR)region,which calls for an infrared photon-counting system at high detection sensitivity and precise temporal ***,we devise and demonstrate an MIR upconversion lidar based on nonlinear asynchronous optical ***,the infrared probe is interrogated in a nonlinear crystal by a train of pump pulses at a slightly different repetition rate,which favors temporal optical scanning at a picosecond timing resolution and a kilohertz refreshing rate ***,the cross-correlation upconversion trace is temporally stretched by a factor of 2×10^(4),which can thus be recorded by a low-bandwidth silicon *** combination with the time-correlated photon-counting technique,the achieved effective resolution is about two orders of magnitude better than the timing jitter of the detector itself,which facilitates a ranging precision of 4μm under a low detected flux of 8×10^(−5) photons per *** presented MIR time-of-flight range finder is featured with single-photon sensitivity and high positioning resolution,which would be particularly useful in infrared sensing and imaging in photon-starved scenarios.

关键词： resolution lidar repetition

Cavity-enhanced metrology in an atomic spin-1 Bose−Einstein condensate

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Frontiers of physics 2024年第3期19卷 185-196页

作者： Renfei Zheng Jieli Qin Bing Chen Xingdong Zhao Lu Zhou School of Physics Hefei University of TechnologyHefei 230009China State Key Laboratory of Precision spectroscopy Department of PhysicsSchool of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China School of Physics and Materials Science Guangzhou University230 Wai Huan Xi RoadGuangzhou Higher Education Mega CenterGuangzhou 510006China Department of Physics Henan Normal UniversityXinxiang 453007China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Atom interferometer has been proven to be a powerful tool for precision metrology. Here we propose a cavity-aided nonlinear atom interferometer, based on the quasi-periodic spin mixing dynamics of an atomic spin-1 Bose−Einstein condensate trapped in an optical cavity. We unravel that the phase sensitivity can be greatly enhanced with the cavity-mediated nonlinear interaction. The influence of encoding phase, splitting time and recombining time on phase sensitivity are carefully studied. In addition, we demonstrate a dynamical phase transition in the system. Around the criticality, a small cavity light field variation can arouse a strong response of the atomic condensate, which can serve as a new resource for enhanced sensing. This work provides a robust protocol for cavity-enhanced metrology.

关键词： nonlinear atom interferometer spin-1 Bose−Einstein condensate spin-mixing dynamics quantum Fisher information parameter estimation

Determination of Coordination Configuration of Rare Earth Ions with Aminoacids in Solutions with Cooperative Vibronic spectroscopy

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Journal of Rare Earths 2000年第1期18卷 14-17页

作者：李润华孟建新曾学然周达君周建英 State Key Laboratory of Ultrafast Laser spectroscopy Zhongshan University Guangzhou 510275 China

The use of cooperative vibronic spectroscopy to measure coordination numbers of the ligands surrounding rare earth ions in solutions was proposed and demonstrated. It is shown that the time-resolved cooperative vibronic spectroscopy is a very useful technique for the determination of the ligand type and ligand number for different coordination groups. Coordination configuration of arginine with Tb3+ in solutions with different pH values was studied. It demonstrates that the carboxy1 of arginine can replace H2O to coordinate with Tb3+ and the coordination number of carboxyl increases with the increase of pH value of the solutions.

关键词： rare earths coordination configuration aminoacid cooperative vibronic spectroscopy