Xiao Li

Hong Kong University of Science and Technology

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Jack Ng

Southern University of Science and Technology

Zhifang Lin

Fudan University

Peng Wang

National University of Defense Technology

Xiaojun Xu

National University of Defense Technology

Yaping Shang

National University of Defense Technology

Jun Chen

Northwest A&F University

Jun Chen

Nanjing Tech University

C. T. Chan

Hong Kong University of Science and Technology

Hongxia Zheng

Tianjin Polytechnic University

Junjie Du

East China Normal University

Cooperative Institutions

Chinese Academy of Sciences

122

Institute of High Energy Physics

University of Science and Technology of China

China Spallation Neutron Source

University of Chinese Academy of Sciences

University of Electronic Science and Technology of China

University High School

Virtual High School

Tsinghua University

China Academy of Engineering Physics

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Observation of Non-Abelian Charged Nodes Linking Nonadjacent Gaps

Physical Review Letters (2022)

Dongyang Wang Biao Yang Mudi Wang Ruo-Yang Zhang Xiao Li

Nodal links are special configurations of band degeneracies in the momentum space, where nodal line branches encircle each other. In $PT$ symmetric systems, nodal lines can be topologically characterized using the eigenvector frame rotations along an encircling loop and the linking structure can be described with non-Abelian frame charges involving adjacent bands. While the commutation rules between the frame charges are well established, the underlying relationship between distant band gap closing nodes remains to be explored. In this Letter, we present a photonic multiple nodal links system, where the nodal lines of nonadjacent bands are investigated with symmetry constraints on frame charges. Through an orthogonal nodal chain, the nodal line from the lower two bands predicts the existence of nodal lines formed between the higher bands. We designed and fabricated a metamaterial, with which the multiple nodal links and the topological connection between nonadjacent nodal lines are experimentally demonstrated.

Line (geometry)

Nodal analysis

10.1103/physrevlett.129.263604

Cite

Citations (8)

Theoretical explanation of the polarization-converting system achieved by beam shaping and combination technique and its performance under high power conditions

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2015)

Peng Wang Xiao Li Yaping Shang Xiaojun Xu

The fiber laser has very obvious advantages and broad applications in remote welding, 3D cutting and national defense compared with the traditional solid laser. But influenced by heat effect of gain medium, nonlinear effect, stress birefringence effect and other negative factors, it's very difficult to get high power linearly polarized laser just using a single laser. For these limitations a polarization-converting system is designed using beam shaping and combination technique which is able to transform naturally polarized laser to linearly polarized laser at real time to resolve difficulties of generating high-power linearly polarized laser from fiber lasers in this paper. The principle of the Gaussian beam changing into the hollow beam passing through two axicons and the combination of the Gaussian beam and the hollow beam is discussed. In the experimental verification the energy conversion efficiency reached 93.1% with a remarkable enhancement of the extinction ratio from 3% to 98% benefited from the high conversion efficiency of axicons and the system worked fine under high power conditions. The system also kept excellent far field divergence. The experiment phenomenon also agreed with the simulation quite well. The experiment proves that this polarization-converting system will not affect laser structure which controls easily and needs no feedback and controlling system with stable and reliable properties at the same time. It can absolutely be applied to the polarization-conversion of high power laser.

Beam parameter product

Gaussian beam

Beam divergence

M squared

10.1117/12.2201130

Cite

Citations (0)

Optical Lattice Experiments

David S. Weiss Karl D. Nelson Xiao Li

Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text D. Weiss, K. D. Nelson, and X. Li, "Optical Lattice Experiments," in Frontiers in Optics 2007/Laser Science XXIII/Organic Materials and Devices for Displays and Energy Conversion, OSA Technical Digest (CD) (Optica Publishing Group, 2007), paper LThD1. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Lattice (music)

10.1364/ls.2007.lthd1

Cite

Citations (0)

First experiment on neutron resonance radiography with a Micromegas detector at the Back-n white neutron source

Journal of Instrumentation (2021)

Keqing Gao Yi Han Qingmin Zhang Ruirui Fan Yang Li

The element identification and imaging methods with a white neutron beam by using different detectors are under development at the Back-n white neutron source of China Spallation Neutron Source. The paper presents the preliminary experimental results with a Micromegas detector. The detector was developed for the beam profile measurements in the Back-n beamline. With upgraded electronics, this system can record the time-of-flight information of the neutrons together with the 2D imaging. The structure of the Micromegas, the improvement of electronics and the experimental setup are presented. A detailed data analysis including the noise suppression, the signal recognition and the event reconstruction are described. In the neutron time-of-flight (TOF) spectrum obtained from the neutron resonance radiography experiment, there are obvious dips due to the resonance absorption of the sample. Subsequently, clear resonance peaks from different elements can be identified form the processed neutron TOF spectrum, which is obtained by subtracting the sample-in spectrum from the sample-out spectrum. By selecting the corresponding resonance peaks, the shapes of different elements including Ag, In and W in a composite sample are successfully identified.

MicroMegas detector

Neutron Detection

Neutron Imaging

10.1088/1748-0221/16/02/p02036

Cite

Citations (3)

Spectral fitting study of the CIE standard illuminant D65 based on monochromatic LED

Chaoyang Zhang Qipeng He Xiao Li Bo He Wensheng Feng

The color assessment cabinet has important applications in the color fields of textiles, pigments, printing and dyeing, packaging, and photography. In order to achieve the spectral matching of CIE standard illuminant D65 using monochromatic LEDs, in this paper, we use genetic algorithm (GA) as the spectral matching algorithm, measure the absolute spectra of monochromatic LEDs and establish a database, optimize the parameters of the algorithm through simulation experiments, and optimize the combination of monochromatic LEDs using decreasing experiments to achieve the purpose of using fewer kinds of monochromatic LEDs to obtain a better fit with the target spectrum. The results show that the correlation indices R^2 and RMSE of 30 monochromatic LED combinations fitting D65 spectrum are 0.905 and 0.946, respectively, with high matching degree of D65 spectrum; 16 LED combinations fitting D65 spectrum are proposed by decreasing experiments, which have good fitting effect and reduce the difficulty of engineering practice.

Standard illuminant

Monochromatic color

Color temperature

Color difference

Color rendering index

10.1117/12.2684251

Cite

Citations (0)

4H‐SiC金属‐酸化物‐半導体デバイスのための酸化物絶縁体と遷移層における電荷トラップにおけるNOアニール処理の効果【Powered by NICT】

Chinese Physics B (2016)

Yifan Jia Lv Hongliang Yingxi Niu Li Ling Qingwen Song

Source

Cite

Citations (0)

Quantitative study of conservative gradient force and non-conservative scattering force exerted on a spherical particle in optical tweezers

Optics Express (2021)

Xiao Li Hongxia Zheng Chi Hong Yuen Junjie Du Jun Chen

We rigorously calculate the conservative gradient force (GF) and the non-conservative scattering force (SF) associated with the optical tweezers (the single beam optical trap). A wide range of parameters are considered, with particle size ranging from the Rayleigh to Mie regime (radius ∼3 µm), dielectric constant ranging from metallic (large and negative) to high dielectrics (large and positive), numerical aperture (NA) ranging from 0.5 to 1.33, and different polarizations. The trap depth associated with GF can reach 123 and 168 k B T per mW for a 0.5 µm-radius polystyrene particle illuminated by a 1064 nm Gaussian beam with NA = 0.9 and 1.3, respectively. This indicates that unless at a low beam power or with a small NA, the Brownian fluctuations do not play a role in the stability. The transverse GF orthogonal to beam propagation always dominates over the transverse SF. While the longitudinal SF can be larger than the longitudinal GF when the scattering is strong, the NA is small, or when absorption is present, optical trapping under these conditions is difficult. Generally speaking, absorption reduces GF and enhances SF, while increasing a dielectric constant enhances GF slightly but boosts SF significantly owing to stronger scattering. These results verify previous experimental observations and explain why optical tweezers are so robust across such a wide range of conditions. Our quantitative calculations will also provide a guide to future studies.

Optical force

Gaussian beam

Rayleigh length

10.1364/oe.434208

Cite

Citations (6)

Selective transport of chiral particles by optical pulling forces

Optics Express (2021)

Hongxia Zheng Xiao Li Huajin Chen Zhifang Lin

We propose a simple approach for chirality sorting based on the optical pulling forces. The scenario is to employ three simple plane waves with the same circular polarization. The three wave vectors have the same longitudinal positive z component while their corresponding transverse projections in the x - o - y plane form a regular triangle. In such an optical lattice, particles with certain chirality will be drawn by the transverse optical force to the periodic intensity maxima, where they are stably trapped and exerted by an optical pulling force along the negative z direction. On the contrary, particles with the opposite chirality are de-trapped transversely away from the intensity maxima and then dispersed in regions where they subject to a positive (pushing) force along the z direction. The phenomena therefore give rise to an alternative all-optical method for selective transport of chiral particles with a wide range of chirality parameters.

Chirality

Optical force

Pressure-gradient force

Maxima

Optical phenomena

10.1364/oe.444627

Cite

Citations (7)

Non-Hermitian non-equipartition theory for trapped particles

Nature Communications (2024)

Xiao Li Yongyin Cao Jack Ng

Abstract The equipartition theorem is an elegant cornerstone theory of thermal and statistical physics. However, it fails to address some contemporary problems, such as those associated with optical and acoustic trapping, due to the non-Hermitian nature of the external wave-induced force. We use stochastic calculus to solve the Langevin equation and thereby analytically generalize the equipartition theorem to a theory that we denote the non-Hermitian non-equipartition theory. We use the non-Hermitian non-equipartition theory to calculate the relevant statistics, which reveal that the averaged kinetic and potential energies are no longer equal to k B T /2 and are not equipartitioned. As examples, we apply non-Hermitian non-equipartition theory to derive the connection between the non-Hermitian trapping force and particle statistics, whereby measurement of the latter can determine the former. Furthermore, we apply a non-Hermitian force to convert a saddle potential into a stable potential, leading to a different type of stable state.

Equipartition theorem

10.1038/s41467-024-46058-5

Cite

Citations (3)

A source of polarization entangled photon pairs based on two-dimensional photonic crystals

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2006)

Xiao Li Yin Wang Wei Zhang Yidong Huang Jiangde Peng

Spontaneous parametric down-conversion in two-dimensional photonic crystal made of semiconductor material with large quadratic nonlinear susceptibility is proposed to generate polarization entangled photon pairs. On one hand, the large quadratic nonlinear susceptibility of AlGaAs crystal insures the high nonlinear conversion efficiency; on the other hand, the abnormal dispersion property of two-dimensional photonic crystal causes the satisfaction of the phase-matching condition. In particular, the dispersion property sensitively depends on the structure of photonic crystal. Then the walk-off between the down-converted photons with orthogonal polarizations can be minimized through appropriate structure parameter design; hence compensation measures to mitigate labeling effect on polarization entangled photon pairs can be eliminated.

Nonlinear photonic crystal

Spontaneous parametric down-conversion

Photon polarization

10.1117/12.688290

Cite

Citations (0)