bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute distance measurement based on asymmetric cross-correlation of femtosecond pulse
Authors: Peng Bo  , Qu Xing-Hua  , Zhang Fu-Min  , Zhang Tian-Yu  , Zhang Tie-Li  , Liu Xiao-Xu  , Xie Yang  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin 300072, China;,   Beijing Aerospace Institute for Metrology and Measurement Technology, Beijing 100076, China
Published: December 2020

Optical frequency comb is a kind of new pulse source, whose repetition rate and phase are locked. Optical frequency comb plays an important role in absolute distance measurement and time-frequency metrology. Lots of laser ranging methods such as time-of-flight and multi-heterodyne interferometry based on femtosecond laser pulse have been used in distance measurement. In this paper, a high-precision distance measurement system based on optical sampling by cavity tuning is set up to realize a long absolute distance measurement. And a kind of error compensation method is proposed based on the asymmetric cross-correlation patterns. In traditional optical sampling by cavity tuning measurement system, the fiber link is inserted into the reference path to extend the non-ambiguity distance, which does not have a good performance in arbitrary distance measurement. In our system, we use a 116-meter-long fiber which is inserted into the measuring path to extend the non-ambiguity distance. Besides, dispersion compensation technique is used to control the shape of the laser pulse. An asymmetric optical pulse is used as the light source, so that we can obtain extremely asymmetric cross-correlation patterns. The cross-correlation patterns can be acquired by sweeping the repetition frequency. We use an arbitrary waveform generator to provide the scanning voltage, and the scanning voltage can adjust the repetition rate of the pulse and has a frequency of 1 Hz. There will be two peaks on the envelope of cross-correlation pattern, and both peaks can be used to obtain the distance information. When the laser propagates in vacuum and the system is stabilized, the distance between these two peaks is constant, and we can use this distance to obtain the important factor N, which is used to describe the number of the pulse. As a result, we can realize absolute distance measurement without the help of other measurement systems. However, due to the dispersion of the medium, the distance between these two peaks is not constant, which means that the asymmetry of the cross-correlation patterns in dispersion medium will influence the measurement results. And the deviation is relevant to the peak-to-peak distance. We use the difference among the peak-to-peak distances at different positions to correct the measurement results. A comparison of our results with those from a commercial He-Ne laser interferometer shows that they are in agreement within 2 μm over 50 m distance, corresponding to a relative precision of 1.9×10-7.
Eliminating spiral wave and spatiotemporal chaos in cardiac tissues by suppressing the rotation of spiral wave tip
Authors: Li Qian-Yun  , Huang Zhi-Jing  , Tang Guo-Ning  ,   College of Physical Science and Technology, Guangxi Normal University, Guilin 541004, China
Published: December 2020

The variation of the function of sodium channel in cardiomyocyte is associated with multiple cardiac diseases. Increasing sodium channel availability can effectively increase sodium influx, leading to enhanced cardiomyocyte excitability, prolonged action potential duration and late sodium current activity, which may cause ventricular arrhythmia. On the other hand, enhancing cardiomyocyte excitability can effectively increase the conduction velocity of the medium in the rotation center of spiral wave, which can restrain the rotation of spiral wave, leading to the disappearance of spiral wave. However, how to increase the excitability of cardiomyocytes while avoiding arrhythmias has not yet been explored so far. In this paper, we study how to regulate the changes of sodium current in cardiac myocytes to control spiral wave and spatiotemporal chaos in a two-dimensional cardiac tissues by using the Luo-Rudy phase I model. We propose such a sodium current control scheme:when the cell is excited, the regulation of sodium current begins. If the absolute value of sodium current obtained from the model equation is less than the absolute value of sodium current control threshold, the sodium current is simply equal to the control threshold of sodium current. In other cases, the absolute value of sodium current cannot exceed the maximum value without control. When the membrane potential rises over-5 mV, the sodium current evolves naturally. This method of regulating sodium current ensures that all cells have almost the same amplitude of sodium current, while without obviously changing the excitation-time. All cells thus have the same excitability under the control of sodium current, so that the excitation of cell is less affected by spiral wave tip. The numerical simulation results show that as long as the control threshold of sodium current reaches a critical value, the rotation of spiral wave tip is effectively suppressed, causing spiral wave to move out of the system boundary and spatiotemporal chaos to disappear after it has evolved into a spiral wave. If the absolute value of sodium current control threshold is large enough, the spiral wave and spatiotemporal chaos would also disappear through conductive block. These results can provide a new idea for antiarrhythmic therapy.
Mechanism of magnetic radial vortex under effect of interfacial DzyaloshinskiiMoriya interaction
Authors: Dong Dan-Na  , Cai Li  , Li Cheng  , Liu Bao-Jun  , Li Chuang  , Liu Jia-Hao  ,   Department of Basic Science, Air Force Engineering University, Xi'an 710051, China;,   Aviation Maintenance NCO Academy, Air Force Engineering University, Xinyang 464000, China
Published: December 2020

Recently, the topological magnetic textures, such as magnetic vortex, skyrmion, meron, have attracted wide attention. Siracusano et al. [Siracusano G, Tomasello R, Giordano A, et al. 2016 Phys. Rev. Lett. 117 087204] found a new topological magnetic configuration, named a magnetic radial vortex. The magnetic radial vortex state is a stable topological magnetic texture. The magnetization in the center of the magnetic radial vortex, namely the radial vortex polarity, points upward or downward. The in-plane component of the magnetization, namely, the radial vortex radial chirality, orientates radially outward or inward. The magnetic radial vortex has become another emerging research hotspot after skyrmion, which can be attributed to its better thermal stability and lower driven current density. In this paper, we investigate the nucleation mechanism of magnetic radial vortex under the effect of interfacial Dzyaloshinskii-Moriya interaction (IDMI) by using the micromagnetic simulation. The results indicate that the smaller the diameter of the soft magnetic nanodisk, the more easily the wider range of the intensity of IDMI is created. When the thickness of the disk is increased by one order of magnitude, the magnetic radial vortex can be formed stably. Therefore, the intensity of IDMI can be further reduced by appropriately choosing the disc size. The magnetic radial vortex can be nucleated no matter whether the initial magnetization configuration is circular vortex or uniform state. However, if the initial state is uniform, the magnetization component along the z-axis direction is prerequisite. In the magnetic radial vortex nucleation process, the nucleation time of the uniform state is significantly longer than that of circular vortex, and the energy variation time of circular vortex is longer than that of the uniform state. In the process of the formation of magnetic radial vortex, the variation of magnetic moment, skyrmion number and energy are determined by different initial magnetization configurations. This work contributes to the understanding of the mechanism of magnetic radial vortex and provides a theoretical guideline for choosing reasonable disc size and IDMI strength. Moreover, the above-mentioned conclusions contribute to the practical applications of magnetic radial vortex in spin electric devices.
Rovibrational spectrum calculations of four electronic states in carbon monoxide molecule: Comparison of two effect correction methods
Authors: Xu Hui-Ying  , Liu Yong  , Li Zhong-Yuan  , Yang Yu-Jun  , Yan Bing  ,   Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China;,   Management Center of Big Data and Network, Jilin University, Changchun 130012, China
Published: December 2020

Accurate calculation of molecular energy is of great significance for studying molecular spectral properties. In this work, the potential energy curve and rovibrational spectrum (Gν) of the ground state X1∑+ and the excited states a3Π, a'3∑+ and A1Π of carbon monoxide molecule are calculated by the multi-reference configuration interaction method. In the calculation, the core-valence correlation correction (CV) effect and scalar relativistic (SR) effect are included.In order to obtain an accurate energy of molecule, two computational schemes are adopted. In the first scheme, i.e. (m MRCI+Q/CBS(TQ5)+CV+SR), the molecular orbital wavefunction is obtained from the Hartree-Fock self-consistent field method by using the basis set aug-cc-pVnZ. The wavefunction is first calculated by the state-averaged complete active space self-consistent field approach. Then the multi-reference configuration interaction method (MRCI) is adopted to calculate the dynamic correlation energy in the potential energy curve. Finally, we use the basis set cc-pCVQZ and aug-cc-pVQZ to calculate the CV effect and SR effect by the MRCI method. In the second scheme (aug-cc-pwCVnZ-DK (n=T, Q, 5)), the potential energy curves (PECs) of these four electronic states are calculated by the MRCI method whose basis set (aug-cc-pwCVnZ-DK) contains the CV effect and SR effect. Finally, in order to reduce the error caused by the basis set, we extrapolate the basis sets of the two computational schemes to the complete basis set. On the basis of the PECs plotted by the different methods, we obtain the spectroscopic parameters of the X1∑+, a3Π, a'3∑+ and A1Π states of the carbon monoxide by solving the internuclear Schrödinger equations through utilizing the numerical integration program “LEVEL”.In this paper, we calculate the SR effect and the CV effect by using different schemes, and the latter is indispensable for accurately calculating the molecular structure. For the lowest two electronic states, we consider the dependence of the two effects on the calculation of the Gaussian basis group (Method B), and find that the accuracy of the rovibrational spectrum is improved. It can be seen that these electronic states have higher requirements for electronic correlation calculation. For higher electronic states, the electron cloud distribution is relatively loose, and the electronic correlation obtained by a single Gaussian basis group can achieve the corresponding calculation accuracy. Of course, since the calculation of the rovibrational spectra is essentially only the relative energy, the offset effect of the electronic correlation effect of different electronic states is also included here in this paper.
Enhanced light absorption and device performances of organic photovoltaic devices with Au tetrahedra nanoparticles
Authors: Li Xue  , Wang Liang  , Xiong Jian-Qiao  , Shao Qiu-Ping  , Jiang Rong  , Chen Shu-Fen  ,   1. Mechanical Engineering Institute, Nanjing Institute of Technology, Nanjing 211167, China;,   2. Institute of Advanced Materials, Nanjing University of Posts and Telecommunications(NUPT), Nanjing 210023, China
Published: December 2020

Organic photovoltaic devices (OPVs) have attracted considerable attention because of their advantages of light-weight, low-cost, large-scale manufacturing process and mechanical flexibility. Unfortunately, in order to achieve efficient carrier extraction, the photoactive layer in OPVs must be rather thin (100 nm or less) due to its extremely low carrier mobilities for most of organic/polymer materials (on the order of 10-4 cm2/(V·s)). Such thin photoactive layers lead to a significant loss of incident sunlight, thereby improving a final low light absorption efficiency and power conversion efficiency (PCE). To promote the light absorption and thus enhance PCE of OPVs, Au tetrahedron nanoparticles (NPs) are synthesized in this work and then they are wrapped with poly (sodium 4-styrenesulfonate) (PSS) to form core-shell structure tetrahedron NPs (Au@PSS tetrahedron NPs). They are further incorporated into the interface of hole extraction layer and light photoactive layer to improve PCE of OPVs by enhancing their surface plasmon resonance effect-induced light absorption. The influences of doping concentration and PSS shell thickness of theses Au tetrahedron NPs on device performances are explored. The results indicate that the best performing PCE occurs at 6% concentration of Au@PSS tetrahedron NPs, reaching 3.08%, while it is further improved to 3.65% with an optimized PSS shell thickness of 2.5 nm, showing an enhancement factor of 22.9% compared with that of the control counterpart. The performance improvement of OPVs mainly originates from the promoted light absorption of donor due to the location of the resonant absorption peak of Au@PSS tetrahedron NPs in the absorption region of donor. Simultaneously, the introduction of the PSS shell promotes the dissociation of excitons and charge transfer. All of these contribute to the increasing of short-circuit current, fill factor and PCE of OPVs.
Picosecond laser-driven proton acceleration study of SGⅡ-U device based on charged particle activation method
Authors: He Shu-Kai  , Qi Wei  , Jiao Jin-Long  , Dong Ke-Gong  , Deng Zhi-Gang  , Teng Jian  , Zhang Bo  , Zhang Zhi-Meng  , Hong Wei  , Zhang Hui  , Shen Bai-Fei  , Gu Yu-Qiu  ,   Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China;,   State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Shanghai Jiao Tong University, International Fusion Sciences and Applications(IFSA) Collaborative Innovation Center, Shanghai 200240, China;,   Center for Applied Physics and Technology, Peking University, Beijing 100871, China
Published: December 2020

The laser-driven proton acceleration experiment is carried out on the SGⅡ-U device based on charged particle activation method, and the target parameters are optimized. The charged particle method is used to measure the maximum cutoff energy of proton, angular profile, total yield and conversion efficiency of laser energy to proton energy for different copper film thickness under the same laser condition. It is found that the optimal copper film thickness for the SGⅡ-U picoseond laser-driven proton experiment is 10 μm, the highest proton energy obtained is about 40 MeV, and the total yield of protons (>4 MeV) is about 4×1012, the conversion efficiency of laser energy to proton energy is about 2%. Thicker or thinner copper film can reduce the maximum cut-off energy of accelerated proton; when the target thickness is reduced to 1 μm, the pre-pulse of the laser begins to have a significant effect on the target normal sheath acceleration (TNSA) proton, proton energy drops sharply, the proton beam porfile exhibits a hollow structure; when the target thickness is increased to 35 μm, although the energy of the proton is reduced, the proton beam spot is more uniform. According to our experimental results, when using SGⅡ-U picosecond laser to generate protons as a backlight diagnostics, a thicker Cu film can be selected which can supply more uniform proton beams. When the target is too thin, the TNSA proton itself has a modulation structure which will cause interference to yield the photographic results; when the protons generated by the SGⅡ-U picosecond are used to generate neutron source, the higher proton energy and yield are required, and 10 μm Cu film is suitable. The further enhancing the TNSA accelerated proton energy and quantity of the SGⅡ-U picosecond laser requires the further improving of the laser contrast.
Ultralow-voltage albumen-gated electric-double-layer thin film transistors
Authors: Liang Ding-Kang  , Chen Yi-Hao  , Xu Wei  , Ji Xin-Cun  , Tong Yi  , Wu Guo-Dong  ,   1. College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;,   2. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
Published: December 2020

In recent years, environment-friendly and biocompatible electronics have received extensive attention. As a kind of natural biological material with rich sources, proteins have been widely used in electronic devices. In this work, electric-double-layer (EDL) thin-film transistors (TFTs) gated by natural chicken albumen are fabricated at room temperature. The indium-tin-oxide (ITO) conductive glass is employed as a substrate. The spin coated chicken albumen film is used as the gate dielectric. The indium-zinc-oxide (IZO) is sputtered on an albumen-coated ITO glass as the channel and the source/drain electrodes with only one shadow mask. The capacitance-frequency measurements demonstrate an ultra-large specific capacitance of the albumen film at low frequencies. For the physical understanding of the capacitive coupling within the albumen film, the phase angle is characterized as a function of frequency. The results indicate that such an ultra-large capacitive coupling can be attributed to the proton migration under the electric field, which results in the EDL effect at the interface of the albumen film. By DC sweep measurements, a low leakage current is observed (<3.0 nA at Vgs=1.5 V), which indicates a good isolation of the albumen-based dielectric. By transfer and output measurements, an ultralow operation voltage of 1.5 V, a high field-effect mobility of 38.01 cm2/(V·s), a low subthreshold swing of 164 mV/decade, and a large on-off ratio of 2.4×106 are obtained for such albumen-gated TFTs. The ultra-large EDL capacitive coupling is responsible for such good electrical characteristics. The dynamic bias stress stability of the albumen-gated TFTs is also investigated. The device exhibits a good reproducibility in response to the repeatedly pulsed gate voltage. A maintainable on-to-off ratio (>106) and no obvious current loss are observed, which suggests that neither chemical doping nor chemical reaction occurs at the albumen-based dielectric/IZO channel interface when the gate potential is biased. After being aged one day in air ambient without surface passivation, the albumen-gated TFTs show a good stability of the electrical properties. Such ultralow-voltage EDL-TFTs gated by albumen electrolyte will be useful for the bioelectronic and low-energy portable electronic products. And our results will also have potential applications in biocompatible artificial neuron networks and brain-inspired neuromorphic systems.
Research progress of mid-and far-infrared nonlinear optical crystals
Authors: Jia Ning  , Wang Shan-Peng  , Tao Xu-Tang  ,   State Key Laboratory of Crystal Materials, Institute of Crystal Materials Shandong University, Jinan 250100, China
Published: December 2020

High-power tunable mid-infrared (MIR) and far-infrared (FIR) lasers in a range of 3-20 μm, especially in the atmospheric windows of 3-5 μm and 8-12 μm are essential for the applications, such as in remote sensing, minimally invasive surgery, telecommunication, national security, etc. At present, the technology of MIR and FIR laser have become a research hotspot. As the core component of all-solid-state laser frequency conversion system, nonlinear optical (NLO) crystals for coherent MIR and FIR laser are urgently needed by continuously optimizing and developing. However, compared with several outstanding near infrared, visible, and ultraviolet NLO crystals, such as β-BaB2O4, LiB3O5, LiNbO3, KTiOPO4, and KBe2BO3F2, the generation of currently available NLO crystals for 3-20 μm laser is still underdeveloped. Traditional NLO oxide crystals are limited to output wavelengths ≤ 4 μm due to the multi-phonon absorption. In the past decades, the chalcopyrite-type AgGaS2, AgGaSe2 and ZnGeP2 have become three main commercial crystals in the MIR region due to their high second-harmonic generation coefficients and wide IR transparency ranges. Up to now, ZnGeP2 is still the state-of-the-art crystal for high energy and high average power output in a range of 3-8 μm. Unfortunately, there are still some intrinsic drawbacks that hinder their applications, such as in poor thermal conductivity and low laser damage threshold for AgGaS2, non-phase-matching at 1.06 μm pumping for AgGaSe2, and harmful two-photon absorption at 1.06 μm for ZnGeP2. In addition, ZnGeP2 has significant multi-phonon absorption in an 8-12 μm band, which restricts its applications in long wavelength MIR. With the development of research, several novel birefringent crystals, as well as all-epitaxial processing of orientation-patterned semiconductors GaAs (OP-GaAs) and GaP (OP-GaP), have been explored together with attractive properties, such as large NLO effect, wide transparency ranges, and high resistance to laser damage.
In this paper, from the angle of the compositions of NLO crystal materials, several kinds of phosphide crystals (ZnGeP2 CdSiP2) and chalcogenide crystals (CdSe, GaSe, LiInS2 series, and BaGa4S7 series) are summarized. In addition, the latest achievements of the orientation-patterned materials such as OP-GaAs and OP-GaP are also reviewed systematically. In summary, we review the above-mentioned attractive properties of these materials such as in the unique capabilities, the crystal growth, and the output power in the MIR and FIR region.
Pressure-induced phenomena and physics in iron-based superconductors
Authors: Guo Jing  , Wu Qi  , Sun Li-Ling  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The discovery of Fe-based superconductor in 2018 opened an illustrious chapter in the history of high temperature superconductors. Over the past ten years, many progresses on experiments, theories and applications have been achieved in the studies of Fe-based superconductors, which have greatly enriched the basic knowledge on the superconductivity of high temperature (Tc) superconductors and laid a solid foundation for uncovering superconducting mechanism of high-Tc superconductors and expanding their applications. In this review article, we present some important progresses and new phenomena/physics exhibited in the pressurized Fe-based superconductors, including pressure-induced superconductivity, pressure-induced reemergence of superconductivity, pressure-enhanced superconducting temperature, the prediction on the highest superconducting temperature for Fe-based superconductors via high pressure studies, the effect of the separated phase structure on the superconductivity and the discovery of a bi-critical point between antiferromagnetic and superconducting phases. It is expected that these high pressure experimental results on Fe-based superconductors, together with the results reported in the same issue through other experimental and theoretical methods, can aid to outline a more complete physical picture for a more comprehensive and deeper understanding on Fe-based superconductors.
Piezoelectric, dielectric, and ferroelectric properties of high Curie temperature bismuth layer-structured bismuth titanate-tantalate (Bi3TiTaO9)
Authors: Zheng Long-Li , Qi Shi-Chao , Wang Chun-Ming , Shi Lei ,   Shandong Experimental High School, Jinan 250001, China,   School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China,   Taishan College, Shandong University, Jinan 250100, China
Published: December 2020

Piezoelectric materials have been extensively employed in numerous devices. With the rapid development of modern information technology, the high temperature piezoelectric materials that can work in extreme environments are in great demand. Therefore, it is urgent to investigate piezoelectric materials with high Curie temperature and strong piezoelectric performance. This paper reports the significantly improved piezoelectric properties of high temperature bismuth titanate-tantalate (Bi3TiTaO9, BTT) polycrystalline ceramics. In this work, the rare-earth cerium ions modified Bi3TiTaO9 piezoelectric ceramics are prepared by the conventional ceramic technique. The introduction of Ce ions significantly enhances the piezoelectric performance of BTT ceramics. The BTT-6Ce (BTT+0.6 wt.% CeO2) exhibits optimized piezoelectric properties with a piezoelectric coefficient d33 of 16.2 pC/N, which is four times the value of unmodified BTT (d33~4.2 pC/N). The dielectric and ferroelectric measurements indicate that Ce ions remarkably reduce the dielectric loss tanδ and increase polarizations, which are beneficial to the piezoelectric properties. The BTT and BTT-6Ce (x = 0.6) ceramics each have a high Curie temperature TC: ~890 ℃ and 879 ℃, respectively. The coercive field Ec of BTT and BTT-6Ce ceramics are 53.8 kV/cm and 57.5 kV/cm, respectively, while the remnant polarizations Pr of BTT and BTT-6Ce ceramics are 3.4 μC/cm2 and 5.4 μC/cm2, respectively, at a frequency of 1 Hz, temperature of 180 ℃, and drive field of 110 kV/cm. The thermal annealing measurements indicate that the BTT ceramics still possess stable piezoelectric properties after being annealed at 800 ℃. The results exhibit that the cerium-modified BTT ceramics are good materials for high temperature applications.
Recent progress on advanced infrared photodetectors
Authors: Hu Wei-Da , Li Qing , Chen Xiao-Shuang , Lu Wei ,   State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Shanghai 200083, China,   University of Chinese Academy of Sciences, Beijing 100084, China
Published: December 2020

Modern infrared detector technology has a history of nearly eighty years. Since the first PbS photodiode was put into use during the World War II, infrared detectors have achieved significant progress, even the third-generation infrared systems have been proposed. In the past decades, the traditional infrared detectors represented by HgCdTe, InSb and InGaAs have been widely applied in military, remote sensing, communication, bioscience, and space exploration. However, the increasing applications demand higher performance infrared detectors. Especially in recent years, the intelligent infrared detection technique was strongly demanded in many high-tech fields such as artificial intelligence, virtual reality systems and smart city. Therefore, the fabricating of infrared detection systems with smaller size, lighter weight, lower power, higher performance and lower price has become an urgent task. At present, the infrared photodetectors are in an age of rapid change, and many new type of advanced infrared photodetectors come to the fore quickly. For the purpose of summarizing these detectors, they are reviewed covering four parts: microstructure coupled infrared detector, infrared detector based on band engineering, new type of low-dimensional material infrared detector, and new directions for traditional infrared detectors. In the infrared detection systems, these photodetectors can be fully used for their prominent performance. The microstructure coupled infrared detector can improve chip integration with high quantum efficiency. Precise design of band structure will raise the operating temperature for mid and long wavelenth infrared photodetectors. Owing to the unique structures and physical properties, low-dimensional material infrared photodetectors have shown their potential application value in flexibility and room temperature detection systems. The ability of avalanche photodetector to detect the extremely weak signal makes it possible using in the frontier science such as quantum private communication and three-dimensional radar imaging systems. The device based on hot electron effect provides a new idea for far infrared detection. The barrier detectors will reduce the manufacturing cost of traditional materials and the design is also very illuminating for other new materials. In this review, firstly we present the history of infrared photodetectors in short. Then the mechanism and achievements of the advanced infrared photodetectors are introduced in detail. Finally, the opportunities and challenges of infrared detection are summarized and predicted.
Surface plasmaons enhanced light-matter interactions
Authors: Yu Hua-Kang , Liu Bo-Dong , Wu Wan-Ling , Li Zhi-Yuan ,   School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510641, China
Published: December 2020

Surface plasmon polaritons (SPPs) have been widely investigated in the past decades. Due to their unique feature of field localization, optical energy can be strongly confined in the subwavelength and even nanoscale space. This strong confinement gives rise to dramatically increased electromagnetic field strength, leading to greatly enhanced light-matter interactions. The properties of SPP are strongly dependent on material, morphology and structure. The wavelength of surface plasmon resonance can be readily manipulated over broadband optical spectra, covering ultraviolet, visible, near infrared to far infrared. In this review article, both working principle and applications of surface plasmon enhanced light-matter interactions, such as fluorescence, Raman scattering, nonlinear optics, heat effects, photoacoustic effects, photo-catalysis, and photovoltaic conversion, are comprehensively reviewed. Besides, the current problems and future research directions of surface plasmons are discussed. Our paper provides valuable reference for future high-performance plasmonic device and technology applications.
Research progress of interface passivation of n-i-p perovskite solar cells
Authors: Li Xiao-Guo , Zhang Xin , Shi Ze-Jiao , Zhang Hai-Juan , Zhu Cheng-Jun , Zhan Yi-Qiang ,   Key Laboratory of Semiconductor Photovoltaic Technology of Inner Mongolia Autonomous Region, School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China,   Academy for Engineering and Technology, Fudan University, Shanghai 200433, China,   School of Information Science and Technology, Fudan University, Shanghai 200433, China
Published: December 2020

In recent years, organic-inorganic hybrid perovskite solar cells have aroused the interest of a large number of researchers due to the advantages of large optical absorption coefficient, tunable bandgap and easy fabrication. Recently, the power conversion efficiency of organic-inorganic hybrid perovskite solar cells has been enhanced to more than 23% in laboratory. In solution processed perovskite solar cells, perovskite and charge transport layer are stacked together, due to the different crystallization rates leading to lattice mismatch near the surface region of perovskite film, resulting in a lot of interface defects, especially at the interface between perovskite and charge transport layer. What is more, the photo-induced free carriers must transfer across the interfaces to be collected. But the defects near the interface can trap photogeneration electrons, thus reducing the carrier lifetime and causing the charges to be recombined, which greatly influence the performance and stability of perovskite solar cells. Therefore, reducing and passivating these defects is critical for obtaining the high performance perovskite solar cells. Now, there have been made tremendous efforts devoting to advancing passivation techniques, such as doping and surface modification, for high efficiency perovskite solar cell with improved stability and reduced hysteresis. These approaches also contribute to improving the energy band alignment between carrier transport layers and perovskite absorber improving device performance, or resistance moisture to enhance device stability. In this review we mainly introduce the formation and the effect of defects on perovskite solar cells, analyze the mechanism for passivating the interfacial defects between charge transport layer and perovskite photo absorption layer for different materials, compare the effects of different passivation materials on the photovoltaic performance of perovskite solar cells, and summarize the role of these materials in passivating the defects. Finally we discuss the research trend and development direction of passivation defects in perovskite solar cells.
Advances in dynamically tunable plasmonic materials and devices
Authors: Shu Fang-Zhou , Fan Ren-Hao , Wang Jia-Nan , Peng Ru-Wen , Wang Mu ,   National Laboratory of Solid State Microstructures and School of Physics,  Nanjing University, Nanjing 210093, China
Published: December 2020

As is well known, plasmonics bridges the gap between nanoscale electronics and dielectric photonics, and is expected to be applied to light generation, photonic integration and chips, optical sensing and nanofabrication technology. So far, most of plasmonic microstructures and nanostructures cannot dynamically tune the properties once their structures are fabricated. Therefore, developing active plasmonic materials and devices is especially desired and necessary. Recently, dynamically tunable plasmonic materials and devices have been intensively investigated with the aim of practical applications. Here in this paper, we review recent research advances in active plasmonic materials and devices. Firstly we summarize three approaches to dynamically tuning plasmonic materials and devices. The first approach is to dynamically change the effective permittivity of metallic microstructures and nanostructures. The second approach is to dynamically adjust the ambient environments of the materials and devices. The third approach is to real-time tune the coupling effects in the nanostructures. Then we take ordinary plasmonic materials, plasmonic metamaterials, and plasmonic metasurfaces for example to show how to make them dynamically tunable. With external fields (such as electrical field, light field, thermal field, and mechanical force field, etc.), various approaches have been demonstrated in dynamically tuning the physical properties of plasmonic systems in real time. We anticipate that this review will promote the further development of new-generation subwavelength materials and optoelectrionic devices with new principles and better performances.
Research progress of surface plasmons mediated photothermal effects
Authors: Wang Shan-Jiang , Su Dan , Zhang Tong ,   School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China
Published: December 2020

Plasmonic nanostructure can efficiently manipulate light on a subwavelength scale, which can break through the optical diffraction limit and significantly enhance the interaction between light and matter. In the study of photoelectric devices based on the plasmonic mechanism, the absorption of light in surface plasmons is usually considered as loss, which needs to be suppressed. However, based on the photothermal effect, the light absorption of plasmonic nanostructure can be effectively utilized and converted into heat. The research of this new type of nano-heat source is a hot topic in the field of plasmonics. In this paper, we review the recent progress of the study of photothermal effects of plasmonic nanostructure, focusing on the physical process of heating effects, and the methods to control the temperature distribution in both the process of heat generation and the process of delivery of heat. Finally, the applications of nano-heat source in the fields of nano-fabrication and broad-spectrum photothermal conversion are also presented.
First-principles study of rare-earth-doped cathode materials Li2MnO3 in Li-ion batteries
Authors: Zheng Lu-Min , Zhong Shu-Ying , Xu Bo , Ouyang Chu-Ying ,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: December 2020

Although Li-ion batteries (LIBs) have had great success in portable electronic devices and electrical vehicles, the improvement of the performances has received intensive attention. Generally, doping is an effective method to modify the battery performance, such as cycling performance. Appropriate doping can effectively reduce the structural deformation of electrode materials during charging and discharging, thus improving the cycling performace of LIBs. Because of the large radius, large charge and strong self-polarization ability of rare earth ions, rare earth element is a promising candidate for doping modification. Motivated by this, we study the structural, electronic and ionic diffusion properties of rare-earth-doped cathode material Li2MnO3 by using first-principles calculations based on density functional theory as implemented in Vienna ab initio simulation package. After the doping of rare earth elements (La, Ce, Pr, Sm), the lattice constants and cell volumes increase with respect to the undoped one. The cell volume of La-doped Li2MnO3 has the biggest change, while the cell volume of Sm-doped one has the smallest change. Due to the different ionic valence states, the electronic structures of the doped Li2MnO3 are various. La-doped Li2MnO3 exhibits metallic characteristic, whereas Ce-, Pr-, and Sm-doped structures are semiconducting with smaller band gap than that of the undoped case. The Li diffusion energy barrier in Li2MnO3 shows complicated variation when the La and Ce are doped. At the sites far away from the rare earth ions, the Li diffusion barriers are lower than that of undoped one. The reason is that the diffusion channels, which are determined by the distance between neighboring O-layers, are enlarged due to the implantment of rare earth ions. However, the situations are various at the sites close to the rare earth ions. The Li diffusion barriers increase essentially when Li ions diffuse from the nearest sites to rare earth ions. Such a result is closely related to the huge changes of local structures around the rare earth ions. In addition, the effect of La doping on the Li diffusion barrier is more obvious than that of Ce doping, which is due to the local structure change around rare earth ions.
Broadband very high frequency localization of lightning radiation sources based on orthogonal propagator method
Authors: Li Shu-Lei , Qiu Shi , Shi Li-Hua , Li Yun , Duan Yan-Tao ,   National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering, Army Engineering University, Nanjing 210007, China
Published: December 2020

Broadband very-high frequency (VHF) localization of lightning radiation sources provides an important means for understanding lightning discharge characteristics and the corresponding physical mechanisms. In order to improve the ability to locate weak radiation sources, the orthogonal propagator method (OPM) is proposed to map the space-time evolution process of lightning discharge channels based on the theory of spatial spectrum estimation. In the method, the linear decomposition of the covariance matrix is used to form the orthogonal propagator, and the spatial spectrum is constructed according to orthogonality of subspaces. Then, the location of lightning radiation sources is determined by searching for the maximum of the spatial spectrum. For broadband VHF signals, the non-coherent subspace method is used to average the effective frequency points in bandwidth to reduce noise interference. Based on a multiple-antenna radiation continuous observation system (MARCOS), locating performance of the method is analyzed by numerical simulation. The method is verified by parameters such as locating error, half-peak width of the spatial spectrum, and angular resolution. Compared with the results from the time reversal technique(FDTR), the location error and recognition probability under a low signal to noise ratio (SNR) of the proposed OPM algorithm are similar to those of FDTR algorithm, but the angular resolution for two radiation sources of OPM algorithm is better than that of FDTR algorithm. Finally, the proposed method is used to map the spatial and temporal development of a classical triggered lightning discharge channels in the summer of 2017. The results show that the proposed method can clearly depict the basic structure of lightning discharge channels with high spatial and temporal resolution. For the upward positive leader of the triggered lightning, the OPM algorithm can locate more radiation sources with a better structure than the FDTR algorithm. It implies that the proposed OPM algorithm is better for locating weak radiation sources than the FDTR algorithm. Meanwhile, the OPM algorithm has better performance for resolving two radiation sources in the same window than the FDTR algorithm. As a result, the proposed OPM method is of great significance for improving the application value of broadband VHF arrays in the study of locating weak radiation sources and lightning initiation mechanisms.
Magneto-electronic properties of InSe nanoribbons terminated with non-metallic atoms and its strain modulation
Authors: Li Ye-Hua , Fan Zhi-Qiang , Zhang Zhen-Hua ,   Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering, School of Physics and Electronic Science,Changsha University of Science and Technology, Changsha 410114, China
Published: December 2020

Employing the first-principles calculation based on the density functional theory, the geometries, magneto-electronicproperties, and strain effects of the zigzag-edged InSe nanoribbons with the Se-edge saturated by H atoms and In-edge terminated by various non-metallic elements X (X = H, B, N, P, F and Cl) are studied. The calculated formation energy and Forcite annealing simulations show that the H-ZN(7)-X has a stable geometry. For F- and Cl- terminated ribbons, they have a magnetic metallic property similar to that in the case of H termination, and for the N termination the nanoribbon has the strongest magnetic property. However, the B and P terminations cause the magnetic properties at the ribbon edge to completely disappear, particularly when the mechanical strain is applied. The magnetic stability of H-ZN(7)-N is enhanced, and the spin polarization efficiency (SP) at the Fermi level can be effectively modulated in a range from zero to 92%, which means that it is possible to design a mechanical switch for controlling the spin transport at low bias. The strain modulating mechanism is related to the fact that the variation of strain-induced bond length leads the unpaired electrons to be redistributed or disappear. The magnetic properties of N-ZN(7)-N are mainly derived from the p orbitals of In, Se and N atoms, thus it is very important to develop non-transition metal magnetic materials.
Simulation study on plasma discharge and transport in cylindrical cathode controlled by expanding electromagnetic field
Authors: Cui Sui-Han , Wu Zhong-Zhen , Xiao Shu , Chen Lei , Li Ti-Jun , Liu Liang-Liang , Ricky K Y Fu , Tian Xiu-Bo , Paul K Chu , Tan Wen-Chang ,   School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China,   Department of Physics and Materials Science, City University of Hong Kong, Hong Kong 999077, China
Published: December 2020

High-power impulse magnetron sputtering (HiPIMS) is a new magnetron sputtering technique which can produce high-density plasmas with a high ionization rate and prepare coatings with a good performance such as large density and high adhesion. To obtain stable discharge and universal materials’ ionization rates, a cylindrical cathode is proposed based on the hollow cathode effect. However, the unusual plasma transport results in a large loss of ions and a low deposition rate. To solve these problems, an expanding electromagnetic field is proposed to control the plasma transport in this work. The particle in cell/Monte Carlo collision (PIC/MCC) method and the plasma diffusion model are used to simulate the plasma transport in and out of the cylindrical cathode with different currents in the electromagnetic coils, respectively. The simulation results reveal that different electromagnetic fields can achieve different plasma density distributions, resulting in different accumulated positions and different diffusion paths. When the coil current is positive, the resistance to axial motion of electrons is small but the resistance to radial motion is large, so that the hollow cathode effect is weakened and the plasma beam tends to output uniformly. When the coil current is negative, the resistance to axial motion of electrons is large but the resistance to radial motion is small, so that the hollow cathode effect is enhanced and the plasma tends to gather on the central axis and then diffuses outward. To verify the simulation results, Ar/Cr HiPIMS discharge experiments are carried out with the cylindrical cathode in a homemade vacuum system. The experiment results indicate that the threshold voltage, the plasma flow shape, the optical emission spectrum (OES) intensity, and the deposition distribution are determined by the electromagnetic coil current. The variation tendency is in coincidence with the prediction of the simulation. Consequently, by adding an expanding electromagnetic field, the plasma discharge in the cylindrical cathode can be easily controlled and the deposition rate is greatly enhanced. This electromagnetic control strategy not only realizes the enhancement and effective control of plasma, but also improves the homogeneity and the deposition rate of the coatings, thus laying a foundation for the industrial application of HiPIMS.