Weiwei Liu

State Grid Corporation of China (China)

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Peixiang Lu

Wuhan University

Bing Wang

Wuhan National Laboratory for Optoelectronics

Hua Long

Huazhong University of Science and Technology

Chengzhi Qin

Wuhan National Laboratory for Optoelectronics

Kai Wang

First Affiliated Hospital of Anhui Medical University

Kai Wang

Huazhong University of Science and Technology

Yiling Song

Wenzhou University

Shaolin Ke

Wuhan Institute of Technology

Lingzhi Zheng

Wuhan National Laboratory for Optoelectronics

Lange Zhao

Huazhong University of Science and Technology

Cooperative Institutions

Huazhong University of Science and Technology

Wuhan National Laboratory for Optoelectronics

Chinese Academy of Sciences

University of Chinese Academy of Sciences

Zhejiang University

University of Science and Technology of China

Tsinghua University

Wuhan Institute of Technology

Nanjing University

State Grid Corporation of China (China)

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Macroscopic effect of plasmon-driven high-order-harmonic generation

Physical review. A/Physical review, A (2017)

Feng Wang Weiwei Liu Lixin He Liang Li Baoning Wang

We present a numerical method to calculate the macroscopic harmonic spectrum generated from the gas-exposed nanostructure. This method includes the propagation of plasmonic and harmonic fields in the macroscopic medium as well as the response of the single atom exposed to plasmonic field. Based on the simulation, we demonstrate that the macroscopic harmonic yields drop dramatically in the high-energy region. This result well interprets the disagreement in the cutoff between the single-atom prediction and the experimental detection. Moreover, we also show that the harmonic cutoff difference induced by a $\ensuremath{\pi}$ shift in carrier-envelope phase (CEP) of laser pulses depends sensitively on the spatial position. However, when the collective effect of plasmon-driven high-order-harmonic generation is considered, this cutoff difference is eliminated.

Cut-off

Harmonic

Cutoff frequency

Harmonic spectrum

10.1103/physreva.96.033407

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Citations (19)

ICONE23-1158 EFFECT OF OXIDATION CHEMISTRY OF SCW ON STRESS CORROSION CRACKING OF AUSTENITIC STEELS

The Proceedings of the International Conference on Nuclear Engineering (ICONE) (2015)

Bin Gong Yongfu Zhao Yanping Huang E. Jiang Weiwei Liu

Austenitic steel is a candidate material for Supercritical Water-Cooled Reactor. This study is to investigate stress corrosion cracking behavior of HR3C under effect of supercritical water chemistry. A transition phenomenon of water parameters was monitored during a pseudo critical region by water quality experiments at 650 °C and 30 MPa.The stress-strain curves and fracture time of HR3C were obtained by slow strain rate tensile tests in supercritical water at 620 °C and 25 MPa. The concentration of dissolved oxygen was 200-1000 μg/kg and the strain rate was 7.5×10^<-7>/s. Recent results showed the failure mode was dominated by intergranular brittle fracture. The relations of oxygen concentration and fracture time were nonlinear. 200-500 μg/kg of oxygen accelerated the cracking but a longer fracture time was measured when oxygen concentration was increased to 1000 μg/kg. Chromium depletion occurred in the oxide layer at the tip of cracks. Grain size increased and chain precipitated phases was observed in the fractured specimens. These characteristics were considered to be contributive to the intergranular stress corrosion cracking.

Brittleness

10.1299/jsmeicone.2015.23._icone23-1_84

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Giant Two‐Photon Absorption and Its Saturation in 2D Organic–Inorganic Perovskite

Advanced Optical Materials (2017)

Weiwei Liu Jun Xing Jiaxin Zhao Xinglin Wen Kai Wang

Organic–inorganic perovskites have attracted great attentions driven by exceptional progress in photovoltaics, photonics, and optoelectronics. Different from the corner sharing framework of 3D perovskite, 2D organic–inorganic perovskites possess a layered staking structure composed of alternative organic and inorganic components. Due to the inherent multi‐quantum‐well‐like structure, it is intriguing to explore the optical properties of 2D perovskites enabled by spatial and dielectric confinement. Herein, the two‐photon absorption (TPA) properties of 2D perovskite phenylethylamine lead iodide ((PEA) 2 PbI 4 ) are systematically studied. The 2D perovskite exhibits a giant TPA and saturation effect under excitation of 800 nm femtosecond laser. The TPA coefficient of a (PEA) 2 PbI 4 flake is measured to be about 211.5 cm MW −1 , which is at least one order of magnitude larger than those of 3D perovskite films and some typical semiconductor nanostructures. The giant TPA can be attributed to the enhanced quantum and dielectric confinement in the organic–inorganic multi‐quantum‐well structure. In addition, a highly thickness‐dependent TPA is observed for the 2D perovskite flakes. The result advocates a great promise of 2D organic–inorganic perovskites for nonlinear optical absorption related optoelectronic devices.

Saturation (graph theory)

10.1002/adom.201601045

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Citations (197)

Experimental study on the role of a resistor in the filter of Hall thrusters

Physics of Plasmas (2011)

Liqiu Wei Chunsheng Wang Zhongxi Ning Weiwei Liu Chaohai Zhang

A filter is a mainly component applied to reduce the discharge current low frequency oscillation in the range of 10–100 kHz. The only form of the filter in actual use involves RLC networks, whose design originates from the 1970s, but even now, researchers are unaware of the actual primary motivations for the resistor’s presence [S. Barral et al., AIAA Paper 2008-4632, 2008]. Therefore, the role of the resistor in the filter is experimentally studied and discussed through the analysis of control system and electric circuit theory. Experimental results and analysis indicate that the presence of a resistor makes the filter having the phase compensation function. The proper phase-angle and amplitude provided by the filter would increase or decrease the ion mobility and be helpful to balance the ion production in the discharge channel and then to decrease the fluctuation of the plasma density and lower the low frequency oscillation.

Oscillation (cell signaling)

Describing function

10.1063/1.3599519

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Nonlinear Non-Hermitian Skin Effect and Skin Solitons in Temporal Photonic Feedback Lattices

arXiv (Cornell University) (2024)

Shulin Wang Bing Wang Chenyu Liu Chengzhi Qin Lange Zhao

Non-Hermitian skin effect (NHSE), i.e., the localization of eigenstates near lattice boundaries, has recently spurred tremendous interest in topological physics. Beyond the well-explored linear NHSE, the interplay of nonlinearity and skin localization represents a cutting-edge area of research, offering novel insights into wave propagation and localization control in various physical systems. Unlike the linear NHSE successfully observed in weak-power optical systems, the observation of nonlinear NHSE and resulting skin solitons remains so far elusive, mainly due to the high energy levels required in most of nonlinear effects. Here we report the experimental demonstration of nonlinear NHSE in a Kerr nonlinear temporal photonic lattice, where the high-power limitation and lack of tunability intrinsic to optical materials are overcome by an artificial nonlinearity arising from opto-electronic feedback. Thanks to Kerr self-trapping, the nonlinear NHSE is demonstrated to possess much better localization strength and robustness at the preferred boundary compared to the linear case. Away from the preferred boundary, Kerr self-trapping can even inhibit NHSE-induced transport and form stable skin solitons. Harnessing the nonlinearity-controlled NHSE, we judiciously design an optical router with a flexibly-tuned output port. Our findings promise great applications in robust signal transmission, routing, and processing.

Skin effect

10.48550/arxiv.2409.19693

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Intelligent Fault Diagnosis with Deep Architecture

Jinrui Gan Peng Wu Guoliang Zhang Shiwen Dong Zhaogang Han

The status judgment of converter valve equipment is an important part of ultra high voltage maintenance. However, accurate judgment of possible failures remains challenging. This paper proposes a novel multi-region deep architecture to improve abnormal judgement by considering long-range context information in increasingly finer spatial regions. Specifically, the specified characteristics of video sequence will be completely explored through C3D and recurrent neural network with LSTM cells, extracting high-level spatio-temporal features. In addition, spatial pyramid crop is proposed to characterize each video at different spatial pyramid levels. These sampling sub-videos can encode locally saliency among categories. Experimental results demonstrate the effectiveness of our model, compared with other state-of-the-art approaches.

Pyramid (geometry)

ENCODE

Deep Neural Networks

10.1109/cyberc49757.2020.00051

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Two-photon-pumped amplified spontaneous emission from Ruddlesden-Popper perovskite flakes

Optics Express (2022)

Xiaohong Li Weiwei Liu Yan Gao Yan Qin Hua Long

Herein, we report the two-photon pumped amplified spontaneous emission (ASE) in the 2D RPPs flakes at room temperature. We prepared high-quality (BA)2(MA)n-1PbnI3n+1 (n = 1, 2, 3, 4, 5) flakes by mechanical exfoliating from the fabricated crystals. We show that the (BA)2(MA)n-1PbnI3n+1 flakes display a tunable two-photon pumped emission from 527 nm to 680 nm, as n increases from 1 to 5. Furthermore, we demonstrated two-photon pumped ASE from the (BA)2(MA)n-1PbnI3n+1 (n = 3, 4, 5) flakes. The two-photon pumped ASE thresholds of the RPPs are lower than lots of the other semiconductor nanostructures, indicating an excellent performance of the RPPs for two-photon pumped emission. In addition, we investigated the pump-wavelength-dependent two-photon pumped ASE behaviors of the RPPs flakes, which suggest that the near-infrared laser in a wide wavelength range can be converted into visible light by the frequency upconversion process in RPPs. This work has opened new avenues for realizing nonlinearly pumped ASE based on the RPPs, which shows great potential for the applications in wavelength-tunable frequency upconversion.

Photon Upconversion

Amplified spontaneous emission

Optical Pumping

10.1364/oe.455104

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Citations (5)

Research of vibration control based on current mode piezoelectric shunt damping circuit

IOP Conference Series Materials Science and Engineering (2017)

Weiwei Liu Qibo Mao

The piezoelectric shunt damping circuit using current mode approach is imposed to control the vibration of a cantilever beam. Firstly, the simulated inductance with large values are designed for the corresponding RL series shunt circuits. Moreover, with an example of cantilever beam, the second natural frequency of the beam is targeted to control for experiment. By adjusting the values of the equivalent inductance and equivalent resistance of the shunt circuit, the optimal damping of the shunt circuit is obtained. Meanwhile, the designed piezoelectric shunt damping circuit stability is experimental verified. Experimental results show that the proposed piezoelectric shunt damping circuit based on current mode circuit has good vibration control performance. However, the control performance will be reduced if equivalent inductance and equivalent resistance values deviate from optimal values.

Equivalent series resistance

10.1088/1757-899x/274/1/012102

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Two-dimensional non-Hermitian Skin Effect in a Synthetic Photonic Lattice

Physical Review Applied (2020)

Yiling Song Weiwei Liu Lingzhi Zheng Yicong Zhang Bing Wang

Non-Hermitian skin effect (NHSE) has led to interesting physics and sophisticated applications beyond the conventional framework. However, NHSE studies have been limited to an individual dimension due to the difficulty of constructing nonreciprocal coupling in higher-dimensional systems. With the concept of synthetic dimension, we realize two-dimensional (2D) NHSE in a synthetic photonic lattice. The synthetic photonic lattice is composed of a spatial dimension and a synthetic frequency dimension, which is constructed by introducing gain and loss and dynamically modulating the complex refractive index in a one-dimensional ring-resonator array. In the synthetic 2D NHSE system, we can manipulate the spatial position and frequency mode of the light in real time, thus enabling programmable light propagation and frequency conversion. Specifically, the incident light can be localized in the spatial dimension and the frequency dimension simultaneously, leading to second-order corner modes in the synthetic 2D NHSE lattice. Besides, the 2D NHSE system exhibits an excellent robustness for the disorder and point defect in the lattice. This work generalizes the non-Hermitian skin effect in synthetic dimension to control the light in different dimensions, which shows great promise for potential applications in on-chip light manipulation, frequency synthesis, and information processing.

Lattice (music)

Robustness

10.1103/physrevapplied.14.064076

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Citations (91)

Thin beds prediction method in the context of strong seismic reflection shielding

Xie Chunlin Gu Haiyan Zihe Wang Weiwei Liu Hu Jiuzhan

In northern Songliao basin, geologic characteristics of channel sand bodies in Fuyu reservoir are laterally discontinuous and vertically interbeded. As the main geologic "sweet points" in Fuyu reservoir are channel sand bodies with thickness of 3-m to 5-m, accurate prediction of these sand bodies is the key to horizontal well deployment. Due to the continuous strong seismic reflection of T2, top surface of Fuyu reservoir, the sandstone characteristics of the upper sand group in context of T2 strong reflection shielding are not obvious, and the problem gives a challenge for predicting sandstone with seismic data. Through the forward modeling method, sandstone reflection characteristics under the T2 strong reflection background are clear and a series of techniques including wavelet decomposition, post-stack resolution improvement, Seismic Motion Inversion (SMI) are carried out, which have effectively predicted the "sweet points" and have offered great support for horizontal wells drilling.

Reflection

10.1190/rege2018-45.1

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