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628 results on '"Dong, Hongxing"'

2. Relaxation Oscillations of an Exciton-polariton Condensate Driven by Parametric Scattering

Author

Tian, Chuan, Chen, Linqi, Zhang, Yingjun, Zhu, Liqing, Hu, Wenping, Pan, Yichun, Wang, Zheng, Zhang, Fangxin, Zhang, Long, Dong, Hongxing, and Zhou, Weihang

Subjects
Physics - Optics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We report observation of coherent oscillations in the relaxation dynamics of an exciton-polariton condensate driven by parametric scattering processes. As a result of the interbranch scattering scheme and the nonlinear polariton-polariton interactions, such parametric scatterings exhibit high scattering efficiency, which leads to fast depletion of the polariton condensate and periodic shut-off of the bosonic stimulation processes, eventually causing relaxation oscillations. Employing polariton-reservoir interactions, the oscillation dynamics in the time domain can be projected onto the energy space. In theory, our simulations using the open-dissipative Gross-Pitaevskii equation are in excellent agreement with experimental observations. Surprisingly, the oscillation patterns are clearly visible in our time-integrated images including many excitation pulses, implying the high stability of the relaxation oscillations driven by polariton parametric scatterings.

Published
2022
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8. Femtosecond dynamics of a polariton bosonic cascade at room temperature

Author

Chen, Fei, Zhou, Hang, Li, Hui, Luo, Song, Sun, Zheng, Zhang, Zhe, Sun, Fenghao, Zhou, Beier, Dong, Hongxing, Xu, Huailiang, Xu, Hongxing, Kavokin, Alexey, Chen, Zhanghai, and Wu, Jian

Subjects
Physics - Optics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Whispering gallery modes in a microwire are characterized by a nearly equidistant energy spectrum. In the strong exciton-photon coupling regime, this system represents a bosonic cascade: a ladder of discrete energy levels that sustains stimulated transitions between neighboring steps. In this work, by using femtosecond angle-resolved spectroscopic imaging technique, the ultrafast dynamics of polaritons in a bosonic cascade based on a one-dimensional ZnO whispering gallery microcavity is explicitly visualized. Clear ladder-form build-up process from higher to lower energy branches of the polariton condensates are observed, which are well reproduced by modeling using rate equations. Moreover, the polariton parametric scattering dynamics are distinguished on a timescale of hundreds of femtoseconds. Our understanding of the femtosecond condensation and scattering dynamics paves the way towards ultrafast coherent control of polaritons at room temperature, which will make it promising for high-speed all-optical integrated applications.

Published
2021
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17. Research on Lightweight Injection Molding (CAE) and Numerical Simulation Calculate of New Energy Vehicle

Author

Pang Longfeng, Zhang Chaoshan, Dong Hongxing, and Liu Yehong

Subjects
plastic instead of steel, injection molding, orthogonal test, parameter optimization, lightweight, numerical simulation, 68r10, 81q30, Mathematics, QA1-939
Abstract

In this paper, the new energy automobile front-end frame of a factory is taken as the research object, the polypropylene plastic is used to replace the traditional sheet metal material, and the hyper mesh is used to load the front-end frame’s six loading loads, which are the locking limit tension and the cushion impact force, respectively, pedestrian impact strength, condenser support strength, radiator support strength, oil cooler support strength, ensure to achieve certain mechanical properties before production. The maximum warpage deformation is 1.023 mm by mold flow analysis with Moldflow. It does not meet the needs of manufacturers, so it is necessary to optimize the process parameters. We use the mold temperature, melt temperature, holding pressure, injection time, and holding time as test factors, and take the amount of warpage as the optimization goal. Then this paper uses the orthogonal test method to design the test plan and establishes 25 groups of 5-level 5-factor orthogonal tests. Moreover, the effect of the deformation on the warpage is analyzed. These are all to obtain the minimum warpage deformation and find the optimal combination of process parameters. Verification by numerical simulation shows that the warpage is reduced to 0.632 mm. By analyzing the range and variance, the combination of process parameters is optimized, and the warpage is effectively reduced. In the premise of satisfying mechanical properties, plastic instead of steel, to achieve a lightweight design. It provides correct theoretical guidance for setting the actual injection molding process parameters.

Published
2023
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46. Universal Surface Repairing Strategy Enabling Suppressed Auger Recombination in CsPbBr3 Perovskite Quantum Dots for Low Threshold Lasing in a Superlattice Microcavity.

Author

Yang, Hongyu, Li, Jingzhou, Wang, Zhanpeng, Zhong, Yichi, Yang, Hanhuai, Dong, Hongxing, and Zhang, Long

Subjects
ELECTRON-hole recombination, QUANTUM dots, OPTOELECTRONIC devices, OPTICAL shaft encoders, SURFACE passivation, LEAD halides, PEROVSKITE
Abstract

Lead halide perovskite quantum dots (LHP QDs) emerge as versatile photonic sources in electroluminescence and laser devices. Their applications in optoelectronic devices are hindered by surface distortion and ligand stripping during the purification process. In addition, the device performance roll‐off suffers from the ultrafast non‐radiative Auger recombination (AR). To address these issues, herein, CsPbBr3 QDs are prepared with sizes ranging from 6.5 to 9.2 nm and the universal surface repairing strategy is proved to efficiently increase the biexciton lifetime and quantum yield up to 1.4 and 3 times, respectively. The strategy provides a PbBrx rich surface and strong binding didodecyldimethylammonium bromide (DDAB) ligands to achieve near‐unity photoluminescence efficiency, which significantly improves their stability against anti‐solvents and aging in ambient conditions. A single‐mode laser device is realized by self‐assembling the QDs into superlattice as optical microcavity, with low threshold of 9.45 µJ cm−2, quality factor of 2187 and ultrafast lifetime of 3.22 ps. The superlattice laser is demonstrated as an optical encoder with large coding bandwidth of 0.133 THz. This work proposes new insight into the non‐radiative AR process in these single‐component CsPbBr3 QDs, and will pave the way for optoelectronic devices working in intense conditions. [ABSTRACT FROM AUTHOR]

Published
2024
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