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269 results on '"Yu, Siu-Fung"'

8. 3D Printing of Arbitrary Perovskite Nanowire Heterostructures

Author

Chen, Mojun, Zhou, Zhiwen, Hu, Shiqi, Huang, Nan, Lee, Heekwon, Liu, Yu, Yang, Jihyuk, Huan, Xiao, Xu, Zhaoyi, Cao, Sixi, Cheng, Xiang, Wang, Ting, Yu, Siu Fung, Chan, Barbara Pui, Tang, Jinyao, Feng, Shien-Ping, Kim, Ji Tae, Chen, Mojun, Zhou, Zhiwen, Hu, Shiqi, Huang, Nan, Lee, Heekwon, Liu, Yu, Yang, Jihyuk, Huan, Xiao, Xu, Zhaoyi, Cao, Sixi, Cheng, Xiang, Wang, Ting, Yu, Siu Fung, Chan, Barbara Pui, Tang, Jinyao, Feng, Shien-Ping, and Kim, Ji Tae

Abstract

Deterministic integration of arbitrary semiconductor heterostructures opens a new class of modern electronics and optoelectronics. However, the realization of such heterostructures continues to suffer from impracticality, requiring energy- and labor-intensive, time-consuming fabrication processes. Here a 3D printing approach to fabricate freestanding metal halide perovskite nanowire heterostructures with a high degree of control over shape and composition is demonstrated. These features arise from freeform guiding of evaporation-driven perovskite crystallization by a femtoliter precursor meniscus formed on a printing nozzle. By using a double-barreled nanopipette as a printing nozzle, "all-at-once" heterostructure fabrication is achieved within seconds. The 3D-printed perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level. This "lithography-free" additive approach opens up the possibility to freely design and realize heterostructure-based devices without the constraints of traditional manufacturing processes.

Published
2023

9. Topological Singularity Pair in Nonreciprocal Non-Hermitian Lossy-dielectric Gyromagnetic Metasurface

Author

Jiang, Yimin, Wong, Wai Chun, Fung, Kin Hung, Yu, Siu Fung, Jiang, Yimin, Wong, Wai Chun, Fung, Kin Hung, and Yu, Siu Fung

Abstract

The transmission properties of a nonreciprocal non-Hermitian metasurface composed of lossy dielectric and gyromagnetic materials are studied with closed-form analytical solutions. It is found that a pair of opposite topological singularities of isolation ratio exist in a two-dimensional (2D) parameter space, and their evolution with parameter adjustment is preliminarily studied. These results provide clues for the design of optical devices. Further study of the mechanism of this singular behavior may reveal the complex systematic effect of non-Hermiticity and non-reciprocity on optical performance. © Published under licence by IOP Publishing Ltd.

Published
2023

11. 3D Printing of Arbitrary Perovskite Nanowire Heterostructures

Author

Chen, Mojun, primary, Zhou, Zhiwen, additional, Hu, Shiqi, additional, Huang, Nan, additional, Lee, Heekwon, additional, Liu, Yu, additional, Yang, Jihyuk, additional, Huan, Xiao, additional, Xu, Zhaoyi, additional, Cao, Sixi, additional, Cheng, Xiang, additional, Wang, Ting, additional, Yu, Siu Fung, additional, Chan, Barbara Pui, additional, Tang, Jinyao, additional, Feng, Shien‐Ping, additional, and Kim, Ji Tae, additional

Published
2023
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17. Stable Single‐Mode Lasing from a Hybrid Perovskite–Polymer Fiber

Author

Wang, Ting, primary, Chen, Weiqing, additional, Loi, Hok‐Leung, additional, Gao, Wei, additional, Xu, Xuhui, additional, Zeng, Longhui, additional, Cheng, Ping Kwong, additional, Ahmed, Safayet, additional, Yu, Xue, additional, Zhao, Feng, additional, Qiu, Jianbei, additional, Yan, Feng, additional, Yu, Siu Fung, additional, and Tsang, Yuen Hong, additional

Published
2022
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22. Design and analysis of a surface plasmon polariton modulator using the electro-optic effect

Author

Kumar, Ashwani, Yu, Siu Fung, and Li, Xiaofeng

Subjects
Modulators (Electronics) -- Design and construction, Modulators (Electronics) -- Properties, Modulators (Electronics) -- Technology application, Circuit design -- Methods, Circuit design -- Technology application, Plasma (Ionized gases) -- Usage, Polaritons -- Usage, Circuit designer, Integrated circuit design, Technology application, Astronomy, Physics
Abstract

A metal--insulator--metal (MIM) waveguide with a periodic change of dielectric materials in its insulator layer is proposed to create a voltage-controlled one-dimensional plasmonic Bragg reflector. KNb[O.sub.3] is used as one portion of the dielectric material so that the refractive index of the insulator layer can be varied by an external applied voltage. In our analysis, the transfer matrix method is employed to design and optimize the transmission spectra of the MIM waveguide Bragg reflector. The reflectivity at the on (bias voltage of 65 V) and off (bias voltage of -65 V) states is shown to be >74% and OCIS codes: 240.6680, 130.2790, 260.3910.

Published
2009

32. Research Progress on Rare Earth Doped Fluoride Multiband Upconversion Laser

Author

Li Hao, 黎浩, primary, Cui Zhenzhen, 崔珍珍, additional, Chen Weiqing, 陈卫清, additional, Qiao Yufang, 乔玉芳, additional, Cao Jiangyan, 曹疆艳, additional, Zhang Mingyu, 张明宇, additional, Yang Xi, 杨玺, additional, Yu Xue, 余雪, additional, Yu Siu Fung, 余兆丰, additional, Qiu Jianbei, 邱建备, additional, and Xu Xuhui, 徐旭辉, additional

Published
2020
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34. All‐Inorganic Perovskite Polymer–Ceramics for Flexible and Refreshable X‐Ray Imaging.

Author

Chen, Weiqing, Zhou, Min, Liu, Yang, Yu, Xue, Pi, Chaojie, Yang, Ze, Zhang, Hao, Liu, Zhichao, Wang, Ting, Qiu, Jianbei, Yu, Siu Fung, Yang, Yang, and Xu, Xuhui

Subjects
X-ray imaging, PEROVSKITE, SCINTILLATION counters, OSTWALD ripening, ANCHORING effect, SCINTILLATORS, POLYMER structure, NANOCRYSTALS
Abstract

Halide perovskites are an emerging scintillator material for X‐ray imaging. High‐quality X‐ray imaging generally requires high spatial resolution and long operation lifetime, especially for targeted objects with irregular shapes. Herein, a perovskite "polymer–ceramics" scintillator, in which the halide perovskite nanocrystals are grown inside a pre‐solidified polymer structure with high viscosity (6 × 1012 cP), is designed to construct flexible and refreshable X‐ray imaging. A nucleation inhibition strategy is proposed to prevent the agglomeration and Ostwald ripening of perovskite crystals during the subsequent precipitation process, enabling a high‐quality polymer–ceramics scintillator with high transparency. This scintillator‐based detector achieves a detection limit of 120 nGy s–1 and a spatial resolution of 12.5 lp mm–1. Interestingly, due to the anchoring effect of the exfoliated atoms provided by the polymer matrix, the scintillator film can be refreshed after a long duration (≥3 h) and high dose (8 mGy s–1) irradiation. More importantly, this inherent characteristic overcomes the long operation lifetime issue of perovskites‐based scintillators. Hence, the authors' exploration of the polymer–ceramics scintillator paves the way for the development of flexible and durable perovskite scintillators that can be produced at a low operation cost. [ABSTRACT FROM AUTHOR]

Published
2022
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35. Research Progress on Rare Earth Doped Fluoride Multiband Upconversion Laser

Author

Qiu Jianbei, Li Hao, Xu Xuhui, Yu Siu Fung, Qiao Yufang, Yu Xue, Cui Zhenzhen, Cao Jiangyan, Chen Weiqing, Zhang Mingyu, and Yang Xi

Subjects
Materials science, business.industry, Rare earth, Doping, Laser, Atomic and Molecular Physics, and Optics, Photon upconversion, law.invention, chemistry.chemical_compound, chemistry, law, Optoelectronics, Electrical and Electronic Engineering, business, Fluoride
Published
2020

42. Ca2+/Sr2+/Ba2+ dependent phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass.

Author

Xu, Xiuxia, Zhao, Junjie, Chen, Xiaotong, Xu, Qian, Wang, Ting, Yu, Siu Fung, Xu, Xuhui, Qiao, Xvsheng, Du, Jincheng, Fan, Xianping, Qiu, Jianbei, and Qian, Guodong

Subjects
GLASS-ceramics, FLUORIDE glasses, PHOTOLUMINESCENCE, GLASS, GLASS construction, PHASE separation, MOLECULAR dynamics
Abstract

Fluoride phase separation is the initial stage of nanocrystallization in oxyfluoride glasses, and it is a key step in achieving transparent glass‐ceramics with good luminescence. In this work, we combine molecular dynamics (MD) simulations and experimental studies to investigate the phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass and glass‐ceramics containing alkali earth fluoride (MF2). The results reveal different phase separation behaviors due to the field strength difference of M2+. The composition and size similarity between the fluoride‐rich regions in the MD simulated glass and the fluoride nanocrystals in the experimental prepared glass‐ceramics are observed, suggesting that the separated fluoride phase is the structural origin of the observed MF2 nanocrystals. Besides, in order to understand the M2+ dependent glass structural features, the crystallization temperatures, the luminescent properties of Eu3+ and Eu2+ doped glass‐ceramics, and the lasing performance of Er3+ doped glass‐ceramics are discussed. Based on these comprehensions, some strategies are proposed to help to efficiently design oxyfluoride glass with desired luminescence performance. [ABSTRACT FROM AUTHOR]

Published
2020
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43. Atomic‐Level Passivation of Individual Upconversion Nanocrystal for Single Particle Microscopic Imaging.

Author

Min, Qiuhong, Lei, Jing, Guo, Xin, Wang, Ting, Yang, Qihua, Zhou, Dacheng, Yu, Xue, Yu, Siu Fung, Qiu, Jianbei, Zhan, Qiuqiang, and Xu, Xuhui

Subjects
PHOTON upconversion, SURFACE passivation, PASSIVATION, PHOTOTHERMAL effect, PHOTOTHERMAL conversion, NANOCRYSTALS, LUMINESCENCE, SIGNAL-to-noise ratio
Abstract

Lanthanide‐doped upconversion nanoparticles (UCNPs) have significant applications for single‐molecule probes and high‐resolution display. However, one of their major hurdles is the weak luminescence, and this remains a grand challenge to achieve at the single‐particle level. Here, 484‐fold luminescence enhancement in LuF3:Yb3+, Er3+ rhombic flake UCNPs is achieved, thanks to the Yb3+‐mediated local photothermal effect, and their original morphology, size, and good dispersibility are well preserved. These data show that the surface atomic structure of UCNPs as well as transfer from amorphous to ordered crystal structure is modulated by making use of the local photothermal conversion that is generated by the directional absorption of 980 nm light by Yb3+ ions. The confocal luminescence images obtained by super‐resolution stimulated emission depletion also show the great enhancement of individual LuF3:Yb3+, Er3+ nanoparticles; the high signal‐to‐noise ratio images indicate that the laser treatment technology opens the door for single particle imaging and practical application. [ABSTRACT FROM AUTHOR]

Published
2020
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