Shifeng Zhou

South China University of Technology, Shengcheng, Guangdong, China

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Publications (88)323.51 Total impact

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    ABSTRACT: A deep-ultraviolet (UV) nonlinear optical BaAlBO3F2 crystal was space-selective precipitated in stoichiometric 50BaF2-25Al2O3-25B2O3 glass by using a 500 kHz femtosecond pulse laser, which was confirmed by X-ray diffraction analysis (XRD). The distribution of BaAlBO3F2 crystals in glass was analyzed by Raman spectra and Raman mapping. The second-harmonic generation (SHG) intensity of BaAlBO3F2 crystals in glass could be tuned by changing the laser average power and exposure time. Absorption spectra were used to investigate the transmittance of the glass sample before and after the femtosecond laser irradiation.
    Journal of Non-Crystalline Solids 07/2015; 420:17-20. DOI:10.1016/j.jnoncrysol.2014.12.023 · 1.72 Impact Factor
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    ABSTRACT: It has been observed that BaCl2:Er3+ phosphors have a higher up-conversion luminescence efficiency than the well-known fluoride regarded widely as the most efficient up-conversion host material. The near-infrared-to-visible up-conversion luminescence is markedly enhanced for BaCl2:Er3+ phosphors when excited simultaneously at two wavelengths (808 and 980 nm) in contrast to the case of single-wavelength excitation. Furthermore, our results demonstrate that the multiwavelength simultaneously excited up-conversion process in BaCl2:Er3+ phosphors allows better and broader harvesting of near-infrared solar energy, which is expected to open the possibilities of the remarkable improvement of the power conversion efficiency of next-generation solar cells.
    Applied Physics Express 03/2015; 8(3):032301. DOI:10.7567/APEX.8.032301 · 2.57 Impact Factor
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    ABSTRACT: A novel approach to modulating the chemical state of dopants by engineering the topological features of a glass matrix is presented. The method allows selective stabilization of dopants on a wide range of length scales, from dispersed ions to aggregated clusters to nanoparticles, leading to various intriguing optical phenomena, such as great emission enhancement and ultra-broadband optical amplification.
    Advanced Materials 10/2014; DOI:10.1002/adma.201403256 · 15.41 Impact Factor
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    ABSTRACT: We report on the persistent luminescence of SrAl2O4: Eu2+, Cr3+ phosphor centered at 760 nm. The phosphor was prepared by sol-gel-combustion method. Persistent luminescence from Cr3+ lasted for hundreds of seconds, comparable to the long afterglow from Eu2+ ions in the visible region based on the continuous energy transfer from Eu2+ ions to Cr3+ ions. The introduction of Dy3+ ions into the phosphor further prolonged the afterglow time of Eu2+ and Cr3+ ions through the depth control of the charge traps. The optimum doping concentrations for Eu2+, Cr3+ and Dy3+ were 1%, 2% and 1.5%, respectively. (C) 2014 Published by Elsevier B.V.
    Materials Chemistry and Physics 10/2014; 147(3):772-776. DOI:10.1016/j.matchemphys.2014.06.018 · 2.13 Impact Factor
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    ABSTRACT: One of the major challenges of near-infrared upconversion photocatalyst concerns strengthening the cooperation between Rare-earth (RE) ions and semiconductor materials for enhancing NIR photocatalytic activity. Herein, the basic energy-transfer (ET) process between RE ions and semiconductor materials is discussed and the appropriate mode, nonradiative ET, is proposed for efficiently coupling them. As an example, a novel NIR-based UC photocatalyst, CaIn2O4:Yb3+,Tb3+ was designed and successfully fabricated, which exhibited high photocatalytic activity under 980 nm irradiation. The present report highlights the potential of ET tuning between RE ions and semiconductors toward high performance of NIR photocatalysis.
    Journal of the American Ceramic Society 09/2014; DOI:10.1111/jace.13232 · 2.43 Impact Factor
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    ABSTRACT: Bismuth nanoparticles are directly precipitated inside a bismuth germinate glass by irradiation with a 1030 nm, 500 kHz femtosecond laser, which are confirmed by means of X-ray diffraction, transmission electron microscope and Raman spectra. In addition, the results of electron probe microanalyzer indicate that the elements distribution around the focal point is induced simultaneously. We suggest that the precipitation of Bi nanoparticles and redistribution of ions with different diffusion coefficients should mainly be ascribed to the heat accumulation effect and thermal diffusion. The results provide a novel approach to produce Bi nanoparticles inside glass and have promising applications for the fabrication of photonic devices.
    Materials Letters 08/2014; 128:204-207. DOI:10.1016/j.matlet.2014.04.120 · 2.27 Impact Factor
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    ABSTRACT: We report on three-dimensional (3D) precipitation of ZnO crystals inside a silicate glass by a 500 kHz femtosecond pulse laser. The precipitation and distribution of ZnO crystals in glass are confirmed and analyzed by Raman spectra and Raman mapping. Mirco- luminescence is observed in the laser modified region when excited by femtosecond pulse laser or Xenon lamp. The effect of laser average power on the precipitation of the ZnO crystals has also been investigated. The possibility of 3D optical data storage using the observed phenomena is demonstrated.
    Optics Express 07/2014; 22(15). DOI:10.1364/OE.22.017908 · 3.53 Impact Factor
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    ABSTRACT: An anomalous near-infrared (NIR) upconversion (UC) emission band at approximately 770 nm is demonstrated in KZnF3:Yb3+,Mn2+ nanocrystals with heavy Mn2+ doping. This band would enable advanced biological imaging with improved resolution and enhanced penetration depth. Careful studies based on structure analysis, excitation and emission spectra, and luminescence decay curves indicate that this unusual NIR emission (770 nm) originates from the 6A1g(S)4T1g(G)→6A1g(S)6A1g(S) transitions of the Mn2+–Mn2+ dimers. The influence of Mn2+ concentration and temperature on the Stokes and UC luminescence properties are also investigated. The proposed mechanism for the observed NIR UC emission involves ground state absorption and excited state absorption processes. The present results not only provide a useful and effective approach to achieving pure NIR UC emission, and also new insights into the development of advanced photonic devices and technologies.
    07/2014; 2(7). DOI:10.1002/adom.201400066
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    ABSTRACT: The success in the fabrication of micro-structures in glassy materials using femtosecond laser irradiation has proved its potential applications in the construction of three-dimensional micro-optical components or devices. In this paper, we report the elemental redistribution behavior in tellurite glass after the irradiation of high repetition rate femtosecond laser pulses. The relative glass composition remained unchanged while the glass density changed significantly, which is quite different from previously reported results about the high repetition rate femtosecond laser induced elemental redistribution in silicate glasses. The involved mechanism is discussed with the conclusion that the glass network structure plays the key role to determine the elemental redistribution. This observation not only helps to understand the interaction process of femtosecond laser with glassy materials, but also has potential applications in the fabrication of micro-optical devices.
    Journal of Alloys and Compounds 07/2014; 601:212–216. DOI:10.1016/j.jallcom.2014.02.178 · 2.73 Impact Factor
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    ABSTRACT: For the first time, we studied the effect of structural relaxation on the NIR spectroscopic properties of bismuth-activated germanium glasses below glass transition temperature. Interestingly, distinct change behavior of NIR luminescence is observed at two different heat-treatment temperature ranges corresponding to two different relaxation behavior of glass structure. Besides, when structural modified by partly substituting B<sub>2</sub>O<sub>3</sub> for GeO<sub>2</sub>, a narrower and more thermal sensitive luminescence is observed, which is inexplicable by "inhomogeneous broadening" and we tentatively attribute it to a defect-involved reason. Fundamentally the results here not only provide us a deeper insight into the optical property of bismuth-activated materials but also increase our understanding of the glassy state, and practically it delivers some valuable guidance in designing bismuth-activated glasses with superior NIR optical properties.
    Optics Express 06/2014; 22(13):15924-15931. DOI:10.1364/OE.22.015924 · 3.53 Impact Factor
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    ABSTRACT: We report enhanced green and red upconversion (UC) luminescence in Ho3+-doped oxyfluoride germanate glass by introducing bismuth near-infrared active centers as sensitizers. The UC excitation bands at 750 and 970 nm show a full width at half-maximum of 20 and 45 nm, respectively. Energy transfer from sensitizers, the excited-state absorption, and phonon-coupled absorption of Ho3+ jointly contribute to the enhanced UC luminescence. Our approach provides an efficient methodology to broaden the excitation bandwidth of UC luminescent materials, which may have the potential for promising application in solar cells.
    Optics Letters 05/2014; 39(10):3022-3025. DOI:10.1364/OL.39.003022 · 3.18 Impact Factor
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    ABSTRACT: Structural design is of great importance to the performance of photocatalysts in environmental remediation. Therefore, micro/nanofibrous morphology and nanoporous local structures have been found to be beneficial to improve the photocatalytic activity. In this investigation, we report the design and fabrication of flexible and thermal stable nanoporous SiO2–TiO2 composite fibers as efficient photocatalysts. Combining electrospinning and modified Stöber techniques, core-shell and mesoporous SiO2 fibers with high flexibility were fabricated and employed as the scaffold for supporting TiO2 nanoparticles. A nanoporous shell of TiO2 nanoparticles was then muffled over the SiO2 fibers to form core@dual-shell SiO2–TiO2 composite fibers with hierarchically porous structure, which were conveniently patterned into a nonwoven, recyclable film. This nonwoven film exhibits better photocatalytic activity for Rhodamine B degradation under UV irradiation compared with some other TiO2-based materials reported in recent years.
    Journal of the American Ceramic Society 05/2014; 97(6). DOI:10.1111/jace.12944 · 2.43 Impact Factor
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    ABSTRACT: A phosphor with remarkable long persistent luminescence features, Zn3Ga2Sn1O8:0.5 Cr3+, suitable for deep and reproducible tissue imaging has been rationally designed and successfully fabricated. This phosphor shows bright and long persistent luminescence over 300 h in the near-infrared region, and permits an enabling long-term, reproducible, real-time and reliable structural imaging of deep tissues. Moreover, the revived luminescence and persistent luminescence under the excitation of near-infrared incoherent light are also demonstrated to reveal an optional multiplexed detection. This new luminescent indicator will allow repeatable visualization of the structural and functional processes in cells, tissues and other complex systems. In addition, multifarious and systematic investigations are successfully carried out to unravel the nature of traps and also to verify the rationality of the material design.
    03/2014; 2(15). DOI:10.1039/C4TC00014E
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    ABSTRACT: Ultrabroadband near-infrared luminescence in the 1.0–2.4 μm range has been observed in bismuth (Bi)-doped oxyfluoride germanate thin films prepared by pulsed laser deposition (PLD). The emission peak position shows a red-shift with decreasing oxygen pressure during PLD growth. Systematic investigation reveals that the origin of the luminescence could be ascribed to Bi clusters. With the sensitization of Bi near-infrared active centers, enhanced broadband 2 μm luminescence of Ho3+ is realized in Bi/Ho co-doped films, and a high energy transfer efficiency is obtained. These results may provide promise to realize planar waveguide lasers in the near-infrared region for integrated optics.
    03/2014; 2(14). DOI:10.1039/C3TC32177K
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    ABSTRACT: The carbon nanodots (CNDs) were synthesized by a simple method of femtosecond laser ablation of bagasse in ethanol. Strong optical limiting effects of as-prepared CNDs to 800 nm femtosecond laser pulses were observed with the threshold of 74 mJ/cm(2). The strong two photon absorption of CNDs is responsible for the optical limiting response. The nonlinear coefficient was determined by the open-aperture Z-scan technique.
    Carbon 03/2014; 69:38–640. DOI:10.1016/j.carbon.2013.12.056 · 6.16 Impact Factor
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    Carbon 03/2014; 69:638–640. · 6.16 Impact Factor
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    ABSTRACT: Although inorganic anti-Stokes fluorescent probes have long been developed, the operational mode of today's most advanced examples still involves the harsh requirement of coherent laser excitation, which often yields unexpected light disturbance or even photon-induced deterioration during optical imaging. Here, we demonstrate an efficient anti-Stokes fluorescent probe with incoherent excitation. We show that the probe can be operated under light-emitting diode excitation and provides tunable anti-Stokes energy shift and decay kinetics, which allow for rapid and deep tissue imaging over a very large area with negligible photodestruction. Charging of the probe can be achieved by either X-rays or ultraviolet-visible light irradiation, which enables multiplexed detection and function integration with standard X-ray medical imaging devices.
    Scientific Reports 02/2014; 4:4059. DOI:10.1038/srep04059 · 5.08 Impact Factor
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    ABSTRACT: Effect of ultraviolet light irradiation on the photoluminescence of carbon dots (CDs) is investigated. After the ultraviolet light irradiation, CDs exhibit red shifted and enhanced green emission, and significantly enhanced emission in the wavelength region from green-yellow to red. Carbonyl groups increase remarkably originated from photochemical oxidation, resulting in more defect energy trapping (DET) states, higher electron density, and stronger n(OH)→π*(CO) interactions. Consequently, a decrease in band gap and more contribution from the DET states related radiative recombination result in an enhancement of green emission and beyond, while ultraviolet emission is reduced and blue shifted due to the decrease of sp2 carbons.
    Optical Materials Express 02/2014; 4(2). DOI:10.1364/OME.4.000213 · 2.92 Impact Factor
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    ABSTRACT: Transparent glasses imbedded with functional nanocrystals have attracted considerable interest and been studied widely in the past several decades, due to their applications in optical devices, such as optical amplifiers, nonlinear optical devices, optical storage, 3D displays, etc. Femtosecond (fs) laser irradiation induced crystallization of glass has been proved to be a powerful tool to realize the space-selective precipitation of various nanocrystals inside glasses. In this review, we highlight our recent research achievements on the fs laser induced precipitation of nanocrystals inside glasses, including nonlinear optical crystal, upconversion luminescence crystal, high refractive index crystal, and metal nanoparticles. These studies not only help to understand the interaction process between fs laser and glassy materials, but also have potential applications in the fabrication of micro-optical devices.
    Journal of Non-Crystalline Solids 01/2014; 383:91-96. DOI:10.1016/j.jnoncrysol.2013.04.015 · 1.72 Impact Factor

Publication Stats

709 Citations
323.51 Total Impact Points

Institutions

  • 2013–2014
    • South China University of Technology
      • Institute of Optical Communication Materials
      Shengcheng, Guangdong, China
  • 2007–2014
    • Zhejiang University
      • • State Key Lab of Silicon Materials
      • • State Key Lab of Modern Optical Instrumentation
      Hang-hsien, Zhejiang Sheng, China
    • Arizona State University
      • Department of Physics
      Phoenix, Arizona, United States
  • 2009–2011
    • The University of Hong Kong
      Hong Kong, Hong Kong
  • 2008
    • The Hong Kong Polytechnic University
      • Department of Applied Physics
      Hong Kong, Hong Kong