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Feng W.-L.,Chongqing University of Technology | Feng W.-L.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Zheng W.-C.,Sichuan University
Molecular Physics | Year: 2015

The high-order perturbation formulas based on the two-mechanism model are used to calculate the spin-Hamiltonian parameters (g factors gi and hyperfine structure constants Ai, where i = x, y, z) of the rhombic Mo5+ oxygen octahedral clusters in molybdenum phosphate glasses. These formulas consist of the crystal-field mechanism in the extensively applied crystal-field theory and of the charge-transfer mechanism (which is often neglected). In the calculations, only three adjustable parameters are applied and the six calculated spin-Hamiltonian parameters are reasonably coincident with the experimental values. The results are discussed. © 2015 Taylor & Francis.


Feng X.,Chongqing University of Technology | Feng W.,Chongqing University of Technology | Feng W.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Xia M.,Chongqing University of Technology | And 6 more authors.
RSC Advances | Year: 2016

A novel red light emitting phosphorescent material MgWO4:Eu3+ is successfully synthesized by the co-precipitation method. The structure, luminescent properties and fluorescence lifetime of the prepared phosphors are characterized using X-ray diffraction (XRD), photoluminescence and luminescence decay spectra. The results indicate that an effective electric dipole transition 5D0-7F2 of Eu3+ red emission with maxima at 615 nm can be achieved in the MgWO4 host while being excited by near-UV light (393 nm) or blue light (464 nm). The CIE chromaticity coordinates of MgWO4:Eu3+ phosphors exhibit emission in the red-light region. Moreover, to explain the fluorescence spectra of MgWO4:Eu3+ phosphors, a complete energy matrix is successfully built by an effective operator Hamiltonian including free ion and crystal field interactions. The fluorescence spectra for the Eu3+ ion at the monoclinic (C2v) Mg2+ site of the MgWO4 crystal are calculated from this matrix. The fitting values are in agreement with the observed results. © The Royal Society of Chemistry 2016.


Ma H.,Chongqing University of Technology | Wang F.,Chongqing University of Technology | Wang F.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Wang W.,Chongqing University of Technology | And 2 more authors.
2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 | Year: 2016

Simultaneously transport multi-band ultra-wideband (MB-UWB) wireless signal and multi-level wired signal over single wavelength in wavelength-division multiplexing passive optical network (WDM-PON) is proposed, which can greatly improve spectrum efficiency and transmission ability of optical infrastructure. © 2015 IEEE.


Yang X.,Chongqing University of Technology | Yang X.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Wang K.,Chongqing University of Technology | Feng X.,Chongqing University of Technology | Luo K.,Chongqing University of Technology
Optik | Year: 2016

Zinc dialuminium oxide, ZnAl2O4 is well-known phosphor host material with spinel structure. Ba substituted compositions, BaxZn1-xAl2O4: Eu2+ (with x = 0.3-1.0) co-doped with 1 mol% Eu have been synthesized by the high-temperature solid-state method. The structure, morphology and luminescent properties of the phosphors have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence techniques. Effect of Ba substitution on structure and photoluminescence has been investigated. The prepared BaxZn1-xAl2O4: Eu2+ phosphors change structure from cubic to clinic with the increasing Ba concentration. The SEM images demonstrate that the grain sizes vary ranging from a few to ten microns with polycrystalline morphology. Photoluminescence characteristic shows intense emission for BaxZn1-xAl2O4: Eu2+ in the blue-green region (λmax = 495 nm) with the strongest emission at x = 0.8 of Ba concentration. The blue-green emission corresponds to transition from 4f65d1 to 4f7 of Eu2+ ion. © 2015 Elsevier GmbH. All rights reserved.


Wang W.B.,Chongqing University of Technology | Wang F.,Chongqing University of Technology | Wang F.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Yu Q.,Chongqing University of Technology | And 3 more authors.
Optics and Laser Technology | Year: 2016

We propose and experimentally demonstrate a bidirectional erbium-doped fiber laser delivering dispersion-managed soliton (DMS) and Q-switched pulse based on a graphene-polyvinyl alcohol (PVA) and nonlinear optical loop mirror (NOLM) saturable absorbers (SAs). In proposed structure, the DMS is achieved in clockwise (CW) direction and Q-switched pulse is obtained in counter-clockwise (CCW) direction. By properly adjusting the intracavity attenuators (ATT) and polarizer controllers (PCs), DMS in the CW direction and Q-switched pulse in the CCW direction can be obtained, respectively or simultaneously. The DMS with full width at half maximum (FWHM) of ~480 fs, signal to noise ratio (SNR) of ~60 dB and repetition frequency about 3.907 MHz is obtained. The Q-switched pulse is established at a pump power of 180 mW with a repetition rate of ~43.5 kHz and FWHM of ~8.18 μs. When the pump power is increased to 700 mW, Q-switched pulse with a repetition rate of ~107.1 kHz and FWHM of ~2.15 μs is generated. When the two type pulses are formed simultaneously, the maximum repetition rate of Q-switched pulse is 55.8 kHz and minimum FWHM is 2.81 μs, the DMS can be formed by properly adjusting PC and ATT in this case. To the best of our knowledge, it is the first time that Q-switched pulse and DMS have been acquired respectively or simultaneously in a fiber laser. © 2016 Elsevier Ltd.


Wang W.,Chongqing University of Technology | Wang F.,Chongqing University of Technology | Wang F.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Zhang Y.,Chongqing Optoelectronics Research Institute | And 3 more authors.
Optoelectronic Devices and Integration, OEDI 2015 | Year: 2015

We propose a figure-eight fiber laser (F8L) based on power-imbalanced nonlinear optical loop mirror (PI-NOLM). The output pulses with width of 571fs, signal to noise (SNR) of 62dB and repetition rate of 2.677MHz are obtained. © OSA 2015.


Wang K.,Chongqing University of Technology | Feng X.,Chongqing University of Technology | Feng W.,Chongqing University of Technology | Feng W.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | And 3 more authors.
Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences | Year: 2016

Fe3+ undoped and doped CaWO4: Pr3+ phosphors have been successfully synthesised by using the solid-state reaction method. The products were characterised by powder X-ray diffraction (XRD), photoluminescence (PL) and fluorescence lifetime testing techniques, respectively. The mean crystallite size (50.7 nm) of CaWO4: Pr3+ is obtained from powder XRD data. PL spectra of both Fe3+ undoped and doped CaWO4: Pr3+ phosphors exhibit excitation peaks at 214, 449, 474, and 487 nm under monitor wavelength at 651 nm, and emission peaks at 532, 558, 605, 621, 651, 691, 712, and 736 nm under blue light (λem=487 nm) excitation. The effect of trace Fe3+ on luminescence properties of CaWO4: Pr3+ phosphor is studied by controlling the doping concentration of Fe3+. The results show that radioactive energy transfers from luminescence centre Pr3+ to quenching centre Fe3+ occurred in Fe3+ doped CaWO4: Pr3+ phosphors. With the increasing concentration of Fe3+, the energy transfer from Pr3+ to Fe3+ is enhanced, and the emission intensity of CaWO4: Pr3+ will be lower. The decay times (5.22 and 4.99 μs) are obtained for typical samples Ca0.995WO4: Pr3+ 0.005 and Ca0.99275WO4: Pr3+ 0.005, Fe3+ 0.00225, respectively. This work shows that nonferrous phosphors can improve the luminescent intensity of the phosphors. © 2016 by De Gruyter 2016.


Wang K.,Chongqing University of Technology | Feng W.,Chongqing University of Technology | Feng W.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Feng X.,Chongqing University of Technology | And 3 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2016

Zn0.997WO4: Pr3 + 0.003 and different concentrations (0.1 mol% to 0.9 mol%) of Pr, Li co-doped ZnWO4 red phosphors were prepared by means of solid-state reaction process. The crystalline, surface morphology and luminescent properties of Zn0.997WO4: Pr3 + 0.003 and Zn1 - x - yWO4: xPr3 +, yLi+ phosphors were investigated by the X-ray diffraction patterns (XRD), scanning electron microscope (SEM) and fluorescent measurements. From powder XRD analysis, the formation of monoclinic structure with C2/h point-group symmetry and P2/c space group of the as-synthesized samples is confirmed. The SEM image showed that surface morphology of the phosphor powder is irregular cylindricality. The luminescent spectra are dominated by the red emission peaks at 607, 621 and 643 nm, respectively, radiated from the 1D2 → 3H4, 3P0 → 3H6 and 3P0 → 3F2 transitions of Pr3 + ions. The concentrations of the highest luminescent intensity is determined at 0.3 mol% Pr3 + and 0.3 mol% Li co-doped ZnWO4 powder crystal, and the peak intensity is improved more than 3 times in comparison with that of 0.3 mol% Pr3 + single-doped ZnWO4. The enhanced luminescence comes from the improved crystalline and from the charge compensation of Li+ ions. The decay curve and CIE chromaticity coordinates of as-prepared samples are also studied in detail. © 2015 Elsevier B.V. All rights reserved.


Zhao F.,Chongqing University of Technology | Jiang Z.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | Feng W.,Chongqing University of Technology | Feng W.,Chongqing Key Laboratory of Modern Photoelectric Detection Technology and Instrument | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2015

High quality ZnS:Eu2+ gas-sensitive materials have been synthesized by the ultrasound assisted hydrothermal/solvothermal method, and a gas sensor which contains ZnS:Eu2+ gas-sensitive film, simple chamber, miniature fiber optic spectrometer as well as the supporting software has been put forward. The gas sensor has good stability and strong anti-jamming capability. It is found that the H2S gas concentration and the sensitive component's fluorescence quenching signal correspond to linear relationship via fluorescence quenching Stern-Volmer equation, which indicates that the gas sensor responds quickly and can be used for high sensitivity real-time online monitoring of H2S gas concentration. ©, 2015, Chinese Optical Society. All right reserved.

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