Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Sol-gel derived mesoporous GaAlPO4 glass for heavy metal ion sequestration
No full textNational Natural Science Foundation of China [61275208]Mesoporous phosphate materials with chemical diversity and a high surface area are essential for their practical applications as heavy metal ion adsorbent materials. Herein, novel gallium aluminum phosphate mesoporous glasses are prepared through a simple aqueous sol-gel route free of any surfactant or template. The glass structure and its evolution from the gel to the final glass were monitored using solid-state NMR techniques, providing detailed insight into the reaction mechanism. During the formation of the mesoporous GaAlPO4 glass, the gallium entered into the PO4 tetrahedron via Ga-O-P bonds. The resulting mesoporous glass samples were tested as adsorbents to remove Pb(II) anions from solution and the ternary oxide glasses show high adsorption capacities (>36.63 mg g(-1), that is 0.18 mmol g(-1)). Owing to their integrated features (including their variable compositions, high specific surface area, tunable pore size and shape flexibility) as well as specific acid-base surface properties, such mesoporous gallium aluminum phosphate materials are also expected to have potential either as catalysts or catalyst supports for industrial applications
Spectroscopic and thermal characterizations of Yb:LaF3 single crystal
No full textNational Natural Science Foundation of China [51302283, 51502321]; Shanghai Natural Science Foundation [13ZR1463400]A Yb3+ doped LaF3 laser crystal was detailed investigated by both spectroscopic and thermal measurements. A peak absorption at 974 nm with FWHM broader than 60 nm makes the crystal suitable to InGaAs LDs. Fluorescence spectrum and calculated spectroscopic parameters show potential of Yb:LaF3 crystal to laser operations around 1009 nm. A relatively long fluorescence lifetime of 2.92 ms was detected for Yb3+:F-2(5/2) manifold. The thermal diffusivity and specific heat capacity in the range of 300-575 K were studied to calculate the thermal conductivity of Yb:LaF3. The results indicate that the Yb:LaF3 crystal is a good candidate for diode-pumped -1 mu m solid-state laser applications. (C) 2016 Elsevier B.V. All rights reserved
Spectroscopic, thermal and cw dual-wavelength laser characteristics of Nd:LaF3 single crystal
No full textNational Natural Science Foundation of China [51302283, 51502321]; Shanghai Natural Science Foundation [13ZR1463400]A Nd-doped LaF3 crystal was grown by Czochralski method, and the rocking curves of (0 0 2) and (1 1 0) diffraction planes show good crystallinity quality of the as-grown crystal. Room-temperature fluorescence spectrum and transmittance spectrum of Nd:LaF3 crystal were investigated, both indicating probable dual-wavelength emissions at similar to 1.04 mu m and similar to 1.06 mu m. The thermal diffusivity and thermal conductivity of Nd:LaF3 crystal were detailed studied. Cw dual-wavelength laser operation of Nd:LaF3 single crystal at 1040 nm and around 1065 nm with LD pumping was demonstrated. A maximum output power of 302 mW was obtained with a slope efficiency of about 18.5% with respect to the pump power. The results of our study indicate the Nd:LaF3 crystal a promising laser crystal. (C) 2016 Elsevier B.V. All rights reserved
Structural, luminescent properties and chemical state analysis of YAG:Ce nanoparticle-based films
No full textNational Natural Science Foundation of China (NSFC) [61205211]; State Key Program of National Natural Science of China [11535010]Y3Al5O12: Ce (YAG:Ce) nanoparticles need annealing treatment at high temperature to transform the amorphous precursors to crystalline YAG phase. However, little is known about Ce chemical state analysis and photoluminescence (PL) properties of YAG:Ce nanoparticles with the different annealing temperatures and atmospheres. In this paper, amorphous nanoparticle-based YAG:Ce films, prepared by electron beam deposition technique on fused silica substrates, have been annealed at different conditions. Ce3+, Ce4+ states and Ce3+/Ce4+ atomic ratio have been distinctly separated and calculated by X-ray photoelectron spectroscopy (XPS). Combined Ce3+/Ce4+ atomic ratio with the microstructures, the Ce chemical state modification and PL properties of YAG: Ce films with different annealing treatments have been investigated throughout. Low temperature annealing in air can cause oxidation of Ce3+, higher temperature (>= 750 degrees C) annealing in air can cause partial reduction of Ce4+ due to the high-temperature pyrolysis. In this paper, value of Ce3+/Ce4+ is the maximum after 850 degrees C annealing in H-2, and YAG: Ce film annealed in H-2 has the maximum luminous intensity, which could be proposed to the increased Ce3+ content. According to the systematical research and analysis, one can find that the Ce3+ content controls the luminescence efficiency. This paper provides a feasible approach to produce YAG: Ce nanoparticle-based films for the practical applications, and provides the understanding about YAG: Ce luminescent properties. (C)2015 Optical Society of Americ
Synthesis of AlN hexagonal bipyramids by carbothermal reduction nitridation
No full textNational Youth Natural Science Foundation of China [51302284, 6140031038]Wurtzite-structured aluminum nitride (AlN) hexagonal bipyramids were prepared via a carbothermal reduction nitridation method using alumina and carbon as the raw materials. The growth of the AlN hexagonal bipyramids is dominated by the vapor-solid (VS) mechanism with Fe2O3, SiO2 and Na2O acting as mineralizers under alternate gas pressures. The preferred growth direction of the AlN hexagonal bipyramids is [0001]. Photoluminescence spectra of the AlN hexagonal bipyramids showed near-band edge emission at 512 nm at room temperature. The AlN hexagonal bipyramids might be useful for optical micro-devices. (C) 2016 Elsevier B.V. All rights reserved
Upconversion luminescence of Ho3+/Yb3+ co-doped CaNb2O6 thin films
No full textNational Nature Science Foundation of China [11474104, 51372092]; China Scholarship CouncilHo3+/Yb3+ co-doped CaNb206 thin films were deposited on Si(100) substrates by pulsed laser deposition and annealed at different temperature in air atmosphere. The structure and properties of the film samples were characterized by using X-ray diffraction, atomic force microscope, Raman spectroscopy, X-ray photoelectron spectroscopy and photoluminescence spectra. It is found that the annealing temperature has a strong effect on the film's structure, morphology, grain size and the up-conversion luminescence properties. Upconversion luminescence intensity of Ho3+/Yb3+ co-doped CaNb206 films is enhanced by increasing the annealing temperature. (C) 2015 Elsevier B.V. All rights reserved
High-speed laser writing of arbitrary patterns in polar coordinate system
No full textNational Natural Science Foundation of China [61627826, 51672292, 61137002]In order to realize high-speed laser writing arbitrary patterns, we establish a set of high-speed polar coordinate laser writing system. Although the polar coordinate laser writing system is generally suitable for fabricating circular symmetric patterns, there are challenges when dealing with arbitrary patterns. Here, we propose an effective method to solve this problem by converting the pattern data from Cartesian coordinates to polar coordinates for high-speed laser writing of arbitrary patterns. Several types of arbitrary patterns are written on chalcogenide thin films with a minimum pattern linewidth of 700 +/- 70 nm and a maximum writing speed of approximately 10 m/s,which corresponds to more than 600 mm(2)/min at 1.0 mu m linewidth. This writing speed is ten times faster than that of the conventional x-y type Cartesian coordinate laser writing system. Published by AIP Publishing
Low-power laser therapy for carpal tunnel syndrome: effective optical power
No full textNational Natural Science Foundation of China [61108077]Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside reflection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed significantly among cases, with the measured laser reflection coefficient ranging from 1.8% to 54%. The reflection coefficient for 36.7% of these 30 cases was in the range of 10-20%, but for 16.7% of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome
Novel mono-cationic fluorescent probes based on different central pi-conjugated bridges for two-photon bioimaging of cellular nuclei
No full textNational Natural Science Foundation of China [61137002, 61178059, 51172253]A series of novel pyridine mono-cationic two-photon fluorescent probes based on different central pi-conjugated bridges, fluorenone (W-pyI), dibenzothiophene (S-pyI), and dibenzofuran (F-pyI), were prepared and studied. Under one-photon excitation in a N,N-dimethylformamide solution, W-pyI, S-pyI, and F-pyI displayed fluorescence quantum yields of 0.401, 0.425, and 0.09, respectively. The two-photon fluorescence performance indicated that these probes possessed two-photon absorption cross-sections of 681 GM (W-pyI), 630 GM (S-pyI), and 620 GM (F-pyI) at 800 nm femtosecond laser excitation. The luminance "turn-on" effect of W-pyI, S-pyI, and F-pyI bonding with calf thymus DNA in Tris-HCl buffer solutions displayed 58-fold, 30-fold, and 25-fold fluorescence quantum yield increments, respectively, and 350-450% two-photon absorption cross-section enhancement. The confocal fluorescence imaging showed clear one-and two-photon fluorescence imaging. The mean co-localization coefficients between these probes and Hoechst 33342 in 3T3 cells ranged from 0.89-0.92, indicating that they showed excellent nuclear targeting abilities. The counterstaining experiments showed these probes possessed good counterstaining compatibility and membrane permeability in the application of multicolor targeting. A time-dependent fluorescence intensity test under continuous femtosecond laser irradiation showed that W-pyI possessed a longer observation time (3000 seconds) and a lower fluorescence attenuation amplitude (7.1%) in the first 300 seconds than S-pyI, F-pyI and other previously reported pyridinium derivatives, demonstrating that the central pi-conjugated bridge "fluorenone" played a key role in improving photostability during probe designing for two-photon bioimaging applications
Dual-Wavelength Laser Output in Nd3+/Yb3+ Co-Doped Phosphate Glass Fiber Under 970 nm Pumping
No full textNational Natural Science Foundation of China [61177083, 61405215, 61505232]; Youth Innovation Promotion Association of the Chinese Academy of SciencesWe report the demonstration of dual-wavelength laser output originating from excited Nd3+ ions and Yb3+ ions in Nd3+/Yb3+ co-doped phosphate glass fiber under 970-nm laser diode pumping. Using a free-space coupling method, laser bands at 1028 and 1053 nm were observed in a 35-cm-long fiber with the corresponding lasing thresholds of 4.3 and 31.5 W at room temperature. Emission and lasing spectra under different pump powers were tested by the optical spectrum analyzer. The 1053-nm laser threshold was found to be temperature sensitive. The mechanism of Yb3+ -> Nd3+ energy transfer under 970 nm pumping was explored. It was proposed that Yb3+ -> Nd3+ energy transfer process with the participation of phonon resulted in 1053-nm laser of Nd3+ ions in this co-doped fiber under 970 nm pumping