Hucheng Yang

Broadband optical amplification in Bi-doped germanium silicate glass

Bi-doped germanium silicate glass is prepared and their optical properties are investigated. The glass sample shows broadband and flat emission characteristics compared with germanate glass. The single-pass optical amplification was measured on a traditional two-wave mixing configuration. Ultrabroadband optical amplification at 1272 and 1560nm is observed simultaneously. The highest gain at 1272nm of germanium silicate glass reaches to 6.73dB excited with single commercially available 980nm laser diode. The glass is promising for optical amplification covering almost all the O, E, S, C, and L bands.

Co-operative downconversion luminescence in Tm3+/Yb3+?:?SiO2?Al2O3?LiF?GdF3 glasses

Oxyfluoride aluminosilicate glasses in the composition of 50SiO2?20Al2O3?20LiF?10GdF3?0.5TmF3?xYbF3 (x = 0, 1.0, 2.5, 5, 7.5, 10, 15, 20, 25 and 30?mol%) have been prepared to study their thermal and optical properties. From the differential thermal analysis measurements, glass transition temperatures and onset crystallization temperatures have been evaluated and from them glass stability factors were calculated. Glass stabilities decreased gradually with fluoride content increment in all the studied glasses. The photoluminescence and decay measurements have also been carried out for all these glasses. In these glasses, an efficient near infrared quantum cutting with optimal quantum efficiency approaching 187% has been demonstrated, by exploring the co-operative downconversion mechanism from Tm3+ to Yb3+, with 467?nm (Tm3+?:?3H6 ? 1G4) excitation wavelength. These glasses are promising materials to achieve high efficiency silicon based solar cells by means of downconversion in the visible part of the solar spectrum.

Broadband near-infrared emission from transparent Ni2+-doped silicate glass ceramics

Transparent Ni2+-doped MgO-Al2O3-TiO2-SiO2 glass ceramics were prepared, and the optical properties of Ni2+-doped glass ceramics were investigated. Broadband emission centered at 1320 nm was observed by 980 nm excitation. The longer wavelength luminescence compared with Ni2+-doped Li2O-Ga2O3-SiO2 glass ceramics is ascribed to the low crystal field hold by Ni2+ in MgO-Al2O3-TiO2-SiO2 glass ceramics. The change in optical signals at the telecommunication bands with or without 980 nm excitation was also measured when the seed beam passes through the bulk gain host.(C) 2007 American Institute of Physics.

Cyan-white-red luminescence from europium doped Al 2 O 3 -La 2 O 3 -SiO 2 glasses

Aluminum-lanthanum-silicate glasses with different Eu doping concentration have been synthesized by conventional melt-quenching method at 1680°C in reductive atmosphere. Under 395nm excitation, samples with low Eu doping concentration show mainly the cyan broad emission at 460nm due to 4f65d1-4f7 transition of Eu2+; and the samples with higher Eu doping concentration show mainly some narrow emissions with maximum at 616nm due to 5D0-7FJ (J=0, 1, 2, 3, 4) transitions of Eu3+. Cyan-white-red tunable luminescence under 395nm excitation has been obtained by changing the Eu doping concentration.

Photoluminescence of Ag nanoparticle embedded Tb3+/Ce3+ codoped NaYF4/PVP nanofibers prepared by electrospinning

Ag nanoparticle embedded NaYF(4):0.05Tb.xCe/PVP (PVP stands for poly(vinyl pyrrolidone)) composite nanofibers have been prepared by electrospinning. A field emission scanning electron microscope and x-ray diffraction have been utilized to characterize the size, morphology and structure of the as-prepared electrospun nanofibers. Obvious photoluminescence (PL) of NaYF(4):0.05Tb.0.05Ce/PVP electrospun nanofibers due to the efficient energy transfer from Ce(3+) to Tb(3+) ions is observed. The PL intensity of the electrospun nanofibers decreases gradually with the addition of Ag nanoparticles. No obvious surface plasmon resonance enhanced luminescence is observed. The reasons for the weakening of the emission intensity with the addition of Ag nanoparticles have also been discussed in this work.

Broadband near-infrared emission from Bi-doped aluminosilicate glasses

Bi-doped sodium–potassium aluminosilicate glasses were synthesized and characterized. Broadband near-infrared (IR) emission covered the whole telecommunication wavelength region, with a maximum peak at about 1250 nm, a full width at half-maximum of about 370 nm, and a lifetime longer than 420 μs. The present glasses are potential materials for tunable lasers and optical amplifiers. The decrease of active Bi center concentration with the increase of Na 2 O content and the addition of CeO 2 are first reported here, and the IR emission center in sodium–potassium aluminosilicate glasses might be ascribed to low-valence-state bismuth, most probably, Bi + .

Cooperative downconversion luminescence in Pr 3+ /Yb 3+ :SiO 2 –Al 2 O 3 –BaF 2 –GdF 3 glasses

Oxyfluoride aluminosilicate glasses with compositions of 50SiO 2 –20Al 2 O 3 –20BaF 2 –10GdF 3 –0.5PrF 3 – x YbF 3 ( x = 0, 1.0, 2.5, 5, 7.5, 10, 15, 20, 25, and 30 mol%) have been prepared to study their thermal and optical properties. From the differential thermal analysis (DTA) measurement, glass-transition temperatures and onset crystallization temperatures have been evaluated and from them, glass-stability factors against crystallization were calculated. Glass stabilities were decreased gradually with fluoride content increment in all the studied glasses. The photoluminescence and decay measurements have also been carried out for these glasses. In these glasses, an efficient near-infrared (NIR) quantum cutting with optimal quantum efficiency approaching 160% have been demonstrated, by exploring the cooperative downconversion mechanism from Pr 3+ to Yb 3+ with 481 nm ( 3 P 0 → 3 H 4 ) excitation wave length. These glasses are promising materials to achieve high-efficiency silicon-base solar cells by means of downconversion in the visible part of the solar spectrum.

Tunable luminescence of CaO-Al(2)O(3)-GeO(2) glasses.

We report tunable luminescence in oxygen-deficient CaO-Al(2)O(3)- GeO(2) glasses. The glass samples were prepared by adding metal Al instead of corresponding oxide (Al2O3). Efficient blue and red emissions were observed when excited by 300 and 370 nm ultraviolet light, respectively. By adjusting the content of metal Al, we could control the quantities of the defects which results in tunable luminescence from blue to white to red. Furthermore the resultant oxygen-deficient glasses have shown bright white luminescence when the excitation wavelength tuned to 335nm. Our method opens a new route for the white light illumination.

Light emission of Cu+ doped porous silica glass for volumetric three-dimensional solid state display

Cu-doped nanoporous silica glass was prepared and broadband upconversion luminescence was observed when excited with a 800 nm femtosecond laser. The optical properties of the Cu-doped nanoporous silica glass were investigated by absorption, steady state excitation and emission, luminescence decay and time-resolved spectroscopy. The analysis of the upconversion mechanism indicates that three-photon absorption is responsible for the visible luminescence. A three-dimensional solid state display was also demonstrated and the full colorization of a volumetric three-dimensional solid state display could be made possible by designing and controlling the combination of doping species in the nanoporous silica glass.

Upconversion Luminescence of Er

NaYF : 0.02Er Yb-PVP composite nanofibers with the diameter of 400 nm have been prepared by electrospinning. Field emission scanning electron microscope and X-ray diffraction have been utilized to characterize morphology and structure of the as-prepared electrospun nanofibers. Their up-conversion lumines- cence is investigated under a 980-nm excitation. Green (538 and 520 nm), red (655 nm), and blue (405 nm) emissions are observed in the up-conversion luminescence spectra, and the intensity of these three emissions changes differently with the variety of Yb content, which has been interpreted successfully in this letter. The color of NaYF : 0.02Er Yb-PVP nanofibers under a 980-nm excita- tion can be changed from green white yellow gradually via changing the Yb content.