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Frequency upconversion of Er[sup 3+] in alkali bismuth gallate glasses have been investigated. The upconversion mechanisms are discussed, and the dominant mechanisms are excited state absorption for the [sup 2]H[sub 11/2]→[sup 4]I[sub 15/2] and [sup 4]S[sub 3/2]→[sup 4]I[sub 15/2] transitions, and energy transfer upconversion for the [sup 4]F[sub 9/2]→[sup 4]I[sub 15/2] transition. Intense green (around 525-550 nm) and red (around 660 nm) emission bands were observed under 800 nm excitation. At a pump intensity of 15.6 W/cm2, frequency upconversion efficiencies of 2.1x10[sup -2] and 4.8x10[sup -3] were obtained for the green and red emissions, respectively. The results are the highest among doped oxide glasses, and are comparable to those reported for Er[sup 3+]/Yb[sup 3+] codoped fluoride glasses. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Dy3+-doped alkaline-earth borate glasses (LKZBSB) with high quantum yield and multifarious emission channels have been fabricated and efficient warm yellowish-white fluorescence is presented under UV light excitation. Judd–Ofelt parameters Ω 2=5.36×10−20 cm2, Ω 4=1.46×10−20 cm2 and Ω 6=1.95×10−20 cm2 indicate a high asymmetrical and covalent environment in the optical glasses. The maximum stimulated emission cross-sections σ em-max corresponding to the 4F9/2→6H15/2, 4F9/2→6H13/2, 4F9/2→6H11/2 and 4F9/2→(6H9/2, 6F11/2) transitions are derived to be 2.64×10−22, 20.07×10−22, 3.45×10−22 and 9.31×10−22 cm2, respectively, and the relevant spontaneous emission probabilities A rad are 174.08, 616.07, 68.95 and 87.10s−1. Quantitative characterization reveals that Dy3+-doped LKZBSB glasses exhibit a quantum yield as high as 16.65%, confirming that the effectiveness of the warm yellowish-white luminescence in Dy3+-doped LKZBSB glasses. Multifarious emission channels and high quantum yield illustrate the great advantages of Dy3+-doped LKZBSB glasses in developing fiber-lighting sources, display devices, tunable visible lasers, and optical signal amplifiers. [ABSTRACT FROM AUTHOR]

Europium and terbium acetylacetonate hydrates were doped into poly methyl methacrylate (PMMA). Efficient purplish-red and green fluorescence was obtained from europium acetylacetonate hydrates (EAH) and terbium acetylacetonate hydrates (TAH) doped PMMA respectively. Judd–Ofelt parameters Ω 2 (19.73×10−20 cm2) and Ω 4 (2.19×10−20 cm2) indicate a high inversion asymmetric and strong covalent environment in PMMA. The maximum stimulated emission cross-sections for the 5D0→7F J (J=1, 2 and 4) transitions in EAH doped PMMA were calculated to be 0.38×10−21, 4.90×10−21 and 0.36×10−21 cm2, respectively. Variable fluorescence color can be efficiently achieved from the cooperation of three fluorescence colors offered by red (Eu3+), green (Tb3+) and blue (ligand) in EAH/TAH codoped PMMA by adjusting the excitation wavelength. These results indicate that PMMA is an effective photoluminescence co-sensitizer and PMMA doped with rare earth acetylacetonate hydrates is a promising candidate for a series of optoelectronic functional devices. [ABSTRACT FROM AUTHOR]

Abstract: A bright and compact orangish-red fluorescence trace is observed in an Eu3+/Sm3+ co-doped K+Na+ ion-exchanged aluminum germanate (NMAG) glass channel waveguide under excitation with a 488nm Ar+ laser. The excitation wavelength range and the emission intensity of Eu3+ in NMAG glass are remarkably improved by the sensitization of Sm3+, and the energy transfer probability and efficiency are calculated to be 151.2s−1 and 25.3%, respectively. Meanwhile, the energy transferred from Sm3+ can be efficiently utilized to generate intense fluorescence of Eu3+ due to the large spontaneous emission probabilities of the Eu3+: 5D0→7F J (J=1, 2, and 4) transitions that reach up to 68.9, 364.7, and 152.6s−1, respectively. Enhanced fluorescence in the Eu3+/Sm3+-doped NMAG glass channel waveguide, which matches the excitation band of most photosensitizers, holds great promise for photodynamic therapy. [Copyright &y& Elsevier]

Abstract: Efficient infrared emissions near the second telecommunication window in Ho3+-doped multicomponent heavy-metal gallate (MHG) glasses have been observed. The maximum stimulated emission cross-sections are calculated to be 2.94×10−21 and 2.08×10−21 cm2 for 1200 and 1390nm emissions, respectively. Excitation spectra reveal that the 642 and 538nm wavelengths are practical pumping conditions for 1.2 and 1.39μm emissions, respectively. Gain cross-sections are evaluated and positive gain bands have been anticipated. The theoretical gain results indicate that the appealing infrared emissions near the second telecommunication window from Ho3+ -doped MHG glasses with low maximum phonon energy of ∼660cm−1 make them attractive in developing ∼1.2μm and E-band (1360–1460nm) optical amplifiers. [Copyright &y& Elsevier]

Abstract: Ho3+-doped low-phonon-energy heavy-metal gallate glasses (LKBPBG) have been prepared and efficient 1.199μm emission originating from the 5I6 → 5I8 radiative transition has been observed under 900nm excitation. The spontaneous emission probability and the maximum stimulated emission cross-section were derived to be 294.31s−1 and 3.46×10−21 cm2, respectively. The ratio of quantum yields between ~1.2 and ~2.0μm emissions was identified to be 16%, demonstrating that the 5I6 → 5I8 transition is favorable for optical amplification. The maximum gain coefficient of 1.84dB/cm at 1.199μm wavelength was anticipated in the ideal status. These results indicate that the Ho3+-doped LKBPBG glasses have a promising potential for the development of ~1.2μm signal amplifier devices. [Copyright &y& Elsevier]

Abstract: Er3+/Yb3+-codoped aluminum oxide (Al2O3) modified tellurite ceramics have been prepared by high-temperature melting. Judd–Ofelt parameters of Eu3+, which was introduced in 15%Na2O–15%Al2O3–70%TeO2 (NAT) ceramic system as a probe, present a medium asymmetry and covalence environment around rare-earth ions. Efficient 551nm green and 668nm red two-photon pumped upconversion fluorescence and strong 1.533μm infrared radiation were observed and recorded in the Er3+/Yb3+-codoped NAT ceramics under the excitation of ∼980nm diode lasers. For 1.533μm near-infrared emission, the maximum stimulated emission cross-section was calculated to be 6.61×10−21 cm2, and the ordinary exhibition referring to tellurite glass system is due to the lowering of refractive index, which is caused by the abundance of Al2O3 composition. Efficient visible upconversion and infrared emissions indicate that Er3+/Yb3+-codoped NAT ceramics are promising substrates in developing color light sources, upconversion display devices, infrared sensors and infrared radiation sources. [Copyright &y& Elsevier]

Abstract: Efficient 2.0μm infrared and visible upconversion emissions have been observed in Ho3+/Yb3+ co-doped mixed-alkali bismuth gallate (LKBBG) glasses having a maximum-phonon energy of 673cm−1. The Judd–Ofelt parameters Ω 2, Ω 4 and Ω 6 of Ho3+ indicate that there is a high asymmetry and strong covalent environment in LKBBG glasses. The large absorption and emission cross-sections of Yb3+ confirm that it is a suitable sensitizer for capturing and transferring pump energy to Ho3+. The emission cross-section profile for the 5I7 → 5I8 transition is derived using the reciprocity method and the peak value is 5.54×10−21 cm2, which is much larger than the value in fluorozircoaluminate glasses. LKBBG glasses exhibit low maximum-phonon energy and large refractive index, and it is possible to achieve an effective 1.66μm U-band emission of Ho3+ under 900nm laser radiation. [Copyright &y& Elsevier]

Abstract: Polarized visible and infrared emission characteristics of Er3+ ions in vapor-transport-equilibration (VTE)-treated LiNbO3 crystals codoped with different concentrations of Zn and Er were investigated in comparison with corresponding as-grown crystals. The results show that the VTE treatment leads to substantial spectral changes of Er3+ emissions at 0.65, 0.98 and 1.5μm regions, and the spectral changes in the 0.98 and 1.5μm regions appear to be Zn-concentration-dependent. It is concluded in combination with X-ray powder diffraction results and optical absorption characteristics reported previously that the VTE treatment resulted in crystalline phase transformation with respect to Er3+ ions from original LiNbO3 to ErNbO4 phase in all crystals studied. The formation of the ErNbO4 phase and the Zn2+ codopants are responsible for the VTE-induced substantial spectral changes. The emission characteristics of the ErNbO4 precipitates in the Zn/Er-codoped crystals are found to be very different from those of the ErNbO4 precipitates in the only Er-doped crystal in the infrared region, and the difference is attributed to the influence of the Zn2+ codopant on the Er3+ ion environment. The mechanism of the crystalline phase transformation is qualitatively explained from the viewpoint of the declined solubility of Er3+ ion in a Li-rich LiNbO3 crystal and from the phase diagram of Li2O–Nb2O5 system. [Copyright &y& Elsevier]

Abstract: Influence of thermal reduction on intrinsic (bipolarons), extrinsic (Er3+) defects and OH− groups in Er:LiNbO3 crystals, which were as-grown and VTE-treated (VTE: vapor transport equilibration) before being reduced, was studied by measuring the polarised or unpolarised optical absorption in visible and near infrared regions. A wide and strong band extending from the optical absorption edge up to the infrared region and peaking around 500nm (∼2.5eV), resulting from the absorption of reduction-induced bipolarons, is observed. Meanwhile, the thermal reduction also induces an additional, relatively much narrow absorption band around 370nm in a crystal whether it is Er-doped or undoped and whether it is congruent or originally VTE-treated. Both the 500nm and the 370nm bands show similar polarisation dependence. The thermal reduction treatment hardly influences Er3+ spectroscopic properties such as absorption amplitude, linewidth, peaking position and polarisation dependence. The original VTE effects on the spectroscopic properties of Er:LiNbO3 crystal are essentially retained still. The thermal reduction has a similar effect on the OH− absorption to a strong VTE treatment: the removal of the OH− groups contained in the crystal. [Copyright &y& Elsevier]

Er3+-doped gallium tellurite glasses have been fabricated and characterized. Efficient green and red upconversion luminescence, and strong infrared fluorescence at 1.53 μm wavelength were observed under the excitation of a 975 nm diode laser at room temperature. The visible upconversion emission bands centered at 524, 546 and 669 nm have been confirmed that two photons contribute to the upconversion processes. The emission peak locates at 1.53 μm with a full-width at half-maximum of ∼58 nm, and the calculated peak emission cross-section is 8.54×10−21 cm2. These values are larger than those in silicate and phosphate glasses. Efficient visible upconversion and infrared luminescence indicate that Er3+-doped gallium tellurite glass is a promising laser and amplifier materials. [Copyright &y& Elsevier]

Abstract: X-, Y- and Z-cut congruently grown bulk Er(1.6, 2.0mol%):LiNbO3 crystals have been thermally treated using the vapor transport equilibration (VTE) technique. Optical absorption and X-ray powder diffraction measurements have been carried out to verify the existence of ErNbO4 precipitates induced by the VTE procedure in these crystals. Scanning electron microscope (SEM) has been used for the direct observation of crystallographic morphology of the ErNbO4 precipitates. The results show that the precipitates lie mainly in the (0001) crystallographic plane of the substrate and preferably grow with a crystallographic morphology of flat polyhedrons with rough dimensions of submicron×micron×micron. The precipitates on the surfaces of Z-cut substrates have only three orientations mutually aligned at approximately 60° or 120° angles being nearly parallel to the crystallographic axes of the host matrix. The SEM results show that VTE conditions and the type of crystallographic cut of the substrate remarkably affect the size and density of the precipitates. [Copyright &y& Elsevier]

Visible and near infrared absorption and emission (488 nm excitation) characteristics of ErNbO4 powder, which were prepared by calcining the Er2O3 (50 mol%) and Nb2O5 (50 mol%) powder mixture at 1100 and 1600 °C for different durations, have been investigated at room temperature. The absorption and emission characteristics of these calcined ErNbO4 powder were summarized and discussed in comparison with those of Er2O3. Weak emission of Er2O3 relative to the calcined ErNbO4 is mainly conducted with absorption difference at the excitation wavelength 488 nm. The obvious spectral changes from Er2O3 to calcined ErNbO4 samples are related to an elevated-temperature-assisted phase transformation according to the solid-state chemical reaction equation: Er2O3 + Nb2O5 ⇌ 2ErNbO4, which results in the changes of the ion environment of Er3+ and hence changes of the Stark levels of Er3+. The further spectral change as the strengthened calcination results from the improvement of ErNbO4 purity in the calcined mixture. The borders between two green transitions and between two near infrared transitions in the emission spectra of both calcined samples and Er2O3 were tentatively identified by referencing earlier reported emission spectra of the precipitated Z-cut VTE Er(2.0 mol%):LiNbO3 crystal and the match relation between absorption and emission spectra of the ErNbO4 powder. A comparison was performed on the spectra of calcined ErNbO4 powder and those of VTE Er(2.0 mol%):LiNbO3 crystals. The results allow to preliminarily deem the contribution of ErNbO4 precipitates, generated inside these crystals by the VTE procedure, to the spectra of these crystals. [Copyright &y& Elsevier]

Abstract: To achieve high-gain S-band waveguide amplifiers and promote the practicality of integrated signal amplification devices, bent waveguide structures based on Tm3+ doped germanate glass substrate have been designed. Using simulated-bend method, the optimal radius for the curved structure is offered to be 1.90cm with a loss coefficient of 0.04dB/cm, as the substrate size is minimally schemed. For the folded-spiral waveguide, the internal gain at 1482nm is derived to be 13.01dB, which is higher than the values of 8.21 and 4.22dB in the U- and S-bend waveguides, respectively, and nearly three times higher than that of the straight one. Simulation results indicate that the optical path design is attractive in realizing the high gain of Tm3+ doped germanate glass channel waveguides for practical S-band amplification. [ABSTRACT FROM AUTHOR]

Abstract: A mixing up-conversion excitation phenomenon in Er3+/Yb3+-codoped aluminum germanate (Na2O–MgO–Al2O3–GeO2, NMAG for short) glasses for K+–Na+ ion-exchanged waveguides was observed and characterized. The green and red up-conversion luminescence of Er3+ is due to a two-photon excitation process under low-power excitation of a 974nm diode laser, however, with increasing the pumping power, the green emission turns to follow a combination of two- and three-photon excitation effects while the red one still agrees with a two-photon excitation law. Under high-power pumping, owing to potential thermal effect, the population ratio between the 2H11/2 and 4S3/2 levels adjusts acutely, which results in a distinct exhibition in 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 emission transitions. Green transmission trace has been observed in K+–Na+ ion-exchanged Er3+/Yb3+-codoped NMAG glass waveguide and it provides an original reference in developing visible waveguide amplifiers and lasers. [Copyright &y& Elsevier]

Abstract: Low phonon energy Tm3+/Ho3+/Yb3+ triply doped bismuth tellurite glasses exhibiting multicolor upconversion fluorescences have been fabricated and characterized. The multicolor fluorescence composed of three primary colors green, red and blue upconversion emissions from Ho3+ and Tm3+ has been investigated. By adjusting the excitation power, the fluorescence colors can be tuned from multicolor to white color, and the dependence of color tunability on pump power has been presented in the CIE 1931 chromaticity diagram. With the increase in pumping power, the color coordinates move along the down-left direction and hit the equal energy point. The upconversion and color tunability via changing the pump power of infrared excitation in Tm3+/Ho3+/Yb3+ triply doped bismuth tellurite glasses will lead to new breakthrough in the field of three-dimensional solid-state displays and white-light emitting devices. [Copyright &y& Elsevier]

Abstract: Polarized downconversion, 980-nm-upconversion and near-infrared emission characteristics of vapor-transport-equilibrated (VTEed) bulk Er (0.4mol%)/MgO (6mol%)-codoped LiNbO3 crystals were investigated. The downconversion and upconversion visible emissions display similar VTE effects including the drop of emission intensity and the weakening of polarization dependence. At 0.98 and 1.5μm regions, the VTE has a weak effect on the emission intensity, but a strong effect on the spectral shape. The crystalline phases in these bulk Er/Mg-codoped VTE crystals are determined by comparing their infrared emission characteristics with those of pure ErNbO4 powder and locally Er-doped MgO (4.5mol%):LiNbO3 crystal. The results show that the Er3+ ions present in these bulk Er/Mg-codoped VTE crystals as a mixture of Er:LiNbO3 and ErNbO4 phases. The percentages of the ErNbO4 phase contained in these VTE crystals were evaluated from the 1531 and 1536nm characteristic absorption areas. The contents of constituent elements were determined by chemical analysis. [Copyright &y& Elsevier]

Abstract: Powerful visible upconversion fluorescence intensities of Er3+ in novel bismuth gallate glasses (LKBBG) and common tellurite glasses (TZN) with low phonon energies and high refractive indices have been compared. Under the same measurement condition, Er3+-doped LKBBG glasses show the stronger upconversion emission intensities than Er3+-doped common tellurite glasses (TZN). The visible upconversion emission bands peaked at 531, 548 and 668nm have been confirmed that two photons contribute to these upconversion processes. The maximum phonon energy obtained in LKBBG glasses is 673cm−1, which is 65cm−1 lower than that in common tellurite glasses, indicating that LKBBG glasses almost possess the lowest maximum phonon energy in all of the oxide glasses. All analyses support that Er3+-doped LKBBG glasses are promising materials for fabricating visible upconversion devices. [Copyright &y& Elsevier]

Abstract: Intense 1.8μm and efficient 1.48μm infrared emissions have been recorded in Tm3+-doped alkali-barium-bismuth-gallate (LKBBG) glasses with low phonon energies under the excitation of 792nm diode laser. The maximum emission cross-sections for 1.8 and 1.48μm emission bands are derived to be 6.26×10−21 and 3.34×10−21 cm2, respectively, and the peak values are much higher than those in Tm3+-doped ZBLAN glass. In low-concentration doping, the full-widths at half-maximum (FWHMs) of the two emission bands are 223 and 122nm, and the quantum efficiencies of the 3F4 and 3H4 levels are proved to be ∼100% and 86%, respectively. When the doping concentration increases to 1wt%, the quantum efficiency of the 3H4 level is reduced to 60% due to the cross-relaxation processes in high-concentration doping. Efficient 1.8μm infrared emission in Er3+/Tm3+-codoped LKBBG glass has also been achieved under the excitation of 970nm diode laser, and the probability and the efficiency of non-radiative energy transfer from Er3+ to Tm3+ are as high as 354s−1 and 58.4%, respectively. Efficient and broad 1.8 and 1.48μm infrared emission bands indicate that Tm3+-doped LKBBG glasses are suitable materials in developing S- and U-band amplifiers and 1.8μm infrared laser. [Copyright &y& Elsevier]

Abstract: Er3NbO7 phosphor was synthesized by sintering a mixture of Er2O3 and Nb2O5 powder in a molar ratio of 3:1 at 1600°C over 55h. Optical absorption and emission characteristics of Er3+ ions in the calcined Er3NbO7 powder were investigated and discussed compared with ErNbO4 phosphor and a Z-cut congruent Er (2mol%):LiNbO3 single crystal. The absorption and emission studies show that, due to different crystal structures, the spectroscopic properties of these niobates have some differences in spectral shape, peak position, and relative intensity, especially at 1.5μm. The most obvious spectral feature of the Er3NbO7 is that the spectral structure of band instead of peak is observed in its absorption or emission spectrum due to the existence of local structural disorder and multiple Er3+ sites. The Er3NbO4 shows stronger upconversion emission than the single crystal but weaker than the ErNbO4. Experimental results show that energy transfer upconversion and/or excited state absorption play a dominant role in the upconversion emissions, and, at higher pump level (>200mW), the thermal effect becomes significant and results in drop of the upconversion intensity. The 1.5μm lifetimes of Er3+ ion in the Er3NbO7, ErNbO4 phosphor, and in the Er:LiNbO3 crystal are measured to be ∼5.3, 2.0, and 2.4ms, respectively. In combination with the measured Raman spectra, the quantum efficiency, multiphonon nonradiative decay rate, and theoretical radiative lifetime of the 1.5μm emission of the two powder materials are expected. The differences in upconversion intensity and measured 1.5μm lifetime between the three materials are explained qualitatively. [Copyright &y& Elsevier]

Abstract: Resonant energy transfer between Pr3+ and Yb3+ ions has been studied in tellurite glasses. The energy absorbed by Pr3+ is transferred efficiently to Yb3+, and fluorescence at around 1μm wavelength is observed. The energy transfer efficiencies for the 3P0 → 3F2 and 1D2 → 1G4 transitions in 0.5wt% Pr3+–1.0wt% Yb3+ codoped tellurite glasses are ∼68% and ∼84%, respectively, and the emission intensity of the 1G4 → 3H5 transition of Pr3+ does not show any significant change, due to a possible back transfer energy from the 2F5/2 → 2F7/2 transition of Yb3+ to the 1G4 level of Pr3+. [Copyright &y& Elsevier]

Abstract: A comprehensive, complete theory suitable for a long period grating (LPG) on/in a planar or channel waveguide is described on the basis of coupled mode theory. The theory aims at key characteristic parameters with respect to the effect of the LPG, including resonance wavelength, transmission power of the guided mode in the waveguide, full-width at half-maximum (FWHM) of the power attenuation band in transmission spectrum of the guided mode, and coupling coefficient between a guided and a coupled mode. The type of the grating including relief and index modulation, different polarization state combinations of the guided mode and the resonant mode, and slanted grating structure are considered in this theory. The influences of the coupling between two guided modes and between a guided mode and a substrate mode are discussed. The role of cladding layer in a long period waveguide grating is demonstrated in particular. Finally, the expressions for the sensitivity of resonance wavelength as a function of external temperature, pressure and surrounding refractive index are derived. [Copyright &y& Elsevier]

Abstract: Er3+-doped alkali–barium–bismuth–tellurite (LKBBT) and alkali–barium–bismuth–gallate (LKBBG) glasses with high refractive indices and low phonon energies have been designed, fabricated, characterized and compared. Intense 1.53μm emissions with widely different widths in the two kinds of glasses were observed and recorded under 980nm diode laser excitation. The full-widths at half-maximum of the 1.53μm emission bands in LKBBT and LKBBG glasses are 58 and 40nm, and the lifetimes of them were measured to be 3.21 and 3.97ms, respectively. The quantum efficiencies for the 4I13/2 level in both glasses are almost 100%. The 1.53μm broad and narrow emissions with high spontaneous emission probabilities and large emission cross-sections indicate that Er3+-doped LKBBT and LKBBG glasses are suitable materials in developing broadband optical amplifier and infrared laser, respectively. [Copyright &y& Elsevier]

Abstract: Er3+–Yb3+ co-doped waveguide amplifiers fabricated using thermal two-step ion-exchange are demonstrated. K+–Na+ ion-exchange process was first carried out in pure KNO3 molten bath, and then field-assisted annealing (FAA) was used to make the buried waveguides. The effective buried depth is estimated to be ∼3.4μm for the buried FAA waveguides. With the use of cut-back method, the fiber-to-guide coupling loss of ∼4.38dB, the waveguide loss of ∼2.27dB/cm, and Er3+ absorption loss ∼5.7dB were measured for a ∼1.24-cm-long waveguide. Peak relative gain of ∼7.0dB is obtained for a ∼1.24-cm-long waveguide. The potential for the fabrication of compact optical amplifiers operating in the range of 1520–1580nm is also demonstrated. [Copyright &y& Elsevier]

Abstract: Eu3+ doped alkali–barium–bismuth–tellurite (Eu3+:LKBBT) glasses were prepared by conventional melt quenching. Twelve emission bands including infrequent blue and green bands are observed and they almost cover whole visible spectral region under violet light radiation. The blue and green emissions of Eu3+ rarely appeared in oxide glasses before, but they have been clearly recorded in Eu3+:LKBBT glasses even in the case of high concentration doping of Eu3+. The analysis based on spontaneous-radiative rate, energy gap and Raman scattering reveals that the obtaining of the abundant multichannel emissions of Eu3+ is due to the higher refractive index and the lower phonon energy in LKBBT glass system. [Copyright &y& Elsevier]

Abstract: Polymeric optical waveguides and devices have applications in sensor, signal processing, and communication systems. In this paper, the characteristics of polymer materials are described, and the fabrication and performances of passive and active polymer devices for photonic applications are reviewed. [Copyright &y& Elsevier]

Abstract: Sm3+-doped alkali–barium–bismuth–tellurite (LKBBT) glass with high refractive index has been fabricated and characterized optically. The refractive index, density, optical absorption, IR transmittance, Judd–Ofelt parameters and spontaneous transition probabilities have been measured, calculated and analyzed. In the LKBBT glass, Sm3+ ions emit intense reddish-orange lights under the excitation of long-wave UV and blue lights. Absorption and excitation spectra indicate that commercial UV and blue laser diodes, blue and bluish-green LEDs and Ar+ optical laser are powerful excitation sources for Sm3+ visible fluorescence in the glass with high optical refractive index. [Copyright &y& Elsevier]

Abstract: Polymeric optical waveguides based on a new synthesized bisphenol A–aldehyde polymer (PA-1 resin) have been fabricated using photolithography and reactive ion etching technique. The polymer is novel with relatively high refractive index, low birefringence and absorption at the optical communication wavelengths. The single-mode channel waveguides exhibit a propagation loss of 0.410.05dB/cm at a wavelength of and 0.50.05dB/cm at for both the TE and TM polarizations. The polarization-dependent loss of the waveguides is 0.10.05dB/cm at these wavelengths. [Copyright &y& Elsevier]

Abstract: Buried channel waveguide amplifiers in Er3+–Yb3+ co-doped phosphate glasses were fabricated by proton beam writing using a focused sub-micron beam of 2.0MeV protons with a fluence ranging from 0.5–6.0×1015 particles/cm2. The waveguides were located at a depth of ∼38μm beneath the surface. Above a threshold fluence of 3.0×1015 particles/cm2, a negative refractive index change occurs, preventing any light confinement in the channel. A peak net gain of ∼1.57dB/cm was measured for waveguides fabricated with a fluence of ∼0.9×1015 particles/cm2. These measurements were performed at 1.534μm signal wavelength, with 100mW pump power at 975nm wavelength. [Copyright &y& Elsevier]

Highly efficient catalytic m-BiVO4: Er3+-Yb3+fibers with sensitive temperature feedback performance provide a new perspective for the application of multifunctional photocatalytic materials in extremely harsh environments. [Display omitted] • Crystal filament blended m-BOEY fiber is prepared by iterative electrospinning. • Flexibility is enhanced and recycling is more convenient through this process. • Photocatalytic ability is improved due to Ln3+ and morphological characteristics. • Real-time temperature feedback and photocatalysis can be realized simultaneously. • Providing a new perspective for photocatalysis in extremely harsh environments. Bi(Er3+-Yb3+)VO 4 fibers prepared by the iterative electrospinning process have excellent crystal filament compatibility. Compared with traditional photocatalytic materials, fibers in our work are admirable in some aspects including large specific surface area, strong three-dimensional weaving capacity, high solar energy utilization rate, high reproducibility, and controllable structure. The working temperature of the catalytic degradation process is monitored and fed back in real time by 2H 11/2 →4I 15/2 and 4S 3/2 →4I 15/2 radiation transitions of Er3+ with excellent sensitivity. Photocatalytic efficiency is greatly improved by broadening the photoresponse range of BiVO 4 and inhibiting the recombination of photo-generated charges, which is attributable to the successful incorporation of rare earth ions. The maximum degradation efficiency of methylene blue (MB) is 98.7% and the degradation constant K is as high as 0.116 min−1 under simulated sun-light irradiation and it also has the same degradation trend under near-infrared (NIR) light irradiation. In general, highly efficient catalytic fibers with sensitive temperature feedback performance provide a new perspective for the application of multifunctional photocatalytic materials in extremely harsh environments to address pressing energy and environmental challenges. [ABSTRACT FROM AUTHOR]

Dy3+, Eu3+ co-doped borotellurite (HKMTZ) glasses are fabricated successfully by pressureless solid-phase reaction for potential applications in white light-emitting diodes (WLED). A novel effect of individual emission of dual-modes between Dy3+ and Eu3+ is observed firstly which reveals the multicolor mechanism that can be tuned easily from reddish-orange (2746 K) to nature-white (4588 K) to cool white (7889 K). And dual-modes emissions of Dy3+ and Eu3+ with independent light-emitting are enabled to be observed under 393 nm excitation due to the strong competition between Dy3+ and Eu3+. Moreover, replacing traditional packaging technology of LED to regard as color-converter has been come up as an efficient method to promote properties of luminescence and thermal stability. The aforesaid phenomena of photoluminescence results demonstrate that Dy3+, Eu3+ co-doped HKMTZ glass is an excellent candidate with tunable multicolor which may possess promising applications for WLED. [Display omitted] • Dy3+, Eu3+ doped HKMTZ glasses are fabricated by solid-phase method as WLED material. • A novel effect of individual emission of dual-phase is identified between Dy and Eu. • Multicolor regulation can be tuned from reddish-orange to nature-white to cool white. • HKMTZ glasses can emit superior white illumination under UVB and UVC excitation. • New research effect for multicolor tuning WLED provides a new dimension of thinking. [ABSTRACT FROM AUTHOR]

The red-emitting phosphor-in-glass (PiG)s have been successfully prepared by a facile one-step co-sintering method on the basis of ultra-low melting Sn-P-F-O glass and CaAlSiN 3 : Eu2+ red phosphors synthesized under atmospheric-pressure (denoted as CASN-AP) and high-pressure (denoted as CASN-HP), respectively. The crystal structure, particle morphology, photoluminescence (PL) properties and surface states of the phosphors were investigated detail by X-ray powder diffraction (XRD), field emission electron microscopy (FESEM), fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS). Under excitation of blue light (460 nm), CASN-AP phosphor with red emission at 659 nm shows a higher luminescent intensity by 23 % than that of CASN-HP phosphor. Moreover, a shorter photoluminescence lifetime and red shift of 9 nm for emission peak can be also found for the CASN-APphosphor, which is ascribed to the increased Si-N bonds and surface Si/N ratio (1.86) demonstrated by the XPS analysis. Besides, the quantum yield and thermal degradation of both phosphors have been investigated. CASN-AP phosphor exhibits higher emission intensity because of its more emitting photons, but a lower quantum yields than CASN-HP phosphor due to its more absorbed photons. Based on the above, the low-temperature melting process for Sn-P-F-O glass does not damage the phosphor and the enhanced (≥35%) red-emitting CASN-AP PiG will be a promising candidate for essential red component in high quality white LEDs. Image 1 • CaAlSiN 3 :Eu2+ phosphor presents high crystallinity even at atmospheric pressure. • The reason for enhancement (23%) of PL intensity for CASN-AP has been explained. • A higher PL intensity (35%) for PiG-CASN-AP will be a promising red component. • 11.2% PL losses for CASN-AP phosphor after 30h socking treatment shows good moisture resistance. • 11.6% and 6.4% PL losses for CASN-AP/CASN-HP phosphor at 150°C have been recorded. [ABSTRACT FROM AUTHOR]

Based on the demonstration of the fluorescent properties, Dy3+ doped borosilicate glasses (NLKSB) were confirmed to be an efficient phosphor under long-wave ultraviolet (UVA) radiation. Ce3+ and Sb3+ are introduced to the Dy3+ doped NLKSB glass system, which extends the excitable region to medium-wave ultraviolet (UVB) and short-wave ultraviolet (UVC) spectral ranges. Sensitization coefficient of Ce3+-Sb3+ to Dy3+ under different wavelengths is in accordance with the multiplication of Ce3+ to Dy3+ and Sb3+ to Dy3+, besides, this unexpected phenomenon is attributed to the effect of band superposition. The enhancement coefficient of quantum yield reaches up to 7.03 for the main emission of Dy3+ under the UVB-LED excitation, which indicates that multiplier effect of sensitization plays an outstanding role in macroscopic applications. The excellent sensitization effect and the effective excitability expansion provide a breakthrough in developing of high-quality lighting devices. Image 1 •. Dy3+ doped NLKSB borosilicate glass is an efficient phosphor under UVA radiation. •. The excitable extension of Dy3+ from UVA to UVC increases excitation selectivity. •. Ce3+ and Sb3+ co-addition provides a new route for remarkable sensitization effects. •. Synergy of Ce3+ and Sb3+ improves the quantum yield of Dy3+ under high-energy UV. •. Multiplier effect of sensitization offers new thoughts in making lighting devices. [ABSTRACT FROM AUTHOR]

Ce3+ activated Lu 3 Al 5 O 12 (LuAG) phosphor-in-glass (PiG) based on tellurite glass with low melting temperature has been synthesized and the LuAG particles are proved to be well-distributed in tellurite glass with the particle size of ~5 μm. The introduction of H 3 BO 3 as a flux is helpful to promote polycrystalline growth and reduce reaction temperature of LuAG:Ce3+ green phosphor, but accompanied by the generation of LuBO 3 impurity phase. Differential fluorescence emission behaviors between LuAG:Ce3+ and LuAG-PiG illustrate that the luminous ability of the LuBO 3 :Ce3+ is strongly restrained while intense pure green light is released in composite. LuAG-PiG combines the admirable formability of tellurite glass with the favorable luminescent capability of LuAG:Ce3+, in which LuBO 3 can be effectively eliminated to achieve LuAG:Ce3+ depuration. Prominent depuration capacity and intense fluorescence emission demonstrate that LuAG-PiG is a potential candidate in developing high-power light emitting diodes lighting. Image 1 • Tellurite glass as an excellent carrier is used to disperse phosphor in LuAG-PiG. • LuAG:Ce3+ particles are well-distributed in glass with the particle size of ~5 μm. • H 3 BO 3 promotes phosphor crystallization and introduces blue emission impure phase. • Intense pure green emission originated from LuAG:Ce3+ depuration is obtained. • Shapeable LuAG-PiG exhibits a potential in developing optoelectronic devices. [ABSTRACT FROM AUTHOR]

Ce3+ activated Y 3 Al 5 O 12 (YAG)-tellurite phosphor-in-glass (PiG) has been synthesized and the YAG:Ce3+ particles are well-distributed in glass matrix. The introduction of flux H 3 BO 3 promotes crystal growth accompanying the generation of YBO 3 impurity phase, which leads to undesired blue light in precursor phosphor under ultraviolet (UV) irradiation. YAG-PiG composite releases efficient pure yellow light with the disappearance of blue light under UV excitation, indicating that the luminescence of the impurity phase is inhibited seriously. The composite combines the excellent formability of tellurite glass with the favorable luminescence capability of YAG:Ce3+, in which the impurity phase can be eliminated effectively during the fabrication of the composite. The excellent thermal stability and prominent fluorescence purification effect make YAG-PiG a potential candidate in developing high-quality yellow light source for optoelectronic clean-room lighting. Image 1 • YAG-PiG is a formable luminescent material where phosphor is dispersed in glass. • YAG:Ce3+ precursor phosphor contains blue-emission YBO 3 impurity phase. • Pure yellow-light output originates from fluorescence purification in YAG-PiG. • The combination of glass and phosphor provides a new route for crystal depuration. • High-quality yellow light in YAG-PiG is a candidate in optoelectronic lighting. [ABSTRACT FROM AUTHOR]

Abstract: Transparent Y–Ti–O nanocrystallized layer was formed in Eu3+ doped sol–gel film after annealing at 600°C. The crystalline particles have been proved to be a single cubic phase of Y–Ti–O and the mean size is identified to be 15.3nm. Red fluorescence was clearly observed under the excitation of UV radiation. Experimental intensity parameters Ω 2 and Ω 4 of the Eu3+ doped nanocrystallized film system are calculated to be 4.02×10−20 and 2.17×10−20 cm2, respectively, indicating a lack of the inversion symmetry of Eu3+ sites and an average covalent environment surrounding Eu3+ ions. The controllable homogeneous Y–Ti–O nanocrystallizations in the sol–gel films provide possibilities in developing illumination, display, optical detection and light conversion devices. [Copyright &y& Elsevier]