Enhanced luminescence from transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics by Ga2O3 addition

Transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics without and with Ga2O3 were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga2O3 addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni2+-doped glass ceramics was largely enhanced by Ga2O3 addition which could mainly be caused by increasing of Ni2+ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga2O3 content was all more than 200 nm. The emission lifetime increased with the Ga2O3 content and the longest lifetime is about 250 mu s. The Ni2+-doped transparent glass ceramics with Ga2O3 addition have potential application as broadband optical amplifier and laser materials. (C) 2007 Elsevier Ltd. All rights reserved.

Enhanced near-infrared emission from Ni2+ in Cr3+ Ni2+ codoped transparent glass ceramics

Transparent Li2O-Ga2O3-SiO2 glass ceramics containing Cr3+/Ni2+ codoped LiGa5O8 nanocrystals were synthesized. The steady state emission spectra indicated that the near-infrared emission intensity of Ni2+ at 1300 nm in Cr3+/Ni2+ codoped glass ceramics was enhanced up to about 7.3 times compared with that in Ni2+ single-doped glass ceramics with 532 nm excitation. This enhancement in emission intensity was due to efficient energy transfer from Cr3+ to Ni2+, which was confirmed by time-resolved emission spectra. The energy transfer efficiency was estimated to be 85% and the energy transfer mechanism was discussed. (C) 2008 American Institute of Physics.

Fluorescence properties and laser demonstrations of Nd-doped high silica glasses prepared by sintering nanoporous glass

Porous glass with high-SiO2 content was impregnated with Nd ions, and subsequently sintered at 1100 degrees C into a compact non-porous glass in air or reducing atmosphere. Sintering in a reducing atmosphere produced an intense violet-blue fluorescence at 394 nm. However, the sintering atmospheres almost did not affect the fluorescence properties in the infrared range. A good performance Nd3+-doped silica microchip laser operating at 1064 nm was demonstrated. The Nd-doped sintering glasses with high-SiO2 content are potential host materials for high power solid-state lasers and new transparent fluorescence materials. (c) 2007 Elsevier B.V. All rights reserved.

High Er3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers

This is about the first reported laser glass with very low no, high Er3+ concentration and no quenching. In this work, a series of high Er3+ concentration (10.6-12.2 x 10(20) ions/cm(3)), low refractive index (n(1550) < 1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment. (C) 2008 Elsevier B.V. All rights reserved.

Three-photon-excited upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation

We report on the bluish green upconversion luminescence of niobium ions doped silicate glass by a femtosecond laser irradiation. The dependence of the fluorescence intensity on the pump power density of laser indicates that the conversion of infrared irradiation to visible emission is dominated by three-photon excitation process. We suggest that the charge transfer from O-2-to Nb5+ can efficiently contribute to the bluish green emission. The results indicate that transition metal ions without d electrons play an important role in fields of optics when embedded into silicate glass matrix. (C) 2008 Optical Society of America.

Transparent Ni2+-doped silicate glass ceramics for broadband near-infrared emission

Transparent Ni2+-doped MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics were fabricated. The precipitated nanocrystal phase in the glass ceramics was identified by X-ray diffraction and transmission electron microscope. Broadband near-infrared emission centered at 1220 nm with full width at half maximum of about 240 nm and lifetime of about 250 mu s was observed with 980 nm excitation. The longer wavelength emission compared with Ni2+-doped MgAl2O4 crystal was attributed to the low crystal field occupied by Ni2+ in the glass ceramics. The present Ni2+-doped transparent glass ceramics may have potential applications in broadband optical amplifiers. (c) 2007 Elsevier B.V. All rights reserved.

Valence state change and refractive index change induced by femtosecond laser irradiation in Sm3+ doped fluoroaluminate glass

We report femtosecond laser induced valence state and refractive index change in transparent Sin(3+)-doped fluoroaluminate glass. The effect of annealing on the induced changes was studied and the thermal stability of these changes was discussed. The results show that the femtosecond laser induced valence state change is more stable than the induced refractive index change. The observed phenomenon could be applied to design the thermally erasable or stable storage medium. (c) 2007 Elsevier B.V. All rights reserved.

Luminescence properties of bismuth-doped lime silicate glasses

Luminescences from bismuth-doped lime silicate glasses were investigated. Luminescences centered at about 400, 650, and 1300 nm were observed, excited at 280, 532 and 808 nm, respectively. These three luminescence bands arise from three different kinds of bismuth ions in the glasses. The visible luminescences centered at 400 and 650 nm arise from Bi3+, and Bi2+, respectively. The infrared luminescences cover the wavelength range from 1000 to 1600 nm when exited by an 808 nm laser diode. The full width at half maximum (FWHM) of the infrared luminescences is more than 205 urn. The intensity of the infrared luminescence decreases with the increment in CaO content. We suggest that the infrared luminescences might arise from Bi+. Such broadband luminescences indicate that the glasses may be potential candidate material for broadband fiber amplifiers and tunable lasers. (C) 2007 Elsevier B.V. All rights reserved.

Bismuth-activated luminescent materials for broadband optical amplifier in WDM system

New broadband near infrared luminescence covering the whole work windows (1260-1625 nm) of the current wavelength division multiplexing (WDM) system was found from bismuth-activated M2O-Al2O3-SiO2 (M = Li, Na) and Li2O-Ta2O5-SiO2 glasses at room temperature in the case of 808 nm-laser excitation. But the near infrared luminescence mechanism of the bismuth-activated glasses is not well understood up to now. The figure-of-merits of bandwidth and gain of the glasses are better than those of Er3+-doped silicate glasses and Ti3+ doped sapphire, implying they are the promising gain-medium candidates for the broadband amplifiers and the widely tunable laser sources. (c) 2007 Elsevier B.V. All rights reserved.

Blue emission from Eu2+ -doped high silica glass by near-infrared femtosecond laser irradiation

Eu2+-doped high silica glass (HSG) is fabricated by sintering porous glass which is impregnated with europium ions. Eu2+-doped HSG is revealed to yield intense blue emission excited by ultraviolet (UV) light and near-infrared femtosecond laser. The emission profile obtained by UV excitation can be well traced by near-infrared femtosecond laser. The upconversion emission excited by 800 nm femtosecond laser is considered to be related to a two-photon absorption process from the relationship between the integrated intensity and the pump power. A tentative scheme of upconverted blue emission from Eu2+-doped HSG was also proposed. The HSG materials presented herein are expected to find applications in high density optical storage and three-dimensional color displays. (c) 2008 American Institute of Physics.

Blue green emission from a Cu+-Doped transparent material prepared by sintering porous glass

A colorless transparent, blue green emission material was fabricated by sintering porous glass impregnated with copper ions. The emission spectral profile obtained from Cu+ -doped high silica glass (HSG) by 267-mn monochromatic light excitation matches that obtained by pumping with an 800-nm femtosecond laser, indicating that the emissions in both cases come from an identical origin. The upconversion emission excited by 800-nm femtosecond laser is considered to be a three-photon excitation process. A tentative scheme of upconverted emission from Cu+ -doped HSG was also proposed. The glass materials presented herein are expected to find application in lamps, high density optical storage, and three-dimensional color displays.

Two-photon excited red upconversion luminescence of thulium ions doped GeS2-In2S3-CsI glass

We report a novel phenomenon in GeS2-In2S3-CsI chalcohalide glass doped with Tm3+ ions. Under irradiation with an 808 nm laser diode, a bright red emission centered at 700 nm is observed for the first time in this glass. The log-log correlation between integrated emission intensity and pump power reveals that a two-photon absorption process is involved in the phenomenon, suggesting that the F-3(3,2) -> H-3(6) transition of Tm3+ ions is responsible for the appearance of the red emission. The results indicate that the indium (In) based chalcohalide glass containing Tm3+ ions is expected to find applications in visible lasers, high density optical storage and three-dimensional color displays. (C) 2009 Elsevier B.V. All rights reserved.