Showing papers by "Jong Heo published in 2005"
TL;DR: In this paper, the emission properties of Tm3+ in (0.85−x), Ge0.25As0.10S0.15CsBr glass were investigated.
Abstract: Emission properties of Tm3+ in (0.85−x)(Ge0.25As0.10S0.65)–0.15GaS3∕2–xCsBr glass (x=0–0.17) were investigated. With 15mol% CsBr addition, the emission intensity of 1.48-μm increased accompanied by a large increase in the lifetime of the Tm3+:H43 level up to 1.2ms. At the same time, a 1.48-μm emission peak splits into two peaks due to the changes in the local structure surrounding Tm3+ ions. To achieve population inversion in Tm3+ ions, Ho3+ or Tb3+ were codoped into 0.70(Ge0.25As0.10S0.65)–0.15GaS3∕2–0.15CsBr glass. The population of the Tm3+:F43 level was effectively quenched with Ho3+ or Tb3+ codoping. Critical distances of Tm3+:F43→Ho3+:I75 and Tm3+:F43:→Tb3+:F0,1,27 energy transfer were 9.1 and 12.7A, respectively. The population density differences were higher with Ho3+ codoping than with Tb3+ due to the crossrelaxation of Tm3+:H43→H53 to Tb3+:F67→F37.
37 citations
TL;DR: In this article, the impact of ground state absorption to (3 F 3, 3 F 4 ) level on the emission was discussed and then efficient excitation schemes were proposed to minimize nonradiative energy transfers among the active ions, the host materials need doping concentration of Pr 2 O 3 tantamount to not more than 0.01
34 citations
TL;DR: In this article, rare-earth ions were preferentially incorporated into β-PbF 2 nanostructured crystals formed upon heat-treatment, which increased the lifetime of Tm 3+ and Ho 3+ ions.
Abstract: Transparent nanostructured glasses were prepared from an oxy-fluoride precursor glass doped with rare-earth ions. Analysis of the local environment of rare-earth ions using site-selective and phonon sideband spectroscopies indicated that rare-earth ions were preferentially incorporated into β-PbF 2 nanostructured crystals formed upon heat-treatment. Lifetimes of various energy levels and emission intensities in Tm 3+ and Ho 3+ ions increased with the formation of nanostructured crystals inside the glass matrix.
26 citations
TL;DR: In this article, the authors show that the fluorescence lifetime of rare-earth elements can be dramatically modified by compositional adjustment of the hosts with an accuracy of not more than 1 mol % without any elaborated thermal treatments.
Abstract: Fluorescence lifetime of hypersensitive 4f-4f transitions of rare-earth elements embedded in amorphous inorganic solids can be dramatically modified by compositional adjustment of the hosts tantamount to not more than 1 mol % without any elaborated thermal treatments. It is possible to modify a spontaneous emission rate of Dy3+:(F-6(11/2),H-6(9/2))->H-6(15/2) transition in chalcogenide Ge-As-S glasses through selective addition of low levels of Ga and CsBr. Along with the change of the spontaneous emission rate, multiphonon relaxation rate involved in the (F-6(11/2),H-6(9/2)) state also significantly varies upon the minute compositional adjustment. The combination of these effects results in the measured lifetime of the fluorescing (F-6(11/2),H-6(9/2)) level being greatly enhanced. Such behaviors are attributed to the hypersensitive nature associated with the H-6(15/2) F-6(11/2) transition and preferential coordination of bromine in the nearest-neighboring shell of the Dy3+ ions, which is formed spontaneously during the vitrification process of the host materials. These experimental observations show the most extreme dependence of the fluorescence lifetime on small compositional changes reported compared to any other noncrystalline solid-state dielectric. As such coutilization of many hypersensitive transitions of rare-earth elements and those host materials used in this study may present a unique opportunity to control absorption and emission properties, especially fluorescence lifetimes, through a minute compositional adjustment.
22 citations
TL;DR: In this article, a least compositional adjustment by Ga and CsBr was made to the Dy3+: 6H15/2 -- 6F11/2 transition in non-crystalline Ge-As-S alloys.
21 citations
TL;DR: In this article, a two-photon up-conversion process was proposed for the Tm 3+ : 1 G 4 → 3 H 6 (480 nm) transition from calcium aluminate glass codoped with Tm3+ /Nd 3+, where an excitation beam with a wavelength of 791 nm first excites Tm-3+ to the 3 H 4 level, and then absorbs the 1060 nm emission from Nd3+ : 4 F 3/2 → 4 I 11/2 to attain the 3H 4 level.
Abstract: Blue up-conversion fluorescence from the Tm 3+ : 1 G 4 → 3 H 6 (480 nm) transition has been observed from calcium aluminate glass codoped with Tm 3+ /Nd 3+ , The mechanism for the up-conversion process consists of a two-photon process. An excitation beam with a wavelength of 791 nm first excites Tm 3+ to the 3 H 4 level, where Tm 3+ again absorbs the 1060 nm emission from Nd 3+ : 4 F 3/2 → 4 I 11/2 to attain the Tm 3+ : 1 G 4 level. Lifetime and intensity variations with compositions suggest the presence of an efficient energy transfer from Nd 3+ to Tm 3+ , The highest 480 nm emission intensity has been obtained from the glass with 0.1 mol% of Nd 2 O 3 and 0.2 mol % of Tm 2 O 3 .
18 citations
TL;DR: In this article, the lifetime and emission intensity of Tm3+:3F4→Tb3+ glasses codoped with Tm 3+ and Tb 3+ ions were investigated.
Abstract: Emission properties and energy transfer of PbO–Bi2O3–Ga2O3–GeO2 glasses codoped with Tm3+ and Tb3+ ions were investigated. The 1.48-μm emission due to the Tm3+:3H4→3F4 transition can be used to amplify the S-band (1460–1530-nm) signal light. With Tb3+ addition, the lifetime and emission intensity of the Tm3+:3F4 level decreased sharply via the Tm3+:3F4→Tb3+:7F0,1,2 energy transfer. Population densities of the 3F4 and 3H4 levels in Tm3+ calculated from rate equations clearly verified that population inversion in Tm3+ ions became possible with as little as 0.1 mol% of Tb3+ addition.
9 citations