Gao Tang

Modified local environment and enhanced near-infrared luminescence of Sm3+ in chalcohalide glasses

Near-infrared luminescence properties of Sm3+ in Ge–Ga–Se and GeSe2–Ga2Se3–CsI glasses were studied and the local environments of Sm3+ were investigated. Strong 1.24 and 1.49μm fluorescence bands with respective bandwidths of 48 and 60nm were observed. About 540μs fluorescence lifetimes were obtained for the two emissions. As CsI was introduced to Ge–Ga–Se glasses, the luminescence properties were greatly enhanced, especially when I∕Ga ratio reaches 1. This enhancement can be attributed to decreased local phonon mode which dominates the multiphonon relaxation. The Sm3+-doped GeSe2-based chalcohalide glasses can be promising materials for optical fiber amplifiers operating at 1.22–1.28 and 1.46–1.53μm bands.

Near-infrared emission properties and energy transfer of Tm3+-doped and Tm3+/Dy3+-codoped chalcohalide glasses

Near-infrared emission properties of Tm3+ in GeSe2–Ga2Se3–CsI glasses were investigated. The increase in emission intensity ratio I1.47 μm/I1.22 μm and the large increase in the lifetime of the Tm3+:H34 level from 189 to 2480 μs can be obtained as CsI concentration changes from 20% to 40%. These improved emission properties result from the appearance of I-containing structural units, which have low phonon energy and are located near the Tm3+ ions, dominating the multiphonon relaxation and cross relaxation. Radiative parameters of Tm3+ were calculated based on the Judd–Ofelt analysis. The potential use of Tm3+-doped GeSe2–Ga2Se3–CsI glasses for S-band fiber amplifiers was discussed. Additionally, the intensity and lifetime of 1.2, 1.3, and 1.47 μm infrared fluorescence on Tm3+/Dy3+-codoped GeSe2–Ga2Se3–CsI glasses were studied, and the energy transfer mechanisms were discussed.

Design of semiconductor CdSe core ZnS∕CdS multishell quantum dots for multiphoton applications

Optical properties of colloidal II-VI semiconductor CdSe cores with ZnS and CdS multishell quantum dots (QDs) have been studied by experimental characterization and theoretical analysis. Due to the ...

Optical properties and local structure of Dy3+-doped chalcogenide and chalcohalide glasses

Abstract Dy 3+ -doped Ge-Ga-Se chalcogenide glasses and GeSe 2 -Ga 2 Se 3 -CsI chalcohalide glasses were prepared. The absorption, emission properties, and local structure of the glasses were investigated. When excited at 808 nm diode laser, intense 1.32 and 1.55 μm near-infrared luminescence were observed with full width at half maximum (FWHM) of about 90 and 50 nm, respectively. The lifetime of the 1.32 μm emission varied due to changes in the local structure surrounding Dy 3+ ions. The longest lifetime was over 2.5 ms, and the value was significantly higher than that in other Dy 3+ -doped glasses. Some other spectroscopic parameters were calculated by using Judd-Ofelt theory. Meanwhile, Ge-Ga-Se and GeSe 2 -Ga 2 Se 3 -CsI glasses showed good infrared transmittance. As a result, Dy 3+ -doped Ge-Ga-Se and GeSe 2 -Ga 2 Se 3 -CsI glasses were believed to be useful hosts for 1.3 μm optical fiber amplifier.

50GeSe2-25In2Se3-25CsI glass doped with Tm3+, Tm3+/Ho3+ and Tm3+/Er3+ for amplifiers working at 1.22 μm

Abstract Se-based chalcohalide glass of 50GeSe 2 -25In 2 Se 3 -25CsI was prepared. The thermal and optical characterizations revealed that this host was thermally and optically superior for practical applications. Strong emission centered at 1.22 μm was observed in all Tm 3+ single-doped, Tm 3+ /Ho 3+ and Tm 3+ /Er 3+ co-doped samples with an excitation of 808 nm wavelength. The emission was attributed to the Tm 3+ : 3 H 5 → 3 H 6 transition. The co-doping of Ho 3+ or Er 3+ largely broadened the width and slightly strengthened the intensity of the 1.22 μm emission. The possible energy transfer processes and luminescence kinetics were figured. In addition, its potential application as the host material for novel optical amplifiers was discussed.

Tm3+-Doped Chalcohalide Glass for Optical Amplifiers at 1.22 and 1.47 µm

50GeSe2–25In2Se3–25CsI chalcohalide glass was prepared with the addition of Tm3+ in 0.1–1.0 wt % concentrations. Radiative parameters evaluated by the Judd–Ofelt analysis suggest a strong covalence nature of the host. Emissions peak at 1.22 and 1.46 µm were observed with the 808 nm laser excitation. The 1.22 µm one is attributed to the Tm3+:3H5→3H6 transition. The Raman spectra of the host suggest that the I-rich local environment of Tm3+ promotes the strong 1.22 µm emission. The emission intensity comes to the maximum at Tm3+ concentration of 0.7 and 0.5 wt % for the 1.22 and 1.47 µm emissions respectively. In addition, its potential application as the host material for novel optical amplifiers was discussed.