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Energy transfers from Er3+ to Ce3+ in tellurite and sulfide glasses were examined under excitation.

Ge-As-Ga-S glasses doped with Tm3+ or Tm3+/Tb were studied for emission properties and electron population densities.

Heavy metal oxide glasses containing GeO[SUB2] were investigated as potential hosts for 1.48 μm fiber-optic amplifiers because of their low phonon energy. Addition of ⩾ 10 mol % GeO[SUB2] to 0.57PbO-0.25Bi[SUB2]O[SUB3] - 0.18Ga[SUB2]O[SUB3] (mole fraction) glass provided thermal stability as well as good emission properties. The optimum glass composition for 1.48 mm amplifiers, considering lifetimes and population of the Tm[SUB3+]:[SUP3]H[SUB4] level, was 0.8 (0.57PbO-0.25Bi[SUB2]O[SUB3] - (0.18Ga[SUB2]O[SUB3] - 0.2GeO[SUB2] (mole fraction). As the concentration of codoped Ho[SUP3+] exceeded 0.2 mol %, the population density of the Tm[SUP3+]:[SUP3]H[SUB4] level decreased sharply and the population inversion between the [SUP3]H[SUB4] and [SUP3]F[SUB4] levels in Tm[SUP3+] was achieved. [ABSTRACT FROM AUTHOR]

Low-temperature midinfrared emission properties of Pr[sup 3+]-doped Ge[sub 30]Ga[sub 2]As[sub 6]S[sub 62] and Ge[sub 28]Ga[sub 5]As[sub 12]Se[sub 55] glasses (at. %) were investigated. Emissions centered at 3400 and 4700 nm were clearly observed from sulfide and selenide glasses, respectively, when the specimens were cooled to 20 K. The measured lifetime of the [sup 1]G[sub 4] level in sulfide glass increased from 320 μs at room temperature to 400 μs at 20 K. The intensity and quantum efficiency of the emission from the Pr[sup 3+]:([sup 3]F[sub 3], [sup 3]F[sub 4]) level in selenide glass also increased as the temperature decreased to 120 K. The enhancement resulted from a decrease in nonradiative multiphonon relaxation at low temperatures. The temperature dependence of the multiphonon relaxation rates indicated that the asymmetrical stretching vibration of GeS[sub 4] tetrahedra (375 cm-1) is primarily responsible for the multiphonon relaxation process in sulfide glass. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spectroscopic properties and room-temperature persistent spectral hole burning mechanisms of Eu[sup 3+] -doped borate glasses were investigated. The depth of the burnt hole increased K. The photoreduction of Eu[sup 3+] to Eu[sup 2+] is a primary mechanism of hole burning and this hypothesis was supported by spectral hole properties, relaxation properties as well as changes in the local structure of Eu[sup 3+] in glasses. [ABSTRACT FROM AUTHOR]

Ge-As-Ga-S glasses codoped with Er[sup 3+] and Pr[sup 3+] were synthesized for fiber-optic amplifiers operating in both 1.3 and 1.5 µm communication windows. The energy transfer between Er[sup 3+] and Pr[sup 3+] in Ge-As-Ga-S glasses was analyzed quantitatively using rate equations. The energy transfer coefficients responsible for two different energy transfer routes were 2.2(±0.05)x10[sup -18] (Er[sup 3+]:[sup 4]I[sub 1 1/2]→Pr[sup 3+]:[sup 1]G[sub 4]) and 5.6(± 0.05) x 10[sup -17] s[sup -1] cm³ (Er[sup 3+]:[sup 4]I[sub 13/2]→Pr[sup 3+]:[sup 3]F[sub 4,3]), respectively. The former transfer process enhanced amplification efficiency in 1.3 µm band, while the latter reduced efficiency in the 1.5 µm band. Numerical simulation of the amplification characteristics demonstrated that signal gains of 30 and 40 dB were possible in 1.3 and 1.5 µm bands, respectively. [ABSTRACT FROM AUTHOR]

Efficient persistent spectral hole burning in Eu[sup 3+]-doped sulfide glasses was observed with the addition of CsBr or KBr. Holes in these glasses showed high initial growth rates, thermal barrier heights, and low relaxation rates. It was also possible to form independent multiholes on the inhomogeneously broadened absorption spectrum. One-photon absorption of the burning light and corresponding reduction of Eu[sup 3+] into Eu[sup 2+] via interaction with local conduction (or charge transfer) bands are the main processes for hole burning. [ABSTRACT FROM AUTHOR]

Reports on the effects of Tb(sup 3+) addition on the population inversion between the (sup 3)H(sub 4) level and (sup 3)F(sub 4) levels in Tm(sup3+). Requirement for the realization of a strong laser action and amplification at 1480 nanometer; Analysis of energy transfer and the population dynamics among the excited levels in Tm(sup 3+).

Mechanisms of cross relaxation in Tm3+ ions doped into PbO- Bi2O3- Ga2O3- GeO2 glass were analyzed. The findings state that despite a small overlap between the emission (3H4- 3F4) and the absobtion (3H6- 3F4) spectra, cross relaxation is mostly governed by a phonon-assisted energy transfer.