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Abstract: Spectroscopic characterization for optical amplification and laser application of the Er3+-doped Bi4Si3O12 glass is performed through its absorption and luminescence spectra. The spontaneous radiative transition probabilities from the first seven excited states to the ending states are calculated to obtain the luminescence branching ratios and radiative lifetimes. Intense infrared to visible luminescence of the Er3+ ion is observed with 4I9/2 state excitation (800nm) under a 200mW laser excitation power. The value obtained for the ratio of the 4I11/2 → 4F7/2 excited-state absorption oscillator strength to the 4I15/2 → 4I11/2 ground state absorption oscillator strength is in accordance with those reported for Er3+-doped materials pumped efficiently at 4I11/2 level excitation wavelengths. Gain cross-section spectra as a function of the inverted population rate and the stimulated emission cross-section spectrum were determined for the 4I13/2 → 4I15/2 infrared (IR) laser transition. The large gain bandwidth of the 4I13/2 → 4I15/2 IR emission has resulted in being close to those reported for Er3+-doped oxide glasses suitable for broadband amplifiers. [Copyright &y& Elsevier]

Abstract: Optical absorption and emission spectra of Ho3+ doped alkali, mixed alkali and calcium phosphate glasses of the type (69.5NH4H2PO4·15Na2HPO4)·15R2CO3 (R=Li, Na and K), (69.5NH4H2PO4·15Na2HPO4)·7.5Li2CO3·7.5R2CO3 (R=Na and K), (69.5NH4H2PO4·15Na2HPO4)·7.5Na2CO3·7.5K2CO3 and (69.5NH4H2PO4·15Na2HPO4)·15CaCO3 have been studied. Variation of Judd–Ofelt intensity of parameters (Ωλ ), peak wavelengths of the hypersensitive transitions (λp ), radiative transition probabilities (A rad) and peak emission cross-sections (σp ) with the variation of alkalis, mixed alkalis and calcium in the phosphate glass matrix has been studied. The shift in peak wavelength of the hypersensitive transition and Judd–Ofelt intensity parameter (Ω 2) are correlated with the structural changes in the host matrix. Radiative lifetimes (τR ) are estimated for certain excited states of Ho3+ in these glass matrices. From the luminescence spectra, the emission cross-sections (σp ) are evaluated for the two emission transitions of Ho3+ ion. Variation of luminescence intensities of the two transitions, absorption and emission cross-sections with the variation of alkalies, mixed alkalies and calcium in the above phosphate glass systems has been studied. [Copyright &y& Elsevier]