Optical characterization, luminescence properties of Er~(3+) and Er~(3+)/Yb~(3+) co-doped tellurite glasses for broadband amplification

摘要

In the present paper, optical absorption and emission spectra and luminescence decay lifetimes of different concentrations, 0.1, 0.3, 0.5, 0.7 and 1.0 mol% of Er~(3+) and 0.1Er~(3+)/0.5Yb~(3+) co-doped tellurite glasses (TeO_2-Bi_2O_3-ZnO-Nb_2O_5) were reported. Judd-Ofelt intensity parameters were determined and used to calculate spontaneous radiative transition probabilities (A_(rad)), radiative lifetimes (τ_R), branching ratios (P) and stimulated emission cross-sections (σ_P) for certain emission transitions. NIR emission at 1.5μm and up-conversion spectra of Er~(3+) and Er~(3+)Ab~(3+) co-doped tellurite glasses were measured under excitation wavelength of 980 nm. The absorption, emission and gain cross-sections for ~4I_(13/2)→~4I_(15/2) transition of Er~(3+) are determined. The peak emission cross-section of this transition is found to be higher (9.95×10~(-21) cm~2) for 0.1 mol% of Er~(3+) and lower (6.81×10~(-21) cm~2) for 1.0 mol% of Er~(3+) doped tellurite glasses, which is comparable to other oxide glasses. The larger peak emission cross-section for lower concentration of Er~(3+) is due to the high refractive index of glass matrix (2.1547), relation established from Judd-Ofelt theory. The observed full-widths at half maxima (FWHM) for lower and higher concentrations of Er~(3+) are 64nm and 96 ran respectively. The larger values of FWHM and peak emission cross-sections are potentially useful for optical amplification processes in the design of Erbium doped fiber amplifiers (EDFs). Under 980 nm excitation three strong up-conversion bands were observed at 530nm, 546nm and 665nm. The pump power dependent intensities and mechanisms involved in the up-conversion process have been studied. The luminescence decay profiles for ~4I_(13/2) level were reported for all glass matrices.