Influence of Er3+ ions on structural and fluorescence properties of SiO2-B2O3- Na2Co3-NaF-CaF2 glasses for broadband 1.53 mu m optical amplifier applications

摘要

The oxyfluoroborosilicate (SiO2-B2O3- Na2Co3-NaF-CaF2) glasses activated with varied concentrations of trivalent Erbium ions have been prepared by using conventional melt quenching method. The structural, optical and luminescence properties were examined with X-ray diffraction, X-ray Photoelectron, Fourier Transform Infrared, Optical absorption, fluorescence emission spectra and lifetime decay analysis. From the absorption spectra of the prepared glasses, oscillatory strength of each band was calculated and evaluated the bonding parameters (13, 8) values. Judd-Ofelt theory had been used to determine the spectral intensity parameters (Omega(lambda) = 2,4 and 6) and some important radiative parameters like total radiative transition probability (A(T)), radiative lifetime (tau(R)) and radiative branching ratios were also calculated for 4I(15/2) -> 4I(13/2) transition. Optical band gap energy (E-opt) estimated/determined for direct and indirect allowed transitions. From the NIR emission spectra, 0.5 mol% Erbium ions activated glass possesses maximum intensity for 4I(13/2) -> I-4(15/2) transition and evaluated the stimulated emission cross-section (sigma(emi)) (9.47 x 10(-21) cm(2)), Gain bandwidth parameter (sigma(emi) x Delta lambda(eff)) (0.823 x 10(-25) cm(3)) and gain per unit length (sigma(emi) x tau(mes)) (51.65 x 10(-25) cm(2)s) for this prepared glass and compared with other reported glasses. Using Mc Cumber theory, sigma(emi) was calculated for I-4(13/2) -> I-4(15/2) transition from the absorption spectrum of 0.5 mol% Er3+ ions doped glass. The lifetime (tau(m)) of I-4(13/2) level was decreased from 6.94, 6.61, 5346, 5.44 and 2.74 ms with the increase in Erbium ions concentrations from 0.05, 0.1, 0.5, 1.0 and 2.0 mol% respectively. This decrease may be due to concentration quenching effect. The high values of (sigma(emi)) (9.47 x 10(-21) cm(2)), (sigma(emi) x Delta lambda(eff)) (0.823 x 10(-25) cm(3)) and tau(m) (5.45 ms) for 0.5 mol% of Er3+ ions activated oxyfluoroborosilicate glass suggesting that the glasses could be used as potential candidate for 1.53 tm optical amplifier applications.