Judd-Ofelt and spectroscopic analysis of erbium ions co-doped with samarium ions in phosphate glasses environment

The influence of Er3+ ions on the optical properties of phosphate glasses doped by a fixed concentration of Sm+3 ions had been investigated. Optical absorption studies were executed to estimate the energy gap and Urbach energy. Judd-Ofelt, J-O, model has been applied to the absorption peaks for Er3+ (4f(11)) transitions to determine the J-O intensity parameters ohm(t) (t = 2, 4, 6). Using the calculated J-O parameters, the radiative transition probabilities (A(r)), Branching ratios (B-r), and radiative lifetime (tau(r)) of various excited states of Er3+ ion have been calculated. The studied photoluminescence spectra under an ultraviolet excitation wavelength (380 nm) showed several visible emission bands confirming the down-conversion process. Energy transfer (ET) from S-4(3/2) (Er3+) to (4)G(5/2) (Sm+3) was affirmed. An intensive green emission peak due to S-4(3/2) -> I-4(15/2) transition had been observed with stimulated emission cross-section of 7 x 10(-21) cm(2).