Ultraviolet emission excitation in RE 3+ activated fluoride fibers

Abstract

Short-wavelength (∼280–410 nm) fluorescence in Er 3+, Tm 3+, Nd 3+ and Ho 3+ doped ZBLAN glasses was studied experimentally and attributed to transitions from the 2P 3/2, 1I 6 and 1D 2, 4D 3/2, 3D 3 states, respectively. Properties of these high-lying metastable levels, such as state energies, transition wavelengths, lifetimes, emission branching ratios and cross-sections, which are important for laser action analysis, were determined. In particular, up-conversion UV emission excitation schemes for Nd 3+ and Ho 3+ doped ZBLAN were studied experimentally and modeled by time dependent rate equations. Violet and ultraviolet laser operation in Nd 3+ and Ho 3+ doped ZBLAN fibers under up-conversion pumping was studied theoretically basing on measured spectroscopic parameters.