Energy transfer coefficients in thulium-doped silica fibers

Abstract

Energy transfer coefficients in thulium-doped silica fibers are key parameters for a reliable numerical modeling and optimization of high-power fiber lasers pumped at 790 nm and emitting around eye-safer wavelength of 2 µm. We report on determination of the energy transfer coefficients by comparing experimental values and rate-equation-based modeling of thulium fluorescence decays. The study was performed using two pump, 792 nm and 1620 nm, and two signal, 800 nm and 2 µm, wavelengths. The following values were obtained k3011 = (1.9 ± 0.2) × 10−22 m3s-1, k1130 = (1.4 ± 0.2) × 10−23 m3s-1 and k1120 = (3.5 ± 0.1) × 10−23 m3s-1. To the best of our knowledge, this study involves so far the most comprehensive comparison of various fluorescence decays in terms of excitation and detection wavelengths as well as excitation powers.