Spectroscopic properties of Ho3+-doped K-Sr-Al phosphate glasses

Trivalent holmium-doped K-Sr-Al phosphate glasses (P2O5-K2O-SrO-Al2O3-Ho2O3) were prepared, and their spectroscopic properties have been evaluated using absorption, emission, and excitation measurements. The Judd-Ofelt theory has been used to derive spectral intensities of various absorption bands from measured absorption spectrum of 1.0 mol% Ho2O3-doped K-Sr-Al phosphate glass. The Judd-Ofelt intensity parameters (Ωλ, x 10-20 cm2) have been determined of the order of Ω2 = 11.39, Ω4 = 3.59, and Ω6 = 2.92, which in turn used to derive radiative properties such as radiative transition probability, radiative lifetime, branching ratios, etc. for excited states of Ho3+ ions. The radiative lifetimes for the 5F4, 5S2, and 5F5 levels of Ho3+ ions are found to be 169, 296, and 317 μs, respectively. The stimulated emission cross-section for 2.05-μm emission was calculated by the McCumber theory and found to be 9.3 x 10-21 cm2. The wavelength-dependent gain coefficient with population inversion rate has been evaluated. The results obtained in the titled glasses are discussed systematically and compared with other Ho3+-doped systems to assess the possibility for visible and infrared device applications. (orig.)