Absorption and emission properties of thulium doped glasses in optical fibers

Optical properties of Tm-doped fibers based on different host glass materials, silica and yttrium-aluminum-garnet (YAG), prepared with different technologies, are studied. We show that crystal-derived fibers offer a wider range of core compositions compared to silica fibers prepared by the modified chemical vapor deposition method in combination with solution doping and provide the possibility to tune optical properties towards new applications. Absorption and emission behavior, including absorption cross-sections, fluorescence intensities, and lifetimes of the 3F4 and 3H4 energy levels, are investigated in the wavelength range from 190 nm to 2150 nm and concentration range from 0.08 mol% up to 1.52 mol% Tm2O3. For a YAG-derived fiber, a new record for silica-based Tm fibers was set with the measured lifetime of the 3H4 transition of 63 µs at a Tm concentration of 0.23 mol% Tm2O3, which provides access to new laser transitions in Tm. As a result of these investigations, an energy level scheme with all observed absorption and emission transitions is presented.