Gain cross-sections of transparent oxyfluoride glass–ceramics single-doped with Ho3+ (at 2.0 μm) and with Tm3+ (at 1.8 μm)

We have developed transparent 3.5 mol% Ho3+ and Tm3+ single-doped oxyfluoride glass–ceramics, where a large fraction of dopant ions is segregated into PbF2-based nano-crystals. The absorption and emission cross-sections corresponding to the 5I7 ↔ 5I8 transitions of the Ho3+ (at 2.0 μm), and to the 3H6 ↔ 3F4 transitions of the Tm3+ (at 1.8 μm), have been obtained and respective gain cross-section spectra have been computed as a function of population inversion. For Ho3+-doped samples, the maximum gain cross-section increased by 20% on ceramming of the precursor glass and reached, for the ensuing glass–ceramics, a value 1.5 times higher than that reported for fluoride glasses. The maximum gain cross-section for Tm3+-doped samples increased 2.5 times on ceramming of the precursor glasses and reached for the ensuing glass–ceramics a value 2–3 times higher than for other fluoride hosts, such as ZBLAN glass, and 1.5 times higher than for silicate and germanate glass hosts. Hence, these Ho3+- and Tm3+-doped glass–ceramics have an advantage for application in planar and fibre lasers/amplifiers at about 2.0, and 1.8 μm, respectively.