Spectroscopic properties of Tm 3+ optical centers at the 3 F 4 – 3 H 6 2-μm laser transition in BaF 2 crystal

Spectroscopic properties of long-lifetime Tm3+optical centers in Ca–Sr–Ba fluorides in the form of single crystals and ceramics at the1G4–3H5magnetic dipole allowed transition

“…To simplify the measurements, low-temperature fluorescence spectra were measured at both the electric and magnetic dipole allowed 1 G 4 -3 H 5 transition. As was shown in [10], an additional magnetic dipole contribution to the transition probability results in a CaF 2 crystal of only ~1.5 times difference in fluorescence lifetime of regular (2 ms) and long-lifetime (2.9 ms) Tm 3+ optical centers.…”

“…First, the increase in the unit cell size in the Ca(5.46 Å)-Sr(5.79 Å)-Ba(6.26 Å) [14] row, which results in both lowering of the local crystal field strength and longer distance to interstitial fluorine leading to a decrease in the electric dipole transition probability. This can be proved by an increase in the measured long-lifetime center fluorescence lifetime at the pure electric dipole two-micron 3 F 4 -3 H 6 transition from 140 ms in CaF 2 [13] to 230 ms in BaF 2 [10]. Second, the probability of the formation of tetragonal type optical centers in the Ca-Sr-Ba row is also different.…”

“…As was suggested in [9], individual cubic and trigonal local symmetry optical centers prevail in SrF 2 and BaF 2 crystals, together with clustered optical centers. Therefore, in [10], Tm 3+ long-lifetime optical centers with a tetragonal local symmetry were suggested to form in BaF 2 crystal, but their properties were shown to differ from those observed for regular tetragonal optical centers in CaF 2 . In this work, we try to compare the spectroscopic properties of these longlifetime tetragonal local symmetry Tm 3+ optical centers in the sequence of Ca-Sr-Ba fluorides and demonstrate that some additional modifications of these optical centers are possible in hot-formed ceramics compared to single crystals.…”