Site-selective spectroscopy ofTm3+centers inCaF2

Refined analysis of the luminescent centers in the Yb3+:CaF2 laser crystal

“…Our positions of the Stark levels of the ground multiplet 2 F 7/2 , however, greatly differ. These positions were almost perfectly reproduced by our crystal field calculations knowing that the corresponding parameters were directly obtained from those derived in the case of Tm 3+ [6], by introducing between the respective parameters the multiplication factors a k such as B kq ðYb 3þ Þ ¼ a k B kq ðTm 3þ Þ and a k ¼ r k ðYb 3þ Þ=r k ðTm 3þ Þ ¼ 1.009, 0.9716, 0.9451 for k ¼ 2; 4; 6, respectively [7]. It was found B 20 ¼ 578 cm À1 , …”

“…3 the excitation and emission spectra associated with the excited-state fluorescence lifetime of 2.1 ms which led to the Stark energy levels the closest to those derived theoretically by using the same procedure as above, i.e. by starting with the crystal field parameters found for Tm 3+ in a C 3v site symmetry [6]. These derived parameters are B 20 ¼ 233 cm À1 , B 40 ¼ 342 cm À1 , B 60 ¼ 137 cm À1 , B 43 ¼ À199 cm À1 and B 63 ¼ À703 cm À1 .…”

Influence of Tm3+ optical centers on spectroscopic properties at the 3F4–3H6 2-μm laser transition

“…1, two lines attributed to tetragonal (C 4v ) -1189 nm and 1198 nm and one line attributed to cubic (O h ) -1186 nm Tm 3 þ optical centers are marked according to Ref. [7]. As is seen, additional longwavelength (1210 nm) absorption lines assigned in Ref.…”

“…1. This absorption transition was chosen as the only one magnetic dipole allowed ground state absorption transition of cubic-symmetry (O h ) optical centers of Tm 3 þ [7]. In Fig.…”

“…Calcium fluoride doped with Tm 3 þ ions is one of the most studied simple fluorides [6][7][8][9]. The interest to this material arises from its good thermo-mechanical properties and efficient formation of clustered Tm 3 þ optical centers with efficient crossrelaxation between neighboring Tm 3 þ ions in clusters, which results in a 200% quantum efficiency of the 3 F 4 upper 2 μm laser level excitation under 790-nm laser diode pumping.…”