Blue luminescence in Tm3+-doped KGd(WO4)2 single crystals

On the influence of dopant ions on blue emission in kgw crystal excited by infrared laser radiation

“…In our opinion, the comparison of the shapes of the calculated and experimental luminescence bands indicated that the blue emission observed in Nd:KGW could not be due to Tm 3+ ions. Moreover, the hypothesis was confirmed by studying blue luminescence of Tm:KGW [5], according to which the 1 G 4 multiplet is populated more efficiently by the radiationless transition from the higher energy multiplet F 4 ) would then be observed (Fig. 2b).…”

Thulium doped monoclinic KLu(WO4)2 single crystals: growth and spectroscopy

“…It is clear that the average Tm-Tm distance in the lowest doped samples is too large in comparison to the critical distance where the cross relaxation phenomena take place, namely ≈ 1.3 nm, therefore energy transfer does not occur and the decays can be expected to be a single exponential as it is indeed found. The average Tm-Tm distance decreases with increasing Tm concentration and it falls into the range where cross relaxation phenom- [Tm 3+ ] N × 10 20 (cm −3 )r (nm) R C (nm) Therefore, at higher thulium concentrations the quenching phenomenon takes place because the Tm-Tm distances decrease and this favors the cross-relaxation mechanisms [34][35][36]. Table 7 summarizes the decay time studied, the luminescence quantum efficiency η (η = τ/τ rad ) and the cross relaxation rates W E , by W E = 1/τ − 1/τ rad (assuming multiphonon decay did not act as a depopulation mechanism) [37].…”

Efficient tunable laser operation of Tm:KGd(WO/sub 4/)/sub 2/ in the continuous-wave regime at room temperature

“…It was only recently that the spectroscopic properties relevant to laser operation were studied for flux grown Tm:KGdW by a part of the present authors [18], [19], [25] and also by others [20], [26]. While in [20], [26] only unpolarized spectra were presented, the systematic studies in [19] and [25] were performed in the orthogonal frame of the optical indicatrix.…”