Fig. 5.
(a) Reconstructed confocal scan of MLB emission filtered in the range of λ = 400-900 nm in air. (b) Upconverted emission power dependence for 3H4→3H6 and (1G4→3H6 + 1D2→3F4) Tm3+ transitions, showing two and three photon dependences, respectively, and characteristic power-dependent saturation at high powers. Blue emission waterfall spectra for excitation intensities of 1.1 × 103, 1.5 × 103, 1.8 × 103, 2.4 × 103, 3.2 × 103, 4.2 × 103, 6.5 × 103, 9.9 × 103 and 1.1 × 104 W/cm2 shown in (c) and 800 nm emission spectra for excitation intensities of 102, 1.3 × 102, 1.7 × 102, 2.1 × 102, 3.0 × 102, 3.8 × 102, 5.9 × 102, 8.9 × 102 and 103 W/cm2 shown in (d).