870 mW blue laser emission at 480 nm in a large core thulium doped ZBLAN fiber laser

Generation of Short Wavelength in Up-Conversion of Tm<sup>+3</sup> Doped Fluoride Glass and Its Application in Fiber Lasers

“…The UV fluorescence emission was gradually reduced to the noise level due to formation of color centers and existence of photo-degradation. Usually, this effect can be eliminated almost totally by circulating blue light or wavelength of 514 nm through the fiber core [2,6].…”

“…Based on our measured emission spectrum and time resolved spectroscopy we proposed the excitation mechanism as following: the first three excitation steps are assumed to occur as described in [6,7,11] . This will reduce the distance between Tm +3 ions resulting in efficient ETU processes and leading to a strong UV emissions [12,13].…”

“…The emitted UV fluorescence emissions did not affected potentially as presented in ref. [6] for fiber lasers. This mainly due to large pump area compared with fiber lasers.…”

“…Among rare earth (RE) ions, Tm +3 showed a versatile candidate that converts low-energy infrared photons to high-energy photons in the visible and ultraviolet spectral under up-conversion processes [5][6][7][8]. The first upconversion-pumped visible laser was demonstrated in a Tm +3 -doped ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN) fiber at 455 nm ( 1 D 2 → 3 F 4 ) and 480 nm ( 1 G 4 → 3 H 6 ) with additionally some UV fluorescence at 288 nm ( 1 I 6 → 3 H 6 ) [9].…”

2.31 [micro sign]m laser under up-conversion pumping at 1.064 [micro sign]m in Tm3+:ZBLAN fibre lasers

“…is the saturation power, hn p is the pump photon energy (1.9 × 10 219 J), A is the fibre area (706.5 mm 2 ), s p is the absorption cross-section (3.5 × 10 223 cm 2 [6]), and t is the lifetime of the level 3 H 4 (8.57 ms [7]). Substituting the appropriate value into (1) gives saturation power of about 4.4 W. …”