Effects of cryogenic cooling on the spectral luminescence of BACs in bismuth-doped aluminosilicate fiber

The results of liquid nitrogen cooling (LNT, 77 K) on the spectral properties of bismuth-doped aluminosilicate fibers (BDFs) have been presented under varying pump wavelengths. It is revealed that the spectral luminescence of bismuth active centers (BACs) is mildly affected upon excitation at 405, 532, and 980 nm at LNT, whereas notable luminescence enhancement (∼1.3 times) is observed in the range of 1100-1350 nm (BACs-Al) under 830 nm pumping. The experimental data on the luminescence shape and kinetics of BACs-Al have been obtained at both room temperature (RT) and LNT with varied pumping powers. It is revealed that the enhanced luminescence is caused by the steep rise of emission around 1300 nm (denoted as BAC-Al (II)), which is more efficiently stimulated at a lower temperature. The key laser parameters of BACs have also been evaluated at both RT and LNT. The obtained results may shed some light on the NIR-emitting nature of BACs, and provide a promising strategy for tuning the spectral NIR luminescence scheme of BDFs.