Low-noise operation of fluoride-based erbium-doped fiber amplifiers with (4)I(11/2)-level pumping

The low-noise operation of fluoride-based erbium-doped fiber amplifiers (EDFA's) is demonstrated with (4)I(11/2)-level pumping for what we believe to be the first time. A noise figure as low as 3.5 +/- 0.5 dB at 1550 nm is achieved by means of 970-nm pumping. It is shown that it is possible to construct fluoride-based EDFA's with a noise figure as low as that of silica-based EDFA's.