Broaden the bismuth-doped fiber amplifier with a gain bandwidth > dB to 170 nm in a two-stage configuration

We present a two-stage bismuth-doped fiber amplifier (BDFA) that achieves ultra-broadband amplification from 1280 to 1480 nm. The two-stage BDFA is designed to limit the reabsorption of bismuth-doped silica fiber (BDSF) by high-power pumps pulled fluorescence. A peak gain of 37.9 dB was obtained at 1340 nm for a −23 dBm input signal, with >23 dB gain from 1300 to 1470 nm. Furthermore, the gain of 40.0 and 36.1 dB was measured at small signal power for 1340 and 1430 nm, respectively, and the 3 dB saturation output power reaches 16.0 and 14.6 dBm, respectively. In addition, the basic properties and luminescence characteristic of two types of BDSFs fabricated using atomic layer deposition and modified chemical vapor deposition technique worked in the configuration were investigated.