Bi-doped fiber amplifier with a flat gain of 25dB operating in the wavelength band 1320-1360nm

Bismuth (Bi) -doped phosphosilicate fibers have been fabricated by the modified chemical vapor deposition (MCVD) -solution doping technique under different process conditions. The influence of fabrication conditions on unsaturable loss in fibers has been investigated. Pump wavelength dependent Bi gain has been studied to obtain a flat gain over a wide bandwidth. A diode pumped all-fiber Bi-doped amplifier with a flat gain of 25 ± 1dB from 1320-1360nm (40nm) has been demonstrated for -10 dBm of input signal power with a noise figure (NF) ranging from 4–6 dB. Moreover, a small signal gain of 29 dB and a NF of 4.5dB at 1340 nm have been achieved for an input signal power of -30dBm