Pump-efficient flattop O+E-bands bismuth-doped fiber amplifier with 116 nm –3 dB gain bandwidth
Yan Ososkov, Aleksandr Khegai, Sergei Firstov, Konstantin Riumkin, Sergey Alyshev, Alexander Kharakhordin, Alexey Lobanov, Alexey Guryanov, Mikhail Melkumov
Abstract
We report on a new record in the field of broadband BDFA in the O+E spectral range. Using only 250 mW single wavelength pump at 1256 nm and a low-OH bismuth-doped fiber containing two types of bismuth active centers, we achieved >23 dB gain from 1325 nm to 1441 nm with flatness <3 dB and a NF of <6.8 dB. Three different pump wavelengths were considered: 1230, 1256, 1270 nm. Pumping at the shortest wavelength enabled wider gain bandwidth – 125 nm but required pump power up to ∼620 mW, whereas the longest one provided higher pump efficiency but narrower gain bandwidth. We also studied multiple wavelength amplification effects in the BDFA to reveal potential problems with simultaneous broadband signal amplification in such amplifiers.