NIR performance comparison of Bi/Er and Yb/Er co-doped fibres as pumped at 808 nm and 830 nm

State-of-the-art optical fiber communication system reaches to transmission capacity from tens to hundreds of Tb/s. The massive capacity crunch has sparked concerns regarding available bandwidth and constantly increasing optical data traffic. Certainly, one way is to broaden the spectral transmission range beyond the narrow gain band of current erbium doped fiber amplifier (EDFA). Either side of Erbium across low-loss transmission window (1.5μm) shown promising results with optical fibres codoped with rare-earth-doped materials such as bismuth/thulium. Hence, it is of crucial importance to develop broadband optical amplifier to fully utilize the uncovered spectral regions with proper choice of pump wavelength(s)/Laser diodes. Here we have compared the performances of Bismuth/Erbium and Ytterbium/Erbium co-doped fibres as pumped to 808nm to one as pumped at 830nm. The pumping excitation conditions and spectral characteristics in BEDF and EYDF are explored to maximize the lasing efficiency. Using equivalent conditions and same section of Bi/Er codoped fiber, an enhanced broadband emission with FWHM ~ 149 nm is observed in Bi active centers (BAC) related to Si around ~1420nm under 808nm excitation as compared to 830nm with its FWHM ~ 125nm at an input power of ~ 55.5 mW. At maximum power, under 808nm pumping, a well-known peak emission of Er3+ at 1536nm noticeably increased due to reabsorption of BAC-Si (~1420nn) with the ratio ~ 1.7 between Er3+ and BAC-Si emission peaks. On the contrary, emission peak of the BAC-Si revealed higher with the ratio of ~ 1.5 than that of Er3+ by 830nm pumping. Afterward, we observed Yb3+ emission at 1040nm and 980 nm using Yb/Er codoped fiber with both pumps at same power. Using 808nm pumping, an extended emission band around ~ 1230 nm appeared namely BAC-Al while the other emission bands associated with BAC-Si (~ 1480nm) and Er3+ (~1536nm) shown similar emission bands with high emission peaks compared to 830nm pump at equivalent pump powers. Furthermore, the emission peak of the BAC-Si is about the same level as that of Er3+ with ratio of RBi/Er~ 1.1 under 808nm pumping while 830 nm pump showed the ~ 5.25 ratio between the emission peaks of BAC-Si and Er3+. We believe that this side-by-side comparison of two pumps and two home-made fabricated codoped fibres could be useful as a promising strategy for the next-generation WDM passive optical networks employing single broadband amplifier and tunable fiber laser covering 1000-1800nm telecommunication bands.