Pump and Signal Optimization in Thulium doped fiber amplifiers for S-Band with Amplified Spontaneous Emission and Ion-Ion Interactions

Thulium-doped fiber amplifiers (TDFAs) communicating in S and near-C bands (1460 nm to 1535 nm) can be a potential and effective solution to the existing and narrow C-band (1550 nm) Erbium-doped fiber amplifiers (EDFAs). However, to establish TDFAs in the existing fiber-optic communication system, its performance concerning the optical conversion efficiency has to be optimized. Therefore, this paper focus on the parametric and schematic optimization of TDFAs. The pump schematic with its respective optical power and the signal wavelength have been optimized in this work considering the amplified spontaneous emissions (ASE) at 800 nm and 1800 nm. Additionally, the constructive effects of ion-ion interaction mechanism (IM) involving homogeneous up-conversion (HUC) and pair-induced quenching (PIQ) on the TDFA's gain and noise figure (NF) characteristics have been analyzed. The findings of early population inversion (at 680 mW instead of 700 mW and at 160 mW instead of 300 mW respectively) are owing to IM effects. The increment of 94.57 % in signal gain and 8.43% decrease in NF for the bidirectional pumping scheme has been obtained for the calculated signal wavelength of 1466 nm. Also, a comprehensive simulation analysis has been carried out on comparative forward and backward pumping schemes with the optimum bidirectional pumping scheme.