Abstract

Fiber amplifiers operating in the L-band can benefit from further extending their gain bandwidth and improving overall operation costs. This work addresses both aspects through an optimization of the host matrix using phosphorus/aluminum (P/Al) as glass modifier and secondly through the use of yttrium as an alternative co-dopant to ytterbium. Fiber samples were fabricated using the modified chemical vapor deposition (MCVD) and solution doping technique. Using a maximum amount of phosphorus consistent with a flat refractive index profile, we find the optimum alumino-phospho-silicate glass matrix. The achieved amplifier exhibits a large gain amplification ranging from 15 to 25 dB, with its peak gain occurring at 1610 nm when pumped with a total power of 1.4 W at 978 nm. The maximum noise figure was 6.3 dB, while the gain ripple within the wavelength range of 1575 to 1626 nm was 76%. Moreover, we have obtained a low level of pair-induced quenching (<3%) using Y rather than Yb as a de-clustering agent for Er³⁺ concentration of 1.2 ×10²⁵ m⁻³. The result provides a viable solution to the 980 nm pumping scheme in a quest to achieve cost-effective and low-noise L-band EDFAs.