Quenching dynamics in highly doped erbium fiber core-pumping, amplifier configuration

This study examines the influence of quenching dynamics on the efficiency of erbium-doped fiber amplifiers (EDFAs) with high erbium-ion (E3+-ions) doping concentrations, comparing pulsed and continuous wave core-pumping methods. Our findings indicate that quenching, driven by energy transfer upconversion, substantially impacts signal gain in these fibers. The core-pumping configuration demonstrated significantly higher gain per unit length than both low-doping EDFAs and cladding-pumping systems, with effective energy storage achievable through short pump pulses to reduce concentration quenching effects. The highly doped homemade fiber (fiber under test - FUT No. 3) achieved a gain per unit length exceeding 8.4 dB/m, outperforming the lower doped commercial fiber (FUT No. 4) by a factor of 6.4, although FUT No. 4 displayed better compatibility with the core-pumping system. Additionally, the highest gain per unit length for a counter-directional, cladding-pumped amplifier configuration with a high-concentration fiber was recorded at 5.9 dB/m at a 1560 nm signal wavelength with a 2 μs pulse duration, positioning FUT No. 3 as a highly efficient option for high-gain applications despite its high doping concentration. Our experimental analysis of quenching dynamics not only highlights an approach for scaling pulse energy using shorter fiber lengths to mitigate nonlinear effects but also provides valuable insights into quenching-influenced gain behavior in pulsed fiber amplifier systems.