Gain Control in Multi-Core Erbium-Doped Fiber Amplifier With Cladding and Core Hybrid Pumping

This paper investigates gain controllability of cladding- and core-pumping hybrid-pumped single-stage and double-stage multi-core (MC) erbium-doped amplifiers (EDFAs) for changes in the input signal power per channel and number of channels. During the gain control, the core-pumping power is adjusted, whereas the cladding-pumping power is kept constant. Static characteristics are experimentally measured, and both kinds of hybrid-pumped MC-EDFAs are gain controlled with a small gain change for both the input signal changes. Dynamic characteristics are investigated by calculating the gain transient response of a surviving channel of the gain-controlled hybrid-pumped MC-EDFAs for signal channel dropping, and the response characteristics are compared with those of reference EDFAs whose erbium-doped fiber (EDF) has the same core parameters as those of EDF used in a conventional practical EDFA. It is shown that there is no significant difference in dynamic gain controllability between the hybrid-pumped MC-EDFAs and reference EDFAs even though the cladding-pumping power is not adjusted and kept constant. The results for the static and dynamic gain control characteristics suggest that constant cladding-pump power has little impact on gain controllability of the hybrid-pumped MC-EDFAs.