Yb-free, SLM EDFA: comparison of 980-, 1470- and 1530-nm excitation for the core- and clad-pumping

We present the results of the experimental study and comparison of Yb-free, Erdoped, all-fiber, alignment free, single frequency (SF) fiber amplifiers operating under 980-, 1470and 1530-nm pumping for the coreand clad-pumping architectures. In the single-mode core-pumped configuration Er-doped fiber amplifiers demonstrated 52% and 60% pump to output efficiencies for 980 and 1480 nm pump wavelength, respectively, producing over 140 mW of SF output power at seed wavelength ~1560 nm and over 180 mW at seed wavelength 1605 nm for 300 mW of pump power. At the same time, when clad pumped, Er-doped 20/125 DC LMA gain fiber demonstrates laser efficiencies of 22.4% pumped at 980 nm up to 20 W of fiber-coupled diode laser pumping. The same LMA fiber demonstrates 33% optical-to-optical efficiency (46% slope efficiency versus absorbed power) when cladding-pumped with 1520-1530-nm fiber–coupled laser diode modules. Detailed analysis of these experiments is presented.