Core-pumped high-power flattened L-band fiber superfluorescent sources

To demonstrate high-power, broad-bandwidth and spectrum-flattened L-band erbium-doped fiber superfluorescent source (SFS), four different corepumped dual-stage double-pass configurations were proposed based on polarization multiplexing technique, offering Walt-level pump power. The impact of the pumping ratio and fiber length arrangement on the spectrum characteristics including flatness, bandwidth, center wavelength and total output power were numerically investigated with the same total length and total pump power. It shows that four structures can basically work at L band（1 565 nm~1 610 nm） and the bandwidth is less sensitive to structure change. Only the backward-pumped dual-stage double-pass configuration can simultaneously provide high flatness and high output power. A SFS with 314 mW output power, 32.41 nm bandwidth, 1 584.84 nm center wavelength and 2.23 dB flatness can be demonstrated while the total pump power and the pump powers of the first and second stages are 750 mW,300 mW and 450 mW，respectively, and the total fiber length, the fiber lengths of the first and second stages are 21 m,18 m and 3 m，respectively.