High-power all-fiber superfluorescent source with fused angle-polished side-pumping configuration

We report high-power operation of a broadband superfluorescent source with an all-fiber configuration. The superfluorescent source yields an amplified spontaneous emission (ASE) output of 43.2 and 25.1 W from both ends, respectively. The maximum combined ASE output is 68.3 W with a slope efficiency of 78.6%. The wavelength bandwidths (FWHM) of the counterpropagating and copropagating ASE output are 31.5 and 18.9 nm, respectively. The fused angle-polished side-pumping coupler is applied to set up the all-fiber configuration. Furthermore, the influence of reflectivity on the laser threshold of the ASE sources is studied theoretically. The experimental results agree with the theoretical analysis. (C) 2011 Optical Society of America