Energy scaling of mode-locked fiber lasers with chirally-coupled core fiber

We report a mode-locked dissipative soliton laser based on large-mode-area chirally-coupled-core Yb-doped fiber. This demonstrates scaling of a fiber oscillator to large mode area in a format that directly holds the lowest-order mode and that is also compatible with standard fiber integration. With an all-normal-dispersion cavity design, chirped pulse energies above 40 nJ are obtained with dechirped durations below 200 fs. Using a shorter fiber, dechirped durations close to 100 fs are achieved at pump-limited energies. The achievement of correct energy scaling is evidence of single-transverse-mode operation, which is confirmed by beam-quality and spectral-interference measurements.