250-fs optical pulse generation by simultaneous soliton compression and shaping in a nonlinear optical loop mirror including a weak attenuation

We report the generation of 30-W peak-power 250-fs-wide pedestal-free optical pulses at 1.54 microm by use of a chirpcompensated optically amplified semiconductor laser followed by simultaneous soliton compression and shaping within a nonlinear optical loop mirror. A weak controllable attenuation is inserted within the loop to permit precise control of the pulse shape. Pedestal-free pulses are obtained after optimization of both the fiber length and the power balance between the counterpropagating pulses within the loop. The corresponding spectrum reveals a twofold split structure that is due to a residual chirp from self-phase modulation.