Long-cavity passively mode-locked fiber ring laser with high-energy rectangular-shape pulses in anomalous dispersion regime

摘要

We report on a long-cavity passively mode-locked fiber laser in the anomalous dispersion regime. The nonlinearnpolarization rotation technique is employed to achieve mode locking. The output pulse from the fiber laser has anrectangular shape and a corresponding Gaussian-shape spectral profile. Stable mode-locked pulses at a repetitionnrate of 278 kHz with single pulse energy as high as 715 nJ are obtained under equal bidirectional pumping power ofn500 mW in cavity. The experimental results demonstrate that the passively mode-locked fiber laser operating in thenanomalous regime can also realize a high-energy pulse, which is different from the conventional low-energy solitonnpulse.