Self-compressed to narrowband picosecond pulses generated by extremely large anomalous net cavity dispersion

An all-fiber laser with passive mode-locking based on the NPE effect was realized with highly chirped Bragg grating (CFBG), which provides extremely large anomalous net cavity dispersion of -81.2 ps². It provides pulses with a spectral width of 0.12 nm, a duration of 16 ps, and an energy of 0.6 nJ. Intracavity evolution of such narrowband pulses was investigated numerically. It revealed a key influence of the spectrum self-compression effect on the pulse formation in a laser cavity. We also showed that a resulting pulse spectral width is not affected by the CFBG bandwidth but by the negative chirp provided by the grating. At the same time, the pulse duration remains almost constant along the fibers in contrast to dispersion-managed fiber lasers. The work demonstrates the great potential of a spectrum self-compression effect for further research of picosecond pulse generation schemes.