Experimental study on all-normal-dispersion mode-locked fiber laser with optimal spectral filtering position

Abstract

Employing nonlinear polarization rotation, an all-normal-dispersion mode-locked fiber ring laser was constructed, in which a fiber filter with 10 nm bandwidth was used in the cavity to provide the additional self-amplitude modulation. The important role of the filter position plays in the high-chirped pulse shaping in the laser has been experimentally demonstrated by choosing different locations of the filter in the cavity. A mode-locked pulse series, with the averaged power of 922 mW, output pulse duration of 62 ps, and pulse repetition frequency of 266 MHz, corresponding to the pulse energy of 35 nJ, was obtained in the optimized filter position under a pump power of 320 mW. By the numerical simulation, the propagation dynamics of pulses in the three cases of spectral filter (SF) position in the cavity are obtained and analyzed. The optimal location of the SF is found, which is in agreement with our experimental result.