Bound-State Soliton and Noise-like Pulse Generation in a Thulium-Doped Fiber Laser Based on a Nonlinear Optical Loop Mirror

Abstract

We demonstrate a thulium-doped, mode-locked, all-fiber laser capable of operating in two generation regimes: dispersion-managed soliton and noise-like pulse (NLP). Employing a nonlinear optical loop mirror as an artificial saturable absorber, the oscillator generated optical pulses with a fundamental pulse repetition frequency of ~15.795 MHz. The total net dispersion of the laser cavity had a slightly anomalous group delay dispersion value of −0.016 ps2. After appropriate adjustment of a polarization controller, bound states of a dispersion-managed soliton composed of three pulses with fixed soliton separations were also observed. NLP generation, tunable over 35 nm from 1943.5 to 1978 nm, was also presented in the same laser setup. To our knowledge, this is the first report of the generation of tunable NLPs in a mode-locked thulium-doped fiber laser based on a nonlinear loop mirror saturable absorber.