Generation of domain-wall solitons in an anomalous dispersion fiber ring laser* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11874040, 11904327, and 61905222), Foundation for Leading Talents of Minhang, Shanghai, and the Specialized Research Fund for the Doctoral Program of Zhengzhou University of Light Industry (Grant No. 0170-13501050036).

Abstract

We report experimental observations performed using a net anomalous dispersion Er-doped fiber ring laser without polarization-selective elements, highlighting the domain-wall solitary pulses generated under the incoherent polarization coupling. By adjusting the pump power and the polarization state appropriately, bright and dark solitons can stably co-exist in the cavity, both centered at 1562.16 nm with a 3-dB spectral width of ∼ 0.15 nm and a repetition rate of 3.83 MHz. Moreover, the 0.8 mm long thulium-doped fiber (TDF) facilitated the mode-locking and self-starting of the laser. This is the first demonstration of a laser being used to generate bright and dark solitons synchronously while using TDF as the saturable absorber (SA). Except possessing the all-fiber structure, the laser exhibits good stability, which may have a significant influence on improvement of the pulse-laser design, and may broaden practical applications in optical sensing, optical communication, and soliton multiplexed systems.