Generation of Polarization-Locked Vector Solitons in Mode-Locked Thulium Fiber Laser

In this paper, we report polarization-locked vector soliton (PLVS) generation in a linear thulium-doped fiber laser. The fiber laser was composed of all-anomalous-dispersion fibers, passively mode-locked with a semiconductor saturable absorber mirror. Approximately 1.2-ps single vector soliton pulses centered at 2023.7 nm were generated. Extra “peak-dip” spectral sidebands were clearly visible in the polarization-resolved optical spectra, indicating coherent energy exchange between the two polarization components of the vector solitons. In addition, multiple-PLVS operation modes were experimentally investigated, and our experimental results were confirmed by numerical simulations. To the best of our knowledge, this is the first observation of polarization-locked single vector soliton generation operating in the 2-μm spectral range.