Polarization domain wall solitons in a quasi-isotropic fibre laser using quantum dot tungsten disulfide

Abstract

A passively fast polarization switching erbium-doped fibre laser using quantum dot tungsten disulfide (QDWS 2 ) as a saturable absorber (SA) has been proposed. It could generate polarization domain walls (PDWs). The PDWs' spectrum can be divided into two separated spectra, which are orthogonally polarized. In detail, the horizontal polarization component wavelength is centred at 1561.1 nm with a repetition rate of 19.347 MHz, a pulse duration of 30 ns, and a signal-to-noise ratio of 73.2 dB at the maximum pump power. The vertical polarization component wavelength is centred at 1561.5 nm, with a pulse duration of 20.4 ns. To the best of our knowledge, this is the first report of a polarization domain wall generated by a QDWS 2 -SA. These results provide a platform to investigate anticorrelated polarization dynamics in quasi-isotropic fibre lasers. Moreover, their robustness and attractive properties could find potential applications in optical communications, data storage, and fibre laser devices.