Passively Q-switched fiber laser with various phases of Ni-S as a saturable absorber

Nanoparticles of NiS (amorphous α and crystalline β phases), Ni 3 S 2 and Ni were obtained by passing H 2 S through a solution of NiSO 4 •7H 2 O followed by drying or annealing of washed precipitate in hydrogen or nitrogen atmospheres. The synthesized materials were mixed with a polymer (polydimethylsiloxane elastomer) and applied to the surface of chemically prepared conical constrictions on SMF-28 fiber. Passive Q-switches were integrated into a specially designed erbium ring fiber laser and tested. For the first time, the generation of µs pulses was realized using these compositions of the binary system Ni-S. The best parameters of a pulsed laser obtained using β-NiS nanoparticles as a saturable absorber were a repetition rate of 21.7 kHz, an average output power of 26.72 mW, and a pulse energy of 1230 nJ.