Passive mode-locked Er-doped fiber laser pulse generation based on titanium disulfide saturable absorber

In this study, titanium disulfide (TiS2) polyvinyl alcohol (PVA) film-type saturable absorber (SA) is synthesized with a modulation depth of 5.08% and a saturable intensity of 10.62 MW/cm2 by liquid-phase exfoliation and spin-coating methods. Since TiS2-based SA has a strong nonlinear saturable absorption property, two types of optical soliton were observed in a mode-locked Er-doped fiber laser. When the pump power was raised to 67.3 mW, a conventional mode-locked pulse train with a repetition rate of 1.716 MHz and a pulse width of 6.57 ps was generated, and the output spectrum centered at 1556.98 nm and 0.466 nm spectral width with obvious Kelly sidebands was obtained. Another type of mode-locked pulse train with the maximum output power of 3.92 mW and pulse energy of 2.28 nJ at the pump power of 517.2 mW was achieved when the polarization controllers were adjusted. Since TiS2-based SA has excellent nonlinear saturable absorption characteristics, broad applications in ultrafast photonic are expected.