Nonlinear optical characteristics of ZrSe 2 and its application for designing multi-wavelength mode-locked operations

In our work, a ZrSe2–polyvinyl alcohol film-type saturable absorber (SA) with a modulation depth of 4.99% and a saturable intensity of 12.42MW/cm2 was successfully prepared and employed in mode-locked Er-doped fiber laser. The fiber laser can generate stable multi-wavelength mode-locked operations with a threshold power of 224 mW and a maximum average output power of 3.272 mW at the repetition rate of 3.38 MHz for the first time, to the best of our knowledge. Our experimental results fully prove that ZrSe2 nanosheets were efficient SA candidates for demonstrating multi-wavelength mode-locked operation fiber lasers due to their tunable absorption peak and excellent saturable absorption properties.