Passively mode-locked Er-doped fiber laser based on a ferromagnetic insulator Cr₂Si₂Te₆ as a saturable absorber

In our work, a new-type, to the best of our knowledge, ferromagnetic insulator and its nonlinear optical absorption characteristics and related ultrafast modulation applications were investigated. Cr₂Si₂Te₆ saturable absorbers (SAs) with a modulation depth and a saturable intensity of 9.7% and 3.5MW/cm² were fabricated. By adjusting the pump power to 120 mW and optimizing the polarization state, traditional soliton operations were obtained successfully; the corresponding duration of pulse and the fundamental repetition rate were ∼1.33ps and 6.70 MHz, and the signal-to-noise ratio was 50 dB. The experimental results reveal that Cr₂Si₂Te₆ with excellent saturable absorption characteristics can be used as a SA to obtain ultrafast pulse lasers.