Mode-locked fiber laser based on Cr2Si2Te6 saturable absorber with a Sagnac loop

A late-model all-fiber mode-locked laser was introduced in this paper. This pulsed Er-doped fiber laser has a novel Sagnac loop structure and uses the tapered fiber coated with two-dimensional layer ferromagnetic insulator Cr2Si2Te6 as a saturable absorber in order to achieve passive mode locking. When the pump power was 167.6 mW, the laser worked at the fundamental repetition frequency of 19.1 MHz with a signal-to-noise ratio of 62.5 dB. The central wavelength of the spectrum was 1561.0 nm, and the maximum output power was 8.9 mW with a minimum pulse width of 5.2 ps. The mutual interference of beams makes the use of the saturable absorber more efficient. The results reveal that this Er-doped fiber laser has great application potential in nonlinear optics and ultrafast photonics.