Nonlinear optical properties of ferromagnetic insulator Cr₂Ge₂Te₆ and its application for demonstrating pulsed fiber laser

Abstract

In our work, a CGT–polyvinyl alcohol film type saturable absorber with a modulation depth of 1.4% and a saturable intensity of 7.9 MW cm−2 was prepared and employed for demonstrating a mode-locked Er-doped fiber laser. The fiber laser was capable of generating stable ∼550 fs pulses centered at 1558.6 nm under a 7.95 MHz repetition rate. Additionally, the threshold of the mode-locking was as low as 24.2 mW. Our experimental results prove that ferromagnetic-insulator CGT nanosheets exhibit excellent ultrafast modulation properties and provide a new opportunity for demonstrating mode-locked operations.