Femtosecond Fiber Laser Based on BiSbTeSe2 Quaternary Material Saturable Absorber

Topological insulator materials, including Bi 2 Te 3 , Sb 2 Te 3 , Sb 2 Te 3 , and Bi 2 Se 3 , have attracted some attention due to their narrow band gaps, high carrier mobility, wide spectral absorption ranges and other characteristics. We report a new multi-compound topological insulator material BiSbTeSe 2 that, compared with the traditional topological insulator composed of two elements, can integrate the physical advantages of each element, helpful to build an experimental platform with rich physical properties. The nonlinear optical characteristics of the quaternary material BiSbTeSe 2 is obtained in the erbium-doped fiber laser. Using the BiSbTeSe 2 as a saturable absorber material, the passive Q-switched and mode-locked fiber lasers are achieved. The pulse duration and signal-to-noise ratio (SNR) of the Q-switched fiber laser are 854 ns and 70 dB, respectively. Meanwhile, the pulse duration and SNR of the mode-locked fiber laser are 259 fs and 87.75 dB, respectively. This work proves that the BiSbTeSe 2 has a considerable application prospect as a saturable absorber in fiber lasers, and provides a new reference for selection of high-performance saturable absorber materials.