Large Energy, Wavelength Widely Tunable, Topological Insulator Q-Switched Erbium-Doped Fiber Laser

We report on the generation of large energy, widely wavelength tunable pulses in an erbium-doped fiber laser passively Q-switched by a topological insulator saturable absorber (TI-SA). The TI-SA is prepared through an optical deposition method. Its saturating intensity and modulation depth are measured to be about 57 MW/cm² and 22%, respectively. We show that the high modulation depth of TI-SA allows the generation of stable Q-switched pulses with per-pulse energy up to 1.5 μJ and its broadband saturable absorption favors the tunable Q-switching operation from 1510.9 nm to 1589.1 nm. Our study suggests that TI: Bi₂Te₃ could be a promising saturable absorber for both the high energy and broadband optical applications.