635-nm Visible Pr3+-Doped ZBLAN Fiber Lasers Q-Switched by Topological Insulators SAs

Passive Q-switching of praseodymium (Pr
³⁺
)-doped fiber lasers at 635 nm with topological insulators (TIs) saturable absorbers (SAs) was experimentally demonstrated for the first time. TIs (Bi
₂
Se
₃
, Bi
₂
Te
₃
) nanosheets were embedded in polyvinyl alcohol for film-forming and incorporated into a visible Pr
³⁺
-doped fiber laser cavity for Q-switching operation, respectively. The Bi2Se3-based Q-switched fiber laser has a wide range pulse-repetition-rate from 191.6 to 454.5 kHz, and the Bi2Te3 one can be continuously tuned from 164.5 to 403.2 kHz. Both the Q-switching lasers have narrow pulse duration of nanosecond (ns)-level. Our results reveal that the TIs-based SAs are available for pulsed operation in the visible spectral range.