All-fiber passively Q-switched 604 nm praseodymium laser with a Bi₂Se₃ saturable absorber.

We experimentally demonstrated a simple passively Q-switched praseodymium (Pr³⁺)-doped all-fiber laser at 604 nm with a Bi₂Se₃ saturable absorber (SA). A Bi₂Se₃/polyvinyl alcohol composite film is sandwiched between two ferrules to construct a fiber-compatible Q-switcher. Two fiber end facet mirrors build a compact-linear resonator. The repetition rate of the achieved 604 nm Q-switching pulse can be widely tuned from 86.2 to 187.4 kHz, and the pulse duration can be as narrow as 494 ns. To the best of our knowledge, this is the shortest operation wavelength of a Bi₂Se₃-based pulsed all-fiber laser at 604 nm.