Bismuth quantum dots as an optical saturable absorber for a 1.3 μm Q-switched solid-state laser.

Two-dimensional bismuth has attracted extensive attention for its unique properties, such as a moderate bandgap, high carrier mobility, and high stability. In this work, a uniform bismuth quantum dots saturable absorber (BiQDs-SA) was successfully fabricated by the liquid-phase exfoliation method. It was successfully employed in a passively Q-switched bulk laser operating at the telecommunication wavelength of 1.3 μm. The as-fabricated BiQDs-SA-based 1.3 μm Q-switched laser not only exhibits low timing jitter but also shows long-term stability for several days. The maximum average output power of 125 mW was obtained with the shortest pulse width of 510 ns and repetition rate of 135 kHz, corresponding to single-pulse energy and pulse peak power of 0.9 μJ and 1.8 W, respectively. The results indicate that BiQDs-SA is a potential optical modulator for passively Q-switched solid-state lasers.