CsPbBr Perovskite Nanocrystals for a Q-Switched Pulsed Fiber Laser in the C-Band Region.

All-inorganic perovskite nanocrystals have been widely reported as promising light-harvesting and light-emitting semiconductor nanomaterials. However, their nonlinear optical properties and laser applications have rarely been explored, especially for pulse laser modulation in the telecommunication C-band window. Herein, we experimentally demonstrated a passively Q-switched erbium-doped fiber laser (EDFL) operation at the C-band region using perovskite CsPbBr nanocrystals as a saturable absorber (SA). The broadband linear optical absorption in the 300-2000 nm range and the nonlinear optical absorption at the C-band range of around 1560 nm were discovered and investigated in CsPbBr nanocrystals. The CsPbBr-based SA exhibited good saturable absorption performance with a modulation depth and saturation intensity equivalent to 19.1% and 10.9 MW/cm, respectively. By integrating the CsPbBr SA into an EDFL cavity, a passively Q-switched operation with a central wavelength of 1560 nm, a threshold pump power of 60 mW, and the shortest pulse duration of 5.96 μs was achieved. In addition, such a Q-switching operation exhibited long-term stability. Our results indicate that the CsPbBr perovskite nanocrystals can serve as an efficient candidate for constructing pulsed lasers in the C-band or even longer NIR wavelength region.