One-Step Fabrication of 0D Cs₄PbBr₆ Perovskite with Nonlinear Optical Properties for Ultrafast Pulse Generation

Low-dimensional lead halide perovskites demonstrate remarkable nonlinear optical characteristics attributed to their distinctive physical structures and electronic properties. Nevertheless, the investigation into their nonlinear optical properties remains in its incipient stages. This study addresses this gap by precisely controlling solvent volumes to synthesize both 0D Cs₄PbBr₆ and Cs₄PbBr₆/CsPbBr₃ perovskites. Remarkably, as saturable absorbers, both pure Cs₄PbBr₆ and Cs₄PbBr₆/CsPbBr₃ composites exhibit favorable nonlinear optical properties within the C-band, showcasing modulation depths of 9.22% and 16.83%, respectively. Moreover, for the first time, Cs₄PbBr₆ and Cs₄PbBr₆/CsPbBr₃ composites have been successfully integrated into erbium-doped fiber lasers to realize the mode-locking operations. The utilization of the Cs₄PbBr₆/CsPbBr₃ composites as a saturable absorber that enables the generation of conventional soliton mode-locked laser pulses with a pulse duration of 688 fs, and a repetition frequency of 10.947 MHz at a central wavelength of 1557 nm. Cs₄PbBr₆ is instrumental in generating laser pulses at a frequency of 10.899 MHz, producing pulse widths of 642 fs at the central wavelength of 1531.2 nm and 1.02 ps at the central wavelength of 1565.3 nm, respectively. The findings of this investigation underscore the potential utility of 0D Cs₄PbBr₆ and Cs₄PbBr₆/CsPbBr₃ composites as promising materials for optical modulation within fiber laser applications.