Perovskite nanoparticle-based nonlinear optical devices for ultrafast photonics applications

Metal halide perovskites have shown wide potential applications in various fields such as light-emitting diodes, photodetectors, and lasers in recent years due to their high photoelectric conversion efficiency, adjustable bandgap, and high carrier mobility. However, as an optical modulator for lasers, it is still limited by slow nonlinear optical response, low damage threshold, and poor stability. In this article, we prepared Cs0.15FA0.85PbI2.85Br0.15 perovskite films and used them as optical modulators to achieve ultrashort-pulse fiber lasers. By exploring the nonlinear optical response of Cs0.15FA0.85PbI2.85Br0.15 perovskite films, a saturable absorber device with 15.2% modulation depth and 20.02 ps recovery time was obtained. Based on this, it was applied in an erbium-doped fiber laser to achieve Q-switching and mode-locking pulses at a wavelength of 1550 nm. Among them, the narrowest Q-switched pulse width can reach 288 ns and the maximum single-pulse energy reaches 145.5 nJ. A soliton mode-locked pulse with a repetition rate of 32.1 MHz was achieved by adjusting the polarization state inside the cavity, with a pulse width of 276 fs and an output power of 35.12 mW. The research results indicate that Cs0.15FA0.85PbI2.85Br0.15 perovskite, as an excellent saturable absorber, has broad application prospects in the fields of ultrafast photonics.