Two-Dimensional CH₃NH₃PbI₃ Perovskite Nanosheets for Ultrafast Pulsed Fiber Lasers

TLDR

Two‑dimensional perovskite nanosheets, with reduced photocarrier recombination and scattering compared to bulk films, have largely unexplored nonlinear optical properties relevant to ultrafast photonics. This study systematically investigates the nonlinear optical behavior of 2D perovskite nanosheets produced by a combined solution‑process and vapor‑phase conversion approach. The authors synthesize the nanosheets and then employ an all‑dry transfer technique to fabricate a saturable‑absorber device from a single nanosheet. The resulting device exhibits strong saturable absorption with large modulation depth and low saturation intensity, enabling stable soliton mode‑locking and picosecond pulse generation at 1064 nm, and suggesting 2D perovskites as promising ultrafast photonic materials.

Abstract

Even though the nonlinear optical effects of solution processed organic–inorganic perovskite films have been studied, the nonlinear optical properties in two-dimensional (2D) perovskites, especially their applications for ultrafast photonics, are largely unexplored. In comparison to bulk perovskite films, 2D perovskite nanosheets with small thicknesses of a few unit cells are more suitable for investigating the intrinsic nonlinear optical properties because bulk recombination of photocarriers and the nonlinear scattering are relatively small. In this research, we systematically investigated the nonlinear optical properties of 2D perovskite nanosheets derived from a combined solution process and vapor phase conversion method. It was found that 2D perovskite nanosheets have stronger saturable absorption properties with large modulation depth and very low saturation intensity compared with those of bulk perovskite films. Using an all dry transfer method, we constructed a new type of saturable absorber device based on single piece 2D perovskite nanosheet. Stable soliton state mode-locking was achieved, and ultrafast picosecond pulses were generated at 1064 nm. This work is likely to pave the way for ultrafast photonic and optoelectronic applications based on 2D perovskites.