Tunable nonlinear optical enhancement of α-FeOOH nanorods/RGO composites

Abstract

High-quality α-FeOOH nanorods/reduced graphene oxide (RGO) composites were prepared by a facile hydrothermal method. Crystal structure and optical properties of the composites were characterized by XRD, SEM, TEM, FT-IR, Raman, UV–vis, PL. These results of characterization showed that the composites were successfully prepared. The third-order nonlinear optical (NLO) properties of the composites were investigated by Z-scan technique under 30 ps laser at 532 nm wavelength with 10 Hz repetition. The composites had larger third-order NLO susceptibility compared to pure α-FeOOH nanorods and RGO nanosheets. The enhancement of NLO performance benefited from synergistic effect of local field effect and charge transfer between α-FeOOH nanorods and RGO. Moreover, the composite with the α-FeOOH nanorods:RGO weight ratio of 2:1 (S3) showed the most robust NLO response. Comparing with RGO, the value of third-order NLO susceptibility χ(3) of S3 was increased by around 60 times and the saturation intensity Isat was nearly decreased by 6 times as the modulation depth M highly increased, respectively. The improved NLO property of α-FeOOH nanorods/RGO composite indicated its possible application in optical switches, mode lockers and other NLO devices.