Optical limiting behavior of metal (Mn, W) oxides decorated nitrogen-doped reduced graphene oxide nanocomposites stimulated by two-photon absorption

Nanopulsed Nd: YAG green laser-induced nonlinear absorption and optical limiting properties of rGO/MnO2, NrGO/MnO2 and NrGO/MnO2/WO3 nanostructures were studied for the first time utilizing single beam Z-scan experiment. Initially, rGO was prepared by solar exfoliation whereas MnO2, WO3, rGO/MnO2, NrGO/MnO2 and NrGO/MnO2/WO3 nanostructures were synthesized by hydrothermal method. XRD was used to determine the structure and crystallite size of the materials. Carbon allotropes and functional groups of the prepared materials were studied using Raman and FT-IR spectroscopy. SEM images showed layered rGO, as well as rod-like MnO2 and flake-like WO3 nanostructures adorned on the top of NrGO layers. EDS analysis validated the presence of C, N, Mn, W, and O. Linear optical study manifested absorption in the UV-Visible region between 200 nm and 800 nm. The occurrence of reverse saturable absorption (RSA) was confirmed by an open aperture Z-scan technique. Compared to its pure analogs and derivatives of graphene, MnO2 decorated NrGO had a higher two-photon absorption coefficient (8.92 x 10-11 m/W) and the lowest optical limiting (OL) threshold (3.29 x 1012 W/ m2). Extensive conjugation for charge transfer in NrGO and rod-like shape, homogeneous decorating, and strong visible absorption in MnO2 combine to provide enhanced nonlinear optical (NLO) response and has the potential use in energy stabilizers and laser safety devices in the 532 nm, 9ns laser domain.