Nonlinear absorption effects and optical limiting properties of rational designed rGO-CNT composite probed by Z-scan technique

Carbon-based materials are in high demand due to their advanced high-tech applications. In contrast to traditional synthesis methods, a single-step green method is demonstrated for reducing graphene oxide. A simple one-step hydrothermal method successfully synthesized reduced graphene oxide (rGO)-multi-walled carbon nanotube (MWCNT). The composite was characterized using X-ray diffraction (XRD), micro-Raman, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), fourier transform infrared spectroscopy (FTIR), UV-visible absorption spectroscopy (UV-Vis) and zeta potential measurements. The present work aims to investigate the feasibility of utilizing nonlinear optical properties of reduced graphene oxide-carbon nanotube (rGO-CNT) composite as an optical limiter. The Z-scan technique was used to study the composite nonlinear absorption properties at a laser intensity of 532 nm. The result displayed that the composite material exhibits strong nonlinear absorption properties, chiefly resulting from the synergistic impact of rGO and CNT. The optical limiting behaviour of the rGO-CNT composite was evaluated, and it demonstrated excellent performance with a limiting threshold of 0.70 × 10¹² W m^–2. Combining MWCNT tubular shape, homogeneous decorating and strong visible absorption with rGO’s extensive conjugation for charge transfer leads to a highly improved nonlinear optical (NLO) response. The excellent optical limiting performance of rGO-CNT composite makes it an ideal candidate for laser safety and energy stabilizer devices operating in the 532 nm, 9 ns laser domain.

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