Advanced Physical Research

The nonlinear optical properties of aluminium (Al) and copper (Cu) nanoparticles synthesized via pulsed laser ablation in liquid were systematically investigated to determine their suitability for advanced photonic applications, particularly optical limiters. Understanding the differences in their nonlinear responses is crucial for selecting the most effective material for laser protection and optical switching devices. Experimental results revealed that Cu nanoparticles exhibit a negative nonlinear refractive index, indicating a strong self-defocusing effect, along with pronounced reverse saturable absorption. These characteristics contribute to efficient suppression of high-intensity laser beams. In contrast, Al nanoparticles demonstrated a positive nonlinear refractive index, corresponding to self-focusing behavior, with nonlinear absorption mechanisms differing significantly from those of Cu. The comparative analysis confirmed that Cu nanoparticles deliver superior optical limiting performance due to their favorable absorption and transmission behavior under varying laser intensities. Overall, the study highlights Cu nanoparticles as a highly promising candidate for optical limiter instruments and related nonlinear optical applications.