<p>This study presents gold–iron oxide (Au@Fe₃O₄) core-shell nanoparticles (NPs) synthesis via pulsed laser ablation in liquid (PLAL) techniques to improve photodetector performance. The nanoparticles' structural, optical, and electrical properties, deposited on porous silicon (PS) substrates, were investigated in detail. The formation of Au@Fe₃O₄ nanoparticles with different cubic gold and monoclinic iron oxide phases was confirmed through X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) images demonstrated core–shell nanoparticles with an average size of 25 nm and a PS&#xa0;generalized sponge-like morphology. PS laser ablation energy (1200 mJ) influenced the nanoparticles' morphology and size. The core–shell structure of nanoparticles was further confirmed by TEM, which clearly showed the differences between the gold core (dark area) and the iron oxide shell (bright area). The optical absorption and photoluminescence spectroscopy indicated a tunable band gap from 2.38 to 2.53 eV for these nanoparticles that strongly depended on the laser energy during the synthesis. The responsivity of Au@Fe₃O₄-NPs/PS photodetectors was enhanced under similar laser energy, with a peak responsivity of 0.189 A/W at 548 nm by introducing Au@Fe₃O₄ nanoparticles to PS substrates. These results strongly indicate the promising potential of Au@Fe₃O₄ nanoparticles for photodetectors in the visible-light-to-near-infrared-spectrum regions, which is important for emerging optoelectronic devices.</p>