Nonlinear optical nanoparticles of Zn/Cu/Al2O4 were synthesized by microwave-assisted combustion method with different fuel to oxidizer ratio. And, these nanoparticles were characterized by various analytical techniques to examine their suitability in fascinating applications. XRD results enunciate that the nanoparticle crystallizes in cubic spinel structure. The morphology and quantitative chemical compositions of Zn, Cu, Al and O elements were obtained from SEM with EDAX analysis. The prepared compound was confirmed by FTIR spectrum. The optical energy bandgaps are studied from UV–Vis absorption spectra. The luminescence emission peaks are observed at 371 nm (Violet), 425 nm (violet), 471 nm (blue) and 637 nm (red). In the application point of view from the Z-scan technique, the third order nonlinear optical parameters such as nonlinear refractive index (n2), nonlinear absorption coefficient (β), and third-order nonlinear susceptibility (χ3) of title compound are calculated. For biological application, the antibacterial activities were tested against Bacillus cereus, Staphylococcus aureus, Shigella flexneri, and Vibrio cholera bacterial species by measuring the inhibition zone. Existing results point out that the synthesized Zn/Cu/Al2O4 nanoparticles are possible candidates for photonics devices, optical switches, optical limiting and also for pharmaceutical applications. Keywords: Zn/Cu/Al2O4 nanoparticles, Combustion method, Optical properties, Luminescence, Z-scan, Antibacterial activity