Pristine and Al/Zr-Doped ZnO Nanorod Arrays for High-Performance Photonic Devices: Synthesis, Structural–Optical Characterization, and Nonlinear Optical Limiting

The effect of metal doping and transforming from rigid to flexible substrate engineering provides an effective method for customizing the nonlinear optical response of ZnO-based nanostructures. In this study, pristine and Al-doped ZnO thin films and Zr-doped ZnO nanorods (ZnONRs) were synthesized on soda-lime glass and poly(dimethylsiloxane) PDMS substrates using RF magnetron sputtering and Hydrothermal growth methods. The incorporation of Zr dopant results in substantial alterations to the defect and electronic structures of ZnO, consequently leading to a notable enhancement in two-photon absorption and optical limiting responses in comparison to undoped nanorods. Zr-ZnONRs/PDMS demonstrated the highest TPA coefficient (2.61 × 10–6 m/W) at an intensity of 16.4 MW/cm2. The optical limiting threshold of Zr-ZnONR/PDMS was determined to be 1.49 mJ/cm2 at an input intensity of 16.4 MW/cm2. Structures supported by PDMS exhibit enhanced nonlinear absorption, attributed to defect-supported carrier dynamics and enhanced light-matter coupling at the flexible interface. These results highlight the synergistic effect of Zr doping and the PDMS medium in enhancing nonlinear optical performance, underscoring the potential of doped ZnO nanorods as efficient and cost-effective materials for optical limiting and compact photonic safety device applications in the visible range.