PMMA/PEG polymer blend engineered with ZnO/TiC NPs for optical response and optical limiting applications

This study examines the linear and third-order nonlinear optical properties of ZnO. TiC-reinforced polymer blend nanocomposite films were made using a solution casting method. UV-Vis spectroscopy showed that adding ZnO and TiC nanoparticles increased light absorption, causing a redshift in the absorption edge, reducing transparency, and narrowing the optical band gap due to improved interfacial interactions and localized electronic states. Third-order optical nonlinearities were assessed using the Z-scan method when a continuous-wave laser at 457 nm was employed. Closed-aperture results indicated a negative nonlinear refraction (self-defocusing behavior), meaning the material spreads out the light. Open-aperture results exhibited a saturable absorption (SA) response. Although there was absorption, the nanocomposites demonstrated good optical limiting abilities. With increasing TiC nanoparticle content, the optical limiting threshold decreased from 7.5 mW for the polymer blend to 5.5 mW for the nanocomposite with the highest TiC content (B/ZT3), accompanied by a reduction in limiting amplitude from 87 mW to 84 mW. These results indicate that TiC is an effective nanofiller for tuning third-order optical nonlinearities, making these composite films suitable for photonic and laser protection applications.