Enhanced Optical Properties of Titania Nanolayers

Laser processing presents an efficient strategy to optimize TiO₂ coatings on quartz substrates for enhanced optical performance and superior crystallinity. In this study, TiO₂ films were deposited via spin-coating, followed by solvent evaporation and CO₂ laser sintering, guided by a heat conduction model. The laser sintering technique produced lower localized temperatures compared to conventional methods, enabling high transmittance (>90%) and low reflectance (<5.5%) within select regions of the visible spectrum. Systematic variation of TiO₂ concentrations yielded precise control over film thickness, porosity, and optical properties, with the latter characterized by an effective medium approach accounting for porosity from nanoparticle deposition and sintering. Increasing nanoparticle (NP) content reduced porosity and enhanced the refractive index through UV-vis dispersion, while higher sintering laser power further decreased reflectance and improved NPs coalescence and bonding. The outcome was that the refractive index remained constant at fixed concentrations, regardless of laser power, due to optimal material densification and minimal attenuation. The findings highlight the critical role of composition and porosity control in tailoring optical characteristics, providing valuable insights for the development of high-performance TiO₂ coatings for photonic applications.