The development of advanced optical coatings exhibiting both exceptional mechanical durability and tunable chromatic properties has emerged as a critical requirement for next-generation photonic applications. This investigation presents the synthesis of Al-N-Si thin films with different Si concentrations deposited on Si wafers and glass substrates through reactive magnetron co-sputtering technology. Comprehensive material characterization was performed utilizing field emission scanning electron microscopy, X-ray photoelectron spectroscopy, grazing-incidence X-ray diffraction, high-resolution transmission electron microscopy, chromatic coordinate analysis, UV-Vis spectroscopy, variable-angle spectroscopic ellipsometry, and nanoindentation techniques. Key findings reveal that the stoichiometric Al_0.92N coating develops columnar grain architecture extending through the film thickness. Si incorporation at 6.8 at.% induces microstructural densification and enhances oxidation resistance while maintaining a hexagonal wurtzite crystallographic structure with predominant (101) orientation. At 10.7 at.% Si concentration, grain refinement to 11.0 nm occurs with preferential (100) orientation development. Optical analysis demonstrates maintained zero extinction coefficients coupled with refractive index reduction to 2.08-1.99 across visible wavelengths. Mechanical testing reveals maximum hardness of 27.1±2.3 GPa, while optical transmission in the hazardous blue spectrum (400-450 nm) decreases to 68.2-79.1%. Notably, the coatings on the Si substrate demonstrate structural coloration spanning visible spectrum (red: 300 nm, green: 241 nm, cyan: 208 nm, blue: 200 nm, purple: 186 nm) through interference modulation. A mechanistic model elucidating Si-mediated structural evolution was established, with particular emphasis on solid solution strengthening mechanism, thin-film interference phenomena, and blue light attenuation principle. This systematic investigation provides fundamental insights into structure-property relationships for multifunctional optical coatings, advancing the development of intelligent surfaces with combined mechanical robustness and controllable optical responses.
 

Aluminum nitride, Reflectance, Transmittance, Structural color, Hardness, Blue light attenuation