A highly efficient visible color filter employing an all-dielectric meta-surface decorated with TiO₂ nanostructures suitable as an excellent refractive index sensor

All-dielectric metasurfaces based on TiO₂ nanogratings (NGs) provide a superior alternative to metallic nanostructures for color filtering, offering low losses, high resonance quality, and ultrahigh transparency in the visible range. These structures generate intense red, green, and blue colorations with high reflection intensity and narrow bandwidth, making them suitable for high-saturation displays, structural color printing, and transparent filters in wearable devices, smart windows, and AR systems. Two-dimensional TiO₂ NGs further provide angle tolerance and polarization-independent performance, supporting wide-angle imaging in cameras, surveillance, and automotive sensors, as well as polarization-insensitive optical communication. Simulations show single or dual resonant peaks in varying media, enabling high-sensitivity sensing for biosensing, chemical analysis, and environmental monitoring. Their low-loss resonances and adaptability allow integration into advanced microscopy, medical diagnostics, tunable lenses, photonic circuits, and security holograms, establishing TiO₂ NG metasurfaces as versatile components for next-generation sensing, imaging, and display technologies.