Optimized wide-angle metamaterial bandpass filters with multi-layer design and 1D photonic crystal integration

We present a wide-angle, incident-insensitive metamaterial bandpass filter integrating gold-coated silicon nanospheres (SiNS) with a 1D photonic crystal (1D-PC) edge filter. This hybrid design leverages localized surface plasmon resonance (LSPR) and photonic bandgap engineering to achieve high optical density (OD ≈ 2.31) in stopbands while maintaining strong passband transmission (peak T≈ 80%). Unlike conventional thin-film filters, it minimizes blue-shift effects and ensures angle- stable performance up to 60◦ incidence. These results demonstrate a promising approach for high-performance optical filters in imaging, sensing, and laser protection applications.