Angle-Insensitive Spectral Imaging Based on Topology-Optimized Plasmonic Metasurfaces

On-chip spectral imaging based on engineered spectral modulation and computational spectral reconstruction provides a promising scheme for portable spectral cameras. However, the angle dependence of modulation units results in the angle sensitivity of spectral imaging, which limits its practical applications. Here, metal is utilized instead of dielectric materials to realize on-chip angle-robust computational spectral imaging based on a group of topology-optimized plasmonic metasurface units under a 30 degrees field-of-view, and demonstrate angle-insensitive spectral imaging in the wavelength range of 450-750 nm for average polarization. Furthermore, it is experimentally verified that the angle-insensitive spectral filtering effects of the fabricated metasurface units, and demonstrated angle-robust spectral reconstruction with a fidelity of over 98% as well as spectral imaging for a standard color checker. This approach expands the application scale of spectral imaging, which has great potential on metal-based on-chip multimodal imaging with dimension of depth, polarization, spectrum and so on. On-chip angle-robust computational spectral imaging based on topology-optimized plasmonic metasurfaces is proposed and experimentally reported. The fidelity of spectral reconstruction realized by an auto-encoder is over 98% under a 30 degrees field-of-view, and spectral imaging for a standard color checker is demonstrated. This approach expands the application fields of spectral imaging chips such as wide-angle or off-axis spectral imaging. image