Full-Color Quasi-Achromatic Imaging with a Dual-Functional Metasurface

Achieving broadband achromaticity in the visible spectrum is critical for enhancing the imaging performance of metalenses. However, many previous studies remain constrained by small device sizes or small numerical aperture. In this study, we propose a polarization-multiplexed metalens capable of generating zero- and high-order Bessel beams to achieve quasi-achromatic correction without size limitations. An image subtraction method with the two polarization channels is developed to mitigate the Bessel beam sidelobes to improve imaging quality. Our results demonstrate an effective quasi-achromatic focusing and imaging over a continuous wavelength range of 450-700 nm with long focus depth. The image subtraction method significantly enhances the image clarity and contrast, providing new insights for full-color imaging and detection.