Broadband and polarization-independent complex amplitude modulation using a single layer dielectric metasurface†

Precise control over amplitude and phase across the entire space is crucial for generating user-defined wavefronts and has significant value for designing flexible optical systems. Metasurfaces have emerged as compact and effective platforms for such control, offering high spatial resolution and continuity. However, traditional methods only work at specific wavelengths or polarization states, and the demonstration of full space complex amplitude control for broadband and unpolarized light remains limited. In this study, we leverage the principle of dual meta-atom interference to simultaneously modulate amplitude and phase using a single layer metasurface. Using a randomly polarized light source, nanoprinting and Fourier holography displays of complex patterns are achieved within the wavelength range of 480–640 nm, and the results are consistent with simulations. This approach presents several key advantages: continuous, precise and robust modulation of complex amplitude as well as polarization-independent and broadband response, which significantly reduce constraints on the light source's property and fabrication and make it well-suited for a variety of practical applications, including holographic displays, high-capacity communications, computational imaging, and laser beam processing.