All-dielectric bifocal isotropic metalens for a single-shot hologram generation device

Planar metalenses are regarded as promising functional nanodevices because of their lightweight, nano-resolution properties, and, therefore, they can serve as versatile platforms for imaging and Fourier transforming. Here, we demonstrate a meta-device that functions as an isotropic bifocal all-dielectric Huygens' metalens to realize nanoscale real-time coaxial digital hologram generation. We design an isotropic bifocal metalens for micro/nano hologram recording, and the metalens utilizes the complete region compared to a previously reported interleaved multifocal metalens scheme. In addition, the hologram generation does not depend on complex polarization conversion, thereby improving the practical efficiency. For high-fidelity reconstruction, compressive reconstruction is utilized to remove twin-image and zero-order items and to suppress noise. Such concept would be extended to white-light achromatic meta-holography and three-dimensional micro/nano in vivo incoherent super-resolution imaging under subwavelength modulation.