Holographic Super-Resolution Metalens for Achromatic Sub-Wavelength Focusing

Optical super-resolution diffractive metalenses have been promising candidates for realizing optical imaging and a microscope beyond the Abbe diffraction limit. An achromatic super-resolution metalens is particularly important for practical applications; however, it remains challenging to achieve high-numerical-aperture achromatic super-resolution metalens for subwavelength focusing. Herein, a holographic approach of realizing a multiwavelength achromatic subwavelength superresolution focusing is proposed. Through wavefront engineering and holographic synthesis, a high-numerical-aperture achromatic super-resolution metalens is demonstrated for subwavelength super-resolution focusing at five different wavelengths of 520, 555, 632.8, 660, and 690 nm. Broadband achromatic performance is also expected. Generally, there is no theoretical limit on the numbe of achromatic wavelengths. The proposed method could be useful in super-resolution related applications, including imaging, microscopy, and data storage.