Superresolution Focusing Using Metasurface with Circularly Arranged Nanoantennas.

Circular lens composed of annularly arranged metal nanoantennas is proposed to achieve far field superresolution focusing. Light illuminating on the nanoantennas' layer approximately acquires paraboloidal phase profile and then focuses into a spot. Lens constructed by monolayer nanoantennas achieve focusing with FWHM (full width at half maximum) of 924 nm and a focal length of 3385 nm, breaking the diffraction limit. Moreover, tri-layered lens realizes subwavelength focusing with FWHM of 320 nm (about 0.49 λ) and the field intensity of focus is optimized to 0.97 a.u. (arbitrary unit). Our proposal shows advances in focusing performance compared with previous work, making it promising in many applications, such as nanolithography, dense storage, and integrated optics. [ABSTRACT FROM AUTHOR]