Holography-Inspired Screens for Sub-Wavelength Focusing in the Near Field

Inspired by the principle of holography we present a concept for making simple transmission screens that can focus an incident wave into a sub-wavelength spot in the near field. The screen is made out of closely spaced, unequal slits cut on a metallic sheet. Fullwave simulations are presented for an example screen that focuses an incident plane wave down to a spot having a peak-to-null beamwidth equal to lambda/10 .