Design of flat lenses using Field Manipulation

This paper proposes a technique for designing flat lenses using Field Manipulation (FM), as opposed to Ray Optics (RO) or Transformation Optics (TO). The lens design consists of 10 layers of graded index dielectric in the radial direction and 5 layers in the longitudinal direction. The central layer in the longitudinal direction primarily contributes to a bulk of the phase transformation, while the other four layers, above and below this middle layer on either side, act as matching layers that help reduce the reflections introduced by the impedance mismatch at the interfaces of the middle layer. We show that the proposed lens design is broadband and has a better than 1 dB higher gain compared to the conventional designs.