Flat-lens design using Field Transformation and its comparison with those based on Transformation Optics and Ray Optics

TL;DR

This paper introduces a flat lens design method using Field Transformation, demonstrating superior broadband gain and scan capabilities compared to traditional Ray Optics and Transformation Optics approaches.

Contribution

The paper presents a novel flat lens design technique based on Field Transformation, with detailed multilayer dielectric structure and performance comparison to existing methods.

Findings

Broadband operation with >1 dB higher gain

Superior scan capability

Better performance over wider frequency band

Abstract

This paper proposes a technique for designing flat lenses using Field Transformation (FT), 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. The paper compares the performance of the lens, so designed, with those based on the RO and TO techniques. We show that the proposed lens design using field transformation is broadband, has a better than 1 dB higher gain compared to the RO and TO based designs over a wider frequency band, and that its scan capability is superior as well.