2D achromatic flat focusing lens based on dispersion engineering of spoof surface plasmon polaritons: broadband and profile-robust

In this paper, we propose the design of two-dimensional (2D) broadband achromatic flat focusing lens (AFFL) through tailoring the weak dispersion region of spoof surface plasmon polaritons (SSPPs) coupled within ultrathin metallic gratings structures. As an example, we demonstrated a 2D AFFL that can operate effectively in 7.0–9.0 GHz. Both the simulation and experiment results show that the AFFL prototype exhibits high focusing efficiency and excellent achromatic focusing performance. More importantly, performances of the 2D AFFL are robust to shape profile of the lens. The achromatic focusing performance keeps almost unchanged even if there are considerable deformations on the lens profile. A deformed AFFL was also fabricated and measured. Both the simulation and experiment results verify the profile robustness of the AFFL. Due to broad bandwidth, light weight and profile robustness, such AFFLs own great applications values in high-gain antennas, conformal radomes and other functional devices. (paper)