An infrared energy harvester based on radar cross-section reduction of chiral metasurfaces through phase cancellation approach

Abstract

Conventional metasurface absorbers rely on high dissipation losses by incorporating lossy materials. In this paper, we propose a novel mechanism of absorption based on phase cancellation of polarization states of scattered fields emerging from adjacent L-shaped chiral meta-atoms (unit cells). A linearly polarized wave forms helicoidal currents in each meta-atom leading to diagonally polarized radiated waves. When phase cancellation is employed by reorienting four such meta-atoms in a supercell configuration, contra-directed chiral currents flow in adjacent cells to cancel all the radiated fields in far-field region leading to a minimal broadside radar cross-section. From the reciprocity, the currents that are induced in the meta-atoms produce a null towards the incident direction which can be utilized for infrared energy harvesting. Full wave electromagnetic simulation indicates near perfect resonant absorption around 52.2 THz frequency. Enhanced bandwidth is shown by adding smaller resonators inside the supercell in nested form leading to dual band absorption at 45.2 THz and 53.15 THz.