Extension of Babinet's relations to reflective metasurfaces: Application to the simultaneous control of wavefront and polarization

TL;DR

This paper extends Babinet's relations to reflective metasurfaces with metallic structures, enabling simultaneous control of wavefront and polarization, demonstrated through theoretical and experimental terahertz applications.

Contribution

It introduces an extension of Babinet's relations to reflective metasurfaces with self-complementary structures, enabling advanced wavefront and polarization control.

Findings

Demonstrated a reflective metasurface half-wave plate in terahertz frequencies.

Achieved simultaneous anomalous reflection and polarization conversion with high efficiency.

Validated the extended Babinet's relations through theoretical and experimental results.

Abstract

We extend Babinet's relations, which are originally derived for transmissive metasurfaces, to reflective metasurfaces embedding planar metallic structures in a substrate containing a reflection mirror. To verify the extended Babinet's relations, we investigate two types of reflective metasurfaces embedding self-complementary structures, which produce $\pi$-phase difference between two orthogonal linear polarizations under specific conditions required for the extended Babinet's relations. Both theoretical and experimental studies demonstrate a metasurface-based half-wave plate with a reflective metasurface including single self-complementary structures in the terahertz regions. In addition, we study a reflective metasurface with embedded self-complementary structures with phase gradient in reflection, and demonstrate simultaneous implementation of anomalous reflection and polarization conversion with high efficiency.