Coherent optical control of polarization with a critical metasurface

TL;DR

This paper demonstrates how a specially designed metasurface can coherently control and rotate the polarization of light beams precisely by tuning their relative phase, leveraging coupled-mode theory and PT symmetry concepts.

Contribution

It introduces a novel metasurface mechanism for phase-controlled polarization rotation based on critical coupled-mode theory and exceptional points.

Findings

Achieves precise polarization rotation with equal-power incident beams

Utilizes coupled-mode theory and PT symmetry to explain behavior

Operates at a critical point associated with exceptional points

Abstract

We describe the mechanism by which a metamaterial surface can act as an ideal phase-controlled rotatable linear polarizer. With equal-power linearly polarized beams incident on each side of the surface, varying the relative phase rotates the polarization angles of the output beams, while keeping the polarization exactly linear. The explanation is based on coupled-mode theory and the idea of coherent perfect absorption into auxiliary polarization channels. The polarization-rotating behavior occurs at a critical point of the coupled-mode theory, which can be associated with the exceptional point of a parity-time (PT) symmetric effective Hamiltonian.