Accessible phases via wave impedance engineering with PT-symmetric metamaterials

TL;DR

This paper demonstrates how wave impedance engineering with PT-symmetric metamaterials enables new control over optical phases, including tuning exceptional points and phase re-entries, surpassing limitations of natural materials.

Contribution

It introduces a method to control wave impedance independently in PT-symmetric systems using metamaterials, allowing access to novel phase behaviors and re-entries.

Findings

Control of wave impedance via metamaterials enables tuning of Exceptional Points.

Access to mixed PT-symmetric and PT-broken phases.

Realization of phase re-entries not possible with natural materials.

Abstract

Optical systems that respect Parity-Time (PT) symmetry can be realized with proper incorporation of gain/loss materials. However, due to the absence of magnetic response at optical frequencies, the wave impedance is defined entirely by their permittivity and, hence, the PT-symmetric character is controlled solely via their refractive index. Here, we show that the separate control of the wave impedance enabled by metamaterials can grant access to further tuning of the Exceptional Points, appearance of mixed phases (coexistence of PT-symmetric and PT-broken phases) and occurrence of phase re-entries, not easily realizable with natural materials.