Optical isolation via unidirectional resonant photon tunneling

TL;DR

This paper introduces a novel tri-layer structure that enables unidirectional resonant photon tunneling, allowing for optical isolation of circularly polarized waves based on their handedness, with practical design guidelines and performance analysis.

Contribution

It presents a new physical mechanism and analytical design framework for optical isolators using epsilon-negative and magneto-optical materials for circular polarization.

Findings

Achieves unidirectional photon tunneling for CP waves

Provides analytical conditions and design formulas

Quantifies isolation performance considering imperfections

Abstract

We show that tri-layer structures combining epsilon-negative and magneto-optical material layers can exhibit unidirectional resonant photon tunneling phenomena that can discriminate between circularly-polarized (CP) waves of given handedness impinging from opposite directions, or between CP waves with different handedness impinging from the same direction. This physical principle, which can also be interpreted in terms of a Fabry-Perot-type resonance, may be utilized to design compact optical isolators for CP waves. Within this framework, we derive simple analytical conditions and design formulae, and quantitatively assess the isolation performance, also taking into account the unavoidable imperfections and nonidealities.