Electromagnetic wave analogue of electronic diode

TL;DR

This paper introduces a chiral electromagnetic diode that mimics electronic diodes by using nonlinear wave propagation effects in metamolecules, enabling highly asymmetric microwave transmission.

Contribution

It presents a novel electromagnetic diode based on nonlinear polarization changes in chiral metamolecules, surpassing natural crystal effects by over 12 orders of magnitude.

Findings

Achieves a 65-fold difference in transmission based on direction.

Demonstrates a nonlinear effect exceeding optical counterparts by 12 orders.

Provides a new approach for nonreciprocal microwave devices.

Abstract

An electronic diode is a nonlinear semiconductor circuit component that allows conduction of electrical current in one direction only. A component with similar functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of the polarization state rotation and is also a key component of optical and microwave systems. Here we demonstrate a chiral electromagnetic diode, which is a direct analogue of an electronic diode: its functionality is underpinned by an extraordinary strong nonlinear wave propagation effect in the same way as electronic diode function is provided by a nonlinear current characteristic of a semiconductor junction. The effect exploited in this new electromagnetic diode is an intensity-dependent polarization change in an artificial chiral metamolecule. This microwave effect exceeds a similar optical effect previously observed in natural crystals by more than 12 orders of magnitude and a direction-dependent transmission that differing by a factor of 65.