Reverse Energy Flows in Two-Dimensional Photonic Crystals and Analogies with Vortex Formation and Analogous Flows in Hydrodynamics

TL;DR

This paper explores how vortex-like energy flow patterns in two-dimensional photonic crystals influence band-gap formation and transmission, drawing analogies with fluid vortex phenomena.

Contribution

It reveals the connection between Poynting vector vortices and photonic band-gap formation, highlighting the role of energy flow patterns in photonic crystal behavior.

Findings

Reverse energy flows originate from vortex structures in the Poynting vector.

Vortex patterns determine whether energy is impeded or transmitted.

Analogies between electromagnetic energy flows and fluid vortex formation are established.

Abstract

This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab. We show that these reverse energy flows, observed in both transmitted and reflected fields, originate from vortex structures in the Poynting vector. The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles. The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded, leading to the formation of photonic band gaps, or instead guided through the structure, enabling transmission.