Wigner time for electromagnetic radiation in plasma

TL;DR

This paper investigates the Wigner time for electromagnetic waves tunneling through plasma layers, revealing plasma frequency as a key factor and discussing negative Wigner times in lossy plasmas, highlighting plasma's importance in tunneling physics.

Contribution

It provides analytical and numerical analysis of Wigner time in plasma layers, emphasizing plasma frequency's role and exploring effects of loss and polarization on tunneling times.

Findings

Plasma frequency governs Wigner time in plasma layers.

Negative Wigner times occur in lossy plasmas near plasma frequency.

Plasma layers are significant for tunneling studies.

Abstract

Wave tunneling is an intriguing phenomenon spanning different branches of physics, from quantum mechanics to classical electrodynamics and optics. The Wigner (or phase) time is proved to be an adequate measure to describe wave transit through a potential barrier or material layer in the tunneling regime. Here, we analytically and numerically calculate the Wigner time for electromagnetic-radiation propagation through the layer of both lossless and lossy plasmas. It is shown that the plasma frequency is the key parameter governing the value of Wigner time allowing us to interpret tunneling as due to the reaction of plasma as a whole. We analyze the Wigner time for obliquely incident waves of TE and TM polarizations and discuss the meaning of negative Wigner times appearing in the lossy case in the low-frequency range and close to the plasma frequency. The results show that plasma deserves attention as a perspective object for tunneling studies.