Reflectivity and Spectrum of Relativistic Flying Plasma Mirrors

TL;DR

This paper investigates the reflectivity and spectrum of relativistic flying plasma mirrors, proposing a new model for better reflectivity estimates and analyzing how frequency-dependent reflectivity affects the reflected photon spectrum.

Contribution

It introduces a new analytical model for plasma mirror reflectivity and examines the impact of frequency dependence on the reflected spectrum using PIC simulations.

Findings

Proposed a new model for plasma mirror reflectivity.

Discovered the peak frequency deviates from $4eta^2\omega$ due to frequency dependence.

Validated findings with one-dimensional PIC simulations.

Abstract

Flying plasma mirrors induced by intense lasers has been proposed as a promising way to generate few-cycle EUV or X-ray lasers. In addition, if such a relativistic plasma mirror can accelerate, then it would serve as an analog black hole to investigate the information loss paradox associated with the black hole Hawking evaporation. Among these applications, the reflectivity, which is usually frequency-dependent, would affect the outgoing photon spectrum and therefore impact on the analysis of the physics under investigation. In this paper, these two issues are investigated analytically and numerically with one-dimensional particle-in-cell (PIC) simulations. Based on our simulation results, we propose a new model that provides a better estimate of the reflectivity than those studied previously. Besides, we found that the peak frequency of the reflected spectrum of a gaussian incident wave deviates from the expected value, $4\gamma^2\omega$, due to the dependence of reflectivity on the frequency of the incident wave.