Electron beam driven generation of frequency-tunable isolated relativistic sub-cycle pulses

TL;DR

This paper introduces a new method to generate frequency-tunable, isolated, relativistic sub-cycle electromagnetic pulses using an electron beam and seed pulse reflection, supported by simulations and a fluid theory model.

Contribution

It presents a novel scheme combining electron beams and seed pulses for tunable sub-cycle pulse generation, with validation through simulations and theoretical modeling.

Findings

Amplification and frequency upshift demonstrated in simulations

Potential to produce mJ-strong mid-infrared sub-cycle pulses

Scheme compatible with current electron beam and terahertz sources

Abstract

We propose a novel scheme for frequency-tunable sub-cycle electromagnetic pulse generation. To this end a pump electron beam is injected into an electromagnetic seed pulse as the latter is reflected by a mirror. The electron beam is shown to be able to amplify the field of the seed pulse while upshifting its central frequency and reducing its number of cycles. We demonstrate the amplification by means of 1D and 2D particle-in-cell simulations. In order to explain and optimize the process, a model based on fluid theory is proposed. We estimate that using currently available electron beams and terahertz pulse sources, our scheme is able to produce mJ-strong mid-infrared sub-cycle pulses.