# Coherent diffraction radiation of relativistic terahertz pulses from a laser-driven micro-plasma-waveguide

## TL;DR

This paper presents a novel method to generate high-energy, tunable relativistic terahertz pulses using a laser-driven micro-plasma-waveguide, with simulations demonstrating 100-mJ pulses at existing laser facilities.

## Contribution

It introduces a new approach combining high-power lasers and micro-plasma-waveguides to produce intense, tunable THz pulses via coherent diffraction radiation.

## Key findings

- Relativistic THz pulses of 100 mJ can be generated.
- The radiation frequency depends on the laser pulse duration.
- The energy correlates with electron bunch charge controlled by laser intensity.

## Abstract

We propose a method to generate isolated relativistic terahertz (THz) pulses using a high-power laser irradiating a mirco-plasma-waveguide (MPW). When the laser pulse enters the MPW, high-charge electron bunches are produced and accelerated to ~ 100 MeV by the transverse magnetic modes. A substantial part of the electron energy is transferred to THz emission through coherent diffraction radiation as the electron bunches exit the MPW. We demonstrate this process with three-dimensional particle-in-cell simulations. The frequency of the radiation is determined by the incident laser duration, and the radiated energy is found to be strongly correlated to the charge of the electron bunches, which can be controlled by the laser intensity and micro-engineering of the MPW target. Our simulations indicate that 100-mJ level relativistic-intense THz pulses with tunable frequency can be generated at existing laser facilities, and the overall efficiency reaches 1%.