Enhanced Terahertz Emission from the Wakefield of CO2 Laser-Created Plasma

TL;DR

This study demonstrates that intense CO2 laser pulses interacting with helium gas can generate highly efficient, high-amplitude terahertz pulses through plasma wakefield mechanisms, with potential for surpassing previous THz field strengths.

Contribution

It reveals a new regime for THz generation using single-color CO2 laser pulses in plasma wakefield interactions, achieving unprecedented field amplitudes.

Findings

THz pulses with amplitudes reaching hundreds of GV/m.

Efficiency depends on target density and laser pulse duration.

Synergistic effects of self-modulation, self-focusing, and pump depletion enhance THz generation.

Abstract

High-field terahertz (THz) pulse generation is investigated through the interaction of an intense single-color CO2 laser pulse with helium (He) gas targets. Employing multi-dimensional Particle-In-Cell (PIC) simulations, this study reveals a substantial enhancement in THz generation efficiency, even with a single-color laser pulse interacting with gas targets in the self-modulated-laser-wakefield (SMLWF) regime. Our study demonstrates that in the presence of photoionization, a synergistic interplay of laser self-modulation, self-focusing, and local pump depletion leads to the generation of robust THz pulses polarized parallel to the laser electric field. The dependence of THz generation efficiency on target density and laser pulse duration has been investigated. Our study identifies a favourable parametric regime for producing THz fields with amplitudes reaching hundreds of GV/m, surpassing those reported in previous studies.