An investigation on THz yield from laser-produced solid density plasmas at relativistic laser intensities

S Herzer,G G Paulus,A Gopal,U Hübner,A Reinhard,M Almassarani,J Polz,F Ronneberger,R Grosse,T May,B Beleites,A Woldegeorgis

doi:10.1088/1367-2630/aaada0

Abstract

We experimentally characterize the generation of high-power terahertz radiation (THz) at the rear surface of a target irradiated by multiple laser pulses. A detailed dependence of the THz yield as a function of laser pulse duration, energy, target material and thickness is presented. We studied the THz radiation emitted mainly in two directions from the target rear surface, namely target normal (acceptance angle 0.87 sr) and non-collinear direction (perpendicular to the target normal direction—acceptance angle 4.12 sr). Independent measurements based on electro-optic diagnostics and pyroelectric detector were employed to estimate the THz yield. Most of the energy is emitted at large angles relative to the target normal direction. THz yield increases with incident laser intensity and thinner targets are better emitters of THz radiation compared to thicker ones.

Highlights

High-power laser matter interaction has been a subject of extensive experimental and theoretical investigations over the last few decades
Spatio-temporal characterization of THz pulse As mentioned in the previous section, the terahertz radiation generated at the target rear surface was measured for two regions, in the forward (FE or target normal direction—acceptance angle of 0.87 sr) and non-collinear direction (NC—perpendicular to the target normal direction—acceptance angle of 4.12 sr)
We have presented an extensive study on the high-power terahertz emission from the target rear surface during high-power laser–solid interaction

Summary

Introduction

High-power laser matter interaction has been a subject of extensive experimental and theoretical investigations over the last few decades. In recent years we have witnessed a remarkable interest in utilizing this process for coherent terahertz generation [6,7,8] This is due to the fact that the plasma produced during such an interaction has many advantages over other well established terahertz generation methods due to their compactness, high damage threshold and high conversion efficiency [7]. Table-top short-pulse lasers are tested workhorses of todays university scale laboratories Interaction of these focused laser pulses with matter in solid or gaseous form can ionize the matter and generate plasmas whose dynamics is affected by the properties of the interacting laser pulse as well as the medium. In the case of terahertz generation solid targets have the upper edge due to high electron density and low re-absorption etc

Methods

Results

Conclusion