Efficiently Laser Driven Terahertz Surface Plasmon Polaritons on Long Metal Wire

TL;DR

This paper reports a highly efficient method to generate intense terahertz surface plasmon polaritons on a long metal wire using a subrelativistic femtosecond laser, achieving record energy conversion efficiency and potential for high-power applications.

Contribution

The study introduces a novel laser-driven scheme for generating high-efficiency, intense THz SPPs on a long metal wire, validated by experiments and simulations.

Findings

Achieved up to 2.4% laser-to-SPPs energy conversion efficiency.

Generated single-cycle ten-megawatt THz SPPs propagating over 25 cm.

Confirmed the excitation mechanism as coherent transition radiation from escaping electrons.

Abstract

We experimentally demonstrate a novel scheme for efficiently generating intense terahertz (THz) surface plasmon polaritons (SPPs) on a sub-wavelength-diameter meter-long metal wire. Driven by a subrelativistic femtosecond laser (a0=0.3, 3 mJ) focused at the wire's midpoint, single-cycle ten-megawatt THz SPPs are excited and propagating bidirectionally along it over 25 cm. The measured laser-to-SPPs energy conversion efficiency is reaching up to ~2.4%, which is the highest value at present. It is proved that the THz SPPs are excited by coherent transition radiation of the subrelativistic laser produced escaping electrons. Particle-in-cell together with CST simulations confirm the experimental observations. Our scheme of using readily available subrelativistic laser should thus be useful to applications requiring terawatt level single-cycle THz SPPs.