Generation of Radio Frequency Radiation by Femtosecond Filaments

TL;DR

This paper explains how femtosecond filamentation plasmas generate broadband radio frequency radiation through plasma wake fields and surface waves, with a model accurately predicting experimental results across different laser systems.

Contribution

The authors develop a four-stage model of plasma wake surface waves that explains RF generation in femtosecond filaments, validated by diverse experimental data.

Findings

The model accurately predicts RF from 800 nm and 3.9 μm laser systems.

Plasma wake fields and surface waves are key to RF generation.

Experimental results match the model's predictions.

Abstract

Recent experiments have shown that femtosecond filamentation plasmas generate ultra-broadband radio frequency radiation (RF). We show that a combination of plasma dynamics is responsible for the RF: a plasma wake field develops behind the laser pulse, and this wake excites (and copropagates with) a surface wave on the plasma column. The surface wave proceeds to detach from the end of the plasma and propagates forward as the RF pulse. We have developed a four stage model of these plasma wake surface waves and find that it accurately predicts the RF from a wide range of experiments, including both 800 nm and 3.9 $\mu$m laser systems.