Strong terahertz radiation from relativistic laser interaction with solid density plasmas

TL;DR

This paper demonstrates a strong, linearly polarized terahertz radiation source generated by relativistic laser interaction with solid targets, with potential applications in nonlinear THz physics.

Contribution

It reports the first observation of high-energy THz pulses from relativistic laser-solid interactions, highlighting a new plasma-based THz generation mechanism.

Findings

Up to 50 microjoules per steradian of THz energy observed.

THz radiation is linearly polarized.

Temporal and spectral properties characterized by electro-optic sampling.

Abstract

We report a plasma-based strong THz source generated by using intense femtosecond laser pulses to irradiate solid targets at relativistic intensity >10^18W/cm2. Energies up to 50 microJ/sr per THz pulse is observed in the specular direction when the laser pulses are incident onto a copper foil at 67.5 degree. The source appears to be linearly polarized. The temporal, spectral properties of the THz are measured by a single shot, electro-optic sampling method with a chirped laser pulse. The THz radiation is attributed to the self-organized transient fast electron currents formed along the target surface. Such a strong THz source allows potential applications in THz nonlinear physics.