Tunable Circularly Polarized Terahertz Radiation from Magnetized Gas Plasma

TL;DR

This paper demonstrates, through simulation and theory, that applying a static magnetic field to a gas target during two-color laser irradiation can generate tunable circularly polarized terahertz radiation with controllable frequency, spectrum, and strength.

Contribution

It introduces a novel method to generate tunable circularly polarized terahertz radiation using a magnetized gas plasma, with detailed theoretical and simulation analysis of the underlying mechanisms.

Findings

Radiation frequency depends on plasma and cyclotron frequencies.

Increasing magnetic field narrows the emission spectrum.

Radiation strength scales with plasma and magnetic parameters.

Abstract

It is shown, by simulation and theory, that circularly or elliptically polarized terahertz radiation can be generated when a static magnetic (B) field is imposed on a gas target along the propagation direction of a two-color laser driver. The radiation frequency is determined by $\sqrt{\omega_p^2+{\omega_c^2}/{4}} + {\omega_c}/{2}$, where $\omega_p$ is the plasma frequency and $\omega_c$ is the electron cyclotron frequency. With the increase of the B field, the radiation changes from a single-cycle broadband waveform to a continuous narrow-band emission. In high-B-field cases, the radiation strength is proportional to $\omega_p^2/\omega_c$. The B field provides a tunability in the radiation frequency, spectrum width, and field strength.