Tunable Circularly Polarized Terahertz Radiation from Magnetized Gas Plasma

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 $\sqrt{ω_p^2+{ω_c^2}/{4}} + {ω_c}/{2}$, where $ω_p$ is the plasma frequency and $ω_c$ 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 $ω_p^2/ω_c$. The B field provides a tunability in the radiation frequency, spectrum width, and field strength.

6 pages, 5 figures