Enhance terahertz radiation and its polarization- control with two paralleled filaments pumped by two-color femtosecond laser fields

Abstract

We present experimentally an obvious enhancement of the terahertz (THz) radiation with two paralleled filaments pumped by two-color laser fields for a full use of a high laser power, compared with single filament. By mapping the 3-dimensional electric trajectories of generated THz fields with a (111) ZnTe crystal, we observe that the total THz polarization from two filaments can be manipulated by varying the time delay between the two orthogonally polarized pumps, which agrees well with the simulations under the photocurrent model. Notably, the power and spectrum of the THz field almost keep unchanged while manipulating the ellipticity of the THz polarization, which is important for a polarization-controllable THz source.

Plasma-based terahertz wave photonics in gas and liquid phases

“…There are mainly three methods used for the THz emission from laser-ionized gas plasma, as illustrated in Fig. 1: (1) single-wavelength laser excitation is utilized to generate plasma in gaseous media for THz wave emission via the ponderomotive force [8,56,57] ; (2) a fundamental laser beam at ω is focused through a β-barium borate (β-BBO or BBO) crystal to produce a second-harmonic (SH) beam at 2ω, which is then mixed with the residual unconverted ω beam in the plasma to create very stronger THz waves [9,10,58–68] , in comparison with that in the first case; and (3) an interferometric phase compensator (PC) based on a two-color Mach–Zehnder interferometer (not displayed in the figure) is used to combine the ω and 2ω beams with a dichroic mirror. Such a PC can control the polarization and phase of each optical beam individually for coherent control of the THz emission [11] .…”

Powerful Elliptically Polarized Terahertz Radiation from Oscillating-Laser-Driven Discharge Surface Currents

“…Some schemes involve additionally static external fields, such as strong magnetic fields of a few hundred Tesla [34] or electric fields of a special geometry [35]. Some other propositions deal with different combinations of pumping laser beams with different intensities, wavelengths, or polarizations [36,37]. However, these are usually schemes driven with TW-class fs lasers and with ∼10 −3 .…”

Frequency tuning for broadband terahertz emission from two-color laser-induced air plasma

“…Of particular interest for these applications, laser-induced air plasma is a prevalent way to generate terahertz emission due to its high field strength, broad spectrum, and high flexibility [9][10][11][12][13]. For example, effective manipulation of terahertz emission polarization [14,15], carrier envelope phase [16] as well as spectrum [12,17] have been realized, which greatly enriches its application scenarios.…”