Simultaneous elliptically and radially polarized THz from one-color laser-induced plasma filament

Non-radially polarized THz pulse emitted from femtosecond laser filament in air.

Femtosecond laser filament could produce THz wave in forward direction. In our experiment, THz pulse emitted from a femtosecond laser filament has been investigated. It was found that the polarization of the studied THz pulse mainly appears as elliptical. This observation supplements the previous conclusion obtained by C. D'Amico et al. that THz wave emitted by a filament is radially polarized....

Generation of elliptically polarized terahertz waves from laser-induced plasma with double helix electrodes.

By applying a helical electric field along a plasma region, a revolving electron current is formed along the plasma and an elliptically polarized far-field terahertz wave pattern is observed. The observed terahertz wave polarization reveals the remarkable role of velocity retardation between optical pulses and generated terahertz pulses in the generation process. Extensive simulations, includin...

Generation of elliptically polarized nitrogen ion laser fields using two-color femtosecond laser pulses.

We experimentally investigate generation of nitrogen molecular ion (N2+) lasers with two femtosecond laser pulses at different wavelengths. The first pulse serves as the pump which ionizes the nitrogen molecules and excites the molecular ions to excited electronic states. The second pulse serves as the probe which leads to stimulated emission from the excited molecular ions. We observe that cha...

Intense and Broadband THz Source using Laser-Induced Gas Plasma

Elliptically polarized high-order harmonic emission from molecules in linearly polarized laser fields.

We perform an accurate polarimetry measurement of high-order harmonic emission from aligned molecules. We find that harmonic emission from N2 can be strongly elliptically polarized even when driven by linearly polarized laser fields. These data have broad implications for understanding molecules in strong fields because they cannot be explained by simple theories based on the strong field appro...