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

Abstract

Abstract:Femtosecond laser filament could produce THz wave at forward direction. In our experiment, THz pulse emitted from a femtosecond laser filament has been investigated. It is 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. The mechanism of generating elliptically polarized THz wave has been interpreted by either four-wave optical rectification or second order optical rectification inside the filament zone where centro-symmetry of the air is broken by the femtosecond laser pulse.

Coherent Polarization Control of THz Waves Generated from Asymmetrically Ionized Gases

“…This result is basically consistent with the recent result reported by S.L. Chin's group [21]. Furthermore, our results indicate that, as the relative optical phase changes by 2π, the polarization direction of the THz wave rotates one complete circle accordingly when at least one optical pulse is elliptically polarized.…”

Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses

“…The elliptical polarization of the strong forward (0 ) radiation suggests a contribution from four-wave (FW) mixing in the presence of spontaneous second harmonic (SH) light. 16 To test this hypothesis experimentally, we relied on the fact that THz power linearly depends on SH intensity in FW mixing. 5,6 As shown in Fig.…”

Detection of the polarization spatial distribution of THz radiation generated by two-color laser filamentation

“…The X-Y graph shows a closed curve, which can be depicted by the ellipse with an ellipticity parameter and an axis tilt [17,18]. Fig.…”

“…Previously [14,16], it has been shown that the integrated field of the THz beam has a radial polarization. In the latest research, these results have been supplemented with the fact that the polarization of the THz field has an elliptic structure [17,18]. This fact can be explained by a four-wave optical rectification [19].…”