Measurement of birefringence inside a filament

Abstract

We quantified the ultrafast birefringence induced in the filament in an atomic gas by measuring the filamentinduced polarization rotation of a probe pulse. Based on the dephasing of the probe's orthogonal polarization components in argon, the experiment was done at 1 atm by copropagating a linearly polarized 400-nm probe pulse with an 800-nm pump pulse which generated the filament. The probe's elliptical polarization states were shown under various initial pump-probe polarization schemes. These states were verified by comparing the filament-induced probe polarization rotation angle and the ellipticity of the probe polarization.

Pulse polarization evolution and control in the wake of molecular alignment inside a filament

“…After the filament, the probe pulse was analyzed by a polarizer and the resulting transmission was projected on a white paper screen. A CCD camera was used to detect the probe scattering from the paper [6,7]. Here the signal was measured by a CCD camera rather than a photodiode, since we were also trying to investigate the alignment-induced spatial (de)focusing effects during our experiment.…”

“…Filamentation induced birefringence in isotropic gas media has attracted increasing attentions owing to its remarkable effects on the spatial and spectral reshaping of a probing pulse [1][2][3][4]. In atomic gases, the ultrafast birefringence was quantified by measuring the filament-induced polarization change of a probe pulse [5][6][7][8]. In molecular gases, besides this instantaneous electronic response, a delayed birefringence was induced by the molecular alignment and revivals.…”

“…al [5] has elaborated the pressure (de-phasing) dependence of the polarization diagram of a probe beam driven by an ultrashort laser filament in an argon cell, with an initial angle of 45° between the linear polarizations of the pump and the probe. More recently, the ultrafast birefringence was quantified in argon by measuring the filamentinduced polarization rotation of a probe pulse [6]. However, detailed measurement of the response of the probe's polarization states caused by molecular alignment induced delayed birefringence has been left aside to date.…”

Polarization-dependent study of THz air-biased coherent detection

“…This verifies that the underlying physical connection between the FW polarization rotation angle and the SH polarization state variation after the plasma is because of the air plasma birefringence. The TFISH ellipticity can also be calculated with the following equation [20,21]:…”

Loss of Polarization in Collapsing Beams of Elliptical Polarization

“…Since several applications of laser filamentation including HHG, THz generation and supercontinuum generation are polarization sensitive [37][38][39], investigating the polarization state of collapsing beams is crucial [40][41][42]. In some of the studies, molecular alignment and delayed birefringence acting on the probe were investigated [43][44][45]. In case of self-induced polarization rotation of the pump, direct measurements [46] using a rotating polarizing cube and indirect measurements [47] using femtosecond laser-induced periodic surface structures (FLIPSS) have observed moderate rotations of the polarization angle pre-and post-collapse.…”