Search results for "Elliptical polarization"

Impact excitation of 42 P-potassium by polarized electrons

1986

The present work investigates the 42 P impact excitation of potassium by longitudinally polarized electrons. Exchange scattering causes a polarization transfer from the primary electron beam to the ensemble of excited atoms which results in a non zero circular polarization of the fluorescence light emitted in foreward direction. The experimental values of light polarization agree well with values calculated using close coupling data of Moores.

Polarization Domain Wall Solitons with Counterpropagating Laser Beams

1998

The coupling between two intense laser beams in a nonlinear dielectric leads to a host of physical effects. In particular, the interaction between the polarization states of two counterpropagating ligth beams may generate polarization domain wall (PDW7) solitons [1]. We present what we believe is the first experimental observation of PDW7 soliton formation in a nonlinear dielectric medium.

The Elliptical Polarization of Light Scattered by a Volume of Atmospheric Air

2010

The scattering of linearly polarized light by aerosol particles produces partly polarized light whose ellipticity is theoretically and experimentally investigated for the specific case of a continental atmospheric aerosol in a volume of air. With the Mie theory and under the assumption of various aerosol size-distribution models, the ellipticity has been computed as a function of the scattering angle for various wavelengths. The computations have been based upon complex indices of refraction: M = 1.5-0.0i, M = 1.5-0.0li, M = 1.5-0.li, M = 1.44-0.0i, M = 1.4-0.0i, M = 1.33-0.0i. The comparison between computed and measured values for the wavelengths of lambda = 0.45 micro to lambda = 0.65 mi…

Poincaré sphere analysis of a ferroelectric liquid crystal optical modulator: application to optimize the contrast ratio

2008

The Poincare sphere representation is used to analyze the polarization transformation achieved with a ferroelectric liquid crystal (FLC) optical modulator. This device acts as a switchable wave-plate, in which the orientation of the principal axes rotates under the action of an applied bipolar voltage. In the standard operational mode for intensity switching, the rotation angle of the principal axes is �θ = π/4 and the phase shift is φ = π (half-wave-plate). However, for wavelengths different from the design one, the FLC deviates from the half-wave-plate performance and the optical contrast is diminished. We use the Poincare sphere representation to perform a theoretical analysis of the int…

Field-free molecular alignment of asymmetric top molecules using elliptically polarized laser pulses

2008

International audience; We show theoretically that a short specific elliptically polarized laser pulse driving an asymmetric top molecule can induce postpulse revivals of three-dimensional (3-D) alignment. By choosing the field ellipticity resulting in the best compromise between the alignment of two molecular axes, we demonstrate that efficient 3-D alignment can be achieved at low temperature. In the experiment, the field-free alignment of moderately cool ethylene molecules is probed by using a technique based on the optical Kerr effect. Control of 3-D field-free alignment opens the door to a large range of applications in chemistry as well as in molecular optics.

Imperfect symmetry breaking

2018

By considering a nonlinear resonator driven by an elliptically polarized beam, we study experimentally the robustness of spontaneous symmetry breaking to controlled asymmetries. In particular, we reveal that different asymmetries can balance each other.

Phase Conjugation in BaTiO/sub 3/ Using Orthogonally Polarized Light Waves

2005

Field-free molecular alignment induced by elliptically polarized laser pulses: Noninvasive three-dimensional characterization

2007

International audience; An investigation of field-free molecular alignment produced by elliptically polarized laser pulses is reported. Experiments are conducted in CO2 at room temperature. A noninvasive all-optical technique, based on the cross defocusing of a probe pulse, is used to measure the alignment along two orthogonal directions which is sufficient to provide a three-dimensional characterization. The field-free molecular alignment produced by a laser of elliptical polarization is in good agreement in terms of amplitude and shape with theoretical predictions. It turns out to be almost equivalent to the superposition of the effects that one would obtain with two individual cross-pola…