scholarly journals Inducing Enantiosensitive Permanent Multipoles in Isotropic Samples with Two-Color Fields

2021 ◽  
pp. 335-352
Author(s):  
Andres F. Ordonez ◽  
Olga Smirnova
Keyword(s):  
Relative Phase ◽  
Electronic Excitation ◽  
Polarization Plane ◽  
Chiral Molecules ◽  
Induce Field ◽  
Uniaxial Orientation ◽  
Linearly Polarized ◽  
3 Omega ◽  
Excited Molecules

AbstractWe find that two-color fields can induce field-free permanent dipoles in initially isotropic samples of chiral molecules via resonant electronic excitation in a one-$$3\omega $$ 3 ω -photon versus three-$$\omega $$ ω -photons scheme. These permanent dipoles are enantiosensitive and can be controlled via the relative phase between the two colors. When the two colors are linearly polarized perpendicular to each other, the interference between the two pathways induces excitation sensitive to the molecular handedness and orientation, leading to uniaxial orientation of the excited molecules and to an enantio-sensitive permanent dipole perpendicular to the polarization plane. We also find that although a corresponding one-$$2\omega $$ 2 ω -photon versus two-$$\omega $$ ω -photons scheme cannot produce enantiosensitive permanent dipoles, it can produce enantiosensitive permanent quadrupoles that are also controllable through the two-color relative phase.

scholarly journals Constraints on Lorentz Invariance Violation with Multiwavelength Polarized Astrophysical Sources

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 44
Author(s):  
Qi-Qi Zhou ◽  
Shuang-Xi Yi ◽  
Jun-Jie Wei ◽  
Xue-Feng Wu
Keyword(s):  
Gamma Ray ◽  
Lorentz Invariance ◽  
Polarized Light ◽  
Polarization Plane ◽  
Polarization Angle ◽  
Intrinsic Polarization ◽  
Frequency Dependent ◽  
Invariance Violation ◽  
Linearly Polarized ◽  
Order Of Magnitude

Possible violations of Lorentz invariance (LIV) can produce vacuum birefringence, which results in a frequency-dependent rotation of the polarization plane of linearly polarized light from distant sources. In this paper, we try to search for a frequency-dependent change of the linear polarization angle arising from vacuum birefringence in the spectropolarimetric data of astrophysical sources. We collect five blazars with multiwavelength polarization measurements in different optical bands (UBVRI). Taking into account the observed polarization angle contributions from both the intrinsic polarization angle and the rotation angle induced by LIV, and assuming that the intrinsic polarization angle is an unknown constant, we obtain new constraints on LIV by directly fitting the multiwavelength polarimetric data of the five blazars. Here, we show that the birefringence parameter η quantifying the broken degree of Lorentz invariance is limited to be in the range of −9.63×10−8<η<6.55×10−6 at the 2σ confidence level, which is as good as or represents one order of magnitude improvement over the results previously obtained from ultraviolet/optical polarization observations. Much stronger limits can be obtained by future multiwavelength observations in the gamma-ray energy band.

ROTATIONAL PROPERTIES OF MICRO-SLABS DRIVEN BY LINEARLY-POLARIZED LIGHT

2005 ◽  
Vol 14 (03) ◽  
pp. 375-382 ◽  
Author(s):  
CHIH-LANG LIN ◽  
IRÈNE WANG ◽  
MARC PIERRE ◽  
ISABELLE COLOMBIER ◽  
CHANTAL ANDRAUD ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Polarized Light ◽  
Polarization Plane ◽  
Light Polarization ◽  
Good Prediction ◽  
Polarization Anisotropy ◽  
Two Photon ◽  
Flat Slabs ◽  
Linearly Polarized ◽  
Optical Torque

We study the rotational motion of objects trapped in a focused laser beam (optical tweezers). Micrometer-sized flat slabs are fabricated using two-photon photopolymerization. These objects, trapped by linearly-polarized light, tend to align parallel to the polarization plane. This alignment effect is attributed to the polarization anisotropy resulting from the object shape and we present a simple electromagnetic approach to estimate the resulting optical torque. Micro-rotors of different sizes are studied experimentally. We characterize the behavior of micro-objects when the light polarization is rotated at constant speed. Our theoretical approach gives a good prediction of how the size of micro-objects affects their rotation efficiency.

scholarly journals Decomposing the internal faraday rotation of black hole accretion flows

2020 ◽  
Vol 498 (4) ◽  
pp. 5468-5488
Author(s):  
Angelo Ricarte ◽  
Ben S Prather ◽  
George N Wong ◽  
Ramesh Narayan ◽  
Charles Gammie ◽  
...  
Keyword(s):  
Event Horizon ◽  
Faraday Rotation ◽  
Polarization Plane ◽  
Time Variability ◽  
Accretion Flows ◽  
Spatially Resolved ◽  
Rotation Measure ◽  
Linearly Polarized ◽  
General Relativistic ◽  
Sgr A

ABSTRACT Faraday rotation has been seen at millimeter wavelengths in several low-luminosity active galactic nuclei, including Event Horizon Telescope (EHT) targets M87* and Sgr A*. The observed rotation measure (RM) probes the density, magnetic field, and temperature of material integrated along the line of sight. To better understand how accretion disc conditions are reflected in the RM, we perform polarized radiative transfer calculations using a set of general relativistic magnetohydrodynamic (GRMHD) simulations appropriate for M87*. We find that in spatially resolved millimetre wavelength images on event horizon scales, the RM can vary by orders of magnitude and even flip sign. The observational consequences of this spatial structure include significant time-variability, sign-flips, and non-λ2 evolution of the polarization plane. For some models, we find that internal RM can cause significant bandwidth depolarization even across the relatively narrow fractional bandwidths observed by the EHT. We decompose the linearly polarized emission in these models based on their RM and find that emission in front of the mid-plane can exhibit orders of magnitude less Faraday rotation than emission originating from behind the mid-plane or within the photon ring. We confirm that the spatially unresolved (i.e. image integrated) RM is a poor predictor of the accretion rate, with substantial scatter stemming from time variability and inclination effects. Models can be constrained with repeated observations to characterize time variability and the degree of non-λ2 evolution of the polarization plane.

Turbidity and the Polarized Light Orientation of the Crustacean Mysidium

1958 ◽  
Vol 35 (3) ◽  
pp. 487-493 ◽  
Author(s):  
RICHARD BAINBRIDGE ◽  
TALBOT H. WATERMAN
Keyword(s):  
Sea Water ◽  
Polarized Light ◽  
Polarization Plane ◽  
Careful Consideration ◽  
Light Illumination ◽  
Turbid Water ◽  
Significant Preference ◽  
Directional Orientation ◽  
Linearly Polarized ◽  
Vertical Beam

1. The influence of the turbidity of the medium on the previously reported directional orientation of the littoral mysid, Mysidium gracile, swimming in a vertical beam of linearly polarized light, has been studied. 2. In carefully clarified sea water the slight preference shown for orientation perpendicular to the polarization plane was not statistically significant. 3. In water made turbid with known amounts of suspended yeast a statistically significant preference for swimming perpendicular to the plane of polarization appeared. 4. This response to the pattern of plarized light illumination appears strontger in highly turbid water than it is in water of moderate turbidity. 5. The mechanism of the observed response seems largely depedent upon discrimination of intensity differences in the light scattered horizontally. 6. These results emphasize the need for careful consideration of the scattering and reflexion artifacts almost invariably present with linearly polarized light.

scholarly journals Research on beam bunching and deflection characteristics of low-power laser under the electromagnetic effect

2019 ◽  
Vol 52 (5-6) ◽  
pp. 379-386
Author(s):  
Chi Zhang ◽  
Yonghua Lu ◽  
Jing Li ◽  
Rui Wang
Keyword(s):  
Experimental Data ◽  
Low Power ◽  
Polarized Light ◽  
Polarization Plane ◽  
Least Square ◽  
Small Range ◽  
Power Laser ◽  
Coil Current ◽  
Optical Elements ◽  
Linearly Polarized

The bunching and deflection characteristics of low-power laser beam were investigated under electromagnetic field. On the basis of the Faraday effect, the cylindrical electromagnetic cavity was designed and implemented in the experiments. Several types of the magneto-optical elements were placed in the electromagnetic cavity individually. In the test of the deflection characteristics of low-power laser, the rotating angle, the polarization plane of linearly polarized light which passed through electromagnetic cavity, was measured by polarization extinction. We focus on the relation between the coil current and the rotating angle. The experimental data show that when the coil current varies in the range of 0–5 A, the rotating angles changed from 0° to 24.1°. Then, a fitting formula about the coil current and the rotating angle was obtained from the experimental data using the least square algorithm. The analysis shows that the rotating angle is proportional to the excitation current and the correlation coefficient is more than 0.9995. In order to study the beam bunching characteristics of low-power laser, the area of the laser facula was measured after the low-power laser passed through the electromagnetic cavity. The experiment data show that the laser facula area changes in a small range and the experimental data meet 3σ criteria.

scholarly journals Ellipticity of High-Order Harmonics Generated by Aligned Homonuclear Diatomic Molecules Exposed to an Orthogonal Two-Color Laser Field

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 110 ◽  
Author(s):  
Dino Habibović ◽  
Dejan B. Milošević
Keyword(s):  
Molecular Orbital ◽  
Laser Field ◽  
Molecular Orientation ◽  
Relative Phase ◽  
Emission Rate ◽  
Polarization Plane ◽  
High Energy ◽  
High Order ◽  
Destructive Interference ◽  
Atomic Orbitals

We investigate emission rate and ellipticity of high-order harmonics generated exposing a homonuclear diatomic molecule, aligned in the laser-field polarization plane, to a strong orthogonally polarized two-color (OTC) laser field. The linearly polarized OTC-field components have frequencies rω and sω, where r and s are integers. Using the molecular strong-field approximation with dressed initial state and undressed final state, we calculate the harmonic emission rate and harmonic ellipticity for frequency ratios 1:2 and 1:3. The obtained quantities depend strongly on the relative phase between the laser-field components. We show that with the OTC field it is possible to generate elliptically polarized high-energy harmonics with high emission rate. To estimate the relative phase for which the emission rate is maximal we use the simple man’s model. In the harmonic spectra as a function of the molecular orientation there are two types of minima, one connected with the symmetry of the molecular orbital and the other one due to destructive interference between different contributions to the recombination matrix element, where we take into account that the electron can be ionized and recombine at the same or different atomic centers. We derive a condition for the interference minima. These minima are blurred in the OTC field except in the cases where the highest occupied molecular orbital is modeled using only s or only p orbitals in the linear combination of the atomic orbitals. This allows us to use the interference minima to assess which atomic orbitals are dominant in a particular molecular orbital. Finally, we show that the harmonic ellipticity, presented in false colors in the molecular-orientation angle vs. harmonic-order plane, can be large in particular regions of this plane. These regions are bounded by the curves determined by the condition that the harmonic ellipticity is approximately zero, which is determined by the minima of the T-matrix contributions parallel and perpendicular to the fundamental component of the OTC field.

scholarly journals Nondipole Effects in Chiral Molecules Measured with Linearly Polarized Light

2015 ◽  
Vol 635 (11) ◽  
pp. 112053
Author(s):  
K P Bowen ◽  
O Hemmers ◽  
R Guillemin ◽  
W C Stolte ◽  
M N Piancastelli ◽  
...  
Keyword(s):  
Polarized Light ◽  
Chiral Molecules ◽  
Linearly Polarized
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