scholarly journals Direct discrimination of structured light by humans

2020 ◽  
Vol 117 (26) ◽  
pp. 14682-14687 ◽  
Author(s):  
Dusan Sarenac ◽  
Connor Kapahi ◽  
Andrew E. Silva ◽  
David G. Cory ◽  
Ivar Taminiau ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Circular Polarization ◽  
Success Probability ◽  
Direct Perception ◽  
Spin Orbit ◽  
Average Sensitivity ◽  
Spatial Modes ◽  
Direct Discrimination ◽  
Left Circular Polarization ◽  
Psychophysical Study

We predict and experimentally verify an entoptic phenomenon through which humans are able to perceive and discriminate optical spin–orbit states. Direct perception and discrimination of these particular states of light with polarization-coupled spatial modes is possible through the observation of distinct profiles induced by the interaction between polarization topologies and the radially symmetric dichroic elements that are centered on the foveola in the macula of the human eye. A psychophysical study was conducted where optical states with a superposition of right and left circular polarization coupled to two different orbital angular momentum (OAM) values (ℓ1andℓ2) were directed onto the retina of participants. The number of azimuthal fringes that a human sees when viewing the spin–orbit states is shown to be equal to the number (N) of radial lines in the corresponding polarization profile of the beam, whereN=|(ℓ1−ℓ2)−2|. The participants were able to correctly discriminate between two states carrying OAM=7and differentiated byN=5andN=9, with an average success probability of 77.6% (average sensitivityd′=1.7,t(9)=5.9,p=2×10−4). These results enable methods of robustly characterizing the structure of the macula, probing retina signaling pathways, and conducting experiments with human detectors and optical states with nonseparable modes.

scholarly journals Determination of the beam waist position for the spin-orbit interaction effect observation

2021 ◽  
Vol 5 (45) ◽  
pp. 661-666
Author(s):  
E.A. Bibikova ◽  
N.D. Kundikova ◽  
A.A. Shulginov ◽  
N. Al-Wassiti
Keyword(s):  
Angular Momentum ◽  
Circular Polarization ◽  
Polarized Light ◽  
Longitudinal Component ◽  
Beam Waist ◽  
Orbit Interaction ◽  
Spin Orbit ◽  
Spin Orbit Interaction ◽  
Sign Change ◽  
Polarization Sign

The spin angular momentum and the extrinsic orbital angular momentum of light are associated with the polarization of light and the light propagation trajectory, respectively. Those momenta are interdependent not only in an inhomogeneous or anisotropic medium but even in free space. This interaction is called the spin-orbit interaction of light. The effects of the spin-orbit interaction of light manifest themselves in a small transverse shift of the beam field longitudinal component from the beam propagation axis in the waist region under the circular polarization sign change. They can be observed both for Gaussian beams and for structured beams. The effects of the spin-orbit interaction of light should be taken into account when nanophotonics devices are created, but the detailed investigation of the effect had not been performed yet due to the low intensity noise image of the beam waist. Precise measurements of the focal waist centerline are needed to determine the transverse shift of the beam field longitudinal component of the asymmetric converging beam's waist under the circular polarization sign change. We propose methods for determining the transverse and longitudinal positions of the beam waist. Computer image processing methods made it possible to obtain the value of the beam waist's transverse position with an accuracy of 0.1 mkm. These methods will allow further testing of the shifts' theoretical predictions, the values of which are the order of 1 mkm. The results obtained can also be used for laser processing of materials by polarized light and precise positioning of the beam's focal spot at a surface.

scholarly journals Current-induced spin–orbit torques

2011 ◽  
Vol 369 (1948) ◽  
pp. 3175-3197 ◽  
Author(s):  
Pietro Gambardella ◽  
Ioan Mihai Miron
Keyword(s):  
Angular Momentum ◽  
Exchange Coupling ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Inversion Symmetry ◽  
Spin Orbit ◽  
Great Flexibility ◽  
Combined Action ◽  
Proper Material

The ability to reverse the magnetization of nanomagnets by current injection has attracted increased attention ever since the spin-transfer torque mechanism was predicted in 1996. In this paper, we review the basic theoretical and experimental arguments supporting a novel current-induced spin torque mechanism taking place in ferromagnetic (FM) materials. This effect, hereafter named spin–orbit (SO) torque, is produced by the flow of an electric current in a crystalline structure lacking inversion symmetry, which transfers orbital angular momentum from the lattice to the spin system owing to the combined action of SO and exchange coupling. SO torques are found to be prominent in both FM metal and semiconducting systems, allowing for great flexibility in adjusting their orientation and magnitude by proper material engineering. Further directions of research in this field are briefly outlined.

Transmissive 2-bit anisotropic coding metasurface

2022 ◽  
Author(s):  
Pengtao Lai ◽  
Zenglin Li ◽  
Wei Wang ◽  
Jia Qu ◽  
Liang Wei Wu ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Electromagnetic Wave ◽  
Circular Polarization ◽  
Orbital Angular Momentum ◽  
Electromagnetic Waves ◽  
Beam Splitter ◽  
Far Field ◽  
Polarization Conversion ◽  
Field Patterns ◽  
Phase Profile

Abstract Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave. However, archiving transmissive coding metasurface is still challenging. Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations. The polarization beam splitter and the OAM generator have been studied as typical applications of anisotropic 2-bit coding metasurface. The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions, respectively. The anisotropic coding metasurface has been experimentally verified to realize an orbital angular momentum (OAM) beam with l = 2 of right-handed polarized wave, resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation. This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.

scholarly journals Circular-Polarization-Selective Transmission Induced by Spin-Orbit Coupling in a Helical Tape Waveguide

2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Yahong Liu ◽  
Qinghua Guo ◽  
Hongchao Liu ◽  
Congcong Liu ◽  
Kun Song ◽  
...  
Keyword(s):  
Circular Polarization ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit

Spin-Orbital Angular Momentum of Light and Its Application

2020 ◽  
Vol 29 (10) ◽  
pp. 28-31
Author(s):  
Teun-Teun KIM
Keyword(s):  
Angular Momentum ◽  
Quantum Entanglement ◽  
Orbital Angular Momentum ◽  
Phase Distribution ◽  
Optical Vortex ◽  
Spin Orbit ◽  
Vortex Beam ◽  
Spin Orbital ◽  
Matter Interaction ◽  
Light Matter Interaction

Like the eletron, the photon carries spin and orbital angular momentum caused by the polarization and the spatial phase distribution of light, respectively. Since the first observation of an optical vortex beam with orbital angular momentum (OAM), the use of an optical vortex beam has led to further studies on the light-matter interaction, the quantum nature of light, and a number of applications. In this article, using a metasurface with geometrical phase, we introduce the fundamental origins and some important applications of light with spin-orbit angular momentum as examples, including optical vortex tweezer and quantum entanglement of the spin-orbital angular momentum.

Phase separation in spin-orbit-angular-momentum coupling Bose–Einstein condensate systems

2020 ◽  
Vol 34 (23) ◽  
pp. 2050241
Author(s):  
Jin Xu ◽  
Jinbin Li
Keyword(s):  
Angular Momentum ◽  
Phase Separation ◽  
Coupling Strength ◽  
Interaction Strength ◽  
Einstein Condensate ◽  
Three Dimensions ◽  
Pitaevskii Equation ◽  
Spin Orbit ◽  
Bose Einstein Condensate ◽  
Bose Einstein

We study the phase separation in three-component spin-orbit-angular-momentum coupled Bose–Einstein condensate with spin-1 in three dimensions. Different types of phase-separation are acquired upon an increase of the coupling strength, magnetic gradient strength, spin-dependent interaction strength and particle number above a critical value. Increasing the value of coupling strength and other related parameters shows distinct behaviors which are produced by repulsion for large strengths of spin-orbit angular-momentum (SOAM) coupling. The present investigation is carried out through a numerical Crank–Nicolson method of the underlying mean-field Gross–Pitaevskii equation.

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