scholarly journals Lateral forces on circularly polarizable particles near a surface

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Francisco J. Rodríguez-Fortuño ◽  
Nader Engheta ◽  
Alejandro Martínez ◽  
Anatoly V. Zayats
Keyword(s):  
Light Propagation ◽  
Polarized Light ◽  
Optical Force ◽  
Optical Forces ◽  
Circularly Polarized Light ◽  
Force Direction ◽  
Electromagnetic Momentum ◽  
Nanophotonic Structures ◽  
And Control ◽  
Light Beams

Abstract Optical forces allow manipulation of small particles and control of nanophotonic structures with light beams. While some techniques rely on structured light to move particles using field intensity gradients, acting locally, other optical forces can ‘push’ particles on a wide area of illumination but only in the direction of light propagation. Here we show that spin–orbit coupling, when the spin of the incident circularly polarized light is converted into lateral electromagnetic momentum, leads to a lateral optical force acting on particles placed above a substrate, associated with a recoil mechanical force. This counterintuitive force acts in a direction in which the illumination has neither a field gradient nor propagation. The force direction is switchable with the polarization of uniform, plane wave illumination, and its magnitude is comparable to other optical forces.

scholarly journals Plasmonic linear nanomotor using lateral optical forces

2020 ◽  
Vol 6 (45) ◽  
pp. eabc3726
Author(s):  
Yoshito Y. Tanaka ◽  
Pablo Albella ◽  
Mohsen Rahmani ◽  
Vincenzo Giannini ◽  
Stefan A. Maier ◽  
...  
Keyword(s):  
Laser Beam ◽  
Incident Light ◽  
Lateral Force ◽  
Diffraction Limit ◽  
Propagation Direction ◽  
Optical Force ◽  
Optical Forces ◽  
Incident Laser ◽  
New Class ◽  
Force Direction

Optical force is a powerful tool to actuate micromachines. Conventional approaches often require focusing and steering an incident laser beam, resulting in a bottleneck for the integration of the optically actuated machines. Here, we propose a linear nanomotor based on a plasmonic particle that generates, even when illuminated with a plane wave, a lateral optical force due to its directional side scattering. This force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light. We demonstrate the arrangements of the particles allow controlling the lateral force distributions with the resolution beyond the diffraction limit, which can produce movements, as designed, of microobjects in which they are embedded without shaping and steering the laser beam. Our nanomotor to engineer the experienced force can open the door to a new class of micro/nanomechanical devices that can be entirely operated by light.

SPATIAL SEPARATION OF POLARIZATION COMPONENTS BY NONLINEAR BEAM RESHAPING IN A J=1 TO J=0 MEDIUM

1992 ◽  
Vol 01 (02) ◽  
pp. 393-420 ◽  
Author(s):  
R.J. BALLAGH ◽  
A.W. McCORD
Keyword(s):  
Optical Pumping ◽  
Polarized Light ◽  
Spatial Separation ◽  
Longitudinal Optical ◽  
Zero Field ◽  
Nonlinear Beam ◽  
Circularly Polarized Light ◽  
Polarized Beam ◽  
Light Beams ◽  
Elliptically Polarized

The diffractive reshaping that circularly polarized light beams undergo when coupled in a medium of homogenously broadened J=1→J=0 atoms is shown to be sensitively dependent on applied magnetic fields. In zero field, an elliptically polarized beam will retain its polarization everywhere in space, but a small longitudinal magnetic field can cause the beam to break up into spatially distinct regions of pure circular polarization. The beam behavior can be understood in terms of an encoding/diffraction sequence. An analytic solution for the atomic response function reveals the important roles played by transverse and longitudinal optical pumping.

scholarly journals Enantioselective fragmentation of an achiral molecule in a strong laser field

2019 ◽  
Vol 5 (3) ◽  
pp. eaau7923 ◽  
Author(s):  
K. Fehre ◽  
S. Eckart ◽  
M. Kunitski ◽  
M. Pitzer ◽  
S. Zeller ◽  
...  
Keyword(s):  
Single Molecule ◽  
Light Propagation ◽  
Polarized Light ◽  
Strong Laser Field ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Single Molecule Level ◽  
The Difference ◽  
Living Nature ◽  
Chiral Species

Chirality is omnipresent in living nature. On the single molecule level, the response of a chiral species to a chiral probe depends on their respective handedness. A prominent example is the difference in the interaction of a chiral molecule with left or right circularly polarized light. In the present study, we show by Coulomb explosion imaging that circularly polarized light can also induce a chiral fragmentation of a planar and thus achiral molecule. The observed enantiomer strongly depends on the orientation of the molecule with respect to the light propagation direction and the helicity of the ionizing light. This finding might trigger new approaches to improve laser-driven enantioselective chemical synthesis.

Differential polarization imaging of sickled cells

1988 ◽  
Vol 46 ◽  
pp. 62-63
Author(s):  
Marcos F. Maestre
Keyword(s):  
Optical Properties ◽  
Theoretical Approach ◽  
Polarized Light ◽  
Polarization Microscopy ◽  
Spectroscopic Techniques ◽  
Polarization Imaging ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Microscopic Scale ◽  
Chiral Structures

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.

scholarly journals Mass-resolved electronic circular dichroism ion spectroscopy

Science ◽  
2020 ◽  
Vol 368 (6498) ◽  
pp. 1465-1468 ◽  
Author(s):  
Steven Daly ◽  
Frédéric Rosu ◽  
Valérie Gabelica
Keyword(s):  
Circular Dichroism ◽  
Three Dimensional ◽  
Polarized Light ◽  
Negative Ions ◽  
Data Interpretation ◽  
Electronic Circular Dichroism ◽  
Circularly Polarized Light ◽  
Chiral Compounds ◽  
Electron Photodetachment ◽  
Circular Dichroïsm

DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet nanosecond optical parametric oscillator laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resembled those of their solution-phase counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.

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