From the abstract: We propose and demonstrate a novel high numerical aperture (NA) focusing
system composed of an annular beam with alternate radially and
azimuthally polarized rings, focused by a devil’s lens (DL), and further
investigate its radiation forces acting upon a Rayleigh particle both
analytically and numerically. Strongly focused cylindrical vector beams
produce either dark-centered or peak-centered intensity distributions
depending on the state of polarization, whereas the DL produces a series
of foci along the propagation direction. We exploit these focusing
properties and show that by selecting an appropriate truncation
parameter in front of the focusing lens, the proposed optical focusing
system can selectively trap and manipulate dielectric micro-particles
with low or high refractive indices by simply adjusting the radius of
the pupil or the beam. Finally, the stability conditions for effectively
trapping and manipulating Rayleigh particles are analyzed. The results
obtained in this work are of interest in possible applications in
optical confinement and manipulation, sorting micro-particles, and
making use of a DL.
Friday 2 December 2016
Paper published in JOSA A
Our paper on the optical trapping forces of a poarization-structured beam focused by a fractal (Devil's) lens has been published as Zhirong Liu and P. H. Jones, 'Radiation forces acting upon a
Rayleigh particle by highly focused alternate radially- and
azimuthally-polarized beams modulated by a Devil's Lens', Journal of the Optical Society of America A 33 2501-2508 (2016).
From the abstract: We propose and demonstrate a novel high numerical aperture (NA) focusing
system composed of an annular beam with alternate radially and
azimuthally polarized rings, focused by a devil’s lens (DL), and further
investigate its radiation forces acting upon a Rayleigh particle both
analytically and numerically. Strongly focused cylindrical vector beams
produce either dark-centered or peak-centered intensity distributions
depending on the state of polarization, whereas the DL produces a series
of foci along the propagation direction. We exploit these focusing
properties and show that by selecting an appropriate truncation
parameter in front of the focusing lens, the proposed optical focusing
system can selectively trap and manipulate dielectric micro-particles
with low or high refractive indices by simply adjusting the radius of
the pupil or the beam. Finally, the stability conditions for effectively
trapping and manipulating Rayleigh particles are analyzed. The results
obtained in this work are of interest in possible applications in
optical confinement and manipulation, sorting micro-particles, and
making use of a DL.
From the abstract: We propose and demonstrate a novel high numerical aperture (NA) focusing
system composed of an annular beam with alternate radially and
azimuthally polarized rings, focused by a devil’s lens (DL), and further
investigate its radiation forces acting upon a Rayleigh particle both
analytically and numerically. Strongly focused cylindrical vector beams
produce either dark-centered or peak-centered intensity distributions
depending on the state of polarization, whereas the DL produces a series
of foci along the propagation direction. We exploit these focusing
properties and show that by selecting an appropriate truncation
parameter in front of the focusing lens, the proposed optical focusing
system can selectively trap and manipulate dielectric micro-particles
with low or high refractive indices by simply adjusting the radius of
the pupil or the beam. Finally, the stability conditions for effectively
trapping and manipulating Rayleigh particles are analyzed. The results
obtained in this work are of interest in possible applications in
optical confinement and manipulation, sorting micro-particles, and
making use of a DL.
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