Also see https://ritdml.rit.edu/browse?value=Swartzlander%2C+Grover+Jr&type=author
Optical vortex coronagraph
Opt. Lett. 30, 3308-3310 (2005)
Gregory Foo, David M. Palacios, and Grover A. Swartzlander, Jr.
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We describe a method to observe dim exoplanets that eliminates light from the
parent star across the entire exit pupil without sacrificing light from the planet
by use of a vortex mask of topological charge m=2.
Broadband nulling of a vortex phase mask
Opt. Lett. 30, 2876-2878 (2005)
Grover A. Swartzlander, Jr.
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A pulse transmitted through a helical vortex phase mask undergoes a temporal
Hilbert transform. The fluence transmitted into the unfavorable plane wave mode
is found to increase as the square of the bandwidth and, to first order, is
independent of the topological charge.
Spatial coherence singularities and incoherent vortex solitons
JOSA B 22, 1437-1442 (2005)
Kristian Motzek, Yuri S. Kivshar, Ming-Feng Shih, and Grover A. Swartzlander, Jr.
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We study spatially localized optical vortices created by self-trapping of partially
incoherent light with a phase dislocation in a biased photorefractive crystal.
In contrast to a decay of coherent self-trapped vortex beams due to the azimuthal
modulational instability, the incoherent vortices are stabilized for large values
of the spatial incoherence; this was confirmed by experiment. We analyze the
spatial coherence properties of the incoherent optical vortices and reveal the
existence of ringlike singularities in the spatial coherence function of a vortex
field that can characterize the stable propagation of vortices through nonlinear media.
Spatial correlation vortices in partially coherent light: theory
JOSA B 21, 1895-1900 (2004)
Ivan D. Maleev, David M. Palacios, Arvind S. Marathay, and Grover A. Swartzlander, Jr.
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Spatial correlation vortex dipoles may form in the four-dimensional mutual coherence function
when a partially coherent light source contains an optical vortex. Analytical and numerical
investigations are made in near- and far-field regimes.
Temporal Correlation Vortices and Topological Dispersion
Phys. Rev. Lett. 93, 093901(1-4)
G. A. Swartzlander, Jr. and Joanna Schmit
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Interference measurements of a polychromatic partially coherent light source verify the existence of
a temporal correlation vortex. Topological dispersion is found to destabilize this singularity.
Spatial Correlation Singularity of a Vortex Field
Phys. Rev. Lett. 92, 143905(1-4) 2004
D. M. Palacios, I. D. Maleev, A. S. Marathay, and G. A. Swartzlander, Jr.
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Experimental and numerical techniques allowed us to predict and verify the existence of a robust
phase singularity in the spatial coherence function when a vortex is present. Though observed in the
optical domain, this phenomenon may occur in any partially coherent vortex wave.
Composite Optical Vortices
JOSA B 11, 1169-1176 (2003)
I. D. Maleev and G. A. Swartzlander, Jr.
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Composite optical vortices may form when two or more beams interfere. Using analytical and numerical techniques,
we describe the motion of these optical phase singularities as the relative phase or amplitude of two
interfering collinear nonconcentric beams is varied. The creation and the annihilation of vortices are found,
as well as vortices having translational velocities exceeding the speed of light.
Interactive Freshman Electromagnetism
ASEE/IEEE Frontiers in Education Conference Proceedings
Paper 1313, IEEE Catalog No. 02CH37351C, ISBN: 0-7803-7445-2
G. A. Swartzlander, Jr. and L. Lebduska
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Electromagnetism is the most complete and tested branch of physics.
Lacking knowledge of vector calculus and field theory, freshmen are
introduced only to snippets of the full picture, and finish the course
generally unenthusiastic about the role of electromagnetism in their lives.
In response to a need for more interactive learning, we designed an electromagnetism
course that incorporated writing-to-learn principles that allowed students to meld
in-class theory with real-world practice. Course exercises included writing biographies
or describing an electro-magnetic phenomenon or device. Students "published"
their drafts and final papers on the open-access web. This exercise necessitated
that students understand principles sufficiently to break them down for a general
audience and also gave them a sense of ownership and pride knowing that others may
read their work. We will discuss how we conducted this course and provide examples
of student work resulting from the course.
Nonlinear cusp diffraction catastrophe and vortex quadrupoles from a smooth initial beam
J. Nonlinear Opt. Phys. and Mat., 11 No. 4, 351-365 (2002)
A. M. Deykoon, M. S. Soskin, and G. A. Swartzlander, Jr.
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Vortex quadrupoles and a nonlinear optical cusp diffraction catastrophe were observed
at the output face of a self-defocusing nonlinear medium. The initial beam had a smooth
cross-sectional intensity profile, but was elongated to an aspect ratio of 2:1. The
power-dependent evolution of the beam is described.
Observed Scattering into a Dark Optical Vortex Core
Phys. Rev. Lett., 88, 103902, 1-4 (2002)
David Palacios, David Rozas, and Grover A. Swartzlander, Jr.
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The dark core of an optical vortex was used to detect on-axis, forward-scattered light from a colloidal
solution in the single and multiple scattering regimes. Using no adjustable parameters we obtain good
agreement with a concentration-dependent scattering model.
Peering Into Darkness
Optics & Photonics News p. 34, Dec 2001
G. A. Swartzlander, Jr.
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Peering into darkness with a vortex spatial filter
Opt. Lett. 26, 497-499 (2001)
G. A. Swartzlander, Jr.
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I propose to use as a window the dark core of an optical vortex to examine a weak background signal
hidden in the glare of a bright coherent source. Applications such as the detection of an astronomical
object, forward-scattered radiation, and incoherent light are described whereby signal enhancements
of at least 7 orders of magnitude may be achieved.
Optical Vortex Solitons
book chapter in OPTICAL SCIENCES, Spatial Solitons
S. Trillo, W. E. Torruellas, (Eds.), Springer Verlag
G.A. Swartzlander, Jr.
The pinched optical vortex soliton
J. Opt. Soc. Am. B 18, 804-810 (2001)
A.M. Deykoon and G.A. Swartzlander, Jr.
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The fast contraction, or pinching, of optical vortices in both thermal and Kerr
self-defocusing media is investigated by numerical techniques. For the thermal case,
heat diffusion across the vortex core is described, and the heretofore unexplained
stability of optical-vortex solitons in thermal media is explained.
Hechtian strand investigations using optical microsurgery techniques
Plant Physiology 122, 1365-1377 (2000)
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C.S. Buer, P.J. Weathers, and G.A. Swartzlander, Jr.
Optical microsurgical techniques were employed to investigate
the mechanical properties of Hechtian strands in tobacco (Nicotiana tabacum)
and Ginkgo biloba callus cells. Using optical tweezers,
a 1.5- mm diameter microsphere coated with concanavalin A
was inserted though an ablated hole in the cell wall of a plasmolyzed
cell and attached to a Hechtian strand. By displacing the
adhered microsphere from equilibrium using the optical trapping
force, the tensions of individual strands were determined. Measurements
were made using both normal and cold-hardened cells, and in
both cases, tensions were on the order of 10-12 N.
Significant differences were found in the binding strengths of cold-hardened
and normal cultured cells. An increased number density of strands
in cold-hardened G. biloba compared with normal cultured cells
was also observed. Although no Hechtian strands were detected in
any Arabidopsis callus cells, strands were present in leaf epidermal
cells. Finally, the movement of attached microspheres was monitored
along the outside of a strand while cycling the osmotic pressure.
Observed rotational enhancement of nonlinear optical vortices
Opt. Lett. 25, 126-128 (2000)
D. Rozas and G.A. Swartzlander, Jr.
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The propagation dynamics of an optical vortex pair is experimentally confirmed to experience
enhanced rotation in a self-defocusing medium. We measured this effect to be 3.5 times larger
than in linear media. The enhancement is attributed to nonlinear refraction within the dark
vortex cores, permitting the vortices to propagate as vortex filaments.
Waveguiding dynamics of optical vortex solitons
Opt. Lett. 24, 55-57 (2000)
C. T. Law, Xingang Zhang, and G. A. Swartzlander, Jr.
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An optical vortex soliton induces a graded-index waveguide over an extended propagation
distance in a self-defocusing nonlinear optical medium. Using numerical techniques, we
determine the waveguide dispersion and optimal size of the guided beam.
Optical vortex filaments
book chapter in Optical Vortices
(Volume 228 in Horizons in World Physics), Mikhail Vasnetsov (Ed)
G.A. Swartzlander, Jr.
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Nonlinear optical catastrophe from a smooth initial beam
Opt. Lett., 24, 1224-1226 (1999),
A.M. Deykoon, M.S. Soskin, and G.A. Swartzlander, Jr.
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We observed an optical cusp diffraction catastrophe with an initially
smooth but elongated Gaussian beam with an aspect ratio of 2:1.
Nonlinear and linear diffraction regimes account for the near-field
elliptical annulus and the far-field spatially complex astroid.
Simultaneous Trapping of Low-Index and High-Index Microparticles Observed with an Optical-Vortex Trap
J. Opt. Soc. Am. B. 16, 533-537 (1999)
K.T. Gahagan and G.A. Swartzlander, Jr
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We report the first observation of the simultaneous three-dimensional
confinement of both a low-index particle and a high-index particle within
a single-beam optical trap by using a strongly focused laser beam containing
an optical vortex. Experimental and theoretical investigations of the trap
stability are described.
Differences in Optical Trapping Prompt Investigations of Agrobacterium Surface Characteristics
J. Industrial Microbiology and Biotechnology, 21, 233-236 (1998)
CS Buer, KT Gahagan, GA Swartzlander, Jr., and PJ Weathers
Order
Comparison of the optical trapping efficiency of Agrobacterium
rhizogenes and A. tumefaciens strains indicates the A. rhizogenes strain,
ATCC 11325, is significantly less efficiently trapped than A. rhizogenes A4,
ATCC 15834, and the A. tumefaciens strain LBA4404. Differences were also
found in capsule generation, growth media viscosity, and transmissions
electron microscopy negative staining. These observations imply a difference
in surface structure exists. Calcofluor fluorescence suggests the difference
involves an exopolysaccharide.
Holographic Formation of Optical-Vortex Filaments
J. Opt. Soc. Am. B, 15, 2226-2234 (1998)
Z.S. Sacks, D. Rozas, and G.A. Swartzlander, Jr.
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An optical-vortex filament is characterized by a dark core of vanishing
size and fluidlike propagation dynamics in the near-field region. This
type of phase singularity does not naturally occur as an eigenmode of a
cylindrically symmetric system, but it can be easily formed by
computer-generated holography. The size of the core is an important
attribute affecting vortex - vortex interactions within a laser beam.
Here we demonstrate a means to minimize the core size, and we experimentally
show that a beam-to-core size ratio exceeding 175 may be readily achieved.
Trapping of Low-Index Microparticles in an Optical Vortex
J. Opt. Soc. Am. B, 15, 524-534 (1998)
K.T. Gahagan and G.A. Swartzlander, Jr.
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The equilibrium position of a low-index particle in an optical-vortex trap
was experimentally measured for two different systems: a buoyant hollow
glass sphere in water and a density-matched water droplet in acetophenone.
Vortex traps are the only known static, single-beam configurations allowing
three-dimensional trapping of such particles in the size range of 2-50 um.
The trap consists of a strongly focused Gaussian laser beam containing a
holographically produced optical vortex. Using experimental and theoretical
techniques, we also explored changes in the trapping efficiency owing to the
vortex core size, the relative refractive index, and the numerical aperture
of the focusing objective.
Insertion of Microscopic Objects Through Plant Cell Walls Using Laser Microsurgery
Biotechnology and Bioengineering, 60, 348-355 (1998)
C.S. Buer, K.T. Gahagan, G.A. Swartzlander, Jr., P.J. Weathers
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A detailed protocol is presented for precisely inserting microscopic objects
into the periplasmic region of plant callus cells using laser microsurgery.
Ginkgo biloba and Agrobacterium rhizogenes were used as the model system for
developing the optical tweezers and scalpel techniques using a single laser.
We achieved better than 95% survival after plasmolyzing G. biloba cells,
ablating a 2-4um hole through the cell wall using a pulsed UV laser beam,
trapping and translating bacteria into the periplasmic region using a pulsed
infrared laser beam, and then deplasmolyzing the cells. Insertion of bacteria
is also described. A thermal model for temperature changes of trapped bacteria
is included. Comparisons with other methods, such as a reverse-pressure
gradient technique, are discussed and additional experiments on plants using
laser microsurgery are suggested.
Experimental Observation of Fluidlike Motion of Optical Vortices
Phys. Rev. Lett, 79, 3399-3402 (1997)
D. Rozas, Z.S. Sacks, & G.A. Swartzlander, Jr.
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We have observed the fluidlike rotation of a pair of identical optical
vortices (OV's) as they propagate through free space. Similar to vortex
filaments in a fluid, the initial rotation rate is found to be inversely
proportional to the squared distance of seperation. Owing to unusually
small vortex cores, we obtained rotation rates that were 2 orders of
magnitude larger than expected for "conventional" large core OV's.
Propagation Dynamics of Optical Vortices
J. Opt. Soc. Amer. B, 14, 3054-3065 (1997)
D. Rozas, C.T. Law, G.A. Swartzlander, Jr.
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Optical vortices in linear and nonlinear media may exhibit propagation
dynamics similar to hydrodynamic vortex phenomena. Analytical and numerical
methods are used to describe and investigate the interaction between vortices
and the background field. We demonstrate that optical vortices that have
quasi-point core functions, such as opotical vortex solitons, may orbit one
another at rates that are orders of magnitude larger than those with
nonlocalized cores.
Numerical Modeling of Nonlinear Beam Propagation Phenomena
Materials Research Society Symposium Proceedings Series, 467. 322 (1997)
G. A. Swartzlander, Jr., A. M. Deykoon, D. W. Jackson, and C. T. Law
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Optical vortex trapping of particles
Optics Letters, 21, 827-829 (1996)
K. T. Gahagan and G. A. Swartzlander Jr.
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We demonstrate three-dimensional trapping of low-index particles
(20-µ-diameter hollow glass spheres in water) by using a single,
strongly focused, stationary dark optical vortex laser beam. The
holographically generated vortex, which is similar to a TEM01* mode beam,
was also used to trap and form ring patterns of high-index particles.
Optical transistor effect using an optical vortex soliton
Laser Physics, 5, 704 (1995)
G.A. Swartzlander, Jr., D. L. Drugan, N. Hallak, M.O. Freeman, and C.T. Law
An optical vortex soliton (OVS) induces a cylindrical waveguide (analogous to a graded optical fiber with variable size)
within a self-defocusing nonlinear medium. The guiding efficiency is experimentally modulated by passing a pulsed
laser through the dark vortex core. Like an electronic transistor, we find that the greater the pump intensity (bias current),
the greater the guiding efficiency and sensitivity (transconductance).
Asymptotic Behavior of the Self-Defocusing Nonlinear Schrodinger Equation for Piecewise Constant Initial Conditions
J. Opt. Soc. Amer. B, 12, 698-703 (1995)
P.B. Lundquist, D.R. Andersen, and G.A. Swartzlander, Jr.
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In this paper we use a transfer matrix method to calculate the asymptotic
behavior of the nonlinear Schrodinger (NLS) equation in a self-defocusing
medium for piecewise constant initial conditions. Treating initial conditions
that consist of m repeated regions, we show that the eigenvalues associated
with this problem appear in bands, and, as m tends to infinity, we obtain the
eigenvalue density of states for these bands. Comparing results from the
transfer matrix approach to the results for a Bloch function method, we show
that the edges of a region with periodic initial conditions result in a
finite number of additional eigenvalues that appear outside the bands.
Polarized Optical Vortex Solitons: Instabilities and dynamics in Kerr nonlinear media
Chaos, Solitons & Fractals 4, 1759 (1994).
C.T. Law and G.A. Swartzlander, Jr.
Optical vortex solitons are known to be stable in a scalar nonlinear system, and they have even been observed. We now explore the effects of polarization on the vortices, and find that they asre unstable in Kerr defocusing media, except when the beam is circularly polarized. Numerical simulations verify this and show remarkable beam evolution, including vortex shedding and reversal of topological charge.
Self-bending of light: comment
Optics Letters -- January 1, 1994 -- Volume 19, Issue 1, p. 71
A. E. Kaplan and G. A. Swartzlander Jr.
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We believe that the effect observed by Xing et al. [Opt. Lett. 18, 479 (1993)] is essentially cross-phase modulation. It was inaccurately identified as self-bending of light, which is a self-action effect well known in the literature.
Optical vortex solitons and the stability of dark soliton stripes
Optics Letters 18, 586-588 (1993)
C. T. Law and G. A. Swartzlander Jr.
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Dark soliton stripes are robust but can decay into optical vortex solitons when subjected to a persistent, long-period, transverse modulation. We explore the nonlinear dynamics of this symmetry-breaking process and determine growth rates, vortex densities, and other characteristics by conducting a nonlinear stability analysis that uses numerical techniques for several cases of special interest.
Optical vortex solitons observed in Kerr nonlinear media
Phys. Rev. Lett. 69, 2503-2506 (1992)
G.A. Swartzlander, Jr. and C.T. Law
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Optical vortex-soliton filaments are observed in a bulk self-defocusing Kerr nonlinear refractive medium. The dark cylindrical core, located at the axis of the 2 pi helical phase ramp, is stationary and stable, with a size that depends inversely on the field strength. Wave guiding of a weak probe beam within the core is reported. A single optical vortex soliton was experimentally and
numerically investigated using a convective Kelvin-Helmholtz instability of dark soliton stripes.
Dark-soliton prototype devices: analysis by using direct-scattering theory
Optics Letters 17, 493-495 (1992)
G. A. Swartzlander Jr.
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Signals encoded as highly stable spatial (or temporal) dark solitons can be used in nonlinear-optical devices such as logic gates, interconnects, multiplexers, and filters. The formation of these waves with the use of simple diffracting (dispersing) elements in prototypical devices is analyzed by using the direct-scattering method, which is also outlined. Noncollisional dark-soliton xor and and gates and dark-soliton level splitting and bands are also described.
Spatial dark-soliton stripes and grids in self-defocusing materials
Phys. Rev. Lett. 66, 1583-1586 (1991)
G.A. Swartzlander, Jr., D.R. Andersen, J. J. Regan, H. Yin, and A.E. Kaplan
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Spatial dark-soliton (SDS) stripes are experimentally found in the transverse plane of a laser beam that passes through a rectilinear diffraction screen before propagating in a self-defocusing nonlinear material. Materials with different mechanisms of nonlinearity manifest the same qualitative results. The SDS nature of the observed phenomenon is verified by numerical simulations of the (2+1)-D nonlinearr Schrodinger equation, analytical solutions for the (1+1)-D case, and their comparison with experimental data.
Spectral measurement of the nonlinear refractive index in ZnSe using self-bending of a pulsed laser beam
Optics Letters 15, 1431-1433 (1990)
Y. J. Ding, C. L. Guo, G. A. Swartzlander Jr., J. B. Khurgin, and A. E. Kaplan
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The nonlinear refractive-index (n2) spectrum of ZnSe near the band gap (~ 450 nm) at 77 K was
measured for the first time to our knowledge by using self-bending of a pulsed laser beam.
The maximum nonlinearity, n2 ~ 1.9 X 10-8 cm2/W, measured by us is
anomalously large, which can be explained by conventional thermally induced band-gap shrinkage.
Direct measurement of the transverse velocity of dark spatial solitons
Optics Letters 15, 783-785 (1990)
David R. Andersen, Duane E. Hooton, Grover A. Swartzlander Jr., and Alexander E. Kaplan
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We describe the direct experimental measurement of the transverse propagation velocities of dark spatial solitons. Good agreement is obtained from a comparison of the velocities measured experimentally and the velocities predicted by the two-dimensional theory of Zakharov and Shabat [Sov. Phys. JETP 37, 823 (1973)].
Continuous-wave self-deflection effect in sodium vapor
J. Opt. Soc. Amer. B 6, 1317-1325 (1989)
G.A. Swartzlander, Jr., H. Yin, and A.E. Kaplan
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Observations of the self-deflection effect for an asymmetrical
continuous-wave laser beam in sodium vapor are described, and comparisons
based on theoretical calculations are made. A self-bending angle as large
as eight diffraction widths was recorded, and strong attenuation of the
on-axis radiation due to self-bending was measured. At ~ 200 °C
the self-deflection angle increased linearly with beam power, and we determined
that (n2)max ~
10 7 cm2/W for intensities below 220 W/cm2.
While numerical calculations, based on an inhomogeneously broadened two-level
system, predict strong saturation of the self-bending effect, we observed
only moderate saturation.
Self-bending of a cw laser beam in sodium vapor
Optics Letters 13, 1011-1013 (1988)
G. A. Swartzlander Jr., H. Yin, and A. E. Kaplan
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Continuous-wave self-deflection of an asymmetrical laser beam, with a deflection angle up to
eight diffraction widths, and strong attenuation of the on-axis radiation were achieved in a
short sodium-vapor cell. We determined that the nonlinear refractive index
&Delta n varied almost
linearly with intensity I, &Delta n ~ n2I, with n2 ~
10-7 cm2/W at ~ 200° C and
intensities less than 220 W/cm2.
Self-deflection of laser beams in a thin nonlinear film
J. Opt. Soc. Amer. B 5, 765-768 (1988)
G.A. Swartzlander, Jr. and A.E. Kaplan.
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The self-deflection of slab laser beams with right-triangular and
semi-Gaussian intensity profiles that pass through a thin nonlinear film
are compared, and semi-Gaussian beam profiles are found to produce
near-maximum self-deflection angles. We also compare symmetric profiles
(both triangular and Gaussian), which, instead of self-(de)focusing,
exhibit strongly counter-self-deflected beams in the far-field region.
This evidence indicates that the self-deflection effect can dominate
over self-focusing.
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