Recently there has been considerable interest in the generation of cylindrical vector beams for numerous possible
applications in nano-biophotonics, optical imaging, the laser processing of materials and the generation of single
photon sources among others. Cylindrical vector optical vortex beams are shown by propagating a fundamental
laser mode through a spun ber. The polarization state of the output from the ber is characterized and the the
process of this mode conversion will be discussed.
We have studied the effect of a 1070 nm continuous wave Ytterbium fiber laser on exponentially growing
Saccharomyces cerevisiae yeast cells over a span of 4 hours. The cells were immobilized onto Concanavalin A covered
microscope slides and the growth was measured using the area increase of the cells in 2D. Using a continuous dual beam
plane wave with a uniform spatial intensity distribution, we found that a continuous radiant flux through a single cell as
low as 0.5 mW in 1.5 hours significantly changed the growth and division rate of S. cerevisiae. With the dual beam setup
used we were able to successfully manipulate single S. cerevisiae cells in 3 dimensions with a minimum flux thorough
the cell of 3.5 mW. In the regime investigated from 0.7 mW to 2.6 mW we found no threshold for the photo damage, but
rather a continuous response to the increased accumulated dose.
We present a technique that involves tailoring the angular spectrum in optical microscopy of
silicon integrated circuits, with a solid immersion lens. Spatial light modulation to select only
supercritical light at the substrate/dielectric interface, yields only evanescent and scattered light
in the interconnect layers. We demonstrated the technique in optical excitation microscopy of
65nm silicon-on-insulator circuits, which enabled localization of a fault during microprocessor
development. Acquiring images with and without angular spectrum tailoring allowed
longitudinal localization of the electrical response to optical excitation. Lateral registration of
electrical response and confocal reflection images to the circuit layout was also significantly
Rigorous vector analysis of high numerical aperture optical systems encounters severe difficulties. While existing
analytic methods, based on the Richards-Wolf approach, allow focusing of nearly planar incident wavefronts, these
methods break down for beams possessing considerable phase jumps, such as beams containing phase singularities. This
work was motivated by the need to analyze a recently introduced metrological application of singular beams that
demonstrated an experimental sensitivity of 20nm under a moderate numerical aperture of 0.4. One of the possibilities to
obtain even better sensitivity is by increasing the numerical aperture of the optical system. In this work we address the
issue of high numerical aperture focusing of the involved singular beams. Our solution exploits the superposition
principle to evaluate the three dimensional focal distribution of the electromagnetic field provided the illuminating
wavefront can be described as having piecewise quasi constant phase. A brief overview of singular beam microscopy is
followed by deeper discussion of the involved high numerical aperture focusing issue. Further, a few examples of
different singular beam focal field distributions are presented.
It was investigated development of singular generic elliptic speckle patterns generated and driven by laser beam in
LiNbO3:Fe crystal by quick-action stokes polarimetry. It is realized through totality of local topological transitions in
random space-time point governed by smoothly varying control parameter (amplitude of funnel bottom in the place of
forthcoming vortices pair nucleation). Vortices pair nucleates when zero amplitude value is reached. Total development
of singular light fields proceeds through the direct and chain topological reactions. Direct reactions possess short spacetime
loop trajectories. Chain reaction trajectory consists from sequence of singularities pair nucleation and annihilation
with singularities from other pairs. They can finish generically on field borders only, don't touch and intersect. Existing
wave front singularities are arranged in the topological network which plays role of its skeleton and keeps integrity
during field development. Its genesis was realized in the speckle field appeared after PDLC cell with variable applied
constant electric field. Nucleation of first optical vortices pairs was observed firstly.
We report on the parametric study of composite-vortex patterns formed by displaced singly-ringed Laguerre-
Gauss beams. We find that rich structures of vortices appear and disappear as the phase, topological charge and
displacement of the component beams is varied. The net topological charge depends on various factors. When
the beams are collinear or nearly collinear the net charge is the largest topological charge of the two component
beams. When they are displaced by about one or more beam widths the net charge is the sum of the topological
charges of the component beams plus the charge of vortices created by the shear phases in the region in between
the two beams. The shear charges depend on the parameters of the problem. The experimental measurements are
consistent with the expectations, although the measured location of the vortices is not necessarily in agreement
with the predictions.
Measurements of viscoelasticity in the microscopic regime are of interest in polymer solutions as well as in
microscopic structures such as cells. Viscoelasticity can be studied using a localized microrheometer based
on optical tweezers. We rotate a birefringent micron-sized calcium carbonate sphere crystallized in a vaterite
structure. By applying a time-dependent torque or using the time-dependent thermal torque, viscoelasticity can
be measured. The torque can be measured purely optically, by measuring the polarization state of the trapping
beam after passing through the particle. We control the torque by controlling the relative amplitudes of two
orthogonally circularly polarized components of the trapping beam with two acousto-optic modulators. This
allows a wide range of oscillation frequencies to be used. We demonstrate applications of the methods on several
Optical traps use forces exerted by specially structured beams of light to localize microscopic objects in three
dimensions. In the case of single-beam optical traps, such as optical tweezers, trapping is due entirely to gradients
in the light's intensity. Gradients in the light field's phase also control optical forces, however, and their quite
general influence on trapped particles' dynamics has only recently been explored in detail. We demonstrate
both theoretically and experimentally how phase gradients give rise to forces in optical traps and explore the
sometimes surprising influence of phase-gradient forces on trapped objects' motions.
We analyze and describe the evolution of the Poynting vector and angular momentum of the Airy beam as it
propagates through space. A numerical approach is used to show the Poynting vector follows the tangent line
of the direction of propagation. A similar approach is used to show that while the total angular momentum of
the Airy beam is zero, the angular momentum of the main intensity peak and the Airy tail are non-zero. These
beams have promise for applications in imaging and spectroscopy where a sample might interact with a changing
momentum and spatially varying angular momentum.
We study the effects of rotation on the stability properties of an astigmatic two-mirror cavity. We show that
rotation can both stabilize and destabilize a cavity and investigate the effects of such a rotationally-induced
transition on the spatial structure and the orbital angular momentum of the cavity modes. Our method relies
on the connection between ray and wave optics and is exact within the time-dependent paraxial approximation.
The angular profile and the orbital angular momentum of a light mode are related by Fourier transform. Any
modification of the angular distribution, e. g. via diffraction off a suitably programmed spatial light modulator,
influences the orbital angular momentum spectrum of the light. This holds true even at the single photon level.
We observe the influence of various angular masks on the orbital angular momentum spectrum, both in the near
and the far field, and describe the resulting patterns in terms of angular diffraction. If photons are entangled in
their orbital angular momentum, diffraction of one photon affects the orbital angular momentum spectrum of
its partner photon, and angular ghost diffraction can be measured in the coincidence counts. We highlight the
role of the angular Fourier relationship for these effects.
This paper introduces a scheme for generation of vortex laser beams from a solid-state laser with off-axis laser-diode
pumping. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer
configuration. This configuration allows controlled construction of p × p vortex array beams from Ince-Gaussian modes,
IGep,p modes. An incident IGep,p laser beam of variety order p can easily be generated from an end-pumped solid-state
laser with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation and
discusses beam propagation effects. The formation of ordered transverse emission patterns have applications in a variety
of areas such as optical data storage, distribution, and processing that exploit the robustness of soliton and vortex fields
and optical manipulations of small particles and atoms in the featured intensity distribution.