scholarly journals Sharp focusing of beams with V-point polarization singularities

2021 ◽  
Vol 5 (45) ◽  
pp. 643-653
Author(s):  
V.V. Kotlyar ◽  
A.G. Nalimov ◽  
S.S. Stafeev ◽  
A.A. Kovalev
Keyword(s):  
Intensity Distribution ◽  
Linear Polarization ◽  
Light Field ◽  
Focal Spot ◽  
Polarization Direction ◽  
Intensity Pattern ◽  
Singularity Index ◽  
Local Maxima ◽  
Sharp Focus ◽  
Sharp Focusing

It is theoretically and numerically shown that when tightly focusing an n-th order vector light field that has the central V-point (at which the linear polarization direction is undetermined), the polarization singularity index n, and a "flower"-shaped intensity pattern with 2(n-1) lobes it forms a transverse intensity distribution with 2(n-1) local maxima. At the same time, a vector light field with the polarization singularity index -n, which has the form of a "web" with 2(n+1) cells generates at the sharp focus a transverse intensity distribution with 2(n+1) local maxima. In the focal spot, either 2(n-1) or 2(n+1) V-point polarization singularities with alternating indices +1 or -1 are formed at the intensity zero.

scholarly journals Sharp Focusing of a Hybrid Vector Beam with a Polarization Singularity

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 227
Author(s):  
Victor V. Kotlyar ◽  
Sergey S. Stafeev ◽  
Anton G. Nalimov
Keyword(s):  
Focal Plane ◽  
Topological Charge ◽  
Light Field ◽  
Stokes Vector ◽  
Elliptical Polarization ◽  
Intensity Pattern ◽  
Singularity Index ◽  
Sharp Focusing ◽  
New Type ◽  
Local Polarization

The key result of this work is the use of the global characteristics of the polarization singularities of the entire beam as a whole, rather than the analysis of local polarization, Stokes and Poincare–Hopf indices. We extend Berry’s concept of the topological charge of scalar beams to hybrid vector beams. We discuss tightly focusing a new type of nth-order hybrid vector light field comprising n C-lines (circular polarization lines). Using a complex Stokes field, it is shown that the field polarization singularity index equals n/2 and does not preserve in the focal plane. The intensity and Stokes vector components in the focal plane are expressed analytically. It is theoretically and numerically demonstrated that at an even n, the intensity pattern at the focus is symmetrical, and instead of C-lines, there occur C-points around which axes of polarization ellipses are rotated. At n = 4, C-points characterized by singularity indices 1/2 and ‘lemon’-type topology are found at the focus. For an odd source field order n, the intensity pattern at the focus has no symmetry, and the field becomes purely vectorial (with no elliptical polarization) and has n V-points, around which linear polarization vectors are rotating.

scholarly journals A mode generator and multiplexer at visible wavelength based on all-fiber mode selective coupler

Nanophotonics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Han Yao ◽  
Fan Shi ◽  
Zhaoyang Wu ◽  
Xinzhu Xu ◽  
Teng Wang ◽  
...  
Keyword(s):  
Phase Shift ◽  
Intensity Distribution ◽  
Linear Polarization ◽  
Mode Conversion ◽  
Polarization State ◽  
Stimulated Emission ◽  
Wavelength Multiplexing ◽  
Mode Converters ◽  
Fiber Mode ◽  
Vortex Beams

AbstractUsing an all-fiber mode selective coupler (MSC) at the visible band, here we experimentally demonstrate a generating and wavelength multiplexing scheme for the cylindrical vector (CV) and vortex beams (VBs). The proposed MSCs act as efficient mode converters to produce spectrally insensitive high-order modes (HOMs) at the wavelength ranging from 450 to 980 nm, which have broad operation bandwidth (more than 7 nm), high mode conversion efficiency (94%), and purity (98%), and low insert loss (below 0.5 dB). By adjusting the polarization state and the phase shift of linear polarization (LP)11 mode respectively, the donut-shaped CVs and circular-polarization VBs are achieved. The focused intensity distribution of the donut beam on the cross- and axial-sections is monitored by using a confocal system. The all-fiber solution of producing and multiplexing HOMs opens a new route for stimulated emission depletion microscopy applications.

scholarly journals Minimal Focal Spot Size Measured Based on Intensity and Power Flow

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5505
Author(s):  
Victor V. Kotlyar ◽  
Sergey S. Stafeev ◽  
Vladislav D. Zaitsev
Keyword(s):  
Linear Polarization ◽  
Energy Flow ◽  
Power Flow ◽  
Focal Spot ◽  
Spot Size ◽  
Optical Vortices ◽  
Focal Spot Size ◽  
Minimum Diameter ◽  
Circular Symmetry ◽  
Energy Flows

It is shown, theoretically and numerically, that the distributions of the longitudinal energy flow for tightly focused light with circular and linear polarization are the same, and that the spot has circular symmetry. It is also shown that the longitudinal energy flows are equal for optical vortices with unit topological charge and with radial or azimuthal polarization. The focal spot has a minimum diameter (all other characteristics being equal), which is measured based on the intensity of an optical vortex with azimuthal polarization. The diameter of the focal spot calculated from the energy flow for light with circular or linear polarization is slightly larger (by a fraction of a percentage). The magnitude of the diameter based on the intensity plays a role in the interaction of light with matter, and the magnitude of the diameter based on the energy flux affects the resolution in optical microscopy which is crucial in sensorial applications.

scholarly journals Randomly Multiplexed Diffractive Lens and Axicon for Spatial and Spectral Imaging

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 437 ◽  
Author(s):  
Vijayakumar Anand ◽  
Tomas Katkus ◽  
Saulius Juodkazis
Keyword(s):  
Intensity Distribution ◽  
Point Spread Function ◽  
Fresnel Zone ◽  
Spherical Wave ◽  
Optical Element ◽  
Intensity Pattern ◽  
Object Space ◽  
Point Spread ◽  
Spread Function ◽  
Complicated Object

A new hybrid diffractive optical element (HDOE) was designed by randomly multiplexing an axicon and a Fresnel zone lens. The HDOE generates two mutually coherent waves, namely a conical wave and a spherical wave, for every on-axis point object in the object space. The resulting self-interference intensity distribution is recorded as the point spread function. A library of point spread functions are recorded in terms of the different locations and wavelengths of the on-axis point objects in the object space. A complicated object illuminated by a spatially incoherent multi-wavelength source generated an intensity pattern that was the sum of the shifted and scaled point spread intensity distributions corresponding to every spatially incoherent point and wavelength in the complicated object. The four-dimensional image of the object was reconstructed using computer processing of the object intensity distribution and the point spread function library.

A Supernova Remnant in Centaurus

1967 ◽  
Vol 1 (1) ◽  
pp. 22-23 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
Magnetic Field ◽  
Brightness Temperature ◽  
Radio Source ◽  
Linear Polarization ◽  
Supernova Remnant ◽  
Polarization Direction ◽  
Western Side ◽  
Single Polarization ◽  
The Magnetic Field

Observations of the composite radio source which includes the catalogued components 1209-52 and 1209-51 (Bolton et al. 1964) have been obtained at frequencies 629, 1410, and 2650 MHz with the 210-ft Parkes telescope. The observations at the highest frequency are shown in Figure 1. The isotherms of full-beam brightness temperature correspond to the single polarization direction shown within the circle representing the half-intensity beamwidth. The polarization vectors (unbroken lines) along the two ridges represent 15-25% linear polarization. The intrinsic angles of polarization, derived from the 1410 and 2650 MHz observations, are represented by the broken lines. They are perpendicular to the magnetic field if the radiation is synchrotron. The corresponding rotation measures (Gardner and Whiteoak 1963) range between +17 and +36 rad. m-2 along the eastern ridge, and between —14 and —4 on the western side.

A focal spot with variable intensity distribution for optical tweezers

2013 ◽  
Vol 10 (4) ◽  
pp. 045602 ◽  
Author(s):  
X Hao ◽  
C F Kuang ◽  
Y H Li ◽  
X Liu
Keyword(s):  
Optical Tweezers ◽  
Intensity Distribution ◽  
Focal Spot ◽  
Variable Intensity
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