Using the Richards-Wolf formulas for an arbitrary circularly polarized optical vortex with integer topological charge m, we obtain explicit expressions all components of electric and magnetic field strength vectors near focus, as well intensity (energy density) energy flux (components Poynting vector) in focal plane aplanatic system. For m=2, from obtained it follows that axis propagates reversed direction, rotating along a spiral around axis. On itself, is maximal decays rapidly distance...

We show that if a nonzero $E$-field intensity is found in the focus of circularly polarized optical vortex with phase singularity or higher-order azimuthally beam polarization singularity, an energy backflow will occur at center focal plane. Using Richards-Wolf formulas, which describe electromagnetic field near tight aplanatic system containing ideal spherical lens, we prove negative on-axis propagation light occurs when focusing (i) left-hand topological charge $m=2$ (ii) conventional...

Using Richards–Wolf formulas, we show analytically that when strongly focusing a circularly polarized axisymmetric non-vortex field (e.g., Gaussian beam or zero-order Bessel–Gaussian beam), spiral energy flow is produced around the sub-wavelength focal spot. This phenomenon can be explained by conversion of spin angular momentum associated with circular polarization state into near-focus orbital momentum, on-axis being strictly zero. It also shown linearly optical vortex topological charge 2...

Using a FDTD-aided numerical simulation we show that sharp focal spot can be generated by spiral metalens made of amorphous silicon, with unit topological charge and aperture (NA = 1). The intensity is nearly round-shaped when using an incident TE-wave, in the form doughnut for TM-wave. We are first to theoretically experimentally pattern has local regions - located symmetrically or asymmetrically both at center on periphery where energy flux inversely directed. discovered effect used moving...

Based on the Richards-Wolf theory, it is strictly shown that in sharp focus of a linearly polarized laser beam, flux spin vector has only transverse components (the effect photonic wheels or helicopter). For optical vortex, orbit-spin conversion leads to appearance both longitudinal and angular momentum (SAM) focus. We show strong circularly Gaussian component SAM maximal axis, with orbital (OAM) being ring. In this way, OAM motion trapped microparticle can be evaluated separately....

We have considered the tight focusing of light with linear polarization. Using Richards–Wolf formalism, it is shown that before and after focal plane, there are regions in which polarization circular (elliptical). When passing through direction rotation vector reversed. If focus a certain area was left polarization, then directly this will be similar right This effect allows linearly polarized to used rotate dielectric microparticles little absorption around their center mass.

In the general case, upon free-space propagation of a paraxial optical vortex (OV) its topological charge (TC) is not conserved, unlike orbital angular momentum (OAM), which remains unchanged. this work, we discuss Gaussian beam with fractional TC in source plane, showing theoretically and numerically way changing (but integer) propagation. There are four evolution scenarios for an original OV that depend on how close to integer even or odd number. If initial plane has arbitrary value, it...

By simulating tight focusing of vector beams with azimuthal polarization fractional order <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0</mml:mn> </mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mi>m</mml:mi> <mml:mn>1</mml:mn> </mml:math> ( <mml:mo>=</mml:mo> is the polarization; linear polarization), it shown that shape intensity distribution in focal spot changes from elliptical ) to round <mml:mn>0.5</mml:mn> and ends an...

An expression to describe the complex amplitude of a family paraxial hypergeometric laser beams propagating in parabolic-index fiber is proposed. A particular case Gaussian optical vortex studied. Under definite parameters, vortices become modes medium. This new derived for wide class solutions nonparaxial Helmholtz equations that parabolic refractive index medium cylindrical coordinate system. As are proportional Kummer's functions, only those them which coincident with Laguerre–Gaussian...

Using near-field scanning microscopy, we demonstrate that a 15-µm zone plate fabricated in 70-nm chromium film sputtered on glass substrate and having focal length outermost zone's width equal to the incident wavelength λ = 532 nm, focuses circularly polarized Gaussian beam into circular subwavelength spot whose diameter at fullwidth of half-maximum intensity is FWHM=0.47λ.This value near-accurate agreement with FDTD-aided numerical estimate FWHM=0.46λ.When focusing linearly along y-axis, an...

In this paper, the tight focusing of high-order cylindrical vector beams (beams with polarization singularity) was investigated. Using Richards-Wolf formalism, there were obtained expressions for all projections electric and magnetic light fields m-order singularity in focus aplanatic system. Also longitudinal component Poynting obtained. It shown that these produce focal areas direction opposite to propagation beam. Moreover, negative values could be comparable absolute value positive...

A four zone subwavelength binary diffraction optical micro element (size of 100x100 mkm) for polarization transformation from linear to radial was calculated and designed. grating period equal 400 nm, a height the 110 nm in gold film wavelength 633 nm. Simulation by FDTD method Rayleight-Zommerfeld integral shown, that despite only zones used different angles there are polarized light beam far field with smooth angle dependence on circle observation position. Experimentally shown near field,...

We designed, fabricated, and characterized a thin metalens in an amorphous silicon film of diameter 30 µm, focal length equal to the incident wavelength 633 nm. The lens is capable simultaneously manipulating state polarization phase light. converts linearly polarized beam into radially light, producing subwavelength focus. When illuminated with Gaussian beam, produces spot whose size at full-width half-maximum intensity 0.49λ 0.55λ (λ wavelength). experimental results are good agreement...

In this paper using FDTD-method, we conduct a comparative modeling of sharp focus the laser light by binary-phase and binary-amplitude Fresnel zone plates, with latter being fabricated as thin metal films 20-30-nm thickness. Subwavelength local maximums are found near rings silver their intensity comparable in focus. They can be explained excitation surface plasmons.

A reverse energy flow is theoretically demonstrated to occur in the interference pattern generated by four plane waves with linear polarization. In some regions of pattern, right-handed triplets plane-wave vectors k $({k}_{z}>0)$, E, and H (comprising a wave vector $\mathbf{E}$- H-field vectors) sum up form an electromagnetic field described triplet $({k}_{z}<0)$, H. It these that negative propagation light occurs. On optical axis orbital flow, proportional intensity, shown be positive,...

Using a binary microlens of diameter 14 μm and focal length 532 nm (NA=0.997) in resist, we focus 633 laser beam into near-circular spot with dimensions (0.35 ± 0.02)λ (0.38 (λ is incident wavelength) at full width half-maximum intensity. The area the 0.105λ(2). light mixture linearly radially polarized beams generated by reflecting Gaussian 100 × four-sector subwavelength diffractive optical microelement gold coating. focusing (the other conditions being same) found to produce an elliptical...

We numerically investigated the focusing of optical vortices with wavelength λ = 532 nm and right-hand circular polarization by using a diffractive lens numerical aperture NA 0.95. The simulation was carried out Richards-Wolf formulae FDTD-method. topological charges equal to ±1 ±2 investigated. It shown that wide-aperture can produce an intensity distribution negative value longitudinal component Poynting vector.

In this paper, we investigate a 16-sector spiral metalens fabricated on thin film (130 nm) of amorphous silicon, consisting set subwavelength binary diffractive gratings and with numerical aperture that is close to unity. The converts linearly polarized incident light into an azimuthally optical vortex focuses it at distance approximately equal the wavelength light, λ = 633 nm. Using scanning near-field microscope, shown experimentally forms elliptical focal spot diameters smaller than...

We have investigated a four-sector transmission polarization converter (4-SPC) for wavelength of 633 nm, that enables the conversion linearly polarized incident beam into mixture and azimuthally beams. It was numerically shown by placing Fresnel zone plate focal length 532 nm immediately after 4-SPC, light can be focused an oblong subwavelength spot whose size is smaller than diffraction limit (with width breadth, respectively, measuring FWHM = 0.28λ 0.45λ, where λ stands full-width at half...

Ultrashort-pulse laser surface and bulk nano- micromachining of dielectrics have multiple promising applications in micro-optics, microfluidics, memory storage. The fundamental principles relate intrinsic inter-band multi-photon (MPA) laser-induced intra-band free-carrier absorption (FCA) to particular ablation mechanisms features. These are yet be quantified into a complete set basic experimental laser-matter interaction parameters, describing photoexcitation, relaxation, final ablation. In...

We discuss interesting effects that occur when strongly focusing light with mth-order cylindrical-circular polarization. This type of hybrid polarization combines properties the cylindrical and circular Reluing on Richards-Wolf formalism, we deduce analytical expressions describe E- H-vector components, intensity patterns, projections Poynting vector spin angular momentum (SAM) at strong focus. The in focus is theoretically numerically shown to have an even number local maxima located along...