arXiv subjects

Aleksandr Bekshaev

Publications and source records attributed to Aleksandr Bekshaev.

22 records · Page 2Linked to original sources

arXiv2011

Polarization-dependent transformation of a paraxial beam upon reflection and refraction: a real-space approach

We analyze the paraxial beam transformation upon reflection and refraction at a plane boundary. In contrast to the usual approach dealing with the beam angular spectrum, we apply the continuity conditions to explicit spatial representations of the electric and magnetic fields on both sides of the boundary. It is shown that the polarization-dependent distortions of the beam trajectory (in particular, the "longitudinal" Goos-Hänchen shift and the "lateral" Imbert-Fedorov shift of the beam center of gravity) are directly connected to the incident beam longitudinal component and appear due to its transformation at the boundary.

physics.optics↗

arXiv2011

Role of Azimuthal Energy Flows in the Geometric Spin Hall Effect of Light

In an oblique section of a paraxial beam with angular momentum, the beam center of gravity (CG) is shifted with respect to its position in the normal cross section. We relate this shift with the internal energy redistribution occurring on the passage between the normal and oblique sections. The transverse orbital flow explains the effect for scalar beams, similar incorporation of the spin flow enables explanation of the CG shift in oblique sections of the elliptically polarized beams. Role of the special properties of the position-sensitive detector placed in the oblique beam section is discussed.

physics.optics↗

arXiv2011

Mechanical action of inhomogeneously polarized optical fields and detection of the internal energy flows

We analyze numerically the correspondence between the mechanical action, experienced by a spherical microparticle, and the internal energy flows as well as spatial and polarization inhomogeneity of the light field incident on the particle. The inhomogeneous incident field is modelled by superposition of two plane waves, the mechanical action is calculated via the Mie theory for dielectric and conducting particles of different sizes and optical properties. It is shown that both spin and orbital components of the field momentum can produce the mechanical action, which can thus be used for experimental study of the internal energy flows in light beams. However, exact value and even direction of the force applied to a particle depends on many details of the field-particle interaction. Besides, forces that are not associated with any sort of the energy flow (we attribute them to the gradient force owing to the inhomogeneous intensity and to the dipole force emerging due to inhomogeneous polarization) can strongly modify the observed mechanical action. The results should be taken into account in experiments employing the motion of probing particles suspended within optical fields. We suppose that situations where an optical field exerts the polarization-dependent mechanical action on particles can be treated as a new form of the spin-orbit interaction of light.

physics.optics↗

arXiv2010

Improved theory for the polarization-dependent transverse shift of a paraxial light beam in free space

Spatial distribution of the longitudinal field component of a circularly polarized optical beam depends on the polarization handedness, which causes the lateral shift of the beam "center of gravity" when its polarization toggles. We present the generalized theory of this effect, which demonstrates its relation with the angular irradiance moments of the beam. The theory is applicable to arbitrary paraxial beams and shows that the lateral shift is the same for all cross sections of the beam.

physics.optics↗