Scattering of inhomogeneous circularly polarized optical field and mechanical manifestation of the internal energy flows

Abstract

Based on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry between the forward- and backward-scattered momentum fluxes in the Rayleigh scattering regime appears due to the spin part of the internal energy flow in the incident beam. The transverse ponderomotive forces exerted on dielectric and conducting particles of different sizes are calculated and special features of the mechanical actions produced by the spin and orbital parts of the internal energy flow are recognized. In particular, the transverse orbital flow exerts the transverse force that grows as a^3 for conducting and as a^6 for dielectric subwavelength particle with radius a, in compliance with the dipole mechanism of the field-particle interaction; the force associated with the spin flow behaves as a^8 in both cases, which testifies for the non-dipole mechanism. The results can be used for experimental identification and separate investigation of the spin and orbital parts of the internal energy flow in light fields.

arXiv comment17 pages, 5 figures. For resubmission, the language is improved, numerical mistakes in Fig. 4 are corrected and discussion is modified accordingly

References in corpus (6)

• Does a Surface Polariton Have Spin?
• Internal flows and energy circulation in light beams
• Angular Momenta and Spin-Orbit Interaction of Nonparaxial Light in Free Space
• Spin-to-orbital angular momentum conversion in focusing, scattering, and imaging systems
• Paraxial Light Beams with Angular Momentum
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Cited by in corpus (7)

• Dual electromagnetism: Helicity, spin, momentum, and angular momentum
• Dynamic Consequences of Optical Spin-Orbit Interaction
• Subwavelength particles in an inhomogeneous light field: Optical forces associated with the spin and orbital energy flows
• Mie scattering and optical forces from evanescent fields: A complex-angle approach
• Possible sorting mechanism for microparticles in an evanescent field
• Ponderomotive manipulation of cold subwavelength plasmas
• Two mechanisms of backward optical forces on Rayleigh particles in structured paraxial light