Formation of Inverse Energy Flux in the Case of Diffraction of Linearly Polarized Radiation by Conventional and Generalized Spiral Phase Plates

Abstract

Recently, there has been increased interest in the shaping of light fields with an inverse energy flux to guide optically trapped nano- and microparticles towards a radiation source. To generate inverse energy flux, non-uniformly polarized laser beams, especially higher-order cylindrical vector beams, are widely used. Here, we demonstrate the use of conventional and so-called generalized spiral phase plates for the formation of light fields with an inverse energy flux when they are illuminated with linearly polarized radiation. We present an analytical and numerical study of the longitudinal and transverse components of the Poynting vector. The conditions for maximizing the negative value of the real part of the longitudinal component of the Poynting vector are obtained.

Tailoring of Inverse Energy Flow Profiles with Vector Lissajous Beams

“…As follows from the theoretical analysis and the results of numerical modeling, with the same pair of indices (p, q), the number of directions with a negative energy flow are different in the three considered cases. We pay special attention to these directions, since it is their appearance that provides an advantage in the distribution of the reverse energy flow for the considered types of VLBs over CVBs [16][17][18][19], circularly polarized vortex beams [14,15], and also linearly polarized beams with trigonometric amplitude [21,23].…”

“…However, to calculate characteristics such as the Poynting vector, expressions for the magnetic component of the field are also required, which can be calculated using Maxwell's equations. In Equation (1), the polarization transformation vectors for the electric and magnetic field are the following [18,23,25]:…”

“…In Refs. [18,21,23], the field R(θ) was considered in combination with a superimposed narrow annular aperture [52]:…”

“…In Ref. [23], the results for fields that can be considered cs-VLBs and ss-VLBs for (p, q) = (p, 0) were also presented. In addition, the numerical calculation was also made for non-integer p.…”

“…In all these cases, the dimensions of the region of the formation of the inverse energy flow are small (approximately of the order of the wavelength) and the location of this region is limited by the optical axis. Some techniques were proposed to overcome these limitationsthe use of annular apertures for the elongation of the area of energy backflow [21,22] and the use of special generalized spiral phase plates to shift the center of the Poynting vector distribution and the maximum negative value of the inverse energy flow from the optical axis [23].…”