Generalized Lorenz-Mie theory in the analysis of longitudinal photophoresis of arbitrary-index particles: On-axis axisymmetric beams of the first kind

The uniform plane wave is the reference solution of Maxwell's equations when it comes to rigorous theoretical investigations of photophoretic forces from the Mie theory. Here, we address the theory of photophoresis for a more general class of on-axis axisymmetric beams of the first kind. To do so, the generalized Lorenz-Mie theory (GLMT) is introduced for the first time in the calculation of analytic and closed-form expressions for the asymmetry factor assuming arbitrary-index micro-sized spheres of arbitrary size parameters. The behavior of the asymmetry factor is illustrated for non-volatile particles illuminated by Gaussian and circularly symmetric zero-order Bessel beams. The theory here presented is valid for arbitrary size parameters and is a first attempt towards the incorporation of real optical wave fields into photophoresis of absorbing particles using the GLMT for arbitrary-shaped beams. (c) 2021 Elsevier Ltd. All rights reserved.