Evaluating the beam shape coefficients of Bessel-Gauss beams with radial quadrature: a comparison with angular spectrum decomposition and finite series methods.

The Bessel-Gauss beam (BGB) stands as a physically realizable beam extensively employed in applications such as micromanipulation and optical trapping. In these contexts, the assessment of beam shape coefficients (BSCs) becomes imperative. Previous research reveals that the BSCs of the BGBs obtained with different methods deviate from each other under certain circumstances. In this paper, the formulation of BSCs employs the radial quadrature method, and a comparative analysis is conducted with counterparts formulated using the angular spectrum decomposition and the finite series technique. Contributions stemming from evanescent waves and the situation of the BSC blowing-ups are discussed, offering a deep insight of pertinent BSC evaluation methods. The paper provides an alternative approach for calculating the BSCs of the BGBs.