Angular spectrum representation of the Bessel-Gauss beam and its approximation: A comparison with the localized approximation

Abstract

The angular spectrum representation of the vector Bessel-Gauss beam is used for discussing the connection between the angular spectrum decomposition (ASD) method and the quadrature method of the generalized Lorenz-Mie theory (GLMT). Under the paraxial condition, the beam shape coefficients (BSCs) obtained in the ASD method can be approximated to the same expressions as those obtained in the localized approximation method. The validity of the approximate method for evaluating the BSCs is numerically studied, based on both the beam's angular spectrum and the off-axis distance.