Expanding non-axisymmetric beams in spherical coordinates with cylindrical wave spectrum decomposition

•Cylindrical wave spectrum decomposition is extended for calculating BSCs of non-axisymmetric beams.•Expressions of the BSCs are obtained as one dimensional integrations and may be numerically implemented reliably and efficiently.•The method can be used for rigorously describing the on-/off-axis located beams. Description of structured beams in spherical coordinates is critical in studying the interaction between beams and spherical particles. The work extends the cylindrical wave spectrum decomposition (CWSD) method to non-axisymmetric beams, applied herein to the elliptical Gaussian beam, cosine Gauss beam and Hermite-Gauss beam as examples. It is shown that for these beams the beam shape coefficients (BSCs) can be expressed in one dimensional integrations and hence numerical calculations can be performed very efficiently. The beam fields reproduced by using these BSCs show satisfactory faithfulness to the rigorous expression of the given fields. Typically, the difference between them is less than 10−8.