Angular spectrum method for acoustic beam in anisotropic media and structures

Abstract The Angular Spectrum (AS) method is commonly used to calculate the propagation of scalar wave fields. This study extends the application of AS to vector wave propagation, specifically addressing acoustic waves in anisotropic media. The approach involves using plane wave spectra to express all possible mode waves, namely one q-P wave and two q-S waves, that propagate in various directions in the medium. These AS are determined by applying boundary conditions at the source surface where the vector waves are generated and the modes waves are coupled. AS decomposition of waves requires the determination of complex wavenumber vectors (or slownesses) through the Christoffel equation, including both propagating and evanescent waves. The determination of the acoustic beam profile in TeO2 crystals is presented as an application example of AS.