Rigorous analysis of the transverse acoustic modes in optical waveguides by exploiting their structural symmetry.

A full-vectorial finite-element-based approach has been developed to find accurate modal solutions of acoustic modes in Ge-doped planar silica waveguides. The structural symmetry is exploited, and Aitken's extrapolation is also used to improve the accuracy of the solution. The spatial dependences of the dominant and nondominant displacement vectors are shown for the fundamental and higher-order transverse modes. The modal hybridness and modal birefringence between the two fundamental transverse modes are also presented.