Ballistic, gate-defined devices in two-dimensional materials offer a platform for electron optics
phenomena influenced by the material’s properties and gate control. We study the ray trajectory
dynamics of all-electronic, gate-defined cavities in bilayer graphene to establish how distinct
regimes of the internal and outgoing charge carrier dynamics can be tuned and optimized by the
cavity shape, symmetry, and parameter choice, e.g. the band gap and the cavity orientation. In
particular, we compare the dynamics of two cavity shapes, o’nigiri, and Limaçon cavities, which fall
into different symmetry classes. We demonstrate that for stabilising regular, internal cavity modes,
such as periodic and whispering gallery orbits, it is beneficial to match the cavity shape to the
bilayer graphene Fermi line contour. Conversely, a cavity of a different symmetry than the material
dispersion allows one to determine preferred emission directionalities in the emitted far-field