Wave surfaces and wave velocities in optics of non-absorbing optically active media

General relations between phase normal vectors, refraction vectors and ray refraction vectors as well as between phase and ray velocities of plane waves are obtained for linear non-absorbing optically active (bianisotropic) media. For such media the geometric constraint on the wave surfaces is discussed. Equality of the group and ray velocities of the monochromatic plane waves in dispersive bianisotropic media is proven. It is shown that the degree of the ray surface equation generally exceeds the degree of the refraction surface and phase velocity surface equations but it cannot be greater than 108. In particular, for gyrotropic dielectric media of symmetry classes 3, 3-bar, 4, 4-bar, 4/m, 6, 6-bar and 6/m it equals 12. The domain of applicability of the duality principle known in optics of anisotropic media is determined