  The magnon spectral problem is solved in terms of the spectrum of a
diagonalizable operator for a generic class of magnetic states that includes
several types of domain walls and the chiral solitons of monoaxial helimagnets.
Focusing on the isolated solitons of monoaxial helimagnets, it is shown that
the spin waves scattered (reflected and transmitted) by the soliton suffer a
lateral displacement analogous to the Goos-Hanchen effect of optics. The
displacement is a fraction of the wavelength, but can be greatly enhanced by
using an array of well separated solitons. Contrarily to the Goos-Hanchen
effect recently studied in some magnetic systems, which takes place at
interfaces between different magnetic systems, the effect predicted here takes
place at the soliton position, what it is interesting from the point of view of
applications since solitons can be created at different places and moved across
the material. This kind of Goos-Hanchen effect is not particular of monoaxial
helimagnets, but it is generic of a class of magnetic states, including domain
walls in systems with interfacial Dzyaloshinskii-Moriya interaction.
