TE-TM decoupling for guided propagation in bianisotropic media

The most general bianisotropic or magneto-electric medium is considered. Necessary and sufficient conditions are established for guided propagation in such a medium to be described in terms of the superposition of TE and TM fields. An additional condition ensures TE-TM decoupling independently of the direction of propagation in the medium. The field components for TE and TM fields are given.