Selective Properties of a Planar Bragg Waveguide

We study wave propagation in a open oversized planar waveguide with periodical Bragg structure, translation vector of which is perpendicular to the direction of wave propagation. Such waveguide can be realized either in a medium with periodic modulation of dielectric constant or in planar waveguide with corresponding corrugation. It is shown that step of corrugation phase provides the existence of a mode with exponentially small diffraction losses. This results in high selectivity over transverse indices of considered waveguide.