Parasitic Scattering of Bloch Surface Waves

One-dimensional photonic crystals (PCs) consisting of alternating homogeneous dielectric layers are considered as a promising platform for integrated photonic systems, since they can support Bloch surface waves (BSWs; surface electromagnetic waves propagating along an interface of a PC), which can be used as information carriers in such integrated systems. Here, we study the parasitic scattering losses arising upon diffraction of BSWs on a dielectric ridge located on the surface of the PC. We demonstrate that under certain conditions imposed on the BSW angle of incidence and the PC parameters (thicknesses and refractive indices of the PC layers), the parasitic scattering losses can be completely eliminated.