Light guiding, bending, and splitting via local modification of interfaces of a photonic waveguide

A general approach to the surface control of the localization, guiding, and redirecting of volume-mode light in photonic waveguides via tailoring their interfaces (surfaces) is proposed. The approach is demonstrated for dielectric rod-type photonic crystal slabs, whose regular and defect parts are distinguished by whether the nanocylinders are covered by metal caps. Thus, the rod-array part of the structure is not changed, while the local modifications are only applied to the interfaces. The basic functionalities, i.e., localized volume wave guiding, bending, and splitting are achievable. Selective dual-mode operation is possible due to the co-existence of a defect mode and a chainlike mode in one structure.