A digital system has a dielectric core waveguide that is formed within a multilayer substrate. The dielectric waveguide has a longitudinal dielectric core member formed in the core layer having two adjacent longitudinal sides each separated from the core layer by a corresponding slot portion formed in the core layer The dielectric core member has the first dielectric constant value. A cladding surrounds the dielectric core member formed by a top layer and the bottom layer infilling the slot portions of the core layer. The cladding has a dielectric constant value that is lower than the first dielectric constant value.