In this work, we report a novel waveguide structure that hybridizes the conventional dielectric waveguides with novel metal/dielectric plasmonic waveguides by incorporating the former inside the dielectric part of the latter. As a result, the strongest field in the waveguide locates at the center of the guide instead of the metal/dielectric interfaces, which can significantly reduce the propagation loss, and meanwhile offer excellent confinement of the plasmonic lightwave. Theoretically the inside wave mode is to be shown a hybrid plasmonic-optical mode. We further analyze the mode properties of such waveguides with various structure dimensions, and demonstrate its wave propagating characteristics with numerical simulations. The theoretical study suggests that such waveguides are promising for ultra-compact integration of lightwave circuit. Additionally, fabrication of such waveguides is compatible with current micro/nanofabrication technologies.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.