Subwavelength confinement in an integrated metal slot waveguide on silicon

We demonstrate propagation losses of less than 0.8 dB/microm in a metal slot waveguide on silicon with a predicted confinement substantially below the optical wavelength (approximately 1.55 microm). We also show compact and efficient coupling of the high-confinement metal slot waveguide with a standard silicon dielectric waveguide with a coupling efficiency of approximately 2.5 dB per facet.