Broadband high-efficiency surface-plasmon-polariton coupler with silicon-metal interface

A high efficiency surface plasmonic coupler composed of a tapered silicon strip waveguide and a subwavelength scale metal gap waveguide is experimentally demonstrated. By tuning the parameters of the taper and the metal gap, the theoretical coupling efficiencies can be as high as 88% for a wide wavelength range. A silicon-gold plasmonic coupler is then fabricated, demonstrating 35% coupling efficiency per facet. Our experimental demonstration is a crucial step for hybrid integration of plasmonic components with conventional dielectric components.