A sodium-based hybrid plasmonic waveguide with ultra-deep subwavelength confinement and low cross-talk

Abstract

Surface plasmon photonics provides a feasible method for achieving high-density photonic integration and low-loss optical field transmission. Here we propose a sodium-based hybrid plasmonic waveguide consisting of a cylindrical sodium nanowire and a Si nano-rib waveguide located on the silica substrate at the wavelength of 1550 nm and investigate the mode properties by using the finite element method. The results indicate that ultra-deep subwavelength modal fields with the mode areas of 9.64 × 10−6A0 ∼ 9.507 × 10−4A0 (A0 = λ2/4) and propagation lengths of 8 ∼ 46.5 μm could be achieved when the thickness of the spacer is less than 4 nm. Moreover, investigations on fabrication tolerance and crosstalk show that the proposed waveguide exhibits a good fabrication error tolerance and very low cross-talk between adjacent structures with a minimum separation distance of around 300 nm, which makes it quite suitable for applications in photonic integration. These findings may have potential applications in the field of photonic devices, such as nanowaveguides, lasers, and sensors.