Reduction of propagation loss by introducing hybrid plasmonic model in graded-grating based “trapped rainbow” system

Hybrid plasmonic waveguide is capable of supporting deep sub-wavelength confinement and long-range propagation length of surface plasmon polaritons (SPPs). In this article, we propose to employ a silica layer between a silver film and silicon layer to improve the propagation characteristic of slow SPPs in the “trapped rainbow” system based on graded grating structure. Finite difference time domain simulation demonstrates that the improved structure is able to localize light of different frequencies at different positions and offers the advantage of supporting slow SPPs with a much lower propagation loss. The proposed structure might find great applications in optical processing and optical communication.