Steptrench plasmonic directional coupler

A novel structure is proposed for plasmonic directional couplers based on the steptrench waveguide. The Coupling length and maximum transfer power have been drived as a function of structural parameters. Analysing the coupler have been done with the aid of a compound method. First, propagation constants of symmetric and anti symmetric modes are extracted with the aid of a mode solver (based on numerical method of finite element). Then coupling length and maximum transfer power are drived based on the previous step. Finally the performance of steptrench coupler is compared with the v-groove coupler, revealing the reduction of coupling length for the proposed structure.