Efficient Coupling in Transverse Strip Metal-Insulator-Metal Structure on Silicon-on-Insulator Layer Stack

This article presents a new directional coupling between two transverse strip metal-insulator-metal (TS-MIM) waveguides on silicon-on-insulator (SOI) platform at 1.55 μm wavelength. The directional coupling between two TS-MIM waveguides shows a coupling length of less than 2 μm for a ridge width and gap width of 150 nm and 50 nm, respectively. Meanwhile, a direct coupling between a hybrid plasmonic (HP) waveguide and a TS-MIM waveguide was also investigated. The maximum optical power transmission from the HP-waveguide to the TS-MIM waveguide will occur at 1.3 μm long TS-MIM waveguide. An HP-waveguide coupled to the TS-MIM waveguide with a tapered tip is incredibly beneficial in nanofocusing applications.