A hybrid plasmonic multimode interference splitter based on metal-gap-silicon waveguides

A new kind of hybrid plasmonic multimode interference (MMI) splitter, based on the metal-gap-silicon (MGS) waveguides, has been firstly theoretically investigated and designed with rigorous finite element method (FEM) and three-dimensional finite-difference time-domain (3D-FDTD) simulations in this letter. At the communication wavelength of 1550 nm the transmission efficiency of the designed 1 x 3 MMI splitter is as much as 70%, and its splitting length is 6.3 mu m. Compared with the MMI splitters based on dielectric-loaded surface plasmon polariton (SPP) waveguides or the Y-like splitters, the transmission efficiency of the novel MMI splitter has been improved greatly, and its functional scale has been reduced to less than a half of the former devices. In view of its excellent performance, it stands to reason that the novel device has more extensive applications in integrated optics and other optical fields.