Subwavelength plasmonic metallic nanopillar based coupler

We theoretically investigate compact plasmonic coupler based on metal nanopillar over silicon on insulator substrate demonstrating routing of light at nanoscale. Proposed geometry demonstrates strong mode confinement, allows sharp bends with low loss and easy integration on chip circuitry. The coupler is optimized for visible regime and can be tuned for specific wavelengths. Plasmonic transverse magnetic (TM) modes are observed and examined using finite difference time domain (FDTD) computations. Coupling length (Lc) and gap width (Wc) for the nanopillar assisted four-port plasmonic coupling structure is optimized to give enhanced efficiency. The structure renders subwavelength light manipulation overcoming conventional photonics with applications in plasmonic circuitry for nanoscale guidance of light in data transmission, integrated chip design etc.