A comparative study of dielectric materials as nano-plasmonic couplers

We present a novel ultra-compact nano-plasmonic coupler using aluminum gallium arsenide (AlGaAs) and silicon-germanium alloy (Si-Ge) as the coupling dielectric materials. The performance of these two materials has been analyzed using the finite-difference time-domain (FDTD) method. The parameters that we have analyzed are coupling efficiency, reflection coefficient, return loss and mismatch loss. At telecom wavelength an efficiency of 51% has been achieved when AlGaAs is used as the dielectric while for Si-Ge it is 48%. The presented structure also provides advantage in the fabrication process since it is a rectangular shaped waveguide having no tapering. The coupler can operate at a broad range of input signal wavelengths.