Performance analysis of gallium lanthanum sulfide and cuprous oxide as nanoplasmonic couplers

Nanoplasmonic couplers using gallium lanthanum sulfide (GLS) and cuprous oxide (Cu₂O) are proposed. Their characteristics and performances are analyzed numerically using the finite-difference time-domain (FDTD) method. A coupling efficiency of 67% has been achieved at the optical communication wavelength when GLS is used as the coupler whereas a coupling efficiency of 56% has been achieved when cuprous oxide is used. The proposed nanoplasmonic couplers can operate at a broad frequency range. The proposed design is also easier to fabricate since it is a flat terminal dielectric waveguide, placed at the entry of a plasmonic waveguide which is based on the metal-dielectric-metal (MDM) configuration.