All-optical broadband variable optical attenuators and switches in plasmonic teeth waveguides

All-optical broadband variable optical attenuators (VOAs) and switches based on plasmonic teeth shaped waveguides have been proposed and numerically investigated. The Finite Difference Time Domain (FDTD) simulation results reveal that VOAs based on three teeth structure filled with CdSe-doped PMMA can continuously attenuate the power of a light beam from 3.7 dB to 39 dB within a broad forbidden band by an external control light. For wavelengths within the forbidden band, the structure can also operate as a switch with presence or absence of pumping light corresponding to on or off state. For a modulation depth of 27 dB, a relatively small variation in the absorption coefficient of CdSe QD-PMMA in side cavity (from κ = 0 to κ = 0.15) is enough.