Remote-controllable refractive-index-sensitive plasmonic waveguide and rake-like switch: designs and FDTD simulations

Abstract

A refractive-index-sensitive plasmonic waveguide, whose transmission characteristics could be controlled remotely by a rake-like switch design, is theoretically studied in the reported work. The distance from the remote control unit to the bus waveguide is more than 0.25 μm, and it still possesses great efficiency even when the distance is increased to 0.535 μm. The switch basically contains two main sections. The first is on the bottom and next to the bus waveguide which functions as a plasmonic resonator that can induce localized surface plasmon resonance (LSPR) and restrict wave propagation at corresponding resonant frequency. The second is on the top and far away from the bus waveguide which functions as a remote controller that can modulate LSPR frequency in the first section. The refractive-index-dependent transmission spectra of this filter were simulated using finite-difference time-domain method. The results have shown that even at a distance as far as 0.5 μm, the ON/OFF switching of the wave propagation in a bus waveguide can still be modulated by adjusting the refractive index of a remote rectangular controller. With only 0.08 difference in refractive index, it could be obtained an on-off switching ratio of 18.7, 20.4 and 25.7 respectively for different waveguides at visible and near infrared wavelength, which shows great potential applications in refractive index sensors and remote-controllable band-stop filters.