Asymmetric band-pass plasmonic nanodisk filter with mode inhibition and spectrally splitting capabilities.

A compact wavelength band-pass filter based on metal-insulator-metal (MIM) nanodisk cavity is proposed and numerically investigated by using Finite-Difference Time-Domain (FDTD) simulations. It is found that the transmission characteristics of the filter can be easily adjusted by changing the geometrical parameters of the radius of the nanodisk and coupling distance between the nanodisk and waveguide. By extending the length of input/output waveguides, the filter shows the resonant mode inhibition function. Basing on this characteristic, a two-port wavelength demultiplexer is designed, which can separate resonant modes inside the nanodisk with high transmission up to 70%. The waveguide filter may become a potential application for the design of devices in highly integrated optical circuits.