Research on nano-plasmonic waveguide filters

In this paper, we review recent progress in our researches on nano-plasmonic waveguide filters based on tooth/teeth-shaped (T-series) and nano-capillary structures. A simple tooth-shaped waveguide is firstly analyzed as a basic building block of wavelength filters and demultiplexers. The structure is then extended to symmetric/asymmetric multiple-teeth and capillary structures. The finite-difference-time-domain method simulation results show that T-series structures are of the characteristic of reflective wavelength filters with symmetric multiple-teeth structures exhibiting wide and sharp bandgaps, while the asymmetrical multiple-teeth structure and the capillary structure can achieve selective narrow-band filtering and wavelength demultiplexing functions, respectively. Both analytic and simulation results show that the central wavelengths of reflective or selective filters have relationships with the depth and width of a tooth or an effective resonator. The filters may have applications to ultrahigh nanoscale integrated photonic circuits.