A multilayered waveguide, which supports surface plasmon polaritons, is considered as an absorption modulator. The
waveguide core consists of a silicon nitride layer and ultrathin layer with the varied carrier density embedded between
two silver plates, which also serve as electrodes. Under applying voltage to electrodes the carrier density in the
transparent conducting oxide layer (we study indium tin oxide - ITO) changes according to the Thomas-Fermi screening
theory. We employ analytical solutions for a multilayered system as well as numerical simulations with the commercial
software package CST Microwave Studio in the frequency domain. We explore different permittivities of the ITO layer,
which can be achieved by utilizing different anneal conditions. To increase transmittance and enhance modulation depth
or efficiency, we propose to pattern the continuous active layer. Dependence from the pattern size and filling factor of
the active material are analyzed for tuned permittivity of the ITO layer. Direct simulation of the device functionality
validates optimization design.
|