Transmission line analogy in plasmonics
D. Dragoman, Univ. of Bucharest, Faculty of Physics, Romania
Plasmonics is a flourishing research field, allowing the development of sensitive optical sensors and optical spectroscopy techniques, as well as the design and fabrication of miniaturized integrated photonic circuits that manipulate electromagnetic fields at a sub-wavelength scale. The propagation of surface plasmon polaritons at metal-dielectric interfaces is generally simulated numerically using softwares such as COMSOL or FTDT techniques. However, both computation time and cost can be significantly reduced by using an analytic approach based on the analogy with the transmission line method in microwaves. This approach has been shown to provide highly accurate results for slot plasmonic waveguides. In this work, examples of using this analogy for designing one-, two-, and three-bit plasmonic logic gates based on straight slot waveguides covered by materials with adjustable dielectric constants, such as graphene, or on several ring-shaped configurations. Then, it is shown that the analogy between transmission lines in microwaves and plasmonics could be extended to metallic nanowire geometries if due account is taken of the effective spatial extent of plasmonic fields. In this way, this rather easy method of plasmon polariton propagation simulation covers the vast majority of configurations of interest.