Rectangular Nano-Wire Analysis at Terahertz and Optical Frequencies Using Interior-Exterior Method and Surface Impedance Model

The field distribution inside metallic rectangular strip can be obtained using the interior-exterior method. The formulation for this method is exact for 2D cases; though, numerical implementation produces inaccuracies. In this paper, we compute the fields inside the rectangular metal strip at terahertz and optical frequencies and compare the field distribution with the bulk model. It is found that simple zeroth order surface impedance model can indeed be used instead of accurate but processor-exhausting techniques at terahertz frequencies. The zeroth order surface impedance model can also be used at optical frequencies, though with cautious. Moreover, a generalized definition of penetration depth is introduced to cover plasmonic propagation regime.