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3D Modeling of Plasmon Excitation by Grating

G.G. Gentili[1], S. Pietralunga[2], M. Bolzoni[1]
[1]Politecnico di Milano, Dipartimento di Elettronica e Informazione, Milano, Italy
[2]INFN-CNR, Istituto di Fotonica e Nanotecnologie, Milano, Italy

Grating-assisted optical coupling into long-range modes of strip plasmonic waveguides is analyzed by a 3D numerical simulation with COMSOL Multiphysics. We used the RF Module and its scattering formulation. A comparison with results obtained using the common 2D approximated analysis is shown for the case of 1D grating coupler and input Gaussian beam. Excited diffracted modal field distribution is calculated as it evolves in propagation. The computation is demanding because of the large box size (40x30x4 lambda^3) and has been carried out on a Linux workstation with 96 GB of RAM. Some peculiar features of 3D analysis compared to 2D analysis are pointed out such as frequency shift of the maximum and higher order mode excitation.