Propagation Loss of Long-Range Surface Plasmon Polariton Gold Stripe Waveguides in the Thin-Film Limit
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Propagation loss experienced by long-range plasmon polaritons in ultrathin gold stripe waveguides embedded in different polymer cladding materials was studied and correlated with atomic-scale characterization of the gold film structure. We identify the main sources of experimentally observed propagation loss which deviates from ideal values in the thin-film limit. Increased loss can be translated to an increased effective thickness of the ultrathin films due to incomplete surface coverage and the presence of diffuse interfaces, both of which depend significantly on the choice of cladding material. The results illustrate the importance of atomic-scale dynamics of metal film formation for the selection of optimum substrate materials for surface plasmon polariton waveguides, resonant transmission structures, and semitransparent electrical contacts.
KeywordsSurface plasmons Optical waveguides Optical polymers Ultrathin metal films
This project was supported by the Icelandic Research Fund, the FP7 IRSES POLATER and POLAPHEN projects, as well as the ESF PLASMON-BIONANOSENSE network. The authors wish to thank Stéphane Kena-Cohen and Stefan Maier for the fruitful discussions.