Single-Mode to Multi-Mode Crossover in Thin-Load Polymethyl Methacrylate Plasmonic Waveguides

摘要

Mode character and mode dispersion of sub-60-nm-thick polymethyl methacrylate dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) are investigated using photoemission electron microscopy and finite element method simulations. Experiment and simulation show excellent agreement and allow identifying a crossover from single-mode to multi-mode waveguiding as a function of excitation wavelength lambda and DLSSPW cross section. Experiment and simulations yield, furthermore, indications for the formation of a surface plasmon-polariton cavity mode in the close vicinity of the waveguides.