Size dependence of surface plasmon modes in one-dimensional plasmonic crystal cavities

The characteristics of surface plasmon polaritons (SPPs) confined in a one-dimensional plasmonic crystal (1D-PlC) cavity are investigated using a cathodoluminescence (CL) detection system equipped with a 200 keV scanning transmission electron microscope (STEM). The dispersion curves of SPPs near the Γ point are derived from the angle-resolved CL spectra, and the SPP cavity modes are observed inside the band gap region. The mode number and wavenumber of the cavity modes are determined from the beam scan CL spectral images. The energy of the cavity mode depends on the cavity length and the angular distribution of the emission from the cavity changes with the mode number of the cavity mode. We also reveal that the phase shift due to the reflection at the cavity edge changes significantly with the resonant energy.