Bismuth Plasmonic Antennas

Bismuth is a particularly promising alternative plasmonic metal because of its theoretically predicted wide spectral bandwidth. In this study, we experimentally demonstrate the correlation between the shape and size of individual bismuth plasmonic antennas and their optical properties. To this end, we employ a combination of scanning transmission electron microscopy and electron energy loss spectroscopy. Bar-shaped and bowtie bismuth plasmonic antennas of various sizes were fabricated by focused ion beam lithography of a polycrystalline bismuth thin film. Our experimental findings demonstrate that these antennas support localized surface plasmon resonances and their dipole modes can be tuned through their size from the near-infrared to the entire visible spectral region. Furthermore, our findings demonstrate that bismuth exhibits a plasmon dispersion relation that is nearly identical to that of gold while maintaining its plasmonic performance even at higher plasmon energies, thus rendering it a promising low-cost alternative to gold.