Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is the generation of light by an ele...
Imaging the hidden modes of ultrathin plasmonic strip antennas by cathodoluminescence.
- Citation data:
Nano letters, ISSN: 1530-6992, Vol: 11, Issue: 10, Page: 4265-9
- Publication Year:
- Chemical Engineering; Chemistry; Materials Science; Physics and Astronomy; Engineering; antenna; cathodoluminescence; LDOS; quantum emitter; Surface plasmon polariton
We perform spectrally resolved cathodoluminescence (CL) imaging nanoscopy using a 30 keV electron beam to identify the resonant modes of an ultrathin (20 nm), laterally tapered plasmonic Ag nanostrip antenna. We resolve with deep-subwavelength resolution four antenna resonances (resonance orders m = 2-5) that are ascribed to surface plasmon polariton standing waves that are confined on the strip. We map the local density of states on the strip surface and show that it has contributions from symmetric and antisymmetric surface plasmon polariton modes, each with a very different mode index. This work illustrates the power of CL experiments that can visualize hidden modes that for symmetry reasons have been elusive in optical light scattering experiments.