Plasmonic Doppler Grating and Photoluminescence-Driven Broadband Directional Optical Nanoantennas

Well-designed plasmonic nanostructures can concentrate and sculpt optical fields at nanometer scale. In this talk, I will present recent progress in my research group about plasmonic Doppler grating sensor and photoluminescence shaping by plasmonic nanostructures. In the first part, I will present the plasmonic Doppler grating (PDG) which offers continuous azimuthal angle-dependent lattice momentum for continuous and broadband coupling between photons and surface plasmons (Fig. 1a). The PDG design is simple and fully designable for applications in two-dimensional continuous color sorting and index sensing [1]. In the second part, I will present broadband directional emission from log-periodic nanoantennas (Fig. 1b). We exploit the plasmon-modulated photoluminescence (PMPL) from gold as an optical source to drive antenna elements precisely at the corresponding working frequencies of the feed elements. Using the photoluminescence, we also present a Yagi-Uda antenna-based nano-spectrometer in the optical regime. Photoluminescence is a unique driving source for optical nanoantennas and finds no counter parts for radio-frequency antennas. Using PMPL as an optical source to drive nanoantennas is a practical and implementable approach to realize broadband directional photon sources [2].