Abstract
Inspired by radio-frequency antenna technology, engineering of plasmonic nanoantenna has gain considerable interests in recent years since it provides the opportunities to manipulate the interaction of high-frequency electromagnetic (EM) wave and matter at nanoscale. In this thesis, we present two topic regarding to the control of light and matter interaction using plasmonic nanoantennas. In the first topic, we present a new design of two dimensional grating with continuous azimuthal angle-dependent periodicity for broadband surface plasmon wave excitation. The Plasmonic Doppler Grating (PDG) consists of a set of non-concentric circular rings that mimics the wavefronts of a moving point source and, therefore, presents azimuthal angle-resolved grating periodicity. The center and span of the working frequency window are fully designable for optimal performance in specific applications. We detail the design, fabrication and optical characterization of the PDG and demonstrate its exemplary applications in azimuthal angle-resolved color sorting, index sensing and surface-enhanced Raman scattering (SERS). We show that broadband source can be sorted continuously into surface plasmons and the variation in surrounding index can be reported as the change of in-plane angle distribution of color. Applications of PDG in grating couplers for silicon photonic circuits, hydrogen sensing, surface plasmon-enhanced spectroscopy and non-linear signal generation are anticipated.In the second topic, we investigate the driving of directional optical nanoantennas via continuum photoluminescence emission from the gold nanostructures upon laser excitation. By employing photoluminescence (PL) spectroscopy and back-focal plane imaging technique, we study the PL emission wavelength and directivity of four different type gold nanoantennas, which is nanorods, Yagi-Uda (YU) nanoantenna, L-shape Yagi-Uda nanoantenna and log-periodic dipole nanoantenna. We show that the PL emission band always match with the operating wavelength of nanoantennas upon modulation of localized surface plasmon resonance modes, therefore rendering the driving of nanoantenna practical. For example, we shows that three different Yagi-Uda nanoantennas can launch the PL with 650 nm, 800 nm and 850 nm wavelength respectively to a single direction without placing any external quantum emitter near the feed element. Consequently, the PL emission also allow us to experimentally investigate the directivity of broadband log-periodic dipole nanoantenna for the first time. In comparison with the radio-frequency antennas, our results show that the element of optical nanoantennas not only can act as a resonator but also can be a local broadband light source. The PL of gold nanoantennas is an ideal nanoscale unidirectional light source that can be applied in wide field such as high-bandwidth wireless optical communication.