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Photonic-plasmonic coupled structures for on-chip nanophotonics applications
  KTH Applied Physics seminars

Thursday 11 October 2012
from 09:15 to 18:00
at FA32
Speaker : Prof. Luca Dal Negro (Boston University)
Abstract : The ability to design and manipulate light-matter interactions at the nanoscale is central to the rapidly growing field of nanophotonics. Efficient strategies for electromagnetic field localization and intensity enhancement are essential requirements for the design and engineering of novel optoelectronic components that leverage resonantly enhanced optical cross sections at the nanoscale, such as optical nano-antennas, plasmon-enhanced biosensors, photodetectors, light sources, and on-chip nonlinear optical elements. Fascinating new scenarios emerge when coupling photonic resonances with localized surface oscillations of conduction electrons supported by metal-dielectric nanostructures, known as Localized Surface Plasmons (LSPs). Analogously to the coupling of atomic and molecular orbitals in solid state and quantum chemistry, LSPs resonances of individual nanoparticles couple by sub-wavelength near-field interactions enhancing the intensity of incident electromagnetic fields over nanoscale spatial regions referred to as “electromagnetic hot-spots”. However, when engineered into arrays of nanostructures separated over distances comparable or larger than the wavelength of light, individual LSPs additionally couple by radiative electromagnetic interactions (i.e., diffractive coupling and multiple light scattering), giving rise to collective photonic-plasmonic modes largely tunable by the array geometry. In this talk, I will present our work on the design, nanofabrication and engineering of coupled photonic-plasmonic arrays of metal-dielectric nanostructures for active nanophotonics device applications. In particular, I will discuss the optical response of complex arrays of metallic nanoparticles with Fourier spectral features that interpolate in a tunable fashion between periodic crystals and disordered random media, referred to as Deterministic Aperiodic Nano Structures (DANS). These structures, modeled by rigorous multiple scattering theory, give rise to characteristic scattering resonances and localized mode patterns enhancing the intensity of optical near-fields over broad frequency spectra and planar optical chips. Specifically, I will focus on the novel opportunities provided to optical biosensing, broadband and multi-band nano-antennas, nanoscale light sources, and thin-film solar cells. Finally, I will discuss our work on the generation and manipulation of structured light carrying Orbital Angular Momentum (OAM) with resonant arrays of metallic nanoparticles, which is relevant to emerging device applications in singular optics, secure optical communication, classical and quantum cryptography.

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