Browsing by Author "Borisov, Andrei G."

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Active quantum plasmonics
    (AAAS, 2015) Marinica, Dana Codruta; Zapata, Mario; Nordlander, Peter; Kazansky, Andrey K.; Echenique, Pedro M.; Aizpurua, Javier; Borisov, Andrei G.; Laboratory for Nanophotonics
    The ability of localized surface plasmons to squeeze light and engineer nanoscale electromagnetic fields through electron-photon coupling at dimensions below the wavelength has turned plasmonics into a driving tool in a variety of technological applications, targeting novel and more efficient optoelectronic processes. In this context, the development of active control of plasmon excitations is a major fundamental and practical challenge. We propose a mechanism for fast and active control of the optical response of metallic nanostructures based on exploiting quantum effects in subnanometric plasmonic gaps. By applying an external dc bias across a narrow gap, a substantial change in the tunneling conductance across the junction can be induced at optical frequencies, which modifies the plasmonic resonances of the system in a reversible manner. We demonstrate the feasibility of the concept using time-dependent density functional theory calculations. Thus, along with two-dimensional structures, metal nanoparticle plasmonics can benefit from the reversibility, fast response time, and versatility of an active control strategy based on applied bias. The proposed electrical manipulation of light using quantum plasmonics establishes a new platform for many practical applications in optoelectronics.
  • Thumbnail Image
    Item
    Bridging quantum and classical plasmonics with a quantum-corrected model
    (Macmillan Publishers Limited, 2012) Esteban, Ruben; Borisov, Andrei G.; Nordlander, Peter; Aizpurua, Javier; Laboratory for Nanophotonics
    Electromagnetic coupling between plasmonic resonances in metallic nanoparticles allows for engineering of the optical response and generation of strong localized near-fields. Classical electrodynamics fails to describe this coupling across sub-nanometer gaps, where quantum effects become important owing to non-local screening and the spill-out of electrons. However, full quantum simulations are not presently feasible for realistically sized systems. Here we present a novel approach, the quantum-corrected model (QCM), that incorporates quantum-mechanical effects within a classical electrodynamic framework. The QCM approach models the junction between adjacent nanoparticles by means of a local dielectric response that includes electron tunnelling and tunnelling resistivity at the gap and can be integrated within a classical electrodynamical description of large and complex structures. The QCM predicts optical properties in excellent agreement with fully quantum mechanical calculations for small interacting systems, opening a new venue for addressing quantum effects in realistic plasmonic systems.
  • Thumbnail Image
    Item
    Quantum effects and nonlocality in strongly coupled plasmonic nanowire dimers
    (Optical Society of America, 2013) Teperik, Tatiana V.; Nordlander, Peter; Aizpurua, Javier; Borisov, Andrei G.; Laboratory for Nanophotonics
    Using a fully quantum mechanical approach we study the optical response of a strongly coupled metallic nanowire dimer for variable separation widths of the junction between the nanowires. The translational invariance of the system allows to apply the time–dependent density functional theory (TDDFT) for nanowires of diameters up to 10 nm which is the largest size considered so far in quantum modeling of plasmonic dimers. By performing a detailed analysis of the optical extinction, induced charge densities, and near fields, we reveal the major nonlocal quantum effects determining the plasmonic modes and field enhancement in the system. These effects consist mainly of electron tunneling between the nanowires at small junction widths and dynamical screening. The TDDFT results are compared with results from classical electromagnetic calculations based on the local Drude and non-local hydrodynamic descriptions of the nanowire permittivity, as well as with results from a recently developed quantum corrected model. The latter provides a way to include quantum mechanical effects such as electron tunneling in standard classical electromagnetic simulations. We show that the TDDFT results can be thus retrieved semi-quantitatively within a classical framework. We also discuss the shortcomings of classical non-local hydrodynamic approaches. Finally, the implications of the actual position of the screening charge density at the gap interfaces are discussed in connection with plasmon ruler applications at subnanometric distances.
  • Thumbnail Image
    Item
    Quantum mechanical effects in plasmonic structures with subnanometre gaps
    (Springer Nature, 2016) Zhu, Wenqi; Esteban, Ruben; Borisov, Andrei G.; Baumberg, Jeremy J.; Nordlander, Peter; Lezec, Henri J.; Aizpurua, Javier; Crozier, Kenneth B.; Laboratory for Nanophotonics
    Metallic structures with nanogap features have proven highly effective as building blocks for plasmonic systems, as they can provide a wide tuning range of operating frequencies and large near-field enhancements. Recent work has shown that quantum mechanical effects such as electron tunnelling and nonlocal screening become important as the gap distances approach the subnanometre length-scale. Such quantum effects challenge the classical picture of nanogap plasmons and have stimulated a number of theoretical and experimental studies. This review outlines the findings of many groups into quantum mechanical effects in nanogap plasmons, and discusses outstanding challenges and future directions.