Dark spots along slowly scaling chains of plasmonic nanoparticles

Year: 2016

Authors: Zito G., Rusciano G., Sasso A.

Autors Affiliation: Dipartimento di Fisica E. Pancini, Università degli Studi di Napoli Federico II, Complesso Univesitario Monte S. Angelo, Via Cintia, Napoli, Italy; CNR, Istituto Nazionale di Ottica, Via Campi Flegrei 34, I-80078 Pozzuoli, NA, Italy

Abstract: We numerically investigate the optical response of slowly scaling linear chains of mismatched silver nanoparticles. Hybridized plasmon chain resonances manifest unusual local field distributions around the nanoparticles that result from symmetry breaking of the geometry. Importantly, we find localization patterns characterized by bright hot-spots alternated by what we term dark spots. A dark spot is associated to dark plasmons that have collinear and antiparallel dipole moments along the chain. As a result, the field amplification in the dark interjunction gap is extinguished for incident polarization parallel to the chain axis. Despite the strong plasmonic coupling, the nanoparticles on the sides of this dark gap experience a dramatic asymmetric field amplification with amplitude gain contrast > 2 x 10(2). Remarkably, also for polarization orthogonal to the axis, gap hot-spots form on resonance. (C) 2016 Optical Society of America

Journal/Review: OPTICS EXPRESS

Volume: 24 (12)      Pages from: 13584  to: 13589

More Information: We acknowledge financial support from Italian Ministry of Education, University and Research, Grant No. FIRB 2012-RBFR12WAPY; and in part from University of Naples Federico II, Compagnia di San Paolo e Istituto Banco di Napoli – Fondazione (LARA).
KeyWords: enhanced Raman-scattering; nanostrucures; hot
DOI: 10.1364/OE.24.013584

Citations: 12
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