Mode-matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation

Boosting nonlinear frequency conversion in extremely confined volumes remains a key challenge in nano-optics, nanomedicine, photocatalysis, and background-free biosensing. To this aim, field enhancements in plasmonic nanostructures are often exploited to effectively compensate for the lack of phase-matching at the nanoscale. Second harmonic generation (SHG) is, however, strongly quenched by the high degree of symmetry in plasmonic materials at the atomic scale and in nanoantenna designs. Here, we devise a plasmonic nanoantenna lacking axial symmetry, which exhibits spatial and frequency mode overlap at both the excitation and the SHG wavelengths. The effective combination of these features in a single device allows obtaining unprecedented SHG conversion efficiency. Our results shed new light on the optimization of SHG at the nanoscale, paving the way to new classes of nanoscale coherent light sources and molecular sensing devices based on nonlinear plasmonic platforms.Comment: 14 pages, 4 figure

"A New Fine Tracking Algorithm for Binary Offset Carrier Modulated Signals"

In this paper, an analysis of a new synchronization technique for Binary Offset Carrier (BOC) modulated signals will be presented. Goal of the proposed method is to improve the synchronization performances by reducing the synchronization errors due to the characteristic BOC cross-correlation function. The synchronization is generally based on the envelope of the cross-correlation between the received signal and the local replicas. In a classical NRZ modulation this envelope is approximately a triangle whose peak corresponds to the perfect synchronization between the incoming signal and local replicas. In the BOC case, instead, the cross-correlation is given by a set of triangles with positive and negative peaks in which only the central one corresponds to the perfect synchronization. This paper will describe a novel technique characterized by a different choice of the local replica. In this manner the cross-correlation envelope is composed by different triangles with positive and negative peaks; this envelope has one and only one zero-crossing that corresponds to the perfect synchronization. In order to demonstrate the effectiveness of the method, a theoretical analysis has been carried on together with computer simulations. In particular, the main properties of the technique, compared with the classical situation, will be presented

A Particle Filter Based Fusion Framework for Video-Radio Tracking in Smart Spaces

One of the main issues for Ambient Intelligence (AmI) systems is to continuously localize the user and to detect his/her identity in order to provide dedicated services. A video-radio fusion methodology, relying on the Particle Filter algorithm, is here proposed to track objects in a complex extensive environment, exploiting the complementary benefits provided by both systems. Visual tracking commonly outperforms radio localization in terms of precision but it is inefficient because of occlusions and illumination changes. Instead, radio measurements, gathered by a user’s radio device, are unambiguously associated to the respective target through the “virtual ” identity (i.e. MAC/IP addresses). The joint usage of the two data typologies allows a more robust tracking and a major flexibility in the architectural setting up of the AmI system. The method has been extensively tested in a simulated and off-line framework and on real world data proving its effectiveness. 1

DISTRIBUTED COOPERATIVE MODE IDENTIFICATION FOR COGNITIVE RADIO APPLICATIONS

none4noM. GANDETTO; A. CATTONI; M. MUSSO; C. REGAZZONIM., Gandetto; A., Cattoni; M., Musso; Regazzoni, Carl