Opto-thermally controlled beam steering in nonlinear all-dielectric metasurfaces

Metasurfaces have recently enabled a further miniaturization of many optical components which are typically bulky and made of different materials. Notably, nonlinear optics in dielectric metasurfaces has been investigated achieving significant Second Harmonic (SH) generation efficiency in χ (2) materials [1] , [2]. In this work, we use a symmetry broken meta-atom shaped as an AlGaAs nano-chair, obtained by removing one quarter of the volume from a nanocylinder with elliptic base, see Fig. 1(a...

La mediazione demandata. La valutazione giudiziale di invio in mediazione e il contenuto dell’ordinanza motivata alla luce della ratio dell’istituto

Discrimination of nano-objects via cluster analysis techniques applied to time-resolved thermo-acoustic microscopy

Time-effective, unsupervised clustering techniques are exploited to discriminate nanometric metal disks patterned on a dielectric substrate. The discrimination relies on cluster analysis applied to time-resolved optical traces obtained from thermo-acoustic microscopy based on asynchronous optical sampling. The analysis aims to recognize similarities among nanopatterned disks and to cluster them accordingly. Each cluster is characterized by a fingerprint time-resolved trace, synthesizing the c...

Controlling the Quality Factor of a Single Acoustic Nanoresonator by Tuning its Morphology

The mechanical vibrations of individual gold nanodisks nanopatterned on a sapphire substrate are investigated using ultrafast time-resolved optical spectroscopy. The number and characteristics of the detected acoustic modes are found to vary with nanodisk geometry. In particular, their quality factors strongly depend on nanodisk aspect ratio (i.e., diameter over height ratio), reaching a maximal value of ≈70, higher than those previously measured for substrate-supported nano-objects. The pecu...