LAUSR

Gold nanoparticle arrangements are identified as plasmonic heaters due to the photo-thermal effects originating from the strong plasmonic confinement of light at the nanoscale. The specific design of the nanoparticle arrangement is crucial to optimize the generation of heat and control its flux. Accurate manipulation of the photo-thermal response of the system is possible by dynamically changing the plasmonic hotspots distribution. Indeed, a macroscopic deformation of the sample results in a nanoscale modification of the relative position of nanoparticles, thus realizing a specific control of the hotspots formation. In this contribution, an analysis of the thermal response of the system based on the interplay between exciting light polarization and sample deformation is reported. The absorption cross section and the production of heat at the nanoscale is considered with the system at rest and under applied mechanical stress. Finally, the implementation of a flexible tag for physical unclonable functions has been studied. The introduction of a defect, obtained by displacing a single nanoparticle of the previously ordered configuration, produces noteworthy variations in the absorption cross section. Indeed, the excitation of the novel arrangement at a proper exciting wavelength, different from the resonant one for the unmodified arrangement, produces a twofold temperature increase with respect to the case of the ordered array considered at the same excitation wavelength. Such a result paves the way for the realization of a novel device to be exploited as a thermal flexible fingerprint for unclonable tags with fast response and low production cost.