Ricerc@Sapienza

Compact samples of nano-helices built by means of a focused ion beam technology with large
bandwidth and high dichroism for circular polarization are promising for the construction of built-in-chip
sensors, where the ideal transducer must be sufficiently confined without compromising its filtering
ability. Direct all-optical measurements revealed the sample’s dichroic character with insufficient details
because of scattering and diffraction interference. On the other hand, photoacoustic measurements
resulted to be a possible alternative investigation, since they directly deal with absorbed power and
allow to get clear evidences of the differential selection for the two opposite polarization states. Multilevel
numerical simulations confirmed the experimental results, proving once again the reliability of
photoacoustic technique and the versatility of this class of dichroic artificial materials.