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.In the last years, the ultimate nanofabrication frontier represented by 3D nanostructures is generating promising and versatile novel nano-photonics devices. In particular, 3D nanostructures with broken symmetry enable exciting complex interactions with chiral light, generating the typical forms of the optical activity, such as the optical rotation (OR), i.e., the polarization plane rotation of the incident light, and the circular dichroism (CD) 1, 2 , i.e., the different absorption levels for left and right circularly polarized (CP) waves 3 . Among the possible 3D chiral geometries, the helix architecture represents, because of its intrinsic chirality, an effective choice to manifest detectable chiral effects [4][5][6][7][8] . However, the engineering of the chiro-optical properties, such as the frequency as well as the absorbed and scattered portions of left-and right-handed circularly polarized light, requires the full control on the geometrical and spatial parameters and on material composition of the 3D nanostructures. Hence, great efforts have been made to develop flexible nanofabrication techniques for the realization of helical based structures with nanometer accuracy 9 . Recently, focused ion and electron beam induced deposition (FIBID/FEBID) have demonstrated the effective capability to tailor helical nanostructures as a function of application-driven chiro-optical properties 10-14 , leading to the nanometer scale controlled fabrication of helix-shaped metal and dielectric nanostructures, organized in dense and ordered arrays of few micron area. Moreover, the FIBID/FEBID approach is particularly suitable for the building and the spatial localization of compact nano-devices as parts of embedded systems, such as built-in-chip sensors and integrated optoelectronic filters, where it is of key importance the integration of nanostructured materials onto small areas.When dealing with 3D nanostructured samples with limited patterned area, commonly used all optical (AO) measurements, though requiring low power levels of inspecting light, are heavily altered by the electromagnetic (e.m.) field escaping from the un-patterned...

Optical technology applied to on-chip wireless communication is particularly promising to overcome the performance limitations of the state-of-the-art networks on-chip. A key enabling component for such applications is the plasmonic antenna coupled to conventional silicon waveguides, which can guarantee full compatibility with standard optical circuitry. In this paper, we propose an antenna array configuration based on tilted plasmonic Vivaldi antennas coupled to a silicon waveguide. The details of the single antenna and of the array design are reported. The radiation characteristics of the array are suitable for on-chip point-to-point communication, i.e. in-plane maximum gain of 14.70 dB for an array with five antennas. The array exploits a travelling wave feeding scheme and, therefore, is compact in size (about 3.5 µm x 8.7 µm).

Networks-on-chip are being regarded as a promising solution to meet the on-going requirement for higher and higher computation capacity. In view of future kilo-cores architectures, electrical wired connections are likely to become inefficient and alternative technologies are being widely investigated. Wireless communications on chip may be therefore leveraged to overcome the bottleneck of physical interconnections. This work deals with wireless networks-on-chip at optical frequencies, which can simplify the network layout and reduce the communication latency, easing the antenna on-chip integration process at the same time. On the other end, optical wireless communication on-chip can be limited by the heavy propagation losses and the possible cross-link interference. Assessment of the optical wireless network in terms of bit error probability and maximum communication range is here investigated through a multi-level approach. Manifold aspects, concurring to the final system performance, are simultaneously taken into account, like the antenna radiation properties, the data-rate of the core-to core communication, the geometrical and electromagnetic layout of the chip and the noise and interference level. Simulations results suggest that communication up to some hundreds of μm can be pursued provided that the antenna design and/or the target data-rate are carefully tailored to the actual layout of the chip.

Optical wireless networks-on-chip (OWiNoC) are considered as a possible solution to overcome the communication bottleneck due to wired interconnects in modern chip multiprocessor systems. The efficient implementation of optical wireless links requires considering many different aspects, including analysis and deep understanding of the effects on the propagation of the electromagnetic field induced by the discontinuities that can be found in a realistic scenario. This letter aims at showing the impact determined by some of these discontinuities on optical links designed in Silicon-on-Insulator technology, exploiting simple point-to-point interconnections as a first example. Measurements and simulations confirm that multi-path phenomena, triggered by the multi-layer structure housing the antennas and the propagation paths, can have a serious impact on the link budget, with fading effects that may compromise the performance of the link. However, in the presented experimental results, thanks to a careful choice of the chip layer structure, received powers higher than those which could have been measured for optical links fabricated in an infinite homogeneous medium are observed, thus resulting beneficial for the connection's power budget.