Experimental Study of Free-space Beam Propagation for Single-photon Quantum Communications

We report on the study the propagation of a laser beam over a 144 free-space link. We report on the losses of the channel, the temporal scintillation of the intensity and, by attenuating the beam, the statistic of arrival of single photons

Experimental Studies Toward the Quantum Communications with Orbiting Terminals

Realization of Quantum Communications in Space requires a deep understanding of issues including link-budget, turbulence mitigation and single-photon terminal synchronization. Here we report on supporting novel experiments on very long-distance links and modeling

Plasmonic response of different metals for specific applications

Each metal presents different characteristics when used in a surface plasmon resonance (SPR) experiment. These include the shape of the SPR figure, the wavelength of better operation, the tendency to oxidize, the sensitivity to environmental changes, the range of refractive indices detectable and the capability of binding to specific targets or analytes. When choosing the metal for our SPR experiment all of these characteristics have to be taken into account. We investigate the behavior of metals, which are less or have never been used in this kind of application, comparing their characteristics to gold. We deeply investigate both theoretically and experimentally the behavior of palladium. This metal leads to an inverted curve with a maximum of reflected intensity instead of a minimum. In fact, in this case we speak of Inverted Surface Plasmon Resonance (ISPR). Aluminum and copper have also been considered because of their potentiality in specific applications

Optical and structural properties of noble metal nanoisLAND

Metallic nanostructures are widely studied because of their peculiar optical properties. They possess characteristic absorbance spectra with a peak due to plasmonic resonance. This feature is directly dependent on the nanostructures shape, size, distribution and environment surrounding them. This makes them good candidates for a variety of applications, such as localized surface plasmon resonance sensing (LSPR), surface-enhanced Raman scattering (SERS) and photovoltaics. A well established technique used to create nanoisland on flat substrates is performing a thermal treatment after the deposition of a thin metal film. While the most widely investigated metal in this context is gold, we have extended our investigation to palladium, which is interesting for sensing applications because it has an excellent hydrogen absorption ability. The morphological properties of the nanoisland depend mainly on the starting thickness of the deposited layer and on the annealing parameters, temperature and duration. The deposition and annealing process has been investigated, and the resulting samples has been tested optically and morphologically in order to optimize the structures in view or their application for sensing purposes

Study of optical materials to be used on Multi Element Telescope for Imaging and Spectroscopy instrument

The European Space Agency mission Solar Orbiter (SOLO) is dedicated to the study of the solar atmosphere and heliosphere. As a part of the payload, the instrument METIS (Multi Element Telescope for Imaging and Spectroscopy) will provide images of the corona, both in the visible range and at the hydrogen Lyman-α emission line (121.6 nm). The realization of optical coatings, based on Al and MgF2, able to reflect/transmit such spectral components is, therefore, necessary. Since optical characteristics of materials in the vacuum ultraviolet range are not well studied and vary greatly with the realization process, we implemented a study of their properties in different deposition conditions. This is aimed to the realization of a custom designed filter able to transmit the 121.6 nm wavelength while reflecting visible light, and thus separating visible from ultraviolet light paths in the METIS instrument

Graphene-like coatings for biosensors devices

The interest in graphene-like materials involves many research areas, including the development of biosensors devices. We have recently studied the use of graphene/metal bilayer for surface plasmon resonance (SPR) equipment devoted to detection of chemical processes and biomolecules recognition. The dual role of graphene is to protect the metal layer underneath and to enhance the bioaffinity by adsorbing biomolecules with carbon-based ring structures. Depending on the application, it may be necessary laser and chemical treatments of graphene to improve the performances of the whole device. The processing effects will be investigated by near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The use of synchrotron light is mandatory for NEXAFS analysis since a continuous EUV source of selected polarization is required. The ideas, the analysis and the results are the subjects of this work

Stability and extreme ultraviolet photo-reduction of graphene during C-K edge NEXAFS characterization

Here, we show research innovation in radiation-matter interaction, with possible photonics and optoelectronics applications in building and maintenance of graphene-based devices, as well as a further confirmation for soft x-ray irradiation as a clean route towards graphene photoreduction. Thus, we have investigated the soft x-rays exposure effects on graphene/nickel samples damaged by nanosecond 1064 nm Nd:YAG laser under laser fluence above the damage threshold. In this regard, NEXAFS analyses reveal the typical GO features in the C K edge spectra of the irradiated specimens. Moreover, the continuous exposures to soft x-rays radiation show the photo-reduction process monitored by NEXAFS in real time. Ten-hour soft x-ray exposure moves the spectra towards the typical one of the graphene

Study of solar wind ions implantation effects in optical coatings in view of Solar Orbiter space mission operation

Low energy ions coming from the quite solar wind are considered among the causes of potential damage of the optical instrumentation and components on board of ESA Solar Orbiter. Predictions of space radiation parameters are available for instruments on board of such mission. Accelerators are commonly used to reproduce the particle irradiation on a spacecraft during its lifetime at the ground level. By selecting energies and equivalent doses it is possible to replicate the damage induced on space components. Implantation of Helium ions has been carried out on different single layer thin films at LEI facility at Forschungszentrum Dresden-Rossendorf varying the total dose. Profile of the implanted samples has been experimentally recovered by SIMS measurements. The change in reflectance performances of such coatings has been experimentally evaluated and modelled. The outcomes have been used to verify the potential impact on the METIS instrument and to drive the optimization of the M0 mirror coating

Graphene-metal interfaces for biosensors devices

Graphene-metals interfaces are investigated in many subject areas both applicative and speculative. The interest mainly stems from the possibility for CVD synthesis of large area graphene on metals. In this case the metal acts as a catalyst for complete dehydrogenetaion of hydrocarbon precursors that leaves carbon behind at the surface. Such bilayer are also very appealing for surface plasmon resonance devices, since graphene acts both as a protective layer and biorecognition element. Several pairs of graphene-metal interfaces have been studied in terms of SPR performance and physicalchemical properties at the interface. With regard to this last aspect, NEXAFS spectroscopy is a powerful method to study single-, double-, and few- layers graphene and to illustrate any evolution of the electronic states