Random Quasi-Phae-Matching in Tantalatio di Litio: origine del fenomeno, confronto tra propagazione bulk e guidata.

We observe second harmonic generation via random quasi phase matching in a 1.5μm periodically poled lithium tantalate. The presence of a slab waveguides allows the comparison between bulk and guided wave configurations.

Optical wireless GEO satellite-to-ground downlinks: rateless codes as solution for scintillation fading

Scintillation fading can corrupt a satellite-to-ground optical wireless links with burst errors. Rateless codes, suitable for erasure channel, are able to eliminate or to reduce these communication errors. We analyzed the performances of three different rateless codes in a simulated Geo satellite-to-ground downlink.

CulnSe2/Zn(S,O,OH) junction on Mo foil by electrochemical and chemical route for photovoltaic applications

Electrodeposition is a convenient technique for the development of low cost materials for photovoltaic (PV) device processing. Using a single step electrodeposition route, several groups have fabricated CIS (CuInSe) and CIGS (CuInGaSe) films [1]. One of the most important requirements for successful application of one-step electrodeposition film formation, is the ability to control composition of the deposited films and to develop polycrystalline microstructures with a low surface roughness and high sintered density. In this preliminary work, CIS films were produced by single bath electrodeposition finding the optimal conditions in order to achieve a dense film with high crystallinity and u…

Responsivity measurements of SiC photodiodes

We investigated the technical features of three novel classes of 4H-SiC vertical Schottky UV photodiodes (henceforth, named SiC8, SiC10, SiC20) employing Ni2Si interdigitated strips whose pitch size is 8, 10 and 20 µm respectively [1] and based on the pinch-off surface effect.

Ethanol vapor optical sensors based on polystyrene opals infiltrated with hydrogel

Responsivity measurements of SiC Schottky photodiodes

We investigated the technical features of three novel classes of 4H-SiC vertical Schottky UV detectors employing Ni2Si interdigitated strips whose pitch size is 8, 10 and 20 µm, respectively, based on the pinch-off surface effect.

Optical turbulence measurements and channel modeling of an indoor Free Space Optics link (Abstract)

Performance Investigation of Fountaine Codes on a Simulated Terrestrial Free Space Optical Channel

Monitoring System of Passive Optical Networks with Remotely Power Supply of Optical Network Terminals

In this paper, the authors, present last results on a low cost method to monitoring Passive-Optical-Network, which it uses Fiber-Bragg-Gratings and a modified Optical-Time-Domain-Reflectometer, and a remote power supply of Optical-Network-Terminals by a bivalent-use cable.

Correlated channel model for terrestrial Free Space Optics: performance analysis of rateless codes

We describe a novel correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by scintillation. With regards to the same channel, we also report simulation results on the error mitigation performance of Luby-Transform and Raptor codes.

All-Optical frequency Shifter in a Periodically Poled Lithium Tantalate Waveguide

A frequency shifting device is fabricated and tested in a congruent Lithium Tantalate waveguide. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained, demonstrating a two-stage parametric conversion.

Correlated Channel Model for terrestrial Free Space Optics and project specifications evaluation of LT code in OOK modulation

Free Space Optics is a wireless line-of-sight communication system able to offer good bandwidth performance as well as straightforward installation and relocation. So that it represents a modern technology that allow to realize large bandwidth communication particularly when it is not possible to employ physical cable or radio technologies. Examples of FSO applications are: wireless backaul, fiber backup, temporary links, metro network extension and last mile access[1]. FSO is based on optical signals propagation in air and that is why it suffers of impairments which depend on atmospheric conditions. In detail, FSO suffers of scattering (i. e. Rayleigh and Mie) losses, absorption and scinti…

Electro-Optical characterization of Silicon Carbide Schottky photodiodes

Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

Fading mitigation coding techniques for space to ground free space optical communications (Euro Med Telco 2014)

In this manuscript, a Geostationary satellite-toground Free Space Optics (FSO) downlink channel model has been implemented, which is able to predict temporal irradiance fluctuations caused by scintillation at a wide range of turbulence conditions and for different values of the zenith angle. In order to mitigate fading events that occur in FSO communications, we have also tested the performance of three different families of Rateless Codes (Luby Transform, Raptor and RaptorQ) into our model and found that RaptorQ is the best candidate to mitigate errors in FSO links.

Cardiovascular parameters detection using a Photoplethismographic system

We propose an innovative, cost-effective and easy to employ photoplethysmographic (PPG) system using Silicon Photomultipliers (SiPMs) sensors to measure cardiovascular parameters that can potentially represent markers for arterial stiffness

Variazione della pressione sistolica e diastolica con la respirazione

L’attività di ricerca in corso riguarda la possibilità di ricavare dati clinicamente significativi dai segnali ottici PPG (PhotoPletysmoGraphy). Il segnale PPG viene utilizzato per ricavare informazioni sul volume e sulla saturazione del sangue che interessa il distretto illuminato dalla luce IR (infrarosso) usata per l’analisi. Il volume di sangue contenuto nel segmento di arteria esaminato dipende dalla pressione e dal ciclo cardiaco, attraverso la rigidità dell’arteria.

FREE SPACE OPTICS LINKS AFFECTED BY OPTICAL TURBULENCE: CHANNEL MODELING, MEASUREMENTS AND CODING TECHNIQUES FOR ERROR MITIGATION

FSO is an optical wireless line-of-sight communication system able to offer good broadband performance, electromagnetic interference immunity, high security, license-free operation, low power consumption, ease of relocation, and straightforward installation. It represents a modern technology, significantly functional when it is impossible, expensive or complex to use physical connections or radio links. Unfortunately, since the transmission medium in a terrestrial FSO link is the air, these communications are strongly dependent on various atmospheric phenomena (e.g., rain, snow, optical turbulence and, especially, fog) that can cause losses and fading. Therefore, in worst-case conditions, i…

Fading mitigation coding techniques for space to ground free space optical communications

Luby Transform Performance Tests on Time-Correlated Channel Model for Geo Free Space Optics Downlinks

Second Harmonic Generation via Random Quasi-phase Matching in a Periodically Poled Lithium Tantalate Waveguide

We observe second harmonic generation via random quasi phase matching in a 1.5μm periodically poled lithium tantalate. The presence of a slab waveguide allows the comparison between bulk and guided wave configurations.

Light Soaking measurements on Ruthenium-based Dye Sensitized Solar Cells

An interesting phenomenon occurring in Dye Sensitized Solar Cells (DSSCs) when exposed to an uninterrupted period of illumination is the so-called light soaking effect, which consists in the increase of the main electrical parameters of the cell, such as the photocurrent and the efficiency. Studying such an effect has noteworthy practical implications, ranging from the optimization of the manufacturing process to stability tests of DSSCs. In this paper, we present an experimental investigation on the performance variation, due to light soaking, of Ruthenium-based DSSCs.

CIGS Thin Film by One-Step Electrodeposition Deposition for Solar Cells

CuInSe2/Zn(S,O,OH) junction by electrochemical and chemical route for photovoltaic applications (GE 2014)

Electrodeposition is a convenient technique for the development of low cost materials for photovoltaic (PV) device processing. Using a single step electrodeposition route, several groups have fabricated CIS (CuInSe) and CIGS (CuInGaSe) films. One of the most important requirements for successful application of one-step electrodeposition film formation is the ability to control composition of the deposited films and to develop polycrystalline microstructures with a low surface roughness and high sintered density.

Optical turbulence measurements and channel modeling of an indoor Free Space Optics link (Versione estesa)

In this work, we propose an indoor experimental set-up able to generate several optical turbulence conditions in a Free Space Optics link. Using this set-up, we prove the effectiveness of an irradiance time-series generator based on the Gamma-Gamma model and able to predict the irradiance fluctuations at the receiver, under both weak and moderate turbulence conditions.