New Trends in Energy Harvesting from Earth Long-Wave Infrared Emission

A review, even if not exhaustive, on the current technologies able to harvest energy from Earth's thermal infrared emission is reported. In particular, we discuss the role of the rectenna system on transforming the thermal energy, provided by the Sun and reemitted from the Earth, in electricity. The operating principles, efficiency limits, system design considerations, and possible technological implementations are illustrated. Peculiar features of THz and IR antennas, such as physical properties and antenna parameters, are provided. Moreover, some design guidelines for isolated antenna, rectifying diode, and antenna coupled to rectifying diode are exploited

Advances in Lasers and Optical Amplifiers: Materials, Components, and Systems

During the last decades a lot of research activities in the field of photonics have been accomplished and today there is a disruptive revolution underway where the photons are used to transmit, store, and process information. Laser and optical amplifier technology plays an important role in these events. In particular, the advances in lasers and optical amplifiers, enabling novel, powerful and exciting applications are based on research results arising from different investigation fields. This special issue is an example of these interdisciplinary contributions to the state of the art of optical amplification. Microresonators, interferometry, accuratemodeling, grating, nonlinear optics, and novel materials are the subjects included in the volume

Innovative Micro- and Nanostructured Materials and Devices for Energy Applications

1 Dipartimento di Ingegneria Elettrica e dell'Informazione (DEI), Politecnico di Bari, Via E. Orabona 4, 70125 Bari, Italy 2 Consiglio Nazionale delle Ricerche-Istituto di Fotonica e Nanotecnologie (CNRIFN), Via alla Cascata 56/C, 38123 Trento, Italy 3 Istituto Italiano di Tecnologia (IIT), Center for Biomolecular Nanotechnologies (CBN), Via Barsanti 1, 73010 Arnesano, Italy 4Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302, Indi

Design of fiber coupled Er3+: Chalcogenide microsphere amplifier via particle swarm optimization algorithm

International audienceA mid-IR amplifier consisting of a tapered chalcogenide fiber coupled to an Er3+-doped chalcogenide microsphere has been optimized via a particle swarm optimization (PSO) approach. More precisely, a dedicated three-dimensional numerical model, based on the coupled mode theory and solving the rate equations, has been integrated with the PSO procedure. The rate equations have included the main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions. The PSO has allowed the optimal choice of the microsphere and fiber radius, taper angle, and fiber-microsphere gap in order to maximize the amplifier gain. The taper angle and the fiber-microsphere gap have been optimized to efficiently inject into the microsphere both the pump and the signal beams and to improve their spatial overlapping with the rare-earth-doped region. The employment of the PSO approach shows different attractive features, especially when many parameters have to be optimized. The numerical results demonstrate the effectiveness of the proposed approach for the design of amplifying systems. The PSO-based optimization approach has allowed the design of a microsphere-based amplifying system more efficient than a similar device designed by using a deterministic optimization method. In fact, the amplifier designed via the PSO exhibits a simulated gain G=33.7 dB, which is higher than the gain G=6.9 dB of the amplifier designed via the deterministic method

Coupled experiment/simulation approach for the design of radiation-hardened rare-earth doped optical fibers and amplifiers

We developed an approach to design radiation-hardened rare earth -doped fibers and amplifiers. This methodology combines testing experiments on these devices with particle swarm optimization (PSO) calculations. The composition of Er/Yb-doped phosphosilicate fibers was improved by introducing Cerium inside their cores. Such composition strongly reduces the amplifier radiation sensitivity, limiting its degradation: we observed a gain decreasing from 19 dB to 18 dB after 50 krad whereas previous studies reported higher degradations up to 0°dB at such doses. PSO calculations, taking only into account the radiation effects on the absorption efficiency around the pump and emission wavelengths, correctly reproduce the general trends of experimental results. This calculation tool has been used to study the influence of the amplifier design on its radiation response. The fiber length used to ensure the optimal amplification before irradiation may be rather defined and adjusted to optimize the amplifier performance over the whole space mission profile rather than before integration in the harsh environments. Both forward and backward pumping schemes lead to the same kind of degradation with our active fibers. By using this promising coupled approach, radiation-hardened amplifiers nearly insensitive to radiations may be designed in the future

Design of Radiation-Hardened Rare-Earth Doped Amplifiers Through a Coupled Experiment/Simulation Approach

We present an approach coupling a limited experimental number of tests with numerical simulations regarding the design of radiation-hardened (RH) rare earth (RE)-doped fiber amplifiers. Radiation tests are done on RE-doped fiber samples in order to measure and assess the values of the principal input parameters requested by the simulation tool based on particle swarm optimization (PSO) approach. The proposed simulation procedure is validated by comparing the calculation results with the measured degradations of two amplifiers made with standard and RH RE-doped optical fibers, respectively. After validation, the numerical code is used to theoretically investigate the influence of some amplifier design parameters on its sensitivity to radiations. Simulations show that the RE-doped fiber length used in the amplifier needs to be adjusted to optimize the amplifier performance over the whole space mission profile rather than to obtain the maximal amplification efficiency before its integration in the harsh environment. By combining this coupled approach with the newly-developed RH RE-doped fibers, fiber-based amplifiers nearly insensitive to space environment may be designed in the future

Development of a Simplified System for the Continuous PEF Treatment of Olives Paste

The olive oil extraction is a complex process that requires several machines arranged in series until the plant is built. Currently, the extraction process does not allow the totality of the oil present in the olives to be extracted, unfortunately a significant amount of the product is lost in the by-products and waste. Recently the pulsed electric fields (PEF) applied to the process have given positive effects by increasing the percentage of oil extracted compared to the traditional plant configuration. In order to allow a greater diffusion of this technology in the mill, a simplified PEF plant it has been developed specifically for small oil extraction plants and an experimental test program has been developed to verify the effectiveness of the technology. A comparative experimental tests plant was carried out using two different varieties of olives (Frantoio and Leccino) treated at two different specific energies (4.0 and 5.0 kJ kg-1), the amount of olive oil lost in the pomace and extractability was found. The results showed that the treatment of the olive pastes in the pre-malaxation (5.0 kJ kg-1) led to significantly increased oil extractability compared to the control by about 4% (absolute value) for the Frantoio variety, and by about 3 % (absolute value) for the Leccino variety, while reducing the percentage of oil lost in the pomace. Further studies on the better adjustment of the operating parameters of the PEF system seem to be needed

Recent advances in radiation-hardened fiber-based technologies for space applications

International audience; In this topical review, the recent progress on radiation-hardened fiber-based technologies is detailed, focusing on examples for space applications. In the first part of the review, we introduce the operational principles of the various fiber-based technologies considered for use in radiation environments: passive optical fibers for data links, diagnostics, active optical fibers for amplifiers and laser sources as well as the different classes of point and distributed fiber sensors: gyroscopes, Bragg gratings, Rayleigh, Raman or Brillouin-based distributed sensors. Second, we describe the state of the art regarding our knowledge of radiation effects on the performance of these devices, from the microscopic effects observed in the amorphous silica glass used to design fiber cores and cladding, to the macroscopic response of fiber-based devices and systems. Third, we present the recent advances regarding the hardening (improvement of the radiation tolerance) of these technologies acting on the material, device or system levels. From the review, the potential of fiber-based technologies for operation in radiation environments is demonstrated and the future challenges to be overcome in the coming years are presented

6 MeV Electron exposure effects on OFDR-based distributed fiber sensors

The impact of exposing an optical fiber to 6-MeV electrons on the performances of optical frequency domain reflectometry (OFDR) distributed sensors is investigated. Six different types of optical fibers with different core compositions and coatings have been tested: four fibers are metal coated (copper, gold, or aluminum) for high-temperature >300 °C) operations while the two others have telecom-grade acrylate coatings for operation below 80 °C. The fiber Rayleigh signature used to perform the OFDR sensing remains almost unaffected after an electron exposure. Indeed, the measured radiation-induced temperature errors are lower than about 3 °C, close to the setup uncertainties, when the OFDR operates as a temperature sensor