523 research outputs found
Design and Characterization of Microwave and Optical Resonators for Biomedical Applications
No full textIn this Ph.D. dissertation, the feasibility investigation, design and characterization of different microwave and optical resonator devices with applications in the fields of medicine, such as cancer radiotherapy, and diagnostic, such as chemical/biological fluid sensing, is detailed. Different microwave and optical resonant structures have been considered, the common thread among them is related to the electromagnetic field theory and the exploitation of the resonance effect to improve their performance. Ad-hoc homemade computer codes have been developed, for accurate investigations, and validated via
experimental data.
Finally, the design and optimization of side-coupled proton linear accelerator microwave cavities via a novel hybrid numerical/analytical approach is reported. Such microwave cavities are typically used in proton linear accelerators devoted to hadron therapy applications. The design hybrid approach has been validated through measurements. An excellent agreement between simulation and experiment has been found in terms of accelerator frequency and accelerating field nonuniformity.
By exploiting the same foregoing hybrid approach, the design and optimization of a novel proton linear accelerator based on on-axis coupled electromagnetic band-gap (EBG) cavities for hadron therapy applications is also reported. The use of EBG cavities allows a very strong reduction (by about 65%) of the peak surface electric field, paving the way to the design and fabrication of very high gradient proton linear accelerators.
The design of optical whispering gallery mode (WGM) microresonators efficiently and selectively excited via tapered optical fibers and long period gratings is illustrated. The design has been well validated via experimental data. A microbubble-based set-up for chemical and biomedical fluid sensing has been also investigated. By proper coupling the WGMs with the tapered fiber modes, resonance shifts higher than i) −40 GHz/wt.% at 1550 nm and ii) −3 GHz/wt.% at 589 nm, have been calculated for a sodium chloride (NaCl) and glucose (C6H12O6) fluid sensing set-ups, respectively
Error-Free 10.7 Gb/s Digital Transmission over 2 km Optical Link Using an Ultra-Low-Voltage Electro-Optic Modulator
No full textWe demonstrate the feasibility of 10.7 Gb/s error-free (BER < 10-12) optical transmission on distances up to 2 km using a recently developed ultra-low-voltage commercial Electro-Optic Modulator (EOM) that is driven by 0.6 Vpp and with an optical input power of 1 mW. Given this low voltage operation, the modulator could be driven directly from the detectors’ board signals without the need of any further amplification reducing significantly the power dissipation and the material budget
The radical right in Europe, between slogans and voting behavior. IHS Political Science Series No. 123, July 2011
No full textThe paper analyzes the radical right‘s attitudes toward the EU focusing in particular on the level of congruence between the programmatic statements of the central office and the voting behavior of their MEPs. It shows that although radical right parties represent a source of opposition to the EU, within the EP they express their dissent making use of the rules of the game, voting with the opposition more than the other forces do, but voting almost as much with the majority. The party public office in the EP is inserted in the legislative process and even more collusive with the other parties of both sides of the political spectrum than the Eurosceptical rhetoric and statements of central office makes the public believe
A finite difference mode solver for active optical waveguides
No full textHighly efficient active Integrated Optical waveguides are currently deeply investigated both theoretically and experimentally in view of their optimal design and characterization. A Finite Difference approach based on the Alternate Direction Implicit technique to calculate the propagation constant and the transversal components of the modes in optical waveguides with complex refractive index is presented. Preliminary results of experimental characterization of such waveguides are reported as well
Testing of active optical waveguides obtained by diluted silver exchange in Er-doped soda lime silicate glass.
No full textRare-earth doped tungsten tellurite glasses and waveguides: fabrication and characterization
No full textTungsten tellurite glasses doped with Er3+, Tm3+, Pr3+, and Ho3+ ions were prepared by melt quenching. The glass matrix was the same for all types of glasses and had a high sodium content in order to allow the fabrication of waveguides using an ion-exchange technique. The absorption spectra of the glasses were measured and the Judd-Ofelt parameters Omega(q), were obtained from the experimental oscillator strengths of the f --> f transitions. Er3+ doped glasses showed a very high quantum efficiency when comparing the calculated radiative decay time with the measured lifetime of the I-4(13/2) metastable level. Ag+ Na+ ion-exchanged planar waveguides were successfully obtained in all types of glasses and characterized by the prism coupling technique. It turned out that the diffusion constant values are very similar for glasses containing different rare-earth ions with the same concentration, while, at least for the Er3+ doped ones, the diffusion constant changes with the ions concentration
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