Dissertations / Theses on the topic 'Ottieri'
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DI, MAIO FABRIZIO. "L'opera di Ottiero Ottieri." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1284.
Full textThe subject of this thesis concerns the Ottieriâ s literary work from his first novel Memorie dellâ incoscienza (1954) to Una irata sensazione di peggioramento (2002), analysing three themes which come over his poetry: industry, sanatorium and politics. The thesis is planned on seven chapters. In the introduction, the characteristics of Ottieriâ s novels are developed: original and unclassifiable, Ottieri has organized an extensive literary project through thirty works connected by a continuous plot of themes and leitmotivs which are linked on different subject as Italian and European literature, history, psychiatry, art, politics. In the first chapter, the Ottieriâ s youthful devotion to fascism is analysed in the light of his own memories (Memorie dellâ incoscienza), an autobiographic novel in which an alter ego (Lorenzo Bandini) analyses the dramatic issues of Italy during the Second World War. In the second chapter the emergent theme concerns the industrial world through four works (two novels: Tempi stretti and Donnarumma allâ assalto, the diary La linea gotica and the play I venditori di Milano) which allow him to be the â pioneerâ of Italian industrial literature. From the third to the fifth chapter, the principal theme which comes over is mental illness; depression, schizophrenia, alienation are bound to be the centre of his literary works and not only of his life. The sixth chapter studies two novels, La storia del PSI and Il poema osceno, which are the summary of his political ideas. The seventh chapter is about the last works of Ottieri; aware of his imminent death, the poet describes his life as a borderline individual and as an unsuccessful writer.
Viglino, Sylvie. "La "letteratura d'azienda" les debuts litteraires de ottiero ottieri et paolo volponi." Paris 3, 1999. http://www.theses.fr/1999PA030019.
Full textThe study of the category of the "letteratura d'azienda" is carried out from the comparative analysis o. Ottieri's tempi stretti and p. Volponi's memoriale, by following the approach of the sociology of literature. The socio-professional profile of these two "olivettiani" authors and the place which they occuped in the cultural and literary field of the fifties and of the sixties are reconstructed and confronted with a view to enlightening their project and the strategy which was adopted by each of them in order to "make a name" in literature and to understanding why, how and with what effects their works were the subject to such a classification
VARAPNICKAITE, SARTORI DOVILE. ""L'IRREALTA' QUOTIDIANA" DI OTTIERO OTTIERI. INDAGINE FILOLOGICA, STRUTTURALE E CRITICA DELLE CARTE AUTOGRAFE." Doctoral thesis, Università Cattolica del Sacro Cuore, 2018. http://hdl.handle.net/10280/44651.
Full text«L’Irrealtà Quotidiana» («Daily Unreality»), written by Ottiero Ottieri, is an essay-diary that collects personal memoirs and intellectual reflections on the feeling of unreality from a social, literary, psychoanalytic and scientific perspective. The text has been reworked multiple times before its final publishing; the author’s autograph manuscripts have been rewritten completely five times and partially more than ten times. Relevant amendments in its structure and contents have been made through the various editing processes. The editing mode has not been univocal: the final text has been subject to some subtractions and many additions aiming to provide a more analytical and lighter explanation of the complex process of the author’s self-development and generational development. The thesis is focused on the archivist, philological, structural and critical analysis of the author’s autograph manuscripts related to «L’Irrealtà Quotidiana». I have developed a theory regarding the chronological order of the author’s manuscripts in an attempt to date the text. I have provided some comments to better understand the dynamics of the title-selection process for each manuscript. Furthermore, I have analysed the origin and processing of the autograph notes. Finally, I have looked at an author-fiction of notable interest included in the essay titled: «Un’autobiografia culturale» («A cultural autobiography») of Vittorio Lucioli. The latter is Ottiero Ottieri’s alter ego.
Puccianti, Tatiana. "Présences de la psychanalyse dans la littérature italienne contemporaine : Giuseppe Berto, Ottiero Ottieri." Paris 8, 1994. http://www.theses.fr/1994PA080851.
Full textThis critical study is about two contemporany italian writers, giuseppe berto and ottiero ottieri. Both bring out the relationship between analyst and analysand. However, the implications of freud's theories are quite different for each writer, as regards the difficultes of existenceand very project of writting. I have tried to show how radically different they are. In the firs place berto's novel il male oscuro (1964) (am. Tr. Incubus) is very much under the sign of a double filiation : one with his actual father whose death brings about neurosis (the topic of the novel), the other with his "literary father". The svevo of la coscienza di zeno (1923). Then a body of texts by ottiero ottieri (novels, poems and one essay) which seem to be centered around il campo di concentrazione (19729: "the journal of a deression written during the depression". These texts follow no litterary model and connot be read according to the oedipian logic of the family romance, inasmuch as they do away with the notions of cause and of a possible solution. Style in il male oscuro, based on free association is wholly pervaded with humour, which enables the reader to identify and to feel pleasure in spite of the gruesome experiences described there. On the contrary, ottieri's writing is shot through with a radical feeling of unreality too close to an overwhelming reality inhibiting any imaginary activity and is characterized by clusters of poetic expressions
Diazzi, Alessandra. "The reception of psychoanalysis in Italian literature and culture, 1945-1977 : Ottiero Ottietri, Edoardo Sanguineti, Giorgio Manganelli, Andrea Zanzotto." Thesis, University of Cambridge, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709511.
Full textGiulietti, Marika. "Telescopi ottici, radio, X: principi e differenze." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/12353/.
Full textMarchetto, Alina. "Telescopi ottici, radio, X: principi e differenze." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18486/.
Full textOss, Valerio. "Telescopi ottici, radio, X: principi e differenze." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25282/.
Full textSantucci, Giulia. "Telescopi ottici, radio, X: principi e differenze." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7200/.
Full textRosini, Gioele. "Ottimizzazione numerica degli impulsi ottici in un interferometro atomico." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23395/.
Full textCoatti, Riccardo. "Analisi comparativa di metodi ottici per la meccanica sperimentale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amslaurea.unibo.it/1088/.
Full textVisotti, Andrea. "Monitoraggio del calo volume ematico in emodialisi tramite sensori ottici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3552/.
Full textLama, Filippo. "Dispositivi ottici per la misura di corrente e di tensione." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11591/.
Full textCavana, Tommaso. "Caratterizzazione di un DMD per la generazione di potenziali ottici." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16952/.
Full textMuci, Elgi. "Ottimizzazione del posizionamento di sensori ottici per il monitoraggio strutturale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23466/.
Full textAltieri, Fabiano. "Approcci biomedici ottici per la stimolazione ed il monitoraggio dell'attività cerebrale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19363/.
Full textEsteki, Abolghasem. "Analisi dello stato dell'arte nello sviluppo di encoder ottici e magnetici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textTrentalancia, Guido. "Sistema interattivo di collaudo per moduli di lettura di codici ottici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8086/.
Full textCavicchioli, Luca. "Generazione e caratterizzazione dinamica di potenziali ottici mediante un dispositivo a microspecchi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16951/.
Full textBisacchi, Andrea. "Progetto di una implementazione veloce del Licklider Transmission Protocol per link ottici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22383/.
Full textMargaria, Matteo. "Analisi di dati satellitari radar e ottici per il monitoraggio di un evento alluvionale." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textFranci, Leonardo. "Scenari finanziari e portafogli ottimi: modelli di previsione e strategie per l'asset allocation tattica." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5454/1/franci_leonardo_tesi.pdf.
Full textMaking a right asset allocation is often a very difficult issue for every investor, who is constantly engaged in combining different asset classes to achieve a portfolio consistent with their preferences. The need to support the decisions of asset managers has nurtured over time a vast literature, that has proposed a number of strategies and formal models of portfolio construction. This thesis aims to provide an overview of some innovative forecasting models and strategies in the field of tactical asset allocation, and then to evaluate their usability by asset managers. Firstly, we will verify the existence of any relationship between the dynamics of some macroeconomic variables and financial markets. The aim is to identify an econometric model capable of directing strategies of asset managers in the construction of their investment portfolios. The analysis takes into account the American financial market, during a period of rapid economic change and high volatility in stock prices. Secondly, we will examine the validity of the momentum and contrarian trading strategies in the Eurozone futures markets, which are well suited to the implementation of these, thanks to the absence of constraints on short selling and the low costs of the transaction. The analysis shows that both anomalies occur permanently. The abnormal returns remain even after subjection to traditional asset pricing models such as the CAPM, the Fama and French model and Carhart model. Finally, using the EGARCH-M approach, we will formulate forecasts on the volatility of stocks returns and we’ll use these as input for determining some subjective views to be included in the Black and Litterman model. Our results indicate, for different value of scalar tau, that the BL portfolio excess returns exceed those of market equilibrium one, although with higher levels of risk.
Franci, Leonardo. "Scenari finanziari e portafogli ottimi: modelli di previsione e strategie per l'asset allocation tattica." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5454/.
Full textMaking a right asset allocation is often a very difficult issue for every investor, who is constantly engaged in combining different asset classes to achieve a portfolio consistent with their preferences. The need to support the decisions of asset managers has nurtured over time a vast literature, that has proposed a number of strategies and formal models of portfolio construction. This thesis aims to provide an overview of some innovative forecasting models and strategies in the field of tactical asset allocation, and then to evaluate their usability by asset managers. Firstly, we will verify the existence of any relationship between the dynamics of some macroeconomic variables and financial markets. The aim is to identify an econometric model capable of directing strategies of asset managers in the construction of their investment portfolios. The analysis takes into account the American financial market, during a period of rapid economic change and high volatility in stock prices. Secondly, we will examine the validity of the momentum and contrarian trading strategies in the Eurozone futures markets, which are well suited to the implementation of these, thanks to the absence of constraints on short selling and the low costs of the transaction. The analysis shows that both anomalies occur permanently. The abnormal returns remain even after subjection to traditional asset pricing models such as the CAPM, the Fama and French model and Carhart model. Finally, using the EGARCH-M approach, we will formulate forecasts on the volatility of stocks returns and we’ll use these as input for determining some subjective views to be included in the Black and Litterman model. Our results indicate, for different value of scalar tau, that the BL portfolio excess returns exceed those of market equilibrium one, although with higher levels of risk.
ORSINI, ENRICO. "Filtri ottici integrati basati su reticoli di Bragg realizzati su materiale ibrido Sol-Gel." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1213.
Full textBragg gratings optical filters can be considered one of the key elements in many integrated optical devices such as wavelength-division multiplexing (WDM), optical fibre sensors, gain-flattening filters and add-drop multiplexers (OADM’s), optical couplers, resonators and modulators. Over the past decade, extensive research has been conducted in order to improve the unconventional fabrication techniques to obtain low-cost optical devices. Several Bragg gratings-based optical devices have been obtained by merging conventional and unconventional fabrication techniques. In my Phd, the device consists of a hybrid titanium (organic/inorganic Sol-Gel material) optical filter for the third’s telecommunication optical windows (1550 nm) based on Bragg gratings loaded channel waveguide. The fabrication of the device is obtained by merging conventional and unconventional technique. The unconventional fabrication technique is the Soft-Litography, a very innovative process based on Replica-molding and UV-nanoimprinting for micro- and nano- fabrication. This process is characterized by low cost and fast processing using relatively inexpensive tools. Starting from sub-micrometric gratings (master) fabricated on Silicon wafer by means of standard Electron Beam Lithography (EBL) a soft mold (stamp) has been produced by replica-molding. Using the stamp, the initial master structures (Bragg gratings) were replicated onto sol-gel photosensitive films by Uv-nanoimprinting. The resulting films underwent a further photolithographic step combined with Reactive Ion Etching (RIE), thus producing a channel waveguide with Bragg gratings on the top. This wavelength filter have been optically characterized by transmission measurements in the range 1450 nm – 1590 nm by a tuneable IR diode laser. The efficiency was about -10 dB and the bandwidth at Full Width Half Maximum (FWHM) 1,7 nm. So, Titanium based wavelength filters, obtained by the merging of conventional photolithography and Soft-Lithography, have been demonstrated. The use of sol-gel technology with S-L methods makes thus possible to produce passive optical devices starting from a hard silicon master. Furthermore, thanks to high versatility of S-L process, a consistent replica of the master optical filter (i.e. channel with Bragg gratings) allows to replicate the pattern (at the nanometric scale) directly on a new sol-gel planar film. The morphological characterization by Atomic force microscopy of the replicated structure (optical filter), shows a good agreement with the Master. In conclusion, this means that we have obtained a simple process, low cost and industrially advantageous, to fabricate nanostructures on Sol-Gel matrix.
Tadei, Francesco. "Analisi di dati satellitari Sentinel ottici e radar per lo studio della copertura del suolo." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/12608/.
Full textChessa, Fabio. "Impiego di sensori ottici di riflettanza per la diagnosi dello stato fisiologico delle colture agricole." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25333/.
Full textPadovan, Marco. "Interfacce nanostrutturate, dispositivi ottici ed elettronici per lo studio della fisiologia di cellule cerebrali non neuronali." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16293/.
Full textSansò, Federica. "Analisi di dati telerilevati ottici e radar per la gestione dei disastri: le alluvioni nel Bangladesh." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2302/.
Full textPugliese, Melania. "Determinazione d'assetto di Cubesat tramite sensori solari basati su tecnologia CMOS." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textFarolfi, Arturo. "Simulazione di sistemi quantistici, approccio numerico e sperimentale nel caso della localizzazione di Anderson." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9135/.
Full textDraicchio, Pasquale. "Modelli e metodi ottimi e metaeuristici per la progettazione multi-obiettivo lean-green di reti logistiche a due livelli." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textCasali, Marco. "Ottimizzazione del funzionamento di un sensore industriale a triangolazione ottica basato su trasduttori lineari d'immagine." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17614/.
Full textPulimeno, Simone. "Identificazione degli eventi di combustione da biomassa tramite lo studio di parametri ottici e retro-traiettorie nel decennio 2010-2020 a Ny-Ålesund, Svalbard." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23070/.
Full textMonaldi, Christian. "Implementazione e test di algoritmi di determinazione d’assetto basati sull’identificazione stellare." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textBertozzi, Enrico. "Progetto ottimo della biforcazione di un vaso sanguigno." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14291/.
Full textGridelli, Eleonora. "Interpretabilità nel Machine Learning tramite modelli di ottimizzazione discreta." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23216/.
Full textLonghi, Giulia. "Processing di dati radar SENTINEL-1 e ottici SENTINEL-2 per lo studio di fenomeni di dissesto dei versanti nella media e alta valle del fiume Reno (Emilia-Romagna)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textBruno, Martina. "Studio di costellazioni di piccoli satelliti applicato a scenari di missione in LEO." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Find full textMazon, John Michael. "Ottica geometrica e ondulatoria, e applicazioni astrofisiche." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25360/.
Full textFalco, Antonella, Castro Giuseppe Lo, Gaetano Roberto De, and Margherita Ganeri. "Donnarumma all'assalto e Memoriale: una lettura critica." Thesis, 2011. http://hdl.handle.net/10955/913.
Full textSalsone, Silvia, Carlo Versace, Giuseppe Lombardo, Christian Zakian, and Roberto Bartolino. "Optical systems for diagnostics: Near-Infrared Imaging technique for detection of dental demineralisation." Thesis, 2012. http://hdl.handle.net/10955/1157.
Full textIn dentistry, a correct detection of caries severity is still a challenging descision-making task that crucially a ects the choice for the best treatment plan. The challenge is to nd both the most objective parameters to detect caries at di erent stages (from an early reversibile stage to a severe one) and the most reliable method(s) that should be used to distinguish these stages. Currently, methods used in clinics are visual inspection, aided with light probe and pick inspection tools, and radiography. The main issue rising by the use of these methods is that both of them are subjective, with possibility for intra- and inter-examiner variability. For this reason, radiography needs an extreme care of interpretation especially when assessing occlusal caries. Visual methods, instead, are a ected by confounding factors, such as stain or uorosis, a ecting the accurate assessment of early caries lesions. Radiography, moreover, should be performed with care considering that the emission of ionising radiation may cause malignant change in tissues, especially for young age patients and are counter-indicated during pregnancy. They are also inadequate for the detection of initial caries and to locate the lesions looking at the superimposition of the tooth along its buccal-lingual axis. The aim of this study was to overcome the limits of the current detection techniques, o ering a non-invasive, objective method for the detection of caries at any stage of the demineralisation process. The proposed method measures the near-infrared (NIR) re ectance response of the tooth at three speci c wavelengths. It is then possible to investigate properties of the sample at the surface and in depth and get an image that maps the lesions on the occlusal view of the sample when combining these wavelengths. Due to the properties of the NIR light, this method is non-invasive, non-contact and allows for detection both at the enamel and at the dentine level. The NIR method o ers objective supporting information to quantify and detect dental caries and is especially suitable for areas a ected by confounding factors, such as stain. The objective of the study was to design and implement a NIR multispetral imaging system, developing e cient image analysis algorithms. In order to prove this objective, an in vitro validation of the technique against gold standard histology was performed together with a comparison to other detection methods - International Caries Detection and Assessment System (ICDAS - clinical visual inspection), bre optic transillumination method (FOTI - visual inspection with light probe), radiography and Quantitative Light-induced Fluorescence method (QLF), used in clinics or in research. A total of 112 teeh, molars and premolars, with di erent lesion severities were used for this study. Histologcal sections were obtained to con rm the lesion severities and used as a gold standard to compare the sensitivity and speci cty among techniques. Visual inspection methods recorded the highest values of sensitivity (ICDAS: >99%, FOTI: 93%) and speci city to dental caries (FOTI: >99%, ICDAS: 90%). However, these methods could have been highly facilitated by the in-vitro viewing of the samples. Sensitivity to dental caries was higher for NIR (91%) than for QLF (88%) and radiography (63%) while speci city was higher for radiography (81%) than for NIR (73%) and QLF (63%). The results from this study suggest that the NIR method has the ability to detect dental caries when other methods fail, providing an alternative to assist in the decision-making process with the further advantage of removing the confounding e ect of stain. This method can enhance patient communication and o ers an objective and safe alternative to ionising radiation methods.
Università degli Studi della Calabria
Nudo, Paola, Sergio Rizzuti, Guido Danieli, and Andrea Fusiello. "Sviluppo, realizzazione e sperimentazione in vitro di un sistema ottico per il rilievo tridimensionale dell’arcata dentale." Thesis, 2014. http://hdl.handle.net/10955/386.
Full textThis thesis describes the development of a 3D scanning system based on an active vision technique that uses structured light to obtain the impression of the dental arch. Currently to realize a dental prosthesis a special doughy sticky material is adopted to impress the patient’s dental arch. This imprinting may be scanned and then analyzed and modified by C.A.D. software. All this process is sometimes too long, and it may take several weeks to obtain the final prosthesis. At that moment, there are only few works that use techniques to shorten the processing times and produce a three dimensional model of a dental arch, but often they don’t allow to obtain optimal results due to a low resolution and a slow acquisition rate. Among all the studies described on literature, it results that the structured light is a relatively simple technique that allows for a relative high resolution. In the last years, the development of all these systems, has draw the attention to those devices able to obtain a structure of patient’s dental arch as a C.A.D. model. The device developed and described in this thesis is a novel kind of optical scanner that allows for a total elaboration time, for the realization of a three dimensional model, which is lower than those of the systems described in literature. The new optical scanner consists of four digital camera, a multimedia DLP mini-projector and a software to manage the hardware and process the images. It is actuated by step motors on an 2D guide, which is held rigidly fixed to the denture of the patient by a self balanced kinematic chain, that allows for small motions of the patient’s head. This system designed allows the relief and automatic reconstruction through the use of structured light with a particular Gray-Code method. This work is mainly divided in two main parts: 1. The study of the optical system calibration 2. The study of the reconstruction of dental arch The technique used relies on a new version of Gray-Code method; which allows to solve the so called “correspondences problems”. The structured light is produced by a mini-projector, which has to undertake a calibration phase as well as the camera used for image acquisition. The second part of this study is related to the analysis and marge of the acquired images. This problem involves the alignement of the cloud of points obtained from the automatic scanning process by each camera. In this phase, all the errors involved in the whole procedure are also investigated.
Università della Calabria
Infusino, Melissa, Cesare Umeton, Raffaele Agostino, and Giovanni Falcone. "Periodic and aperiodic structures realized by innovative soft-metter based techniques." Thesis, 2014. http://hdl.handle.net/10955/553.
Full textIl presente lavoro di tesi `e basato sullo studio e l’utilizzo di tecniche sperimentali per la realizzazione di strutture periodiche ed a-periodiche su diverse scale di grandezza. La prima tecnica oggetto di studio rappresenta un nuovo approccio rispetto alle usuali tecniche olografiche e prevede l’utilizzo delle pi`u recenti tecnologie realizzate nell’ambito dell’olografia diffrattiva, quali i modulatori di fase spaziale. I modulatori di fase spaziale consentono la produzione di distribuzioni di intensit`a sia periodiche che a-periodiche ed in generale rendendo possibili geometrie difficilmente realizzabili con le classiche tecniche di interferenza a multi-fascio. Il sistema fotosensibile di partenza `e costituito da una miscela di pre-polimeri e cristalli liquidi nematici: la separazione di fase tra le due componenti `e indotta dalla fotopolimerizzazione. L’impiego dei cristalli liquidi consente la realizzazione di strutture dinamiche le cui propriet`a ottiche sono modificabili attraverso l’applicazione di stimoli esterni, quali campi elettrici ed ottici. Le strutture relizzate hanno una periodicit`a micrometrica che le rende applicabili nel campo dell’ottica. La seconda tecnica studiata si basa su fenomeni di auto-assemblaggio nei polimeri a blocchi e consente il raggiungimento di scale di grandezza inferiori: la periodicit`a delle strutture realizzate raggiunge infatti poche decine di nanometri. Nella tecnica di autoassemblaggio la separazione di fase tra le componenti `e regolata semplicemente dalla temperatura del sistema e le strutture risultanti hanno delle caratteristiche fortemente dipendenti dalle dimensioni dei costituenti. 3
Università della Calabria
De, Carlo Martino. "Integrated optomechanical devices for sensing." Doctoral thesis, 2021. http://hdl.handle.net/11589/213841.
Full textOptomechanics is a developing field of research exploring the interaction between light and mechanical motion. The modern nanofabrication techniques for mechanical devices and ultralow dissipation optical structures have provided a way for giving an important experimental progress to optomechanics, both for applications and for fundamental investigations. In this thesis optomechanics will be investigated in different aspects, in its general meaning, both theoretically and experimentally. There are different ways in which light and mechanics interact with each other. In this thesis three different macro areas of optomechanics have been developed: optical gyroscopes, optomechanical forces and photoacoustic spectroscopy. The interaction between light and mechanical motion has been investigated starting from the concept of optical gyroscopes. Optical gyroscopes are sensors of angular velocity. In the present state of the art, the physical principles and the configurations used for realizing optical gyroscopes are not suitable for miniaturizing them to the microscale. In this thesis some new configurations exploiting the concept of "exceptional points" have been presented and investigated. According to the relativistic effect called Sagnac effect, the resonance frequencies of two counterpropagating modes in a ring resonator are separated by a quantity proportional to the angular velocity of the frame. However, the possibility of miniaturizing the optical gyroscope is limited by the fact that the resonance splitting is proportional to the radius of the ring resonator. In the first chapter the concept of parity-time symmetry has been introduced as a solution for the integration of angular velocity sensors. By setting up two coupled optical resonators designed to be at the so called "exceptional point", it could be demonstrated that the eigenfrequency splitting is proportional to the angular velocity of the device, with a sensitivity that is several orders of magnitude higher than the classical Sagnac gyroscope. In this thesis it has been demonstrated that one problem of the parity-time symmetric gyroscope is the instability of the optical eigenmodes when the system is in rotation. That is why the idea of the anti-parity-time-symmetric gyroscope was proposed, using a U-shaped auxiliary waveguide to indirectly couple two optical resonators. The proposed solution has been shown to be an interesting alternative for angular velocity sensing, thanks to the easy readout scheme and the absence of modes instability. A simple broadband source, together with a photodetector could be used to read the output of the sensor. Finally, a new configuration for an anti-parity-time-symmetric gyroscope has been proposed. It is different from the U-shaped configuration and uses only an auxiliary straight waveguide to indirectly couple two optical resonators. This architecture has been shown to be much more robust, insensitive to some fabrication errors, with respect to the U-shaped one. The second area of optomechanics that has been investigated in this thesis includes optomechanical forces. In particular, a generalized model able to calculate the mechanical displacement of only one degree of freedom of a general optomechanical setup has been developed. The model initially proposed by Rakich has been extended to systems where gain or loss are considered. Then, the model has been used to evaluate the effect of optical forces in parity-time symmetric system with suspended waveguides in the coupling region. It has been demonstrated that it is possible to enhance the optical forces thanks to condition of parity-time symmetry. Secondly, an analytical modelling of the dynamics of optomechanically coupled suspended optical waveguides has been proposed, including a modelling of the damping, with the squeezing effect. Such an analytical model, together with the numerical proposed algorithm can be used to find the evolution of the system in the time domain of complex optomechanical structures, such as optomechanical switches. Also, an experimental work on an optomechanical switch has been shown. All the fabrication steps to fabricate the integrated optomechanical device has been explained. The most critical part during the fabrication has been the underetching of suspended waveguides. In fact, using a wet HF etching process caused the suspended waveguides to get stuck. Using a ZEP mask and a vapor HF etching, unexpected HF bubbles appeared on the surface. So, a hard mask has been used to guarantee the successful underetching of the device. Finally, the experimental measurement on the chip showed the expected behaviour of the device. Finally, Photoacoustic Spectroscopy has been analysed. The state-of-art Quartz-Enhanced PhotoAcoustic Spectroscopy (QEPAS) sensor has been modelled and simulated and a new semi-integrated sensor has been proposed. One problem of the state-of-art QEPAS sensors is the necessity of alignment for optical components. Moreover, the dimension of all the devices involved in the setup makes it difficult to realize portable and compact sensors. The idea proposed in this thesis is to integrate all the optical components needed to guide the light in the proximity of the Quartz Tuning Fork to drastically reduce the dimension of the overall setup and to avoid the problem of optical alignment. The possibility of using integrated optical waveguides to guide light makes it possible to use optical resonators to enhance the photoacoustic signal that is read through a Quartz Tuning Fork. The proposed setup is meant to use an integrated laser bonded to a Silicon chip, where all the waveguides are realized. In this case a very small mechanical resonator can be bonded over the Silicon chip, in order to enhance the amplitude of the pressure signal. In such a way, performance comparable with the state-of-art QEPAS sensor can been achieved. Such a result could pave the way to a new generation of compact QEPAS sensor, that could overcome the problem of the size of the setups and of the alignment of optical components.