Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-12T14:28:27Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese _Diógenes Soares Moura_final.pdf: 4560976 bytes, checksum: efbc9854c7666e2a40de8b98b027e62d (MD5) / Made available in DSpace on 2016-09-12T14:28:27Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese _Diógenes Soares Moura_final.pdf: 4560976 bytes, checksum: efbc9854c7666e2a40de8b98b027e62d (MD5) Previous issue date: 2016-02-25 / CAPEs / O presente trabalho explora a utilização de lasers na região do infravermelho do espectro eletromagnético em aplicações biomédicas. O uso dos lasers na indústria, para processamento de materiais e em aplicações médicas, como a realização de cirurgias, têm atraído grande interesse nas últimas décadas. Neste trabalho, laser infravermelho foi explorado no corte de bolsas de sangue e no desenvolvimento de sistema de avaliação de elasticidade de hemácias baseado em técnica de aprisionamento óptico. No corte de bolsas de sangue foram determinados os parâmetros da ablação como tempo de perfuração, taxa de ablação e diâmetro dos furos para diferentes fluências e taxas de repetição do laser. Neste trabalho foram utilizados laser pulsados no regime de femtossegundos, com comprimento de onda de 800 nm, com taxa de repetição de 10 Hz e 1 KHz. Os resultados mostraram uma dependência do processo de ablação com o aumento da fluência e da taxa de repetição do laser. Além disso, foram avaliados os resíduos gasosos emitidos durante o processo de ablação das bolsas. A avaliação dos parâmetros de ablação à laser de bolsas de sangue consiste em um estudo pioneiro e introduz um novo direcionamento no processo de corte das mesmas. No desenvolvimento de um sistema para avaliação automática de elasticidade de hemácias aprisionadas opticamente foram utilizados lasers contínuos nos comprimentos de onda de 785 nm e 1064 nm. O sistema permite obter o valor da elasticidade de uma célula em 20 segundos, o que imprime uma redução significativa do tempo do processo de avaliação (60 ×) comparada ao método convencional. O sistema automático pode ajudar a expandir as aplicações de pinças ópticas em Hematologia e Hemoterapia. Além disto, o sistema construído foi utilizado para avaliar danos em hemácias aprisionadas opticamente. Foi verificada uma dependência da elasticidade das células com o comprimento de onda, potência do laser incidente e com tempo de aprisionamento da hemácia. Observou-se que as hemácias, após 2 minutos de exposição ao laser de 785 nm tornaram-se até ~ 104% menos deformáveis que as hemácias controle. A exposição ao laser de 1064 nm de 2 minutos a 10 mW induziu um aumento de até ~ 20% na rigidez celular. Atribuiu-se a dependência do comprimento de onda dos danos ópticos à absorção do laser pela hemoglobina. As modificações observadas nas propriedades elásticas das células estudadas estabelecem novos limites para aplicações utilizando lasers em hemácias. / This work explores the use of lasers in the infrared region of the electromagnetic spectrum in biomedical applications. The use of lasers in industry for materials processing and in medical applications, such as in surgeries, have attracted great interest in recent decades. In this work, infrared lasers were explored in blood bags cutting and in the development of a red blood cells elasticity evaluation system based on optical trapping technique. For the blood bags cutting process, ablation parameters such as drilling time, ablation rate and ablation diameter for different laser fluence and repetition rates were determined. In this work we used pulsed laser in femtosecond regime, with a wavelength of 800 nm, with repetition rate of 10 Hz and 1 KHz. The results showed a dependence of the ablation process with laser fluence and repetition rate. In addition, the waste gases emitted during the blood bags ablation process were evaluated. The evaluation of the blood bag laser ablation parameters consists of a pioneering study and introduces a new direction in the blood bag cutting process. In the development of a system for automatic evaluation elasticity of optically trapped red blood cells (RBCs), continuous laser at a wavelength of 785 nm and 1064 nm were used. The system allows to obtain the value of cell elasticity in 20 seconds, establishing a significant reduction in the assessment process time (× 60) compared to the conventional method. The automated system can help expand the applications of optical tweezers in Hematology and Hemotherapy. In addition, the constructed system was used to evaluate damage to red blood cells optically trapped. A dependence of the cells elasticity with the wavelength and power laser and with cell time trapping was observed. The results shows that the red blood cells was up to ~104% less deformable after 2 minutes of 785 nm laser exposition. The 2 minutes exposure to 10 mW of 1064 nm laser induced an increase up to ~ 20% on cell rigidity. We ascribed the wavelength dependence of the optical damages to the laser absorption by the hemoglobin. Moreover, the increase of RBCs rigidity could be associated to initial changes optically caused in the hemoglobin after irradiation. The results establish new limits for laser applications in RBCs, by identifying considerable modifications on their elastic properties.

With the unique advantage of great isolation from the thermal environment, levitated optomechanics has emerged as a powerful platform for various fields of physics including microscopic thermodynamics, precision measurements, and quantum mechanics. Experiments with optically levitated micro- and nanoparticles have already obtained remarkable feats of zeptonewton force sensing and ground-state cooling. The novel system has also been proposed to assess various theories including the objective collapse models and macroscopic quantum mechanics. <br><div><br></div><div>This thesis reports experimental results on a levitated Cavendish torsion balance, a GHz nanomechanical rotor, and a torque sensor with unprecedented sensitivity realized with optically levitated nanoparticles in a vacuum environment. The system at room temperature achieves a sensitivity of (4.2±1.2)×10−27Nm/ √ Hz surpassing the sensitivity of most advanced nanofabricated torque sensors at cryogenic environments. Calculations suggest potential detection of Casimir torque and vacuum friction under realistic conditions. Moreover, the nanoparticles are driven into ultrafast rotations exceeding 5 GHz, which achieves the fastest humanmade nanomechanical rotor. Such fast rotations allow studies on the ultimate tensile strength of the nanoparticles as well. <br></div><div><br></div><div>Subsequently, the electron spin control of nitrogen vacancies (NV) in optically trapped diamond naoparticles is demonstrated in low vacuum. The configuration is analogous to trapped atoms and ions which serve as a quantum system with internal states. The effect of the air pressure, surrounding gas, and laser power on the electron spin resonance (ESR) are studied, and the temperature of the diamond is also measured with the ESR. The levitated nanodiamonds will provide the means to implement a hybrid spin-optomechanical system.<br></div>

[pt] As pinças ópticas tornaram-se uma ferramenta importante na pesquisa multidisciplinar, permitindo a manipulação e estudo de partículas em micro e nanoescala. Aqui, descrevemos o desenvolvimento de dois experimentos de pinça óptica no cerne da optomecânica levitada: uma pinça óptica a vácuo Gaussiana e uma pinça óptica a vácuo com luz estruturada. No experimento Gaussiano, descrevemos em detalhes sua construção e seu uso para testar características de movimento estocástico sujeito a forças efetivas não-lineares geradas através de feedback elétrico. Em seguida, passamos para a configuração de luz estruturada. Utilizando um Modulador Espacial de Luz, desenvolvemos uma pinça óptica a vácuo com a capacidade de gerar potenciais ópticos arbitrários, incluindo não-linearidades e armadilhas para múltiplas partículas. Os experimentos desenvolvidos neste trabalho abrem caminho para novos métodos de controle de movimento de partículas, forças e interações, expandindo ainda mais a caixa de ferramentas da optomecânica levitada. / [en] Optical tweezers have become an important tool in multidisciplinary research, allowing for the manipulation and study of micro- and nano-scale particles. Here, we describe the development of two optical tweezer experiments at the heart of levitated optomechanics: a Gaussian and a structured light vacuum optical tweezer. In the Gaussian experiment, we describe in detail its construction and its use to test features of stochastic motion subject to nonlinear effective forces generated via electric feedback. Next, we move to the structured light setup. Using a Spatial Light Modulator, we develop a vacuum optical tweezer with the capability of engineering arbitrary optical landscapes, including non-linearities and multi-particle traps. The experiments developed in this work pave the way to novel methods for controlling particle motion, forces and interactions, further extending the levitated optomechanics toolbox.

Depuis les premiers travaux d’Ashkin sur les pinces optiques classiques, beaucoup d’efforts ont été fait pour piéger des nano particules. Néanmoins, elles peuvent difficilement piéger des particules inférieures à 200 nm à cause des limites imposées par la diffraction. Cette limite peut être dépassée grâce aux forces optiques de gradient provenant du champ évanescent généré et amplifié par des nano cavités photoniques. Cependant, cette approche est confrontée à deux verrous importants pour les applications : La surface de piégeage est très faible ce qui rend peu probable la capture d’une nanoparticule animée d’un mouvement brownien et pour les pinces « ultimes » de type nanoantenne où le mode est confiné dans des régions nanométriques, leur excitation en espace libre n’est pas très efficace. L’objectif de ce travail vise à lever ces deux verrous. Pour augmenter la surface de piégeage, nous présenterons d’abord une approche utilisant le mode de Bloch d’une cavité étendue à double période dans un cristal photonique fabriqué sur SOI. Nous montrerons que cette approche permet le piégeage de particules de 200, 100 et 75 nm sur une surface étendue de 5x5 µm² en utilisant un faisceau laser d’excitation en espace libre. Dans un deuxième temps, nous nous intéresserons à l’excitation optique en espace libre de structures nanométriques. Nous présenterons une structure hybride nano antenne – cristal photonique, où le cristal photonique joue le rôle de réservoir à photons pour la nano antenne. Cela permet ainsi un effet « entonnoir à photon» où la lumière issu d’un faisceau large (5µm) est concentrée dans la nanoantenne. Nous démontrerons la pertinence de cette approche par le piégeage particules de 100 nm. / Since the first work on optical tweezers by Ashkin, a lot of efforts have been made to trap nanoparticles. However, optical tweezers are diffraction limited and can hardly trap particles below 200 nm. This limit can be overstepped using the optical gradient forces of an evanescent field generated and amplified by a photonic nano cavity. Nonetheless, this approach faces two major issues for applications: the trapping section is very small, making the capture of a Brownian motion animated particle very unlikely, and for the “ultimate” nano antennas with nanometric optical modes, their excitation from free space is not effective. The goal of this work is to overcome these two difficulties. To increase the trapping surface, we will first present a device using slow Bloch modes within a double period extended cavity designed in a photonic crystal made out of SOI. We will show that this approach allow for the trapping of 200, 100 and 75 nm particles on an extended surface of 5x5 µm² using a free space laser beam excitation. Secondly, we will investigate the free space excitation of nanometric structures. A photonic crystal – nano antenna mixed structure will be presented, where the photonic crystal is used as a photon pool for the nano antenna. This lead to a funnel effect where the light coming from a large free space laser beam (5µm wide) is focused into the nano antenna. The trapping of 100 nm particles will demonstrate the relevance of this approach.

Cette thèse présente la réalisation d’un piège optique dans une configuration originale, le piston optique, où le contrôle sur la phase de l’interférence d’un faisceau incident avec sa réflexion sur un miroir permet de réaliser différents types d’expériences. Nous avons d’abord étudié les propriétés thermodynamiques d’une compression progressive du piston qui fait passer la dynamique de la particule piégée d’une région de stabilité vers une région de bistabilité mécanique. Dans le contexte de la résonance stochastique où une force extérieure périodique est appliquée sur cette dynamique bistable, une approche exploitant le facteur de Mandel ainsi qu’une analyse des délais entre les transitions d’états métastables se révèle efficace pour interpréter nos mesures dans différents régimes de forçage. Nous montrons également comment des nanoparticules métalliques peuvent être piégées aisément dans un tel piston optique et nous exploitons notre configuration pour mesurer de faibles effets de forces optiques. Enfin, nous piégeons des nano-objets chiraux uniques et nous montrons comment la configuration de notre piston permet de réaliser des expériences de reconnaissance chirale par polarimétrie différentielle. / This thesis describes the experimental realization of an original optical trap, the optical piston, where controlling the phase of the interference of an incident beam with its reflection on a mirror allows achieving various experiments. We have first looked into the thermodynamics associated with a progressive compression of the piston leading the dynamics of a trapped particle from a region of stability to a region of mechanical bistability. In the context of stochastic resonance where a periodic external force is applied on this bistable dynamics, an approach exploiting the Mandel factor and a time-delay analysis on the hopping events between metastable states have proven efficient in interpreting the different results acquired in different regimes of drive. We have also shown how metallic nanoparticles can be trapped fairly easily in this kind of optical piston and we exploit our configuration to measure weak optical forces. Finally, we trap unique chiral nano-objects and we show how the configuration of our piston allows the realization of chiral recognition experiments by differential polarimetry.

In the master's thesis, there has been described and explained the principle of operation of the second generation coherence controlled holographic microscope (CCHM2) designed at the Brno University of Technology. There has also been listed theoretical description of the operation of the optical trap, together with the calculation of the forces acting on it, ways of measuring the stiffness of the optical trap and the principle of~creating a time-shared optical traps. The optical tweezers forming a separate module connectable to CCHM2 was designed. Simulation and optimization of parameters of the optical system, mechanical design, manufacturing documentation, current source to power the laser diode which allows to control the diode output power by the controller card connected to the PC was designed. The galvano-optics mirror angle is controlled by the PC card too. The optical tweezer has been designed, manufactured and tested in conjunction with the CCHM2.

Όταν ηλεκρομαγνητική (ΗΜ) ακτινοβολία, προερχόμενη από κάποια πηγή, προσπίπτει σε σύνολο από σωμάτια τότε λαμβάνουν χώρα δύο φαινόμενα. Πρώτον, ασκούνται δυνάμεις στα σωμάτια οι οποίες οφείλονται αποκλειστικά στην σκέδαση της ΗΜ ακτινοβολίας της πηγής από αυτά. Οι δυνάμεις αυτές ονομάζονται Optical Trapping Forces. Δεύτερον, τα ίδια τα σωμάτια σκεδάζοντας την ΗΜ ακτινοβολία της πηγής, λειτουργούν και αυτά ως πηγές ακτινοβολίας. Έτσι ασκούν δυνάμεις το ένα στο άλλο. Οι δυνάμεις αυτές ονομάζονται Optical Binding Forces. H παράλληλη δράση των δύο αυτών ειδών δυνάμεων έχει ως αποτέλεσμα την δημιουργία ευσταθών δομών από τα σωμάτια. Προκειμένου την θεωρητική πρόβλεψη των δομών που αναπτύσσονται, χρειαζόμαστε έναν ταχύτατο αλγόριθμο υπολογισμού των δυνάμεων. Ο πιο ταχύς αλγόριθμος θα είναι το αποτέλεσμα της εύρεσης ενός αναλυτικού τύπου υπολογισμού των δυνάμεων. Η κατασκευή και η παρουσίαση του αναλυτικού τύπου αυτού είναι και το περιεχόμενο της εργασίας που ακολουθεί. / When the electromagnetic radiation, originating from a source, meets an ensemble of particles, there are two phenomena which take place. First, there are forces acting on these particles due exclusively to the scattering of the electromagnetic radiation from the particles. These are the so-called “Optical Trapping Forces”. Second, particles themselves act as sources of radiation since they scatter the radiation, and they exert forces one to another. These are the so-called “Optical Binding Forces”. The coexistence of these two different forces results in the creation of stable structures where the particles are self-organized. To achieve the theoretical prediction of these structures, we need a very efficient algorithm to calculate the forces. The fastest possible and thus more efficient algorithm originates from the analytical formula of the forces. The construction and the solution of the forces analytical formula is the content of this research work.