<pre>Bridging the gap between the classical and quantum regimes has consequences not only for fundamental tests of quantum theory, but for the relation between quantum mechanics and gravity. The field of levito-dynamics provides a promising platform for testing the hypotheses of the works investigating these ideas. By manipulating a macroscopic particle's motion to the scale of its ground state wavefunction, levito-dynamics offers insight into the macroscopic-quantum regime.</pre><pre><br></pre><pre>Ardent and promising research has brought the field of levito-dynamics to a state in which these tests are available. Recent work has brought a mesoscopic particle's motion to near the ground state. Several factors of decoherence are limiting efficient testing of these fundamental theories which implies the need for alternative strategies for achieving the same goal. This thesis is concerned with investigating alternative methods that may enable a mesoscopic particle to reach the quantum regime. </pre><pre><br></pre><pre><pre>In this thesis, three theoretical proposals are studied as a means for a mesoscopic particle to reach the quantum regime as well as a detailed study into one of the most important factors of heating and decoherence for optical trapping. The first study of cooling a particle's motion highlights that the rotational degrees of freedom of a levitated symmetric-top particle leads to large harmonic frequencies compared to the translational motion, offering a more accessible ground state temperature after feedback cooling is applied. An analysis of a recent experiment under similar conditions is compared with the theoretical findings and found to be consistent. <br></pre> <pre>The second method of cooling takes advantage of the decades long knowledge of atom trapping and cooling. By coupling a spin-polarized, continuously Doppler cooled atomic gas to a magnetic nanoparticle through the dipole-dipole interaction, motional energy is able to be removed from the nanoparticle. Through this method, the particle is able to reach near its quantum ground state provided the atoms are at a temperature below the nanoparticle ground state temperature and the atom number is sufficiently large.</pre> <pre>The final investigation presents the dynamics of an optically levitated dielectric disk in a Gaussian standing wave. Though few studies have been performed on disks both theoretically and experimentally, our findings show that the stable couplings between the translational and rotational degrees of freedom offer a possibility for cooling several degrees of freedom simultaneously by actively cooling a single degree freedom.</pre></pre>

<p>  </p> <p>Integrated photonics has provided an elegant way to bring the table-top bulky optical systems from the research lab to our daily life, thanks to its compact size, robustness, and low power consumption. Over the past decade, Silicon Nitride (Si3N4) photonics has become a leading material platform, benefiting from its record-low loss, large Kerr nonlinearity, and compatibility with the foundry process. However, the lack of electro-optical effect makes it challenging to actively tune the Si3N4 photonic circuits for advanced applications, such as LiDAR, spectroscopy, and atomic clocks. During my PhD research, I have developed a new platform of piezoelectric control of Si3N4 photonics through stress-optical effect. By integrating an<br> Aluminum Nitride (AlN) piezoelectric actuator, I demonstrated the tuning of Si3N4 optical microring resonator at sub-microsecond speed with nano-Watt power consumption. Microwave frequency (GHz) acousto-optic modulation (AOM) is realized by exciting high-overtone bulk acoustic wave resonant modes (HBAR), which are tightly confined in an acoustic Fabry-Pérot cavity. Maximum of 9.2 GHz modulation is achieved which falls into the microwave X-band. </p> <p><br></p> <p>The applications of the Piezo-on-Photonic platform are extensively explored in the quasi-DC and high frequency regimes. By working as a stress-optical tuner at low frequency, it allows me to actively tune a Kerr frequency comb into different states, and stabilize it over several hours, which can serve as the light source for the next-generation chip-based LiDAR engine. On the other hand, the GHz frequency AOM has helped me demonstrate a magnetic-free integrated optical isolator, a device that transmits light in only one direction. Three AlN HBAR actuators are integrated closely on the same Si3N4 microring resonator, which generate an effective rotating acoustic wave and break the transmission reciprocity of the light. A maximum of 10 dB isolation is achieved under 300 mW total radiofrequency power, with minimum insertion loss of 0.1 dB. Finally, the application of the same technique in quantum microwave to optical converter is theoretically analyzed, showing potential for building future quantum networks. The initial experimental attempt and outlook for future improvements are investigated. </p> <p><br></p> <p>In conclusion, this thesis investigated a novel Piezo-on-Photonic platform for flexible and efficient control of the Si3N4 photonic system, and its applications in a wide variety of advanced devices are demonstrated, with the potential of being key building blocks for future optical systems on-chip.  </p>

[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.

[pt] A optomecânica é um campo em crescimento que estuda sistemas nos quais luz e movimento mecãnico estão acoplados por meio de pressão de radiação. Neste trabalho apresentamos a teoria básica acerca de cavidades ópticas e pinças ópticas, duas importantes ferramentes frequentemente utilizadas em experimentos de optomecânica, bem como suas implementações práticas. No que diz respeito a cavidades ópticas, nós apresentamos a implementação de cavidades de Fabry Pérot formadas por um espelho plano e um espelho esférico e de cavidades formadas por dois espelhos esféricos, tanto na configuração confocal como na configuração não confocal, e comparamos a performance dessas diferentes cavidades. No que diz respeito a pinças ópticas, nós apresentamos uma pinça óptica capaz de aprisionar esferas micrométricas em um meio aquoso e a usamos para estudar o movimento de partículas aprisionadas. / [en] Optomechanics is a growing field that studies systems where light and mechanical motion are coupled via radiation pressure. In this work, we present the basic theory regarding optical cavities and optical tweezers, two important tools that are often used in optomechanical setups, as well as their experimental implementations. On the subject of optical cavities, we present the implementation of Fabry Pérot cavities formed by one plane mirror and one spherical mirror and cavities formed by two spherical mirrors, both on the confocal and on the non-confocal configuration, and compare the performance of these different cavities. On the subject of optical tweezers, we present an optical tweezer capable of trapping micro-spheres in a water medium and use it to study the movement of trapped particles.

Les systèmes optomécaniques, dans lesquels les vibrations d'un résonateur mécanique sont couplées à un rayonnement électromagnétique, ont permis l'examen de multiples nouveaux effets physiques. Afin d'exploiter pleinement ces phénomènes dans des circuits réalistes et d'obtenir différentes fonctionnalités sur une seule puce, l'intégration des résonateurs optomécaniques est obligatoire. Ici nous proposons une nouvelle approche pour la réalisation de systèmes intégrés et hétérogènes comportant des cavités à cristaux photoniques bidimensionnels au-dessus de guides d'ondes en silicium-sur-isolant. La réponse optomécanique de ces dispositifs est étudiée et atteste d'un couplage optomécanique impliquant à la fois les mécanismes dispersifs et dissipatifs. En contrôlant le couplage optique entre le guide d'onde intégré et le cristal photonique, nous avons pu varier et comprendre la contribution relative de ces couplages. Cette plateforme évolutive permet un contrôle sans précédent sur les mécanismes de couplage optomécanique, avec un avantage potentiel dans des expériences de refroidissement et pour le développement de circuits optomécaniques multi-éléments pour des applications tels que le traitement du signal par effets optomécaniques. / Optomechanical systems, in which the vibrations of a mechanical resonator are coupled to an electromagnetic radiation, have permitted the investigation of a wealth of novel physical effects. To fully exploit these phenomena in realistic circuits and to achieve different functionalities on a single chip, the integration of optomechanical resonators is mandatory. Here, we propose a novel approach to heterogeneously integrated arrays of two-dimensional photonic crystal defect cavities on top of silicon-on-insulator waveguides. The optomechanical response of these devices is investigated and evidences an optomechanical coupling involving both dispersive and dissipative mechanisms. By controlling optical coupling between the waveguide and the photonic crystal, we were able to vary and understand the relative strength of these couplings. This scalable platform allows for unprecedented control on the optomechanical coupling mechanisms, with a potential benefit in cooling experiments, and for the development of multi-element optomechanical circuits in the frame of optomechanically-driven signal-processing applications.

Orientador: Gustavo Silva Wiederhecker / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-09-02T10:33:51Z (GMT). No. of bitstreams: 1 Luiz_GustavoDeOliveira_D.pdf: 5507367 bytes, checksum: 506db63a5a93a33d67a84dbb1f7b33ce (MD5) Previous issue date: 2017 / Resumo: Nas últimas décadas a optomecânica de microcavidades chamou a atenção de cientistas e engenheiros, que encontraram na interação entre luz e ondas acústicas aplicações que variam de sensores de massa com resolução atômica, até a preparação de estados quânticos de osciladores harmônicos mesoscópicos, passando por simuladores quânticos, filtros ópticos controláveis opticamente, criação de estados topológicos para luz e fônons, apenas citando alguns exemplos. Apesar das diversas demonstrações de vários dispositivos, sendo discos e cristais fotônicos os formatos mais comuns, há ainda um grande esforço no sentido de aperfeiçoá-los reduzindo perdas ópticas e mecânicas e suprimindo outros fenômenos de óptica não-linear, como absorção de dois fótons, que podem impedir seu funcionamento apropriado. Como ressonadores ópticos e mecânicos tipicamente compartilham a mesma estrutura nestes dispositivos, seus projetos são acoplados, dificultando o aprimoramento independente de cada um. Nesta tese usamos dispositivos optomecânicos de campo próximo, cuja interação entre modos mecânicos e ópticos se dá através do campo evanescente do último, para desacoplar o projeto mecânico do óptico, o que nos permitiu estudar a otimização do ressonador mecânico sem qualquer efeito sobre a cavidade óptica. Com um ressonador mecânico de silício composto por dois osciladores acoplados, pudemos demonstrar que o correto equilíbrio das massas de cada oscilador é um método simples e eficiente para suprimir as perdas devido à radiação de energia mecânica para o substrato na escala de frequência de 50 MHz. Este processo permitiu que fatores de qualidade limitados por perdas relacionadas ao material e à superfície, da ordem de 10 mil à temperatura ambiente e de 50 mil a aproximadamente 25 K, fossem obtidos. Também observamos nestes dispositivos o fenômeno de auto-pulsação, que apresenta uma dinâmica própria tão interessante quanto a optomecânica, apesar de impedir a operação apropriada dos osciladores optomecânicos. Estudamos este fenômeno separadamente e demonstramos que estes pulsos, ocorrendo em duas cavidades ópticas acopladas por seus campos evanescentes, podem sincronizar com o campo óptico sendo o único intermediador. Ambas as demonstrações têm implicações importantes, abrindo caminho para o desenvolvimento de novas plataformas de interesse tanto científico quanto tecnológico, como estruturas para o estudo de estados topológicos para a luz e para ondas acústicas e geradores de sinal de radio-frequência de alto desempenho. Além disso, os dispositivos foram todos produzidos em uma fábrica comercial, o que também demonstra que sua fabricação está pronta para ser escalada para produção em massa / Abstract: Cavity optomechanics in the micro-scale has attracted the attention of scientists and engineers on the last few decades, who encountered applications to the interaction of light and acoustic waves ranging from atomic resolution mass sensors to the preparation of quantum states of mesoscopic harmonic oscillators, passing by quantum simulators, optically controllable optical filters, formation of topological states for both photons and phonons, just to mention a few examples. Although various devices have been demonstrated, with disks and photonics crystals being the most common designs, there is still a large effort to improve them by reducing optical and mechanical losses and suppressing other non-linear phenomena, such as two-photon absorption, that may affect their proper operation. Because optical and mechanical resonators typically share the same structure in these devices, their designs are coupled, which complicates the independent improvement of each one. In this thesis we used near-field optomechanical devices, whose mechanical modes interact with the optical through the latter¿s evanescent field, to decouple the mechanical design from the optical, what allowed us to focus all attention on the mechanical resonator. With a silicon mechanical resonator composed of two coupled oscillators, we could demonstrate that the correct balance of the masses of the oscillators is an efficient and simple way to suppress losses due to energy radiation to the substrate at the 50 MHz frequency range. This strategy led to material and surface limited quality factors close to 10k at room temperature and 50k at approximately 25 K. We also observed the phenomenon of self-pulsing in these devices, which presents dynamics as interesting as the optomechanical interactions do, in spite of being a problem for the proper operation of the optomechanical devices. We studied this phenomenon separately and demonstrated that these pulses, when occurring in two evanescently coupled optical cavities, may synchronize with the optical field being the sole intermediary. These two demonstrations have important implications, paving the way for new platforms of scientific and technological interest, such as structures for the study of topological states for both light and acoustic weaves as well as high efficiency radio-frequency signal generators. Moreover, these devices were all fabricated in a commercial foundry, which also demonstrates that the fabrication of such technology is ready to be scaled up to mass production / Doutorado / Física / Doutor em Ciências / 153044/2013-6 / CNPQ

Exploiter le degré de liberté angulaire de la lumière pour contrôler les forces optiques ouvre une nouvelle voie pour la manipulation optique de systèmes matériels. Dans ce contexte, notre travail porte sur l’interaction lumière-matière en présence de chiralité, qu’elle soit matérielle ou ondulatoire. Expérimentalement, nous avons utilisé des gouttes de cristaux liquides cholestériques interagissant avec un ou plusieurs champs lumineux polarisés circulairement et nous avons apporté une description quantitative de nos observations. Notre principal résultat correspond à la démonstration que la pression de radiation optique peut être contrôlée par l’hélicité du photon. Ce phénomène est ensuite utilisé, d’une part pour faire une démonstration de principe du tri de la chiralité matérielle via une approche optofluidique et d’autre part pour réaliser un piège optique tridimensionnel sensible à la chiralité de l’objet piégé. / Exploiting the angular momentum degree of freedom of light to control the mechanical effects that result from light-matter exchanges of linear momentum is an intriguing challenge that may open new routes towards enhanced optical manipulation of material systems. In this context, our work addresses the interplay between the chirality of matter and the chirality of optical fields. Experimentally, this is done by using cholesteric liquid crystal droplets interacting with circularly polarized light and we provide with theoretical developments to quantitatively support our observations. Our main result is the demonstration of optical radiation force controlled by the photon helicity. This phenomenon is then used to demonstrate the optofluidic sorting of material chirality and the helicity-dependent three-dimensional optical trapping of chiral liquid crystal microspheres.

No description available.

L'étude du couplage optomécanique, soit l'interaction entre un résonateur mécanique et la lumière venant mesurer sa position est née avec les recherches visant à détecter les ondes gravitationnelles. Ce couplage limite la sensibilité des mesures interférométriques nécessaires à leur observation.Cette limite est d'origine quantique : à tout appareil de mesure est associé un bruit (le bruit de phase des lasers). De plus, en vertu des inégalités de Heisenberg toute mesure d'un système le perturbe. On parle d'action en retour (liée aux bruits d'intensité des lasers). La lumière étant un objet quantique, il n'est pas possible de réduire simultanément les fluctuations de phase et d'intensité. La sensibilité d'une mesure interférométrique a donc pour minimum la limite quantique standard. Cette limite n'a jamais été observée à température ambiante.Nous décrivons dans ce manuscrit les effets de la pression de radiation sur un résonateur mécanique plan-convexe utilisé comme miroir de fond d'une cavité Fabry-Perot de grande finesse. A température ambiante, le bruit de pression de radiation est largement masqué par le bruit thermique. Ceci conduit à la mise en place d'une expérience pompe-sonde et à mesurer les corrélations entre ces deux faisceaux. En outre, cette expérience est très sensible au désaccord du laser avec la cavité. Nous utilisons une modulation de la position du résonateur afin de s'asservir le mieux possible à la cavité. Compte tenu du faible niveau de corrélations à mesurer, nous caractérisons les limites qu'impose le bruit classique des lasers. Nous présentons également le développement de nouveaux résonateurs optomecaniques en quartz. / Optomechanical coupling, that is the interaction between mechanicals modes of a resonator and light sensing its position, is a field of study that was born with the gravitational waves quest. This coupling poses limits to the sensitivity of interferometric measurements needed to detect them.This limit is of quantum origin. Indeed, every measurement apparatus has its own noise, we call it measurement noise. Moreover according to the Heisenberg inequalities, every measurement of a system disturbs it in some way. We call it back-action. In optomechanics, the measurement noise is the laser phase-noise while back-action stems from intensity-noise. Both of them have quantum origin and cannot be made arbitrary small. The sensitivity of classic interferometric measurement is then the result of a tradeoff between those two noises and cannot be lower than what is called the standard quantum limit. This limit has never been observed at room-temperature in a table-top experiment. The effects of radiation-pressure on a plano-convex resonator embedded in a high-finesse Fabry-Perot cavity are described in this work. At room-temperature the quantum radiation pressure noise is overwhelmed by thermal noise. This lead to use a pump-probe experiment where two laser beams are send in the cavity and measure their correlations. This experiment is extremely sensitive to the cavity- laser detuning. We propose to modulate the mirror position and use this precisely lock the lasers to the cavity. The correlations we aim to measure are extremely low so we characterize the limits put by classical noise of the laser system on the experiment. We also present the development of new quartz resonators.

Les oscillateurs de référence de haute pureté sont actuellement utilisés dans un grand nombre d’applications allant du contrôle de fréquence aux horloges pour les radars, les GPS et l’espace... Les tendances actuelles dans ce domaine requièrent des architectures miniaturisées avec la génération de signaux directement dans la gamme de fréquences d’intérêt, autour de quelques GHz. Récemment, de nouvelles architectures basées sur les principes de l’optomécanique ont vu le jour dans ce but. De tels oscillateurs optomécanique génèrent non seulement des signaux hyperfréquences directement dans la gamme de fréquences GHz avec éventuellement un faible bruit de phase, mais permettent également un degré élevé d'intégration sur puce. Ce travail de thèse s'inscrit dans cette démarche. L’oscillateur optomécanique étudié se compose de cavités à cristaux photoniques suspendues couplées à des guides d’ondes silicium sur isolant intégrés dans une architecture tridimensionnelle. Ces cavités abritent des modes optiques fortement confinés autour de 1550nm et des modes mécaniques dans le GHz. De plus, ces structures présentent un recouvrement spatial entre phonon et photon élevé. Il en résulte un couplage optomécanique amélioré. Cette force de couplage optomécanique améliorée est ici sondée optiquement sur des structures à cristaux photoniques de conception optimisée. Ces cavités sont réalisées dans des matériaux semi-conducteurs III-V dont la piézoélectricité nous permet d'intégrer des outils supplémentaires pour sonder et contrôler les vibrations mécaniques via un pilotage capacitif, piézoélectrique ou acoustique. Ce contrôle total des modes mécaniques et de l’interaction optomécanique ouvre la voie à la mise en œuvre de circuits intégrés pour le verrouillage par injection et des boucles de rétroaction permettant de réduire le bruit de phase de l’oscillateur. / High purity reference oscillators are currently used in a wide variety of frequency control and timing applications including radar, GPS, space... Current trends in such fields call for miniaturized architectures with direct signal generation in the frequency range of interest, around few GHz. Recently, novel optomechanically-enhanced architectures have emerged with this purpose. Such optomechanically-driven oscillators not only generate microwave signals directly in the GHz frequency range with possibly low phase noise but also are amenable to a high degree of integration on single chip settings. This PhD work falls within this scope. The optomechanically-driven oscillator under study consists of suspended photonic crystal cavities coupled to integrated silicon-on-insulator waveguides in a three-dimensional architecture. These cavities harbor highly-confined optical modes around 1,55 µm and mechanical modes in the GHz and most importantly, feature a high phonon-photon spatial overlap, all resulting in an enhanced optomechanical coupling. This enhanced optomechanical coupling strength is here probed optically on photonic crystal structures with optimized design. These cavities are hosted in III-V semiconductor materials whose piezoelectricity enable us to integrate additional tools for probing and controlling mechanical vibrations via capacitive, piezoelectric or acoustic driving. This full control over the mechanical modes and optomechanical interaction, paves the way towards the implementation of integrated injection locking circuits of feedback loops for reducing the phase noise of the oscillator.