No description available.

No description available.

No description available.

This thesis investigated single nanoparticle/molecule detections using a whispering gallery mode (WGM) microcavity, with focuses on sensing with the cavity optomechanical oscillation (OMO). The high quality (Q) factor and small mode volume properties of a WGM microcavity make it possible to establish a strong intracavity power density with a small amount of input optical power. Such a high optical power density exerts a radiation pressure that is sufficient to push the cavity wall moving outward. The dynamic interaction between the optical field and the mechanical motion eventually results in a regenerative mechanical oscillation of the WGM cavity, which is termed as the optomechanical oscillation. With a high Q spherical microcavity, the observation of OMO in heavy water is reported. To the best knowledge of the author, this is the first demonstration of the cavity OMO in an aqueous environment. Furthermore, by utilizing the properties of reactive sensing, cavity OMO, and optical spring effect, we demonstrated a new sensing mechanism that improves the WGM microcavity sensing resolution by several orders of magnitude. Finally, we conducted the demonstration of in-vitro molecule sensing by detecting single bindings of the 66 kDa Bovine Serum Albumin (BSA) protein molecules at a signal-to-noise ratio of 16.8. / Graduate

Whispering Gallery Mode (WGM) microcavities have a wide range of applications from fundamental physics researches to engineering applications due to their ultra high quality factor (Q). For example, an ultra-high Q WGM cavity can be used as an bio/nanosensor since a nano particle bound to the surface of the cavity will result in a resonance wavelength shift. In the last decade lots of research have been conducted on this topic, as a result, WGM biosensors are emerging as one of the mainstream senors. This thesis presents an efficient beam propagation method (BPM) simulation tool to study the light propagation behaviour in WGM cavities. Using this tool, the perturbation of the cavity properties caused by a polystyrene nano bead attached to the surface of a WGM silica microcavity is investigated. Furthermore, we numerically verify a three times sensitivity enhancement by fabricating a nanohole at the surface of the WGM cavity sensor. In addition, we study the open cavity structures, cavity-waveguide coupling, huge WGM cavities, and deformed microcavities radiation. Finally, the impact of fabrication inaccuracy on asymmetric WGM cavities is investigated in terms of quality factor degradation. / Graduate

No description available.

This thesis presents a full-vectorial mode matching method for whispering gallery microcavity analysis. With this technique, optical properties such as resonance wavelength, quality factor and electromagnetic field distribution of an arbitrarily shaped microcavity can be computed with high accuracy. To illustrate this, a mode matching analysis that involves a single propagating whispering gallery mode is performed on a microtoroid in the presence of individual nonplasmonic nanoparticle on its surface. This method is also extended to the analysis of cavity adsorbed by a plasmonic nanoparticle at a wavelength close to plasmon resonance where the resulting field distortion invalidates other approaches. The simulation demonstrates high efficiency and is in close agreement with experimental measurements reported in previous work. Furthermore, we extend our mode matching analysis to the case where multiple whispering gallery modes are involved in the course of light propagation. The new formalism is performed on a cavity-waveguide coupling system to investigate the light delivery from a tapered optical waveguide to a microcavity at high precision. A novel hybrid integration scheme to implement an ultra-high quality factor microcavity on a silicon-on-insulator platform is proposed based on the related modelling results. / Graduate / 0752 / 0544 / duxuanmax@gmail.com

A pair of light beams that have orthogonal polarizations and equal intensity can be generated through reflection and refraction of a monochromatic light at a dielectric surface. Sytematic procedures to design beam splitters which can produce such output light beams are described in this thesis. Two designs that are of particular interest are prismatic substrates coated by a single layer and a double layer of thin films. Specific examples of each beam splitter in the visible and infrared are included. The performance of each beam splitter as a function of incidence angle, film thickness, and wavelength is also discussed.

Darbe, naudojantis informacinėmis technologijomis, sukurta elektroninė informacinė priemonė, nagrinėjanti optinius prietaisus, jų veikimo principus bei panaudojimą praktikoje. Medžiaga pateikiama tinklalapio forma internetinėje svetainėje adresu http://optometrija.3v.lt. / In the work using information technologies an electronic information tool was created, which deals with optical devices, their working principles and use in practice. The material presented in the form of an online website at http://optometrija.3v.lt.

Neste trabalho foi desenvolvido um estudo sistemático das propriedades estruturais, mecânicas e ópticas de filmes de carbeto de silício amorfo hidrogenado (a-Si1-xCx:H) produzidos pela técnica de deposição química a vapor assistida por plasma (PECVD) a baixas temperaturas (320°C), utilizando silana (SiH4) e metano (CH4) como gases precursores do silício e carbono, com a finalidade de avaliar sua aplicabilidade em processos de microfabricação. Foram depositadas duas séries de filmes de a-Si1-xCx:H, com e sem diluição de hidrogênio da mistura gasosa, variando alguns parâmetros, como potência de RF, concentração de metano e fluxo de silana. Os filmes depositados com a mistura gasosa diluída em hidrogênio apresentaram valores maiores de módulo de elasticidade, dureza, gap óptico e índice de refração, comparados com os filmes depositados sem a adição de hidrogênio; no entanto esses filmes apresentaram também valores maiores de stress residual, ocasionando deformações e em alguns casos a quebra das microestruturas fabricadas. No caso das amostras depositados sem a adição de hidrogênio na mistura gasosa, os filmes com conteúdo de carbono maior que 45% depositados com baixa densidade de potência (50 mW.cm-2) apresentaram baixos valores de stress residual compressivo (menores que 60 MPa) e, as microestruturas fabricadas com eles mostraram que o material possui uma superfície livre de defeitos e uma excelente aderência ao substrato, mostrando a viabilidade de poder utilizá-lo como material estrutural e de mascaramento em processos de microfabricação. Além disso, esses filmes são transparentes para comprimentos de onda acima de 600 nm na região visível do espectro eletromagnético, apresentando-o como um material promissório para a fabricação de guias de onda. Finalmente, com o incremento da potência de RF para 100 W na deposição do filme quase estequiométrico com a mistura gasosa não diluída em hidrogênio, conseguiu-se duplicar a taxa de deposição para aproximadamente 12 nm/min, incorporando uma maior quantidade de carbono (~57%), porém também aumento o valor do stress residual compressivo para ~267 MPa. No entanto, as estruturas suspensas fabricadas com este material não apresentaram deformações notáveis. / In this work a study of structural, mechanical and optical properties of hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films, obtained by plasma enhanced chemical vapor deposition (PECVD) at low temperatures (320°C), using silane (SiH4) and methane (CH4) as a gaseous precursors of silicon and carbon, respectively is performed, intending to assess their suitability in microfabrication processes. Two series of a-Si1-xCx:H films were deposited, with and without hydrogen dilution of the gaseous mixture, varying parameters, such as RF power, methane concentration and silane flow. The films deposited with hydrogen diluted gaseous mixture showed higher values of elastic modulus, hardness, optical gap and refractive index, compared with films produced without hydrogen dilution; however these films present higher values of compressive residual stress, causing deformations and in some cases cracks in the microstructures utilizing these films as structural material. In the case of the films deposited without hydrogen dilution of the gaseous mixture, those with carbon contents higher than 45% deposited at low power densities (50 mW.cm-2) presented lower values of compressive residual stress (lower than 60 MPa), and the microstructures fabricated with these materials do not show defects in the surface and have a good adherence to the substrate, demonstrating the feasibility of using these materials as structural and masking materials in microfabrication processes. Moreover, these samples are transparent to wavelengths larger than 600 nm in the visible range of the spectrum, making it suitable to the fabrication of waveguides. Finally, with the increase in the RF power to 100 W in the deposition process without hydrogen dilution a sample close to stoichiometry presented an increase in the deposition rate to approximately 12 nm/min and in the carbon content (~57%); however the compressive residual stress also increased. In spite of that, the microstructures fabricated with this material do not show notable deformations.