Browsing by Subject "supercontinuum generation"

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    Fabrication of novel core-shell nanostructures for photonics applications
    (2013) Khudiyev, Tural
    Developments in nanoscale fabrication and characterization techniques have led to fundamental changes in the scientific understanding of many fields, and novel nanostructures have been utilized to investigate the conceptual underpinnings behind a diverse array of natural phenomena. However, nanofabrication methods are frequently hindered by issues such as misalignment, small batch sizes, high production costs and constraints in material choice or nanostructure diversity, which decrease their potential utility and prevent their widespread application in nanoscale optics and photonics. In this work, a new top-down nanofabrication method is described, which is called Iterative Size Reduction (ISR), where step-by-step reduction is utilized to decrease structure dimensions from macro- to nanosizes and produce indefinitely long one-dimensional core-shell nanostructures with properties highly suitable for use in optical applications. Plateau-Rayleigh instabilities are then utilized to thermally degrade ISR-produced nanowire arrays into complex core-shell schemes, which are produced successively in a hitherto-undescribed transitory region between core-shell nanowires and core-shell nanospheres. A diverse array of optical phenomena have been observed on fabricated novel core-shell nano-platforms, which are utilized in the design of novel nanostructures for emerging photonics applications. Briefly, (a) the resonant Mie scattering behavior is characterized on glass-polymer nanostructures and these nanostructures are designed for large-area structural coloration, (b) a novel non-resonant Mie scattering regime responsible for the scattering characteristics exhibited by all-polymer core-shell nanowires is described, (c) a nanoscale analogue to the thin film interference phenomenon is demonstrated that occurs on the core-shell boundary of ISR-produced micro- and nanostructures, (d) an unusual photonic crystal structure observed in the neck feathers of mallard drakes is investigated and imitated, (e) a series of all-polymer core-shell nanowires to function as novel light-trapping platforms and sensors are engineered and (f) the generation of supercontinuum light in well-ordered arrays of As2Se3 nanowires is reported.
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    Lasing action and supercontinuum generation in nano- and micro-structures
    (2009) Akbulut, Duygu
    Supercontinuum generation is the substantial broadening of electromagnetic radiation due to nonlinear interactions with the transporting medium. It nds application in a wide range of areas, including spectroscopy, frequency metrology, optical coherence tomography and telecommunications. Whispering gallery mode microresonators con ne light in a micron scale area via total internal re ection mechanism. Among these structures, microtoroid is especially interesting since it combines ultrahigh quality factor and chip integrability. Applications of such structures include nonlinear and quantum optics, biological and chemical sensing, telecommunications and quantum electrodynamics. In the rst part of the present work, continuum generation from a nanostructured chalcogenide glass (As2Se3) core, high temperature polymer (polyethersulfone, PES) cladding ber was experimentally investigated. Simulation results for nonlinear interactions inside a microtoroid are also provided. In the second part, polymer coated toroidal microresonators were employed for observation of laser action. Owing to high quantum e ciency of the polymer, the observed lasing threshold has a very low value of 200 pJ/pulse despite free space excitation.