23 research outputs found

    Recent Progress in Optical Fiber Research

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    This book presents a comprehensive account of the recent progress in optical fiber research. It consists of four sections with 20 chapters covering the topics of nonlinear and polarisation effects in optical fibers, photonic crystal fibers and new applications for optical fibers. Section 1 reviews nonlinear effects in optical fibers in terms of theoretical analysis, experiments and applications. Section 2 presents polarization mode dispersion, chromatic dispersion and polarization dependent losses in optical fibers, fiber birefringence effects and spun fibers. Section 3 and 4 cover the topics of photonic crystal fibers and a new trend of optical fiber applications. Edited by three scientists with wide knowledge and experience in the field of fiber optics and photonics, the book brings together leading academics and practitioners in a comprehensive and incisive treatment of the subject. This is an essential point of reference for researchers working and teaching in optical fiber technologies, and for industrial users who need to be aware of current developments in optical fiber research areas

    Probing the Interstellar Medium Toward Timing Array Millisecond Pulsars with the Murchison Widefield Array

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    Millisecond pulsars are highly sought-after targets for timing-array experiments that aim to detect ultra-low frequency gravitational waves. However, there are multiple challenges before this goal can be achieved. Interstellar medium effects on pulsar signals are amongst them. The magnitudes of these effects are much stronger at longer radio wavelengths, therefore low-frequency observations with the Murchison Widefield Array are especially promising for the related studies. This thesis presents such a study for two millisecond pulsars

    On electromagnetic observables from supermassive black hole accretion flows

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    Relativistic jets have been observed to originate from the centers of many galaxies. It is likely that the jets are powered by spinning supermassive black holes via a dynamical interaction between magnetic fields close to the hole and the warped spacetime predicted by general relativity. This dissertation describes a series of projects aimed at understanding and identifying signatures of the physical quantities relevant to the black hole–jet connection in both observational and theoretical contexts. I start with a review of astrophysical black hole accretion systems and the radiative physics that governs the generation of electromagnetic signals from hot leptons near the hole. I then describe the numerical tools I use to simulate the accretion and generate synthetic images and spectra, paying particular attention to my contributions and extensions to the code. Next, I discuss my contribution to the theoretical analysis of the first event-horizon-scale black hole accretion flow images, which were produced by the Event Horizon Telescope. The remainder of the dissertation covers projects designed to support a theory-based guide for the next generation of electromagnetic black hole observation in the context of the jet–hole connection. I begin by describing two projects focused on understanding the composition of the jet near the hole. The first project studies mass entrainment through the jet–disk boundary layer as a mechanism to feed the jet at small scales. The second project studies electron–positron drizzle pair creation due to the background radiation field produced by the hot accretion flow. I conclude with a discussion of black hole glimmer, a novel universal signature of black hole spin that can be measured from high-resolution black hole movies and used to determine the orientation and magnitude of a black hole’s angular momentum vector

    Polarimetric Synthetic Aperture Radar, Principles and Application

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    Demonstrates the benefits of the usage of fully polarimetric synthetic aperture radar data in applications of Earth remote sensing, with educational and development purposes. Includes numerous up-to-date examples with real data from spaceborne platforms and possibility to use a software to support lecture practicals. Reviews theoretical principles in an intuitive way for each application topic. Covers in depth five application domains (forests, agriculture, cryosphere, urban, and oceans), with reference also to hazard monitorin

    Quantum concepts in optical polarization

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    We comprehensively review the quantum theory of the polarization properties of light. In classical optics, these traits are characterized by the Stokes parameters, which can be geometrically interpreted using the Poincaré sphere. Remarkably, these Stokes parameters can also be applied to the quantum world, but then important differences emerge: now, because fluctuations in the number of photons are unavoidable, one is forced to work in the three-dimensional Poincaré space that can be regarded as a set of nested spheres. Additionally, higher-order moments of the Stokes variables might play a substantial role for quantum states, which is not the case for most classical Gaussian states. This brings about important differences between these two worlds that we review in detail. In particular, the classical degree of polarization produces unsatisfactory results in the quantum domain. We compare alternative quantum degrees and put forth that they order various states differently. Finally, intrinsically nonclassical states are explored and their potential applications in quantum technologies are discussed

    Měření optické aktivity elipsometrií Muellerovy matice

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    This master thesis is focused on the Mueller matrix spectroscopic ellipsometry measurements of the optically active materials. The first part is devoted to the rigorous theoretical description of the optical activity using Condon-Fedorov approach. The effect of material symmetry on the optical activity is discussed. We propose a novel Mueller matrix ellipsometry method of the saccharide solution optical activity measurement within the spectral range from 193~nm to 1700~nm. The mutarotation rate constants are obtained with high accuracy. We extend the standard Woollam RC2 Mueller matrix ellipsometer using a homemade temperature control system. The theoretical description of the optical activity in quartz waveplate including the model of Mueller matrix is proposed.Tato diplomová práce se zabývá měřeními opticky aktivních materiálů prostřednictvím spektroskopické elipsometrie Muellerovy matice. První část práce je věnována rigoróznímu teoretickému popisu optické aktivity za použití Condonova-Fedorovova přístupu. V práci je diskutován vliv materiálové symetrie na optickou aktivitu. V práci byla dále navržena unikátní metoda měření chirálních roztoků sacharidů užitím elipsometrie Muellerovy matice v spektrálním rozsahu od 193 nm do 1700 nm. Z těchto měření byly s vysokou přesností stanoveny mutarotační konstanty. Za účelem teplotně závislých měření roztoků sacharidů, standartní elipsometr Muellerovy matice byl inovován námi navrženým systémem pro cílené řízení teploty chirálního roztoku. Pro popis optické aktivity křemenných fázových destiček byl odvozen teoretický model Muellerovy matice, který zahrnuje efekt optické aktivity v těchto destičkách.9360 - Centrum nanotechnologiívýborn

    Abstracts on Radio Direction Finding (1899 - 1995)

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    The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

    Interferometric observations to analyze circumstellar environments and planetary formation

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    Protoplanetary disks have a rich structure, with different physics playing a role in different regions of the disk. They are under constant evolution, due to a combination of various physical and chemical processes, e.g., accretion, photo-evaporation, gas-dust interactions, grain growth, and the interaction with protoplanets. The dynamic ranges involved span orders of magnitudes on spatial scales, orbital times, temperatures, and dust- or gas-densities. The extreme dynamic ranges involved in the structure and composition of these objects mean that very different observational techniques have to be combined together to probe their various regions. This work makes use of new interferometric and spectroscopic measurements in the infrared, together with published mid-infrared images and spectral energy distribution fluxes from UV to mm-wavelength, to instruct a new comprehension of the well-known IRS48 object, and uncover part of the delicate balance of physical processes at stake. This PhD reports the first direct imaging of the full extents of a polycyclic aromatic hydrocarbon and very small grains ring in a young circumstellar disk, presents a revised model for the IRS48 object to explain the rich and complex dust- and gas-environment observed from near-infrared to centimeter wavelengths. Also, the spectral type of the spectroscopic binary MWC361 is determined. This will lead to a precise characterization of the stellar parameters of this binary, opening a new window on the studying of the disappearance of the circumsecondary disk of the binary, while the circumprimary disk is still present. The leitmotif throughout this thesis is the understanding of the last moments of circumstellar disks, and the search for the processes which dissipate them. This particular step of the disk-evolution is one the most mysterious to date, yet it sets critical constraints on the by-product of circumstellar disks, exoplanets
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