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Dissertations / Theses on the topic 'Single-crystal optics'
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Thomas, P. A. "Optical activity in crystals." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379979.
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Burek, Michael John. "Free-Standing Nanomechanical and Nanophotonic Structures in Single-Crystal Diamond." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718746.
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Realizing complex three-dimensional structures in a range of material systems is critical to a variety of emerging nanotechnologies. This is particularly true of nanomechanical and nanophotonic systems, both relying on free-standing small-scale components. In the case of nanomechanics, necessary mechanical degrees of freedom require physically isolated structures, such as suspended beams, cantilevers, and membranes. For nanophotonics, elements like waveguides and photonic crystal cavities rely on light confinement provided by total internal reflection or distributed Bragg reflection, both of which require refractive index contrast between the device and surrounding medium (often air). Such suspended nanostructures are typically fabricated in a heterolayer structure, comprising of device (top) and sacrificial (middle) layers supported by a substrate (bottom), using standard surface nanomachining techniques. A selective, isotropic etch is then used to remove the sacrificial layer, resulting in free-standing devices. While high-quality, crystalline, thin film heterolayer structures are readily available for silicon (as silicon-on-insulator (SOI)) or III-V semiconductors (i.e. GaAs/AlGaAs), there remains an extensive list of materials with attractive electro-optic, piezoelectric, quantum optical, and other properties for which high quality single-crystal thin film heterolayer structures are not available. These include complex metal oxides like lithium niobate (LiNbO3), silicon-based compounds such as silicon carbide (SiC), III-V nitrides including gallium nitride (GaN), and inert single-crystals such as diamond.
Diamond is especially attractive for a variety of nanoscale technologies due to its exceptional physical and chemical properties, including high mechanical hardness, stiffness, and thermal conductivity. Optically, it is transparent over a wide wavelength range (from 220 nm to the far infrared), has a high refractive index (n ~ 2.4), and is host to a vast inventory of luminescent defect centers (many with direct optical access to highly coherent electron and nuclear spins). Diamond has many potential applications ranging from radio frequency nanoelectromechanical systems (RF-NEMS), to all-optical signal processing and quantum optics. Despite the commercial availability of wafer-scale nanocrystalline diamond thin films on foreign substrates (namely SiO2), this diamond-on-insulator (DOI) platform typically exhibits inferior material properties due to friction, scattering, and absorption losses at grain boundaries, significant surface roughness, and large interfacial stresses. In the absence of suitable heteroepitaxial diamond growth, substantial research and development efforts have focused on novel processing techniques to yield nanoscale single-crystal diamond mechanical and optical elements.
In this thesis, we demonstrate a scalable ‘angled-etching’ nanofabrication method for realizing nanomechanical systems and nanophotonic networks starting from bulk single-crystal diamond substrates. Angled-etching employs anisotropic oxygen-based plasma etching at an oblique angle to the substrate surface, resulting in suspended optical structures with triangular cross-sections. Using this approach, we first realize single-crystal diamond nanomechanical resonant structures. These nanoscale diamond resonators exhibit high mechanical quality-factors (approaching Q ~ 10^5) with mechanical resonances up to 10 MHz.
Next, we demonstrate engineered nanophotonic structures, specifically racetrack resonators and photonic crystal cavities, in bulk single-crystal diamond. Our devices feature large optical Q-factors, in excess of 10^5, and operate over a wide wavelength range, spanning visible and telecom. These newly developed high-Q diamond optical nanocavities open the door for a wealth of applications, ranging from nonlinear optics and chemical sensing, to quantum information processing and cavity optomechanics. Beyond isolated nanophotonic devices, we also developed free-standing angled-etched diamond waveguides which efficiently route photons between optical nanocavities, realizing true on-chip diamond nanophotonic networks. A high efficiency fiber-optical interface with aforementioned on-chip diamond nanophotonic networks, achieving > 90% power coupling, is also demonstrated.
Lastly, we demonstrate a cavity-optomechanical system in single-crystal diamond, which builds upon previously realized diamond nanobeam photonic crystal cavities fabricated by angled-etching. Specifically, we demonstrate diamond optomechanical crystals (OMCs), where the engineered co-localization of photons and phonons in a quasi-periodic diamond nanostructure leads to coupling of an optical cavity field to a mechanical mode via the radiation pressure of light. In contrast to other material systems, diamond OMCs possess large intracavity photon capacity and sufficient optomechanical coupling rates to exceed a cooperativity of ~ 1 at room temperature and realize large amplitude optomechanical self-oscillations.Engineering and Applied Sciences - Applied Physics
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Otto, Tobias. "Local-scale optical properties of single-crystal ferroelectrics." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1149623191001-10491.
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Das Ziel dieser Arbeit ist die optische Untersuchung von ferroelektrischen Domänen und Domänenwänden auf lokaler Skala. Dafür wurden neuartige nichtinvasive Ansätze entwickelt, die auf der Anwendung optischer Rastersondenmikroskopie basieren. Die untersuchten Schlüsseleigenschaften umfassen den elektrooptischen Effekt für verschiedene Domänenorientierungen und die Brechungindexänderungen an Domänenwänden an Bariumtitanat-Einkristallen. Die lokale Messung der elektrooptischen Eigenschaften wurde mit räumlich stark begrenzten elektrischen Feldern durchgeführt, die mittels elektrisch leitfähigen Spitzen angelegt wurden. Dieser experimentelle Ansatz erlaubt nicht nur die Messung verschiedener elektrooptischer Koeffzienten, sondern auch die Unterscheidung von allen auftretenden, auch antiparallelen, Domänenausrichtungen. Durch Anlegen eines zusätzlichen elektrischen Feldes mittels der gleichen Spitze konnte auch das ferroelektrische Schalten mit dieser optischen Methode untersucht werden. Die Experimente wurden durch eine numerische Modellierung der elektrischen Feldverteilung und der resultierenden elektrooptischen Antwort begleitet. Die Ergebnisse der Modellierung sind dabei in sehr guter Übereinstimmung mit den experimentellen Ergebnissen. Dies erlaubt auch die Trennung von Beiträgen verschiedener elektrooptischer Koeffzienten und den entsprechenden Feldkomponenten. ür die experimentelle Untersuchung von den theoretisch vorhergesagten Brechungsindexprofilen einzelner Domänenwände, wurde die Sensitivität der optischen Sonde auf lokale Änderungen des Brechungsindex mittels Polarisations- und Positionsmodulation erhöht. Obwohl die Abbildung einer einzelnen Domänenwand nicht gelang, konnte damit zumindest eine obere Grenze für den optischen Effekt einer Domänenwand experimentell gewonnen werden, welche verträglich mit den theoretischen Vorhersagen istThe goal of this thesis is the optical investigation of ferroelectric domains and domain walls at the very local scale. For that, novel noninvasive approaches based on optical scanning probe microscopy are developed. The key properties investigated are the electrooptic effect for different domain orientations and refractive-index changes at single domain walls of barium titanate single crystals. The local probing of the electro-optic response is performed with strongly confined electric fields, applied via a conductive tip. With this approach we can not only probe different electro-optic coeffcients, but also identify all occurring domain orientations, even antiparallel ones. The application of additional bias fields by the same tip is used to investigate ferroelectric switching and domain growth by optical means. The experiments are supported by numerical modelling of the electric-field distribution and the resulting electro-optic response. The modelling shows excellent agreement with the measurements, and allows us to separate the contributions of different electro-optic coeffcients and their associated electric-field components. For the experimental observation of the theoretically predicted refractive-index profiles at single ferroelectric domain walls, polarization and position modulation of the optical probe is used to obtain high sensitivity to local modifications of the refractive index. An upper limit to the optical effect to the optical effect of a single domain wall is deduced from the experiment, which is compatible with the effect predicted by theory
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Seigneur, Hubert P. "Modeling and design of a photonic crystal chip hosting a quantum network made of single spins in quantum dots that interact via single photons." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4614.
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In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits and traveling qubits to exchange information coherently while demonstrating little error and loss in the process; such interface is indispensable for the realization of a functional quantum network. Furthermore, a carefully orchestrated dynamic control over the propagation of the flying qubit showed high-efficiency capability for on-chip single-photon transfer. Using the optimized dispersion properties obtained quantum mechanically as design parameters, a possible physical structure for the photonic crystal chip was constructed using the Plane Wave Expansion and Finite-Difference Time-Domain numerical techniques, exhibiting almost identical transfer efficiencies in terms of normalized energy densities of the classical electromagnetic field. These promising results bring us one step closer to the physical realization of an integrated quantum technology combining both semiconductor quantum dots and sub-wavelength photonic structures.ID: 029049734; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 247-254).
Ph.D.
Doctorate
Optics and Photonics
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Potter, Jason. "The average holographic interferometry with single mode optical fibres and the photorefractive crystal - bismuth silicon oxide." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316927.
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Li, Meiting. "Single crystal silicon Lorentz force actuated micromirror and MEMS blazed grating for optics and sensors." Elsevier, 2016. http://hdl.handle.net/1993/31649.
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Micromirrors and diffraction gratings were developed for spectroscopy and magnetic field sensor in this thesis. MEMS blazed gratings were successfully fabricated in different grating periodicities to cover a wide infrared wavelength range. Lorentz force actuated micromirrors were investigated, and two types of mirrors were fabricated: rotating and pop-up micromirrors. The deflection angle of the mirrors was controllable by altering the driving current on the mirror. Deflection angle vs. driving current was studied for different mirror types and different spring dimensions.
A Lorentz force based magnetic field sensor is also demonstrated. The sensor employs the rotating micromirror as a resonator. With an AC current flowing around the micromirror, a periodic Lorentz force is generated which drives the resonator. The rotational amplitude of the micromirror is measured with an optical positioning system and external circuits. The highest resolution of the magnetic field sensor is 0.4 nT at 50 mArms, and 53 mHz filter bandwidth. With appropriate current level, this sensor can measure a wide range of magnetic field, from nT to T.October 2016
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Cali, Serdal. "An Experimental Study On Single Crystal Diamond Turning Of Optical Quality Silicon." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609235/index.pdf.
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Silicon is commonly used in infrared (IR) imaging systems. The surface quality is
an important issue in optics manufacturing since surface roughness affects optical
performance of imaging systems. Surface quality of an optical component is
determined by number of factor, including cutting parameterscutting speed, depth of cut and feed in radial direction. In this thesis, an experimental study has been performed to investigate the relation between cutting parameters and average roughness of the surface of silicon. In the experiments, silicon specimens, which have a diameter of 50 mm, were face turned by using a 2-axis CNC single point diamond turning machine. The specimens were machined by using either constant spindle speed or constant cutting speed. Two different tools with rake angles of -15 degrees and -25 degrees were used. The attained surfaces were measured by using a white light interferometer, which has a resolution of 0.1nm. The experiments were designed according to the factorial design method, considering cutting parameters. The effects of cutting parameters and tool rake angles on surface quality of silicon were observed. The best average surface roughness obtained was about 1 nm which is quite better than the acceptable average surface roughness level of 25 nm.
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Francis-Jones, Robert J. A. "Active multiplexing of spectrally engineered heralded single photons in an integrated fibre architecture." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690725.
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In recent years, there has been rapid development in processing of quantum information using quantum states of light. The focus is now turning towards developing real-world implementations of technologies such as all-optical quantum computing and cryptography. The ability to consistently create and control the required single photon states of light is crucial for successful operation. Therefore, high performance single photon sources are very much in demand. The most common approach of generating the required nonclassical states of light is through spontaneous photon pair generation in a nonlinear medium. One photon in the pair is detected to "herald" the presence of the remaining single photon. For many applications the photons are required to be in pure indistinguishable states. However, photon pairs generated in this manner typically suffer from spectral correlations, which can lead to the production of mixed, distinguishable states. Additionally, these sources are probabilistic in nature, which fundamentally limits the number of photons that can be delivered simultaneously by independent sources and hence the scalability of these future technologies. One route to deterministic operation is by actively multiplexing several independent sources together to increase the probability of delivering a single photon from the system. This thesis presents the development and analysis of a multiplexing scheme of heralded single photons in high-purity indistinguishable states within an integrated optical fibre system. The spectral correlations present between the two photons in the pair were minimised by spectrally engineering each photonic crystal fibre source. A novel, in-fibre, broadband filtering scheme was implemented using photonic bandgap fibres. In total, two sources were multiplexed using a fast optical switch, yielding an 86% increase in the heralded count rate from the system.
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Gamez, Jimmy Ray. "The Effects of Diameter Fluctuations and Coiling on the Sensitivity of Sapphire Single Crystal Optical Fiber Evanescent Wave Fluorescence Sensors." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/1980.
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The purpose of this research was to determine the effect of diameter fluctuations on the sensitivity of sapphire multimode optical fibers used as evanescent wave fluorescence sensors. It was predicted that fluctuations in the diameter of the fiber would act as a series of bi-tapers converting lower order modes to higher order modes increasing the evanescent wave penetration depth thereby increasing the excitation of a cladding of fluorescent fluid. Induced fluorescence from the fluid cladding would then couple back into the fiber more efficiently increasing the sensitivity of the sensor.
The effect of coiling the fiber on the sensitivity of the sensor was also explored. Coiling the fiber converts lower order modes into higher order modes and increases the sensing length while maintaining a small probe size. However, coiling experiments produced unexpected results and in the course of studying these results a layer of material was discovered coating the surface of the sapphire fibers.
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Valdo, Ana Karoline Silva Mendanha. "Planejamento de novas formas cristalinas com propriedades desejadas em óptica não linear através da protonação da trans-1,2-di(4-piridil)etileno." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7952.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This work investigates the trending of crystallization in non-centrosymmetric space groups to study second harmonic generation (SGH) in the field of non linear optics. Using trans-1,2-di(4-pyridil)ethylene (BPE) four unpublished compounds were obtain, being them BPEH2Cl2·2H2O (1), BPEH2Br2 (2), BPEH2(H2PO4)2 (3) e BPEH2(H2PO4)2·H3PO4 (4). In these structures was possible to analyse the pattern of formed synthons, which showed to be function of geometry and polarizability and not only of acid strength of acid that generates the counter ion. The structure 1 showed pseudo symmetry and had the space group determined by the combination of observed signal of second harmonic generation and statistical parameters of refinement in different space groups. Under the incidence of LASER with emission on 974 nm it was observed a signal dependent of the incident power in 487 nm for single crystals of these structure, proving the absence of inversion center in 1. All structures were characterized by single-crystal X-ray diffraction (SXRD), with additional caracterizations for structure 1 using the techniques X-ray powder diffraction (PXRD), photoluminescence, measurement of second harmonic generation signal and theorical calculation of SHG effects and eletrical properties.
Esse trabalho investiga a tendência de cristalizações em grupos espaciais não centrossimétricos para o estudo de geração de segundo harmônico (GSH) na área de óptica não linear. Utilizando a trans-1,2-di(4-piridil)etileno (BPE) quatro compostos inéditos foram obtidos, sendo eles BPEH2Cl2·2H2O (1), BPEH2Br2 (2), BPEH2(H2PO4)2 (3) e BPEH2(H2PO4)2·H3PO4 (4). Nessas estruturas foi possível analisar o padrão de síntons formados, que mostram ser dependentes da geometria e polarizabilidade e não só da força ácida do ácido que gera o contra-íon. A estrutura 1 apresentou pseudosimetria e teve o grupo espacial determinado pela combinação do sinal de geração de segundo harmônico e estatística do refinamento em diferentes grupos espaciais. Sob incidência do LASER em 974 nm foi observado um sinal dependente da potência em 487 nm para os cristais dessa estrutura, comprovando a ausência do centro de simetria em 1. Todas as estruturas foram caracterizadas por difração de Raios X por monocristal (DRXM), com caracterizações adicionais para estrutura 1 pelas técnicas de difração de Raios X de pó (DRXP), fotoluminescência, obtenção do sinal de geração de segundo harmônico e cálculos teóricos dos efeitos de GSH e de propriedades elétricas.
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Gherardi, David Mark. "Studies of particle and atom manipulation using free space light beams and photonic crystal fibres." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/703.
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Petrie, Christian Matthew. "Characterization of the Performance of Sapphire Optical Fiber in Intense Radiation Fields, when Subjected to Very High Temperatures." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405011475.
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Hill, William Cary. "Low Modal Volume Single Crystal Sapphire Optical Fiber." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78792.
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This research provides the first known procedure for cleanly and consistently reducing the diameter of single-crystal sapphire optical fiber (SCSF) below the limits of standard production methods, including the first production of subwavelength-diameter optical fiber (SDF) composed of single-crystal sapphire. The first known demonstration of an air-clad single crystal sapphire optical fiber demonstrating single-mode behavior is also presented, and the single-mode cutoff wavelength and diameter are determined.
Theoretical models describing and predicting the optical behavior of low modal volume sapphire optical fibers are also presented. These models are built upon standard weakly-guiding optical fiber theory, which is found to be accurate once experimentally-determined properties of the SCSF are substituted for theoretical values.
Reduced modal dispersion is also observed in the form of decreased laser pulse broadening in reduced-diameter SCSF. The improvements in spatial resolution for distributed sensing systems such as Raman distributed temperature sensing are also predicted based on the measured decrease in pulse duration.
This research also provides an enhanced understanding of the etching behavior of sulfuric and phosphoric acids on sapphire surfaces, including the first reporting of etching rates and activation energies for a-plane sapphire surfaces. Morphological changes of sulfuric and phosphoric acids at and beyond the temperature ranges used in etching were also tested and discussed in detail, especially regarding their practical impact on observed etching behavior.
The demonstration of LMV single-crystal sapphire optical fibers enables the adaptation of numerous sensing schemes requiring low modal volume or single-mode behavior to be utilized in extreme environments.Ph. D.
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Laidler, Ian. "Laser induced damage in single crystal calcium fluoride." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/11137.
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The thesis describes the establishment of a laser damage facility in the ultra violet. The laser is a pulsed excimer laser (25 n sec) capable of an output energy of 1 Joule at wavelengths of 193, 245, 308, 337 and 351 nm. The problems involved in making reliable damage threshold measurements are addressed, such as energy calibration, beam attenuation, damage detection and temporal and spatial beam profiling. A computer controlled frame store and video system enabling single shot spatial profiling and peak fluence measurements to be performed is described. Such a system is essential if reliable results are to be obtained from lasers whose spatial output cannot be described by a Gaussian. Using the damage facility, work has been performed on single crystal Caf2 laser windows ascertaining the bulk and surface damage thresholds as a function of crystal purity, surface finishing and polishing procedures. The results of a T.E.M. study give an insight into the fundamental damage mechanism of this material to be electron avalanche breakdown. The role of transient primary defects in the bulk breakdown of CaF2 has been investigated using dye laser probe techniques, and indicate that the presence of U.V. generated self trapped excitons, acting as sinks for the conduction band electrons, greatly enhances the damage threshold. Work on coatings using a LIMA (Laser-induced ion mass analyser) is reported and the potential of this machine as a laser damage diagnostic tool is explored.
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Carrano, John Con. "High-performance ultraviolet photodetectors fabricated on single-crystal GaN /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Cheng, Yujie. "Mode Volume Reduction in Single Crystal Sapphire Optical Fibers." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77387.
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This research provides the original work on the geometry factors selection for single crystal sapphire optical fiber (SCSF) to improve the optical property in sensing applications. Single crystal sapphire fibers were fabricated with a Laser Heated Pedestal Growth (LHPG) system, which was constructed in-house at Virginia Tech. The cost effective, high efficiency and fully operational Laser-heated Pedestal Growth (LHPG) system as well as the fiber fabrication process were also demonstrated in this research. The results indicated the windmill single crystal sapphire optical fiber (SCSF) will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that are limited by the optical property of unclad single crystal sapphire optical fiber (SCSF).Ph. D.
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Thompson, R. J. "Topographical, chemical and optical studies of single crystal rubrene." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1417136/.
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This thesis presents a study of material characterisation methods and techniques, which can determine the effects of surface and structural defects on the properties of single crystal rubrene. A method of cleaving is devised to produce surfaces free from previous exposure to the ambient. This method reproducibly provides large terraces intersected by straight, well orientated step edges. Atomic force microscopy studies show the cleaved surfaces undergo environmentally dependent molecular reorganization. This results in the formation of nanoscale ‘beads’ at molecular step edges and narrow ‘fingers’, one molecule high. The beads show an insulating behaviour with increased conduction at the surrounding surface. The methodology of applying time of flight secondary ion mass spectroscopy to rubrene crystals is developed to study the chemical composition both at and below the surface. This shows a uniform oxide (C42H28O) covering the surface with an increased concentration of peroxide (C42H28O2) located at crystallographic defects. To investigate the effect of surface and defects on exciton dynamics in rubrene a confocal photoluminescence (PL) arrangement is designed and built. An extended PL distribution is imaged providing evidence of exciton diffusion within the material. This diffusion is seen to increase within the bulk with a suppression of emission at 603nm. Defects are seen to affect PL with emission of the 650nm PL band having a greater contribution in the presence of defects. This emission is also spatially displaced from the maximum intensity of the other bands. These results imply the existence of a defect mediated recombination pathway. These studies show that environmental reactions readily occur at the location of crystallographic defects and step edges. This is of importance to the operation of rubrene electrical devices. This work provides a set of techniques and developed methodologies which enable the characterisation of technologically important processes on rubrene. These should extend to other organic single crystals such as pentacene and tetracene.
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Wustholz, Kristin Lee. "Single-molecule orientations and photophysics in dyed salt crystals /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/8564.
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Green, Ben L. "Optical and magnetic resonance studies of point defects in single crystal diamond." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58600/.
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This thesis reports research on point defects in single crystal diamond studied by a number of techniques including electron paramagnetic resonance (EPR), ultraviolet-visible absorption (UV-Vis), photoluminescence (PL) and infrared absorption (IR). Natural diamond samples have been investigated, in addition to high pressure high temperature (HPHT) and chemical vapour deposition (CVD) grown synthetic diamond samples. The effects of low temperature electron irradiation on boron-doped synthetic diamond have been studied. For samples irradiated with 5 x 10 [superscript] 17 e-cm-2 at 100 K, the post-irradiation neutral boron and neutral vacancy concentrations are found to depend approximately linearly on the starting boron concentration in each sample. A CVD-grown sample is annealed and characterised at each annealing stage by PL, IR and UV-Vis. The results are explained in a model whereby some interstitials are mobile during irradiation and complex with the boron: there is no evidence for the interaction of boron and vacancies. The 1:913 eV (648:2 nm) photoluminescence transition is studied in type IIb diamond samples under applied uniaxial stress. The transition is found to occur between states of A' & A" symmetry. An associated local mode with energy 178:2meV (1437 cm-1) is determined to have A' symmetry. The emission is tentatively ascribed to a boron-containing interstitial complex. Complications of performing uniaxial stress on natural samples are discussed with reference to the 2:526 eV (490:8 nm) emission observed in plastically deformed type IIa diamond. Using 15N-doped HPHT-grown diamond, a new EPR spectrum is observed and identified as belonging to (NVN-). Hyperfine analysis shows that the unpaired electron probability density is localised approximately 100% on the two nearest neighbour carbon atoms. Using estimates of the 14N quadrupolar interaction strength, (NVN-) is identified in a 14N-doped synthetic diamond. The P2 spectrum is created in a 15N-doped synthetic sample following irradiation and HPHT annealing. The published spin Hamiltonian parameters are signifi cantly improved upon and for the first time the P2 spectrum is unambiguously assigned to (N3V)0. Both ([superscript]15 N 3 V)0 and ([superscript]15Ns)0 are shown to spin polarise upon illumination with light of energy A 2:4eV, with ([superscript]15 N s)0 spin polarisation argued to arise due to long-range interaction with ([superscript]15 N 3 V)0.
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McMillan, Alex. "Development of an all-fibre source of heralded single photons." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557827.
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The preparation of single photons in a pure quantum state is a subject of great interest in physics, enabling the control of light at an unprecedented level. The ease with which certain degrees of freedom of photon states, such as polarisation, can be manipulated, along with the inherent resilience of photons to decoherence, makes them well suited for use as qubits. Recent rapid developments in the transmission and processing of quantum information, as well as the likely technological impact of potential real-world applications such as quantum cryptography and quantum computation, mean that the demand for high performance single photon sources is likely to increase in the near future. One approach to producing single photon states, which are known to be in a well-defined spatio-temporal mode without destructively measuring them, is to take advantage of nonlinear optics. Nonlinear processes can be used to realise frequency conversion by generating a single, correlated pair of photons from an intense pump laser source. The detection of one of the photons from a pair can then be used to indicate the presence of the other photon in the pair, a procedure known as heralding. This thesis describes the development of a source of heralded single photons at 1550 nm, generated directly in the core of a photonic crystal fibre (PCF). By taking advantage of low loss fibre components for the required spectral filtering of the generated photon state, a heralding fidelity of 52% was achieved. The source was designed to be used with a picosecond pulsed fibre laser, making it relatively low cost and maintenance free. With 148 mW of average pump power a heralded output photon rate of 6.4 × 104 s-1 was observed, demonstrating the brightness of the source. The purity of the generated single photons was established by measuring non-classical interference, with a visibility of 70%, between the photons output from this source and a source based on a PPLN waveguide. The fabrication of a series of birefringent PCFs for the generation of spectrally pure state photons at 1550 nm is also discussed. These PCFs will be useful for incorporation in the next generation of high performance, fibre-based photon sources.
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Zhang, Pinyi. "The properties of single crystal sapphire fibers and the polarimetric optical sensor for high temperature measurements." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020350/.
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Cruddace, Robin. "Magnetic resonance and optical studies of point defects in single crystal CVD diamond." Thesis, University of Warwick, 2007. http://wrap.warwick.ac.uk/2964/.
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Defects in single crystal diamond grown by chemical vapour deposition (SC-CVD) have been studied using electron paramagnetic resonance (EPR) and optical techniques. Annealing studies in the temperature range of 900 - 1600°C have been performed and the changes in EPR and Fourier transform infrared (FTIR) spectra for nitrogen doped SC-CVD have been documented. It has been possible to model the annealing behaviour of several hydrogen related defects and the associated kinetics and annealing parameters have been determined. Previously unreported optical absorption lines have been detected in the as-grown and annealed nitrogen doped samples. FTIR spectroscopy has been performed in conjunction with an applied uniaxial-stress to investigate hydrogen related absorption features in diamond. Several absorption lines have shown to shift and split under the application of uniaxial-stress and the symmetry and stress-splitting parameters for these defects have been determined. Models for the defects responsible are proposed. The mid-infrared absorption line at 3123 cm-1 is suggested to originate from a C-H stretch mode at the paramagnetic negative nitrogen-vacancy-hydrogen complex. For a 3123 cm-1 absorption line with a Lorentz linewidth of 3.8(2) cm-1, 1 cm-1 of absorption at 3123 cm-1 corresponds to 25(10) ppm of NVH- centres. A previously unreported paramagnetic defect has been detected and is given the label WAR1. It has an S = 1 ground state and a pseudo-C3v symmetry; the g and D spin Hamiltonian parameters have been determined and suggest that the defect is vacancy related.
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Al-Saie, Ahmed Mohammed. "Electrical and optical properties of pure and metal-doped single crystal of arsenic triselenide." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/11232.
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Burrow, Guy Matthew. "Pattern-integrated interference lithography: single-exposure formation of photonic-crystal lattices with integrated functional elements." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44804.
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A new type of photolithography, Pattern-Integrated Interference Lithography (PIIL), was demonstrated. PIIL is the first-ever integration of pattern imaging with interference lithography in a single-exposure step. The result is an optical-intensity distribution composed of a subwavelength periodic lattice with integrated functional circuit elements. To demonstrate the PIIL method, a Pattern-Integrated Interference Exposure System (PIIES) was developed that incorporates a projection imaging capability in a novel three-beam interference configuration. The purpose of this system was to fabricate, in a single-exposure step, representative photonic-crystal structures. Initial experimental results have confirmed the PIIL concept, demonstrating the potential application of PIIL in nano-electronics, photonic crystals, biomedical structures, optical trapping, metamaterials, and in numerous subwavelength structures. In the design of the PIIES configuration, accurate motif geometry models were developed for the 2D plane-group symmetries possible via linearly-polarized three-beam interference, optimized for maximum absolute contrast and primitive-lattice-vector direction equal contrast. Next, a straightforward methodology was presented to facilitate a thorough analysis of effects of parametric constraints on interference-pattern symmetries, motif geometries, and their absolute contrasts. With this information, the design of the basic PIIES configuration was presented along with a model that simulates the resulting optical-intensity distribution at the system sample plane. Appropriate performance metrics were defined in order to quantify the characteristics of the resulting photonic-crystal structure.
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Karaagac, Hazbullah. "Structural, Electrical And Optical Characterization Of Ge -implanted Gase Single Crystal Grown By Bridgman Method." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606522/index.pdf.
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In this work, structural, electrical and optical characterization of as-grown, Ge-implanted, and annealed GaSe single crystals grown by using 3-zone vertical Bridgman-Stockbarger system, have been studied by carrying out X-ray Diffraction (XRD), electrical conductivity, Hall effect, photoconductivity, and spectral transmission measurements. The temperature dependent electrical conductivity of these samples have been measured between 100 and 400 K. As a result, it was observed that upon implanting GaSe with germanium following annealing process, the resistivity is reduced from 2.1x109 to 6.5x105 Ω
-cm. Also it was found that Ge-implantation followed by annealing at 500 oC increases the conductivity in exponential fashion. From the temperature dependent conductivities, the activation energies have been found to be 4, 34 and 314 meV for as-grown, 36 and 472 meV for as-implanted, and 39 and 647 meV for implanted and annealed at 500 oC GaSe single crystals. Using XRD measurements it was observed that there is an increase in peak intensities at specific annealing temperatures (300 and 500 C) and a decrease in higher annealing temperatures (700 C). Temperature dependent carrier concentration and Hall mobility measurement were performed in the temperature range of 230 - 410 and 100 - 400 K for as-grown and Ge-implanted and annealed GaSe samples, respectively. All of the samples in this study were found to be p-type with the help Hall measurements. In addition, the density of donor and acceptor atoms are found for each sample and results are compared with each other. In addition, using photoconductivity measurement the relation between photocurrent and illumination intensity and the character of photoconduction were determined. As a result it was found that while at specific temperature intervals impurity scatterings are dominant, in other intervals phonon scatterings start to dominate. Finally, in order to determine annealing dependent change of band gap of unimplanted and Ge-implanted GaSe samples at room temperature, the transmission measurement have been carried out as a optical characterization part of our study. As a consequence of this measurement it was observed that there is almost no considerable change in optical band gap of samples with increasing annealing temperatures for as-grown GaSe samples and a slight shift of optical band gap toward to high energy for Ge-implanted samples with annealing process.
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Karabulut, Orhan. "Structural, Electrical And Optical Characterization Of N- And Si-implanted Gase Single Crystal Grown By Bridgman Method." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1135755/index.pdf.
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Single crystals of GaSe were grown from the melt using 3-zone vertical Bridgman-Stockbarger system. In order to determine the doping effect, nitrogen and silicon ions were implanted to the grown crystals. Surface morphology and stoichiometry were examined using scanning electron microscope equipped with EDAX and structure properties were examined by x-ray diffraction technique. It was observed that the resulting ingot was stoichiometric and the structure was hexagonal. To identify the effects of ion implantation on the physical properties of the samples depending on annealingelectrical conductivity, hall measurements, current-voltage characteristics, photoconductivity and photoluminescence measurements were carried out in the temperature range of 100-450 K. Also spectral transmission measurements were carried out for all the samples at room temperature. It was observed that both N- and Si- implantation followed by annealing process decreased the resisitivity values from 107 to 103 (&
#61527
-cm). Temperature dependent conductivity measurements were analyzed to deduce the dominant transport mechanisms. The trap levels were also investigated by the space charge limited currents (SCLC) measurements. The temperature dependence of hole concentrations showed that as-grown, N- and Si-implanted samples behave as partially compensated p-type semiconductors. Using suitable statistical method, transport parameters such as acceptor level, donor and acceptor concentrations were extracted from the experimental data. Trapping centers and recombination mechanisms were determined from the temperature dependent photoconductivity measurements by investigating the relation between photocurrent and illumination intensity. N- and Si- implantation effects on GaSe were also examined by spectral photoconductivity and transmission measurements. And lastly, radiative recombination mechanisms in as-grown GaSe were investigated through photoluminescence (PL) measurements and the information related to the structural defects, the exciton levels and the structure of the forbidden gap were investigated.
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Kabro, Pierre. "Optical spectroscopy, crystal field analysis, upconversion and energy transfer studies of Er³§+ doped yttrium vanadate single crystals." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25909.pdf.
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Schelew, Ellen N. "Nonlinear optical response of triple-mode silicon photonic crystal microcavities coupled to single channel input and output waveguides." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63353.
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Optical and opto-electronic components play important roles in both classical and quantum information processing technologies. Despite fundamental differences in these technologies, both stand to benefit greatly from moving away from bulky, individually packaged components, toward a scalable platform that supports dense integration of low power consumption devices. Planar photonic circuits, composed of devices etched in a thin slab of high refractive index material, are considered an excellent candidate, and have been used to realize many key components, including low-loss waveguides, light sources, detectors, modulators, and spectral filters. In this dissertation, a novel triple-microcavity structure was designed, externally fabricated, and its linear and nonlinear optical properties were thoroughly characterized. The best of the structures exhibited both high four-wave mixing conversion efficiencies and low threshold optical bistability, which are relevant to frequency conversion and all-optical switching applications.
The device consisted of three coupled photonic crystal (PC) microcavities with three nearly equally spaced resonant frequencies near telecommunication wavelengths (λ ~ 1.5 μm), with high quality factors (~ 10⁵, 10⁴ and 10³). The microcavity system was coupled to independent input and output PC waveguides, and the cavity-waveguide coupling strengths were engineered to maximize the coupling of the input waveguide to the central mode, and the output waveguide to the two modes on either side.
A novel and sophisticated measurement and analysis protocol was developed to characterize the devices. This involved measuring and modelling the linear and nonlinear transmission characteristics of each of the modes separately with a single tunable laser, as well as the frequency conversion efficiency (via stimulated four-wave mixing) when two tunable lasers pumped two of the modes, and the power generated in the third mode was monitored.
Comparisons of the entire set of model and experimental results led to the conclusion that this structure can be used to achieve both low-power-threshold optical switching and high efficiency four-wave-mixing-based frequency conversion. The advantages of this structure over others in the literature are its small footprint, multi-mode functionality and independent input and output channels. The main disadvantage that requires further refinement, has to do with its sensitivity to fabrication imperfections.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Gamez, Jimmy Ray. "The effects of diameter modulation and coiling on the sensitivity of sapphire single crystal optical fiber evanescent wave fluorescence sensors." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002884.
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Atalay, Ramazan. "Optical and Structural Properties of Indium Nitride Epilayers Grown by High-Pressure Chemical Vapor Deposition and Vibrational Studies of ZGP Single Crystal." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/phy_astr_diss/60.
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The objective of this dissertation is to shed light on the physical properties of InN epilayers grown by High-Pressure Chemical Vapor Deposition (HPCVD) for optical device applications. Physical properties of HPCVD grown InN layers were investigated by X-ray diffraction, Raman scattering, infrared reflection spectroscopies, and atomic force microscopy. The dependencies of physical properties as well as surface morphologies of InN layers grown either directly on sapphire substrates or on GaN/sapphire templates on varied growth conditions were studied. The effect of crucial growth parameters such as growth pressure, V/III molar ratio, precursor pulse separation, substrate material, and mass transport along the flow direction on the optical and structural properties, as well as on the surface morphologies were investigated separately.
At present, growth of high-quality InN material by conventional growth techniques is limited due to low dissociation temperature of InN (~600 ºC) and large difference in the partial pressures of TMI and NH3 precursors. In this research, HPCVD technique, in which ambient nitrogen is injected into reaction zone at super-atmospheric growth pressures, was utilized to suppress surface dissociation of InN at high temperatures.
At high pressures, long-range and short-range orderings indicate that c-lattice constant is shorter and E2(high) mode frequency is higher than those obtained from low-pressure growth techniques, revealing that InN structure compressed either due to a hydrostatic pressure during the growth or thermal contraction during the annealing. Although the influence of varied growth parameters usually exhibit consistent correlation between long-range and short-range crystalline orderings, inconsistent correlation of these indicate inclination of InN anisotropy.
InN layers, grown directly on α-sapphire substrates, exhibit InN (1 0 1) Bragg reflex. This might be due to a high c/a ratio of sapphire-grown InN epilayers compared to that of GaN/sapphire-grown InN epilayers. Optical analysis indicates that free carrier concentration, ne, in the range of 1–50 × 1018 cm–3 exhibits consistent tendency with longitudinal-optic phonon. However, for high ne values, electrostatic forces dominate over inter-atomic forces, and consistent tendency between ne and LO phonon disappears.
Structural results reveal that growth temperature increases ~6.6 ºC/bar and V/III ratio affects indium migration and/or evaporation. The growth temperature and V/III ratio of InN thin films are optimized at ~850 ºC and 2400 molar ratio, respectively. Although high in-plane strain and c/a ratio values are obtained for sapphire-grown epilayers, FWHM values of long-range and short-range orderings and free carrier concentration value are still lower than those of GaN/sapphire-grown epilayers.
Finally, vibrational and optical properties of chalcopyrite ZGP crystal on the (001), (110), and (10) crystalline planes were investigated by Raman scattering and infrared (IR) reflection spectroscopies. Raman scattering exhibits a nonlinear polarizability on the c-plane, and a linear polarizability on the a- and b-planes of ZGP crystal. Also, birefringence of ZGP crystal was calculated from the hydrostatic pressure difference between (110) and (10) crystalline planes for mid-frequency B2(LO) mode.
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Moraes, Jair Ricardo de. "Estudo da preparação de microcristais de LiLa(WO4)2:TR3+ para aplicações fotônicas." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-05062013-235000/.
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Estudou-se neste trabalho a preparação de LiLa(WO4)2:TR3+ (LLW:TR) nas formas de fibras monocristalinas (micro-pulling-down) e de microcristais pó cerâmico (método dos precursores poliméricos). No que se refere às fibras: a taxa de puxamento no crescimento de LiLa(1-x)Eux(WO4)2 para 0≤x≤1 é influenciada pela diferença de raio iônico do Li e das TR; a estrutura tetragonal da scheelita descreve as composições 0≤x≤1; a incorporação do Eu gera distorções na estrutura sem reduzir a simetria local do íon; uma queda de luminescência para x>0,20 é observada; e as estruturas para 0≤x≤1 foram modeladas através de simulação atomística com bastante precisão. No que se refere aos microcristais: o efeito do controle de pH na preparação de LLW:Nd 1,0 mol% foi avaliado; obteve-se aglomerados de morfologia irregular e com tamanhos médios entre 22-48 μm, cujo aumento é maior em função da temperatura do que do tempo de calcinação. No que se refere à construção experimental do diagrama de fases do sistema xLi2W2O7-(1-x)La2W2O9: confirmou-se que o LLW (formado numa região de homogeneidade de 0,48≤x≤0,55) se decompõe peritéticamente a 1000°C; a dopagem por TR influencia sua fusão; dados do crescimento, de DTA e de DRX de fibras de LLW, crescidas com composições baseadas neste diagrama, corroboram o mesmo. O processo de obtenção de fibras foi otimizado, com um excesso mínimo de 1,5 mol% de Li2W2O7.In this work, the preparation and characterization of LiLa(WO4)2:RE3+ (LLW:RE) microcrystals as single crystal fibers (micro-pulling-down technique) and as powder (polymerizable complex method) was studied. Concerning the fibers: the pulling rate for LiLa(1-x)Eux(WO4)2 (0≤x≤1) is influenced by the difference between the constituents ionic radii; the tetragonal scheelite-like structure describes all compositions; the Eu incorporation distorts the LLW lattice without reducing the dopant local symmetry; a luminescence quenching for x>0.20 was observed; and the structure modelling for 0≤x≤1 by atomistic simulation was carried out with good precision. Concerning the powder microcrystals: the pH control effect on the preparation of Nd:LLW 1,0 mol% was evaluated; they presented irregular morphology and agglomerates with average sizes of 22-48 μm with higher increase for the calcination temperature than for the time. Concerning the experimental construction of the phase diagram of the system xLi2W2O7-(1-x)La2W2O9: it was confirmed that the LLW (formed in the a homogeneity region of 0.48≤x≤0.55) decomposes peritectically at 1000°C; RE-doping influences the LLW melting; growth, DTA and XRD data of LLW fibers (grown from the compositions based on this diagram) confirmed it. The process of fiber obtaining was optimized with a minimum excess of 1.5 mol% of Li2W2O7.
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Chen, Hengjun. "Une opportunité pour les lasers visibles : les cristaux à base d'oxyde activés par des ions Tb3+ ou Dy3+." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEC012.
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Les lasers visibles sont nécessaire et utilisés dans large domaine d’applications. À ce jour, l’obtention de sources lasers visibles de haute qualité repose sur un processus de conversion de fréquence des lasers à base de Nd3 + ou Yb3+ émettant dans l'infrarouge. Une nouvelle classe de lasers activés par des ions Lanthanides fonctionnant directement avec des transitions d'émission dans la région spectrale visible a été développée récemment. Ces lasers ne présentent pas l'inconvénient des lasers visibles traditionnels, tels que la perte d'énergie inévitable pendant le processus de conversion de fréquence, ce qui ouvre des perspectives de recherche prometteuses. Un défi de ce sujet reste, jusqu'à présent, la génération d’émission laser efficaces utilisant des matériaux à base d'oxyde activés par des ions Tb3+ ou Dy3+. Ces travaux de thèse se concentrent sur la fabrication et l'étude des propriétés physiques d’une sélection de monocristaux à base d'oxyde activés par des ions Tb3+ ou Dy3+: Ba3Tb(PO4)3, Sr3Tb(BO3)3, TbAl3(BO3)3, Li6Tb(BO3)3, Ca4TbO(BO3)3, KTb(WO4)2, Dy:CaYAlO4, Dy:Ca4YO(BO3)3, et Dy:Ca2AlSiO7. La technique classique de croissance cristalline dite Czochralski a été utilisée pour la préparation de monocristaux et les conditions de croissance ont été optimisées. Des monocristaux de bonne qualité optique de ces composés ont été obtenus. Les propriétés thermiques en particulier celle des cristaux à base de Tb3+ ont été étudiées. La majeur partie des travaux a été concentrée sur la caractérisation de leurs propriétés optiques, y compris les indices de réfraction, les spectres d'absorption et d’émission, les paramètres de Judd-Ofelt, la dynamique de fluorescence et l'absorption de l'état excité. Les sections efficaces de transitions et les durées de vie de l'état excité des cristaux d'oxyde activés par Tb3+ se sont avérées être comparables à celles des fluorures. Le cristal Dy:CaYAlO4 conduit à de meilleures propriétés spectroscopiques pour une emission laser dans le jaune comparativement aux résultats publiés pour le cristal de Dy: YAG. Des test lasers ont été envisagés en utilisant des sources de pompage laser à base de semi-conducteurs émettant dans le bleuVisible lasers are useful in a variety range of fields. To date, the regime of high-quality visible lasers rely on the frequency conversion of Nd3+- or Yb3+-based infrared-emitting lasers. A new class of Ln3+-activated lasers operated directly with emission transitions in the visible spectral region has been developed recently, which do not feature the inconvenience of the traditional visible lasers, such as the inevitable energy loss during the frequency conversion process, and have promising research prospects. A challenge of this subject remains, up till now, to generate efficient laser emissions using Tb3+- or Dy3+-activated oxide-based gain materials. This PhD thesis concentrates on the fabrication and physical-property study of several selected Tb3+- or Dy3+-activated oxide-based single crystals: Ba3Tb(PO4)3, Sr3Tb(BO3)3, TbAl3(BO3)3, Li6Tb(BO3)3, Ca4TbO(BO3)3, KTb(WO4)2, Dy:CaYAlO4, Dy:Ca4YO(BO3)3, and Dy:Ca2AlSiO7. The conventional Czochralski technique was employed for the single-crystal preparation and the growth conditions were optimized. Single crystals of these compounds with good optical quality were obtained. Thermal properties of the Tb3+-based crystals were studied. The main effort was devoted to characterization of their optical properties, including the refractive index, absorption and emission spectrum, Judd-Ofelt parameters, fluorescence dynamic, and excited-state absorption. The transition cross-sections and upper-state lifetimes of the Tb3+-activated oxide crystals were found to be comparable to those of the fluorides. The Dy:CaYAlO4 crystal has better spectroscopic properties for yellow laser operation compared to the reported results of the Dy:YAG gain medium. Laser experiments were essayed using pump sources of blue-emitting semiconductor lasers
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Reuther, Christoph. "Züchtung und Charakterisierung von Sr3Gd2[BO3]4-Einkristallen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-115924.
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Polykristallines Sr3Gd2[BO3]4 (SGB) konnte mithilfe einer stöchiometrischen Mischung aus SrCO3, Gd2O3 und B2O3 durch zweimaliges Sintern bis 1.350 °C phasenrein erzeugt werden. Ein Exzess von 3 Ma% B2O3 musste der Mischung beigesetzt werden, um das an B2O3 gebundene Wasser auszugleichen [125].
Kristalle des SGB ließen sich mit verschiedenen Orientierungen erfolgreich mit dem Czochralski-Verfaren synthetisieren. Unter Einsatz eines arteigenen, b-orientierten Keimes, einer Translation von 1 mm/h und einer Rotation von 4 /min konnten Kristalle mit guter Qualität bei hoher Erfolgsrate produziert werden. Bei den gezüchteten Kristallen waren keine Segregationserscheinungen zwischen Gadolinium und Strontium feststellbar. Jedoch weist das Auftreten von Fremdphasen (vor allem Gd2O3) in wenigen Kristallen auf eine mögliche, geringfügige Bevorzugung des Sr in der Struktur hin.
Die Härte des Materials ist mit ca. 5,5 nach Mohs bestimmt, die Dichte mit 5,15(1) g/cm3. SGB ist nicht hygroskopisch, lässt sich aber in mineralischen Säuren lösen. Die Schmelztemperatur konnte mit 1.461+/-5 °C bestimmt werden.
Einkristallines SGB besitzt ein Transmissionsfenster zwischen 215-3.450 nm. Das entspricht einer Bandlücke von 5,4 eV. In diesem Bereich werden über 80% des eingestrahlten Lichtes transmittiert. Im ultravioletten Spektrum finden sich für Gd charakteristische Absorptionsbanden, die durch Elektronenübergänge erzeugt werden. Im mittleren Infrarotbereich lassen sich um die Absorptionskante mehrere Absorptionsbanden, deren Ursache ungeklärt ist, feststellen. Sie stehen offensichtlich im Zusammenhang mit dem Auftreten von [BO3]3- -Gruppen, da sie auch bei anderen Boraten, wie dem Ca4Gd[O|(BO3)3] [99], vorkommen. Gepulvertes SGB weist im Bereich von 550-1.600 cm-1 zahlreiche Absorptionsbanden, die auf verschiedene Schwingungen innerhalb der [BO3]3- -Gruppe zurückgeführt werden können, auf. Es folgen zu kleineren Wellenzahlen hin vermutlich Sr-O- und Gd-O-Schwingungen.
Die thermische Ausdehnung von SGB-Kristallen ist anisotrop sowohl zwischen den kristallographischen Richtungen a, b und c als auch über die Temperatur innerhalb einer Richtung. Sie kann im Mittel zwischen 150-830 °C mit alpha11=18,1(2)*10-6/K, alpha22=8,9(3)*10-6/K und alpha33=20,3(4)*10-6/K angenommen werden. Die Ausdehnungskurven deuten mehrere Effekte an, wobei ein Effekt im Bereich von 450-700 °C und vermutlich zwei weitere im Bereich von 800-1.000 °C zu beobachten sind. Aufgrund der Stetigkeit der Kurve ist wahrscheinlich von Phasenübergängen höherer Ordnung auszugehen.
Zur Struktur des SGB konnten wichtige Grundverständnisse gewonnen werden. So lässt sich die Struktur bei Raumtemperatur nicht durch eine orthorhombisch zentrische Metrik beschreiben, da die Einzelreflexe bei Einkristallmessungen eine Aufspaltung im Bereich von 0,1 ° zeigen. Dies deutet auf das Vorhandensein von Zwillingen und auch auf eine mögliche monokline Metrik hin. Es fällt dabei besonders auf, dass die Aufspaltung mit zunehmendem Theta-Winkel nicht größer wird, so dass auch andere Phänomene für die Reflexaufspaltung verantwortlich sein könnten. Dennoch ergeben die ermittelte Raumgruppe Pnam, die zugehörigen Gitterparameter (a0=0,7408 nm, b0=0,8757 nm, c0=1,6057 nm) und Atomkoordinaten ein vereinfachtes Modell zur Veranschaulichung der Struktur. Hoch- und Raumtemperaturstruktur sind bis 700 °C unter Annahme des vereinfachten Modells isomorph, wobei die Gitterparameter entsprechend der Ausdehnung vergrößert sind. Die Gd- und Sr-Positionen sind untereinander mischbesetzt. Außerdem deutet sich eine Positionsfehlordnung einer Sauerstoff-Position an, der Ligand eines Borions auf spezieller Lage ist. Hinweise auf die korrekte Struktur liefern die entdeckten Phasenübergänge und Hochtemperatur-Einkristalldaten. Der in der Dilatometrie entdeckte Effekt zwischen 450-700 °C korreliert mit dem Rückgang der Reflexaufspaltung, die bei ca. 700 °C nicht mehr sichtbar ist, wobei sich dieser Rückgang vermutlich von Raumtemperatur bis 700 °C erstreckt. Damit bestätigt sich, dass der erst genannte Effekt als Phasenübergang höherer Ordnung aufgefasst werden kann. Die festgestellte Positionsfehlordnung von Sauerstoff verringert sich mit steigender Temperatur. Die Mischbesetzung ändert sich ebenfalls bis ca. 500 °C. Beide Effekte sowie auch größeren Schwingungsellipsoide der Sauerstopositionen um die allgemeine Borlage sind vermutlich Ausdruck für den stattfindenden Phasenübergang und verstärken die Annahme einer Zwillingsbildung.
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Apriyanto, Haris. "Study, analysis and experimental validation of fiber refractometers based on single-mode, multimode and photonic crystal fibers for refractive index measurements with application for the detection of methane." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0022.
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La mesure de l'indice de réfraction a été étudiée depuis qu'Ernest Abbé aie initialement conçu un réfractomètre en 1869, appelé le réfractomètre d'Abbé. Depuis lors, de nombreux réfractomètres ont été développés tels que le réfractomètre à prisme optique ainsi que le réfractomètre à fibre optique, en raison de leurs applications étendues pour la détection de divers paramètres physiques, biologiques et chimiques. Récemment, un grand nombre de chercheurs ont mis au point des réfractomètres basés sur des fibres optiques, exploitant des mécanismes tels que la résonance des plasmons de surface (SPR), les interférences multimodes, les fibres à réseaux de Bragg (FBG), les fibres à réseaux à longues périodes (LPG), les fibres optiques coniques et la fibre multimode à gaine dénudée. Les capteurs fibrés sont avantageux grâce à leur immunité contre les interférences électromagnétiques, passivité électrique au niveau de la sonde de détection et potentiel de mesure in situ à long terme. Cette thèse concerne le développement de modèles complets fonctionnels et précis pour les réfractomètres à fibres optiques basés sur la modulation d'intensité optique, en particulier la réfractométrie à fibre multimode à gaine dénudée ainsi que les systèmes hybrides associant fibres monomode et multimode, et un réfractomètre hybride tout fibré utilisant des fibres à cristaux photoniques. L'objectif clé de ce travail est de caractériser les performances de ces réfractomètres à fibres optiques basés sur la modulation d'intensité en termes de réponse en puissance, de sensibilité, de résolution et de dynamique de mesure. Les résultats de simulation qui sont corroborés expérimentalement démontrent que la très grande sensibilité obtenue dans la zone II (c'est-à-dire le régime de détection typiquement utilisé pour mesurer l'indice du milieu supérieur à l'indice de gaine mais inférieur ou égal à l'indice du coeur) pour tous les trois réfractomètres. Cependant, la sensibilité dans la Zone (c’est-à-dire le régime de détection pour lequel l’indice du milieu à mesurer est supérieur à celui du coeur) est très faible. Ainsi, un refractomètre fibré hybride monomode-multimode est utilisé pour améliorer la sensibilité dans la Zone III. D'autre part, la sensibilité pour la zone I (c'est-à-dire le régime de détection pour mesurer l’indice du milieu inférieur à l'indice de la gaine) a été améliorée en augmentant l'absorption des ondes évanescentes à l'aide du réfractomètre hybride tout fibré à base de fibres à cristaux photoniques à coeur solide. En termes d'application réelle du réfractomètre à fibre pour la détection biochimique, une preuve de concept pour un capteur du gaz méthane a été démontrée en utilisant les supramolécules de cryptophane-A qui permettent de piéger les molécules du méthane. Le cryptophane-A incorporé dans un film hôte à base de styrène acrylonitrile (SAN) est appliqué sur la zone dénudée du capteur comme une région fonctionnalisée. L'indice de réfraction de cette couche sensible augmente proportionnellement avec l'augmentation de la concentration du méthane, ce qui induit une variation de la puissance optique transmise dans le capteur fibréRefractive index measurement has been studied since Ernest Abbé initially designed a refractometer in 1869, which is named the Abbé refractometer. Since then, numerous types of refractometers have been developed by employing either the optical prism-based refractometer or the optical fiber-based refractometer, due to their wide-ranging applications such as for sensingvarious physical, biological and chemical parameters. Recently, a large number of researchers have been developing refractometers based on optical fibers, exploiting mechanisms such as surface plasmon resonance (SPR), multimode interference, fiber Bragg gratings (FBG), long period gratings (LPG), tapered optical fibers, and striped-cladding multimode fibers (MMF), for their advantages in immunity against electromagnetic interference, electrical passivity at the sensing probe, and capability to long term in-situ measurement. This thesis concerns the development of comprehensively functional and accurate models for optical fiber refractometers based on optical intensity modulation, in particular for stripped-cladding MMF refractometry as well as hybrid systems involving a combination of single-mode-multimode fiber refractometery and the all-fiber hybrid refractometer using photonic crystal fibers. A key objective of this work is to characterize the performance of these intensity-based optical fiber refractometers in terms of their power response, sensitivity, resolution, and dynamic range. The simulation results which are corroborated experimentally demonstrate very high sensitivity being obtained in Zone II (i.e. the sensing regime typically employed for measuring a sensing medium index higher than the cladding index but less than or equal to the core index) for all three types of refractometers. However, the sensitivity in Zone III (i.e. the sensing regime for which the sensing medium index is higher than the core index) is very low. A hybrid single-mode fiber - multimode fiber configuration is used to improve the sensitivity in Zone III. On other hand, the sensitivity for Zone I (i.e. the sensing regime typically employed for measuring a sensing medium index lower than the cladding index) has been improved by increasing evanescent wave absorption using the all-fiber hybrid refractometer based on solid-core photonic crystal fibers. As a further potential of the fiber refractometer for applications in biochemical sensing, the proof-of-concept for a methane gas sensor has been demonstrated using supramolecular cryptophane-A which enables to trap the methane molecules. Cryptophane-A incorporated into a functionalized film of StyreneAcrylonitrile (SAN) host is applied to a de-cladded region of the sensor as the sensitive region. The refractive index of this functionalized layer increases proportionally with increasing methane concentration, subsequently inducing variations in the transmitted optical power along the fiber sensor
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Yeung, Anson Chi-Ming Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Polymer segmented cladding fibres: cross fibre modelling, design, fabrication and experiment." Publisher:University of New South Wales. Electrical Engineering & Telecommunications, 2009. http://handle.unsw.edu.au/1959.4/43656.
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This thesis presents the first research on polymer-segmented-cladding-fibre (PSCF), an emerging class of microstructured- optical-fibres (MOFs), which allows single-mode operation with ultra-large-core area. This research covers the modelling, design, fabrication and experiment of the polymer optical cross-fibre (4-period-SCF) whose cross-sectional view resembles a cross. A new wedge waveguide model has been formulated and applied to demonstrate that for any given parameters, the cross fibre gives the same performance for single-mode operation as the N-period-SCFs (for N = 2, 6 and 8). These fibres behave identically if the high-index segment angle, θ1, is the same and the low-index segment angular width, θ2, is sufficiently large for negligible adjacent mode coupling effects. This remarkable finding has significant ramifications for SCF fabrication, design and performance. Theoretical predictions confirmed by experiments demonstrated that a cross-fibre is all that needed to fabricate a large-core single-mode-fibre with no geometry-induced birefringence. The high-index outer ring effects on the cross fibre single-mode performance have been systematically investigated for the first time. The study reveals that the ring index value higher than its core index has very strong effects on single-mode performance. Within a narrow range of θ1, the minimum fibre length required for single-mode operation is reduced but outside this angle range, longer single-mode length is required. Furthermore, the fibre can be anti-guiding if θ1 exceeds the cutoff angle. Incorporating the fabrication constraints, the optimal cross-fibre design with high-index ring is achieved by optimising the relative index difference, high-index segment angle and core-cladding diameter ratio. Two preform-making techniques developed for the cross-fibres fabrication include the cladding-segment-in-tube method and the core-cladding-segment-in-tube method. The innovative approach in these methods overcomes the problems of bubble formation and fractures, which are related to the fibre structure complexity and the polymer intrinsic properties and their processing. It enables the successful drawing of single-mode fibres. This thesis reports the first experimental demonstration of single-mode operation of large-core cross-fibre. Three experimental studies with different cross-fibre designs have demonstrated (i) large-core single-mode operation, (ii) high-index ring effects on fibre performance and (iii) cross-fibre optimal design trial. Apart from this, the 8-period-SCF fibre performance has been demonstrated experimentally.
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Abdulmalic, Mohammad A. "A Tailor-Made Approach for Thin Films and Monolayer Assemblies of bis(oxamato) and bis(oxamidato) Transition Metal Complexes." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-118769.
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The present work is dealing with the synthesis and characterization of mono- to trinuclear Cu(II)- and Ni(II)-containing bis(oxamato) and bis(oxamidato) complexes, respectively. It will be derived to which extent the spin density distribution of mononuclear complexes, determined by electron paramagnetic resonance studies experimentally and calculated by quantum mechanical calculations, can be regarded as a measure of the magnitude of magnetic superexchange interactions of corresponding trinuclear complexes. The usability of tailor-made trinuclear complexes for their deposition in form of thin film by spin-coating is described as well as the magneto-optical characterization of these thin films. It is shown, that the tailor-made functionalization of mono- to trinuclear bis(oxamidato) complexes with long alkyl chains is suited to allow these complexes to assembly in monolayers on, e.g., HOPG(0001) (highly-oriented pyrolytic graphite), whereas the functionalization of the alkyl chains with S atoms allows the generation of self-assembled monolayers on metallic gold. Furthermore it is shown, that the functionalization of mono- and trinuclear Cu(II)-containing bis(oxamato) complexes with ferrocenediyle fragments allows to modify the magnetic properties by making use of the oxidation process Fe(II)/Fe(III)Die vorliegende Arbeit befasst sich mit der Darstellung und Charakterisierung ein- bis dreikerniger Cu(II)- bzw. Ni(II)-haltiger bis(oxamato) oder bis(oxamidato) Komplexe. Es wird abgeleitet, inwiefern die aus Elektronenenspinresonanz- Untersuchungen experimentell und die quantenmechanisch berechneten Spindichteverteilungen einkerniger Komplexe ein Maß für die Größe der magnetischen Superaustauschwechselwirkungen korrespondierender dreikerniger Komplexe darstellt. Die Eignung maßgeschneiderter dreikerniger Komplexe zu ihrer Überführung in dünne Filme im nm-Bereich mittels Rotationsbeschichtung auf Si/SiO2-Substraten wird beschrieben sowie die magneto-optische Charakterisierung dieser dünnen Filme. Es wird gezeigt, dass durch gezielte Funktionalisierung mit langkettigen Alkylresten ein- bis dreikernige Cu(II)-haltige bis(oxamidato) Komplexe geeignet sind, auf Substraten wie HOPG(0001) (hochorientiertes pyrolytisches Graphit) zu Monolagen zu assemblieren während die zielgerichtete Funktionalisierung der Alkylketten mit S-Atomen es ermöglicht selbst-assemblierte Monolagen auf metallischem Gold zu generieren. Zusätzlich wird beschrieben, dass durch die Funktionalisierung von ein- und dreikernigen Cu(II)-haltigen bis(oxamato) mit Ferrocendiylresten die magentischen Eigenschaften durch den Oxidationsprozess Fe(II)/Fe(III) gezielt modifiziert werden können
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Chen, Yen-Fu, and 陳彥甫. "Optical and physical properties of LuVO4 single crystal." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/92841927262593249789.
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碩士國立交通大學
電子物理系所
104
LuVO4 was firstly grown by Czochralski method in 1996 and was expected to be an attractive polarizer material owing to its high transmittance from VIS to NIR. However, the study of the single crystal LuVO4, has been mostly focused on the optical parts. In this thesis, we want to know more about this crystal by doing all kinds of experiments. We used the Bulgaria method to grow the single crystal with the dimension of 1x0.5x0.05cm3. At first, we used the single crystal XRD to confirm we got the high quality and the correct structure. Then we did many kinds of experiments. In the optical part, we measured the Raman spectrum and the ellipsometer. In the physical part, we measured the XRD, XAS, and the EDS. In the magnetic part, we used the SQUID to measure the M-T in different temperature. In the electric part, we used the LCR meter to measure the relative permittivity and dielectric loss. In conclusion, we got the more complete Raman spectrum, and the Birefringence picture. The crystal has no magnetism and the relative permittivity is quite stable.
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Yu, Yean Cherng, and 余遠成. "Nonlinear optical material β-BBO single crystal growth." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/07636460530321693476.
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Wang, Jia-Wei, and 王嘉維. "The Growth and Optical Properties of Single Crystal AgGaS2." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/61163372667175811942.
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碩士國立交通大學
光電工程研究所
85
In this study, the Silver thiogallate (AgGaS2) single crystals were grown by Vertical Bridgman method under different temperature gradients. In the as-grown crystals, we observe lots of precipates exited in the crystals which dominate the transmittance of light. After heat treatment with 0.5% Ag2S at 900℃ for 8 days, these precipates have been reduced significantly and the transmission of light in crystals have been apparently improved. By using various measurements, we obtain that the transmission range is 0.48→13 μm; the effective SHG coefficient at 1.064μm is 0.77 pm/V; and the energy band-gap at room temperature is 2.682 eV. Due to the stress resulting from thermal expansion in the crystals during the cooling process, a few twins were generated. In order to ease this stress during cooling, we suggest to use a c-axis oriented seeded crystal for the crystal growth. Instead of using conventional X-ray method, we develop a full optical technique to find the crystal's c-axis, and its axis direction can be precisely determined to less than 1 degree.
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tsai, chia-wei, and 蔡佳偉. "Growth and Characterization of Organic Nonlinear Optical Material-DAST Single Crystal." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/45797337210925634531.
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碩士國立臺灣大學
化學工程學研究所
88
Growth of Nonlinear optical (NLO) crystal is the key component in optoelectronic devices used in information processing and storage. Due to their highly nonlinear properties and the design versatility in synthesis, organic NLO crystals have attracted much attention recently. Most of organic NLO crystals have problems in their weak mechanical properties and low melting points, which make their real applications difficult. Organic salts are better candidates for applications, but their NLO properties are much poorer. A recently discovered salt, DAST (4-dimethylamino-N-methyl-4-stiblazolium tosylate), is an exception. However, a large single crystal with a high quality is difficult to grow and the growth limitations are not well known. In this project, we have compared two configurations to grow DAST single crystals from the methanol solution. Beside the initial seed quality, it is found that the convection, which affects the mass transport, is a critical factor for the growth. Without convection, the growth from the bottom of the vessel seems to provide a better growth control and single crystals up to 1x1x0.5 cm3 can be obtained in several days. On the contrary, the growth with an enhanced mixing by ACRT (accelerated crucible rotation technique) is still more difficult to get a larger crystal. To better understand the role of convection on the growth, flow visualization has also been carried out. For the ACRT configuration, it is found that the spin-down stage provides a better global mixing, which has been confirmed by experiments. Other growth configurations are under consideration.
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Satyanarayan, M. N. "Growth And Study Of Certain Physical Properties Of KTiOPO4 Single Crystals." Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1585.
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Otto, Tobias [Verfasser]. "Local scale optical properties of single crystal ferroelectrics / vorgelegt von Tobias Otto." 2006. http://d-nb.info/980303478/34.
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Saripalli, Ravi Kiran. "Structural, Optical and Electrical Studies on Multi-Functional Organic Single Crystals." Thesis, 2017. http://etd.iisc.ernet.in/2005/3807.
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In this thesis, the physical properties of certain multi-functional organic crystals were studied in detail. This study involves the growth of single crystals of Glucuronic acidγ-lactone (GAL), Imidazoliumtartarate (IMLT), (Bis)imidazoliumtartarate (BIMLT), and Diisopropylammonium iodide (DPI) and investigations of their optical, dielectric, piezoelectric, pyroelectric, and ferroelectric properties as a function of temperature and dependence on crystal structure in these organic crystals.
Piezoelectric resonance was observed at certain frequencies when dielectric constant was monitored along the b-plate of GAL crystals. The electro-mechanical coupling coefficient estimated at the resonance near 1 MHz frequency revealed an exceptionally large value in GAL similar to that in inorganic lead titanate. The dependence of the piezoelectric resonance frequency on temperature was studied in detail. These crystals showed excellent second- and third-order nonlinear optical properties as well as high laser damage threshold. The high values of χ(2) andχ(3), laser damage threshold, and low UV cut-off makes GAL crystals an interesting prospect for NLO and laser applications. Towards this goal, GAL crystals were studied in detail with regard to determination of directions of dielectric axes, optic axes, and collinear phase-matching.
Single crystals of another promising NLO organic crystal, IMLT were also grown which showed interesting dielectric, piezoelectric, and NLO properties. The dielectric dispersion with temperature provided an insight to the polarization mechanisms. Like GAL, IMLT also exhibits piezoelectric resonance. The existence of only one easy axis of vibration in IMLT enabled the candidate to identify the first resonance peak as corresponding to the fundamental mode of oscillation in the sample. This also helped to determine many piezoelectric parameters. By angular phase matching, one direction of phase matching in IMLT was identified. The conversion efficiency of IMLT along this direction was determined which was high in comparison to that in a standard KDP crystal. At piezoelectric resonance frequencies, the electro-optic response due to photo-elastic contributions is enhanced. Single crystals of organic ferroelectric BIMLT were grown by mixing two moles of imidazole with one mole of l-tartaric acid. The controversy with regard to the phase transition temperature of BIMLT was clarified by the DSC and structural analysis in this work. Previously, studies on BIMLT were limited to polycrystalline samples and single crystals with inclusions primarily due to the difficulty in growing good quality single crystals from aqueous solution. However, by experimenting the growth process using different solvents, good quality single crystals were achieved without the trapping of mother solution. This remarkable find is a notable result in these crystals for ferroelectric applications. The mechanism of ferroelectricity in BIMLT is mainly attributed to the transfer of protons along N–H---O hydrogen bonds in the direction of b-axis.
Interestingly, the values of spontaneous polarization and Curie-temperature in the organic ferroelectric material DPI were significantly high and comparable to several popular inorganic ferroelectrics. The polarization obtained in this material is the highest among reported organic ferroelectrics. In addition to the high Curie temperature and spontaneous polarization, there were unique phase transitions that were revealed in DPI. The mechanism of ferroelectricity is quite complex, mainly being displacive type on account of the change in orientation of dipoles with electric field. Some contribution to ferroelectricity comes from the order-disorder nature of Nitrogen atom.
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CHINJEN, CHUNG-REN, and 鄭江崇仁. "The optical and photorefractive properties of hydrogen-reduced and rhodium-doped barium tiatanate single crystal." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/12304010831769224501.
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Fu, Ying-Jhe, and 傅英哲. "Magneto-Optical Properties of Single InAs Quantum Dot and Their Coupling to Photonic Crystal Cavity." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/69781590552387154216.
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博士國立交通大學
電子工程學系 電子研究所
102
This dissertation mainly researches the photoluminescence characteristics of single quantum dot. We report on the magnetic responses of neutral exciton (X), biexcitons (XX) and positive/negative trions (X+/X-) in single self-assembled InAs/GaAs quantum dots. Unlike the conventional quadratic diamagnetic shift for neutral excitons, the observed X- diamagnetic shifts are small and nonquadratic. In particular, we also observed a reversal in sign of the conventional diamagnetic shift. A theoretical analysis indicates that such anomalous behaviors for X- arise from an apparent change in the electron wave function extent after photon emission due to the strong Coulomb attraction induced by the hole in its initial state. This effect can be very pronounced in small quantum dots, where the electron wave function becomes weakly confined and extended much into the barrier region. When the electrons gradually lose confinement, the magnetic response of X- will transit gradually from the usual quadratic diamagnetic shift to a quartic dependence, and finally into a special paramagnetic regime with an overall negative energy shift. On the other hand, we purpose to study the coupling effect between single quantum dot and photonic crystal cavity, a method for designing H1 photonic crystal cavity is introduced to enhance its quality factor (Q factor). The highest theoretical Q factor of 120,000 is obtained. The Fourier transformation of field distribution shows that the enhancement arises from the component reduction of leaky mode. The Q-factor improvement has also been demonstrated experimentally with the highest value of 11700. Our design could be useful for studying light-matter interaction in H1 cavity as the mode volume only increases slightly. Finally, we successfully demonstrated the strong coupling effect in the H1 photonic crystal cavity embedded single InAs/GaAs quantum dot. Two polariton states arise from the hybridization of the cavity mode and quantum dot, which reflect in the alterations of observed emission characteristics, such as emission wavelength, full width half maximum and intensity. Via analysis, the strongest coupling effect occurs at about 37.75 K, while Rabi splitting is equal to 156.7 μeV.
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Yan, Ruey-Charng, and 顏瑞常. "Studies of Structural and Optical Properties in Single Crystal AgGaS2 Grown by Vertical Bridgman under Different Annealing Conditions." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/57184321280413748090.
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碩士國立交通大學
電子物理學系
84
In this study we disscuss the structure and characteristics of AgGaS2 single crystal under different annealing conditions. Becsuse 1 wt.%excess S in melt is used,a second phase of Ga2S3 besides the phase of AgGaS2 is easily to be form ed as the precipitate during solidification. These precipitate need to be remo ved by thermal annealing ,otherwisethey will form the absorption centers and affect the optical propertiesof crystal seriously. In our experiment , we focus on five different thermal annealing conditions, such as to use materials of A g2S 、Ag、AgGaS2powder、Ga and S to obtain a crystal of better quality. we find that a betterquality of crystal can be obtain by annealing the crystal at tem peratureof 930C for 7 days under gas ambient of Ag2S.