Licentiatavhandling (sammanfattning) Norrköping : Linköpings universitet., 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet., 2007. / Härtill 7 uppsatser.

The communication modes are a mathematical technique for the description of structural information in optical fields. These modes are orthogonal, optimally  connected functions characteristic of the optical system. Mathematically they are obtained by the singular value decomposition (SVD) of the operator that represents the field propagation. In this dissertation, the foundations of the technique are described, and the theory is extended and applied to a variety of specific systems.   In the Fresnel regime, the communication modes are closely related to the prolate spheroidal wavefunctions (PSWF). Within this approximation, the numerical propagation of the field in a one-dimensional optical system in terms of the PSWFs is demonstrated and the problem of assessing the best achievable realization of a given target field is addressed. Simplified equations for field propagation are presented. Approximate modes in large-aperture systems are derived and shown to agree with Gabor's theory on optics and information. The longitudinal resolution of an axicon is analyzed in terms of the communication modes. It is shown that in a generalized axicon geometry the communication modes are expressible in terms of the PSWFs, and that in usual circumstances a version of the large aperture approximation applies, resulting in quadratic waves in the aperture domain and sinc functions in the image domain   Eigenequations for the communication modes in scalar near-field diffraction are derived and applied to a simplified scanning near-field optical microscope (SNOM) geometry. It is suggested that the resolution of a SNOM system is essentially given by the width of the lowest-order communication modes. The best-connected mode is shown to effectively reduce to the Green function.   Within the context of random fluctuations the communication modes are defined for the cross-spectral density of partially coherent fields. These modes are compared to the well-known coherent modes. Expressions for the effective degree of coherence are derived, and it is demonstrated that optical fields of any state of coherence may readily be propagated through deterministic systems by means of the communication modes. Results are illustrated numerically in an optical near-field geometry.   The communication modes theory is further extended to vector diffraction on the basis of Maxwell's equations. The polarization properties of the electromagnetic communication modes as represented by the Stokes parameters are analyzed numerically for an example of a near-field geometry. The work presented in this dissertation shows that the communication modes are an advanced, versatile tool that can be applied to deterministic and random, scalar and electromagnetic optical systems in far-field and near-field arrangements. The method is likely to find further uses in applications such as polarization microscopy. / QC 20100802

At the heart of quantum physics lies the principle of superposition, and at the heart of information theory lies the bit. Perhaps the most useful property of quantum systems is that they can be loaded with information bits, so-called qubits, that are indefinitely both 0 and 1 until a measurement is made. Another consequence is that several qubits can become entangled, which is manifested by the non-classical correlations between such quantum systems when measured in all possible bases. Within the rapidly progressing fields of quantum information and quantum communication these quantum effects are utilized to perform tasks such as quantum computing and quantum cryptography. In this thesis we present experimental and theoretical work using single photon sources to prepare ``flying'' photonic qubits. We describe work using mainly quasi-phase-matched nonlinear crystals to generate beams of entangled photon pairs, that are either encoded in polarization at near-visible wavelengths, or in time at optical fiber telecommunication wavelengths (1550 nm). The optical fiber is the medium used for transporting the qubits over a long distance, and it is therefore essential to couple the photons well into the fibers. By focusing the beams optimally, we have investigated how this problem can meet the requirement of creating photons of a narrow frequency bandwidth and a high photon flux. Furthermore, we have generated truly single photons that are heralded by an electrical signal. As a result of modifying the statistics of such sources we have been able to show the effect of photon antibunching. In two separate works, we have implemented a quantum key distribution system based on faint laser pulses at the telecom wavelength of 1550 nm, as well as protocols based on entanglement for performing authentication of key distribution in quantum cryptography. / QC 20100909

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 4 uppsatser.

Photonic circuits can transmit data signals in a much higher speed thanconventional electronic circuits. However, miniaturization of photonic circuitsand devices is hindered by the existence of light diffraction limit. A promisingsolution to this problem is by exploiting plasmonic systems for guiding andmanipulating signals at optical frequencies. Plasmonic devices are generallycomposed of noble metals and dielectrics, whose interfaces can confine surfaceplasmon polaritons, a hybrid wave that is free of diffraction limit. Plasmonicwaveguides and devices are serious contenders for achieving next-generationphotonic integrated circuits with a density comparable to the electronic counterpart. This thesis addresses the design issues of passive plasmonic devices whichare critical for realization of photonic integration, including plasmonic waveguides,splitters, couplers, and resonators, investigated with both the finitedifferencetime-domain method and the finite-element method. In particularwe present, firstly, a coupler which efficiently couples light between a silicondielectric waveguide and a hybrid plasmonic (HP) waveguide. A coupling efficiencyas high as 70% is realized with a HP taper as short as 0.4μm. Theexperimental result agrees well with the numerical simulation. Secondly, wenumerically investigate and optimize the performances of 1×2 and 1×3 HPmultimode interferometers (MMIs), which split light from a silicon waveguideto multiple HP waveguides. Total transmission over 75% can be achieved inboth cases. Thirdly, we study the coupling and crosstalk issues in plasmonicwaveguide systems. Several methods for crosstalk reduction are proposed.Finally, HP nanodisk micro-cavities are designed and are numerically characterized.With a radius of 1μm, a high quality factor of 819 and a highPurcell factor of 1827 can be simultaneously achieved, which can be useful forrealizing efficient nano-lasers. / QC 20110523

<p>Developing an automatic control system from original stage is quite time consuming, a lot of works must be done before the final result, in order to save designing time and money, a systematic way to carry through development is necessary. This project will give an experience about using a systemic method to develop an automatic control system for metal dosing and transfer from original stage. The project will be divided into several different phases, and each phase focuses on some different important tasks. In this project a research of PLCs and stepper motors and then give suitable suggestions of selection of them have been done. One of important roles for this project is to develop a prototype machine and use computer to model and simulate prototype and whole machine, therefore, in this project, using SDL assistant with Matlab to model and simulate both prototype and whole machine have been processed. Because of some unexpected condition, this project doesn’t include real PLC programming.</p>

Wireless Sensor Networks appear as a technology, which provides the basisfor a broad field of applications, drawing interest in various areas. On theone hand, they appear to allow the next step in computer networks, buildinglarge collections of simple objects, exchanging information with respect totheir environment or their own state. On the other hand, their ability tosense and communicate without a fixed physical infrastructure makes theman attractive technology to be used for measurement systems.Although the interest inWireless Sensor Network research is increasing,and new concepts and applications are being demonstrated, several fundamentalissues remain unsolved. While many of these issues do not requireto be solved for proof-of-concept designs, they are important issues to beaddressed when referring to the long-term operation of these systems. Oneof these issues is the system’s lifetime, which relates to the lifetime of thenodes, upon which the system is composed.This thesis focuses on node lifetime extension based on energy management.While some constraints and results might hold true from a moregeneral perspective, the main application target involves environmental measurementsystems based onWireless Sensor Networks. Lifetime extensionpossibilities, which are the result of application characteristics, by (i) reducingenergy consumption and (ii) utilizing energy harvesting are to be presented.For energy consumption, we show howprecise task scheduling due to nodesynchronization, combined with methods such as duty cycling and powerdomains, can optimize the overall energy use. With reference to the energysupply, the focus lies on solar-based solutions with special attentionplaced on their feasibility at locations with limited solar radiation. Furtherdimensioning of these systems is addressed.It will be shown, that for the presented application scenarios, near-perpetualnode lifetime can be obtained. This is achieved by focusing on efficient resourceusage and by means of a carefully designed energy supply.

No description available.

<p>Currently there are very significant interests in printed electronics in the world. The possibility to produce electronics in a roll to roll printing process will considerably reduce the cost of the electronic devices. However, these new devices will most probably not replace the traditional silicon based electronics, but will be a complement in low cost applications such as in intelligent packages and other printable media. One interesting area is printable low cost sensors that add value to packages. In this thesis a study of the performance of low cost sensors is presented. The sensors were fabricated using commercial printing processes used in the graphical printing business. The sensors were characterized and evaluated for the intended application. The evaluated sensors were moisture sensing sensor solutions and touch sensitive sensor solutions.</p><p>A printable touch sensitive sensor solution is presented where the sensor is incorporated into a high quality image such as in point of sales displays. The sensor solution showed good touch sensitivity at a variety of humidity levels. Four printed moisture sensor concepts are presented and characterized. Firstly, a moisture sensor that shows good correlation to the moisture content of cellulose based substrates. Secondly, a sensor that measures the relative humidity in the air, the sensor has a measuring accuracy of 0.22% at high relative humidity levels. Thirdly, a moisture sensor that utilizes unsintered silver nano-particles to measure the relative humidity in the air, the sensor has a linear response at very low relative humidity levels. And fourth, an action activated energy cell that provides power when activated by moisture. A concept of remote moisture sensing that utilizes ordinary low cost RFID tags has also been presented and characterized. The remote sensor solution works both with passive and semi-passive RFID systems. The study shows that it is possible to manufacture low cost sensors in commercial printing processes.</p> / <p>Det är för närvarande ett stort intresse för tryckt elektronik. Att kunna tillverka elektroniska komponenter i en rulle till rulle process möjliggör en reducering av tillverkningskostnaden. Dessa nya komponenter kommer sannolikt inte konkurrera ut den traditionella kiselbaserade elektroniken utan kommer att kunna komplimentera kiselelektronik i segment där kostnaden är väldigt viktig som i intelligenta förpackningar och andra tryckta medier. Ett intressant område är tryckta sensorer som kan addera värde till förpackningar. I denna avhandling presenteras en studie kring tryckta sensorer som kan tillverkas till låg kostnad. Sensorerna är tillverkade i kommersiella grafiska tryckpressar. Sensorerna karakteriseras och utvärderas för de applikationer som de är tänkta för. I denna avhandling har fuktsensorer och beröringskänsliga sensorer undersökts.</p><p>Det presenteras en tryckt beröringskänslig sensor som integreras i ett högkvalitativt grafiskt tryck. Denna sensor är tänkt att användas i reklamskyltar för att skapa interaktivitet. Sensorn har en bra känslighet vid varierande fukthalter. Även fyra fuktsensorer presenteras och utvärderas. Den första sensorn mäter fukthalten i cellulosabaserade substrat och visar en bra korrelation till fukthalten i substratet. Den andra sensorn mäter den relativa fukten i luften, denna sensor har en mätnoggrannhet på 0.22% för höga fukthalter. Den tredje sensorn använder partiklar i nanostorlek för att mäta fukthalten i luften. Denna sensor fungerar väldigt bra vid låga fukthalter. Den fjärde sensorn är en energicell som producerar el när den blir fuktig. Även en fuktsensor som kan läsas av på håll utvärderas. Detta sensorkoncept är baserad på vanliga RFID taggar och kan användas med både passiva och semi-passiva taggar. Denna avhandling visar att det är möjligt att tillverka sensorer till en låg kostnad in en traditionell grafisk tryckpress.</p>