Les solutions pour lutter contre la contrefaçon permettant une sécurisation des produits dépendent des capacités de mesure à l’échelle microscopique de points imprimés. Les recherches explicitées dans ce manuscrit ont donc été consacrées au développement d’un équipement et de méthodes permettant de mesurer les imprimés à l’échelle microscopique. Un microscope en réflexion avec lumière polarisée a été associé avec un appareil photographique numérique. La matrice de Bayer a été retirée de la surface du capteur photographique et des images raw ont été enregistrées. La platine du microscope, l’appareil photographique, un photomètre et un thermomètre ont été contrôlés directement dans une interface logicielle développée en Python. Une méthode de mesure permettant d’élargir la gamme dynamique de reflectances mesurées a été proposée. L’appareil et les méthodes de mesures ont permis d’améliorer la précision et d’automatiser la mesure des points de trame à l’échelle microscopique. Les élargissements physique et optique des points de trame ont alors été séparés et analysés. Une méthode d’ajustement des pics de l’histogramme, correspondant à l’encre et au papier, avec une fonction Gaussienne a été proposée. Des algorithmes de seuillage ont été employés pour séparer l’élargissement optique et physique des points de trame. Une méthode objective d’évaluation des algorithmes de seuillage a été développée pour déterminer leurs performances sur les images de tramés. Cette méthode d’évaluation procède à une simulation des effets de la diffusion de la lumière et des défauts générés par l’imagerie afin de générer des images tests et images de référence. 30 algorithmes de seuillage de la littérature ont été évalués et ont présenté une dépendance avec le pourcentage de couverture de l’encre. Deux nouveaux algorithmes de seuillage ont alors été développés spécialement pour traiter les imprimés tramés. Le premier algorithme détermine le déplacement du pic correspondant à l’encre sur l’histogramme. Le deuxième algorithme proposé se base sur une pseudo-déconvolution permettant de prétraiter les images et se basant sur une séparation des effets de l’élargissement optique. Une caractérisation de l’élargissement optique et physique a alors été menée sur 2708 images d’imprimés tramés. Enfin, un modèle de l’élargissement physique et un modèle de l’élargissement optique des points de trame ont été proposés. Le modèle physique se base sur une génération de particules d’encre placées selon une fonction de probabilité et sur une fusion des particules d’encre. Le modèle a été évalué en considérant 43269 points de trame différents, mesurés automatiquement sur le microscope. Un nouveau modèle prédisant la réflectance des tramés a été développé, basé sur une double convolution avec deux fonctions différentes d’étalement du point. Ce modèle a permis de simuler de manière précise les effets principaux de la diffusion de la lumière dans le tramé, tout en simulant les effets de piégeage de la lumière à proximité des bords des points de trame. / Applications in the field of product security and authentication to prevent counterfeiting rely on abilities of microscale measurements of printed dots. Thus, researches described in this manuscript have been directed toward the development of measurement methods and apparatus to characterize halftone dot at the microscale. A polarized reflection optical microscope has been adapted with a commercial digital camera. The Bayer matrix was removed from the surface of the camera and raw images were retrieved. The microscope stage, the camera, the photometer and the thermometer were controlled directly in a Python graphic user interface specifically developed. A high dynamic range capture method was proposed and tuned specifically to obtain richer information on the ink and paper regions. The measurement apparatus and methods helped improve the accuracy and automate the measurements of the halftone dots at the microscale. The physical and optical dot gains were then separated and analyzed. A Gaussian fitting of the ink and paper histogram peaks was proposed to measure automatically the ink and paper region reflectance as a function of the ink coverage. Thresholding algorithms were applied to separate optical and physical dot gain. An objective threshold evaluation method was developed in order to define the best threshold algorithms for halftone images. The method was based on a simulation of the optical dot gain effects and of the microscope distortions to obtain test images and ground truth images. 30 threshold algorithms from literature were evaluated and demonstrated dependency on the ink surface coverage of the halftones. Two novel threshold algorithms were then developed specifically to process halftones. The first threshold algorithm was based on the determination of the amount of ink peak shift. The second threshold algorithm proposed a pretreatment of the images by applying a pseudo-deconvolution strategy, removing the optical dot gain from the halftones. Characterizations of the optical and physical dot gains were then conducted analyzing 2708 different halftones. Finally, a physical dot gain model and an optical dot gain model were proposed in order to predict the halftone reflectances from raster to print. The physical dot gain model was based on the generation of single ink particles placed according to a probability mask and on a fusion of the ink particles. The model was evaluated with 43269 dot morphologies that were captured automatically on the microscope. A novel halftone reflectance model was proposed based on a double convolution with two different paper point spread functions. It allowed an accurate reproduction of the main effects of the light diffusion with, at the same time, an accurate reproduction of the light entrapment near the edges of the dots.

I present photonics applications of PbS quantum-dot-doped (QD-doped) glasses. The dissertation consists of two major parts: bulk material applications (Cr:forsterite laser modelocking, bleaching dynamics, optical gain, and photoluminescence) and the fabrication of QD-doped ion-exchanged waveguides.When this work began, these PbS QD-doped glasses were the state-of-the-art in QD glasses due to their narrow size distribution. Modelocking of a Cr:forsterite laser using this glass as a saturable absorber had been demonstrated, with little understanding of the dynamics. This work began by studying the dynamics of the saturable absorber to explain the ps-pulse width.In the bulk measurements, I functioned as secondary researcher. In the laser modelocking and bleaching measurements, my contribution was laser cavity alignment, sample preparation, collecting autocorrelation traces, and aiding in the setup and data collection for the bleaching measurements. On this work, I coauthored one refereed journal article in Applied Physics Letters [1] and one refereed conference paper [2], for which I am third and second author, respectively.For the gain measurements, I aided in the setup and data collection, whereas I set-up and took most of the luminescence data. The gain measurements resulted in one second-author refereed journal article in Applied Physics Letters [3] and I presented the luminescence results at CLEO2000 [4].I took the lead role in the waveguide fabrication and characterization and authored refereed journal articles in Applied Physics Letters [5], Journal of Applied Physics [6], and Journal of the Optical Society of America B [7]. I also presented an invited talk at Photonics West [8] and presented at CLEO2004 [9]. Additionally, I have been a coauthor of presentations at the Nanotechnology Symposium (2006), American Ceramic Society [10], and Photonics Europe (2006) [11]. A book chapter in The Photonics Handbook, 2nd edition [12] also discusses this work.The next step is to focus on reducing the waveguide losses. This requires new, circular wafers with better surface quality and glass homogeneity. I suggest using silver-film ion exchange followed by a field-assisted burial to eliminate the surface interaction.

Doctor of Philosophy / Department of Chemistry / Viktor Chikan / Semiconducting nanoparticles have emerged in the past few decades as an interesting material with great potential in various interdisciplinary applications such as light-emitting devices, solar cells and field-effect transistors, mostly notably for their size-dependent electronic structure and properties. Manipulation of their electronic-optical characters through defects control is one of the most important approaches towards realization of these applications. This thesis focuses on understanding the role of defects, including their impact on carrier density and conductivity at both room and elevated temperature, their impact on growth kinetics of colloidal nanoparticles and new opportunities for dopant control. To achieve these goals, colloidal CdSe quantum dots are doped with gallium atoms and important changes in electronic and optical properties of the material are reported, which shows a significant impact on the growth kinetics of quantum dots, and reveals clues about the mechanism of the gallium dopant incorporation into the CdSe. It is shown that the gallium doping significantly impacts the conductivity of CdSe thin film made of the quantum dots as well as the photoluminescence and chemical reactivity of the quantum dots, in agreement with the expected n-type character. P3HT/CdSe hybrid cells are constructed with Ga-, In- and Sn-doped CdSe QDs, demonstrating high conductivity and stronger electronic coupling which leads to enhanced charge separation and transport efficiency, both essential for hybrid inorganic-organic solar cells. This work also demonstrates a novel heating method that can drastically improve size distribution control of colloidal nanoparticle synthesis. Sub-2-nm ultra-small CdSe QDs are prepared with the induction (magnetic) heating and show excellent agreement of its emission profile compared with natural sunlight. The impact of extreme high heating rate on the development of more accurate nucleation and growth theories are also discussed. Finally, this study also investigates the stabilization of charges from intrinsic defects by looking for altered blinking behaviors of CdSe nanorods (NRs) under different polar environments. TMOS-PTMOS gradient films are prepared with infusion withdrawal dip-coating technique. Although no significant differences are observed of the fluorescence statistics of these NRs, permanent bleaching induced by exciting laser light is discovered, which significantly lowers raw blinking spot count and increases the “off” time of these fluorophores.

There are at least two types of response to stimuli: an automatic response that happens before conscious thought (a Type 1 response) and a deliberative, intentional response (a Type 2 response). These responses are related to behavior associated with the affective loading of the stimulus presented. Prior research has shown, for example, that a Type 1 tendency to spend more time looking at fear-provoking stimuli is associated with higher levels of general anxiety, while a Type 2 tendency to spend more time looking away from happy faces is associated with higher levels of depressive symptoms. Some stimuli categories elicit mixed responses, indicated by discrepant Type 1 and Type 2 responses. For example, alcoholics in recovery tend to look toward alcohol-themed pictures in the first 200 milliseconds, then look away. This suggests that alcoholics in recovery have an automatic draw to alcohol that is overridden by the conscious application of a cognitive schema to avoid alcohol. Sexual response studies to date have measured Type 1 and Type 2 responses separately; however, no study has yet measured both types of response within the same person. This study was the first to examine both Type 1 and Type 2 responses to erotic stimuli within the same individual as a test of within-individual variation of attentional responses to sexual stimuli. Results do not support a connection between either attentional bias or conflicting Type 1 and Type 2 responses and sexual desire or distress. Implications of these non-findings are discussed in theoretical and methodological contexts, and future research is suggested.

Doctor of Philosophy / Department of Chemistry / Viktor Chikan / Doping quantum dots to increase conductivity is a crucial step towards being able to fabricate a new generation of electronic devices built on the “bottom-up” platform that are smaller and more efficient than currently available. Indium, tin, and gallium have been used to dope CdSe in both the bulk and thin film regimes and introduce n-type electron donation to the conduction band. CdSe quantum dots have been successfully doped with indium, tin, and gallium using the Li4[Cd10Se4(SPh16)] single source precursor combined with metal chloride compounds. Doping CdSe quantum dots is shown to effect particle growth dynamics in the “heterogeneous growth regime.” Doping with indium, tin, and gallium introduce donor levels 280, 100, and 50 meV below the conduction band minimum, respectively. Thin films of indium and tin doped quantum dots show improved conductivity over films of undoped quantum dots. Transient Absorption spectroscopy indicates that indium doping introduces a new electron energy level in the conduction band that results in a 70 meV blue shift in the 1Se absorption bleach position. Novel characterization methods such as in-situ fluorescence growth monitoring, single quantum dot EDS acquisition, static and time-resolved temperature dependant fluorescence spectroscopy were developed in the course of this work as well. These results show that doping CdSe quantum dots with indium, tin, and gallium has not only been successful but has introduced new electronic properties to the quantum dots that make them superior to traditional CdSe quantum dots.

Människans förmåga att känna lukter samt känna igen ansikten är två aspekter som är viktiga för människor. I denna studie undersöktes det om obehagliga och behagliga lukter påverkar vilket emotionellt ansikte som kopplas samman med de två olika lukterna. Trettioåtta deltagare deltog i studien och experimentet genomfördes framför en dator i ett test med dot probe paradigmen. Deltagarna fick en lukt placerad under näsan och skattade sedan luktens positivitet/negativitet samt intensitet. Därefter gjordes testet med dot probe och slutligen skattades luktens intensitet ytterligare en gång samt att de skulle matchas ett emotionellt ansikte till lukten. Resultatet visade ingen signifikant skillnad mellan lukterna för dot probe, dock fanns en skillnad mellan skattningarna på lukterna före och efter dot probe.

In this thesis, novel multi-section laser diodes based on quantum-dot material are designed and investigated which exhibit a number of advantages such as low threshold current density; temperature-insensitivity and suppress carrier diffusion due to discrete nature of density of state of quantum-dots. The spectral versatility in the range of 1.1 µm – 1.3 µm wavelengths is demonstrated through novel mode-locking regimes such as dual-wavelength mode-locking, wavelength bistability and broad tunability. Moreover, broad pulse repetition rate tuning using an external cavity configuration is presented. A high peak power of 17.7 W was generated from the quantum-dot laser as a result of the tapered geometry of the gain section of the laser has led to successful application of such device for two-photon imaging. Dual-wavelength mode-locking is demonstrated via ground (?=1180 nm) and excited (?=1263 nm) spectral bands with optical pulses from both states simultaneously in the 5-layer quantum-dot two-section diode laser. The widest spectral separation of 83 nm between the modes was achieved in a dual-wavelength mode-locked non-vibronic laser. Power and wavelength bistability are achieved in a mode-locked multi-section laser which active region incorporates non-identical QD layers grown by molecular beam epitaxy. As a result the wavelength can be electronically controlled between 1245 nm and 1290 nm by applying different voltages to the saturable absorber. Mode-locked or continuous-wave regimes are observed for both wavelengths over a 260 mA – 330 mA current ranges with average power up to 28 mW and 31 mW, respectively. In mode-locked regime, a repetition rate of 10 GHz of optical pulses as short as 4 ps is observed. Noticeable hysteresis of average power for different bias conditions is also demonstrated. The wavelength and power bistability in QD lasers are potentially suitable for flip-flop memory application. In addition, a unique mode-locked regime at expense of the reverse bias with 50 nm wavelength tuning range from 1245 nm to 1290 nm is also presented. Broad repetition rate tunability is shown from quantum-dot external cavity mode-locked 1.27 µm laser. The repetition rate from record low of 191 MHz to 1 GHz from fundamental mode-locking was achieved. Harmonic mode-locking allows further to increase tuning up to 6.8 GHz (34th-order harmonic) from 200 MHz fundamental mode-locking. High peak power of 1.5 W can be generated directly from two-section 4 mm long laser with bent waveguide at angle of 7° at 1.14 GHz repetition rate without the use of any pulse compression and optical amplifier. Stable mode-locking with an average power up to 60 mW, corresponding to 25 pJ pulse energy is also obtained at a repetition frequency of 2.4 GHz. The minimum time-bandwidth product of 1.01 is obtained with the pulse duration of 8.4 ps. Novel tapered quantum-dot lasers with a gain-guided geometry operating in a passively mode-locked regime have been investigated, using structures that incorporated either 5 or 10 quantum dot layers. The peak power of 3.6 W is achieved with pulse duration of 3.2 ps. Furthermore, the record peak power of 17.7 W and transform limited pulses of 672 fs were achieved with optimized structure. The generation of picosecond pulses with high average power of up to 209 mW was demonstrated, corresponding to 14.2 pJ pulse energy. The improved optical parameters of the tapered laser enable to achieve nonlinear images of fluorescent beads. Thus it is for the first time that QD based compact monolithic device enables to image biological samples using two-photon microscopy imaging technique.

Implementation of optical refrigeration (OR) in quantum dot (QD) materials was achieved for the first time. An OR experiment was designed and carried out in our lab and a maximum temperature drop around 0.68 K was observed in the zinc-blende crystalline CdSe/CdS (core/shell structure) QD samples under laser excitation. The cooling effect was achieved by utilizing the energy up-conversion photoluminescence (PL) of CdSe/CdS QDs with sub-band excitation. While the cooling efficiency of the system was estimated and optimized by a semi-empirical model built during this research. <div><br></div><div>This work has proved the capability of QD materials to be used as a cooling substance for OR, which significantly expanded the possible candidates for OR. The technique could have many applications, such as harvesting cooling effect from sun light with the help of metamaterials, which can produce quasi-monochromatic light. It may also be used to cool QD in optical traps, which leading may help to develop new ultra-sensitive sensors and application for quantum information science.</div>

中國網路市場近兩年的火紅讓許多人注意到中國的快速成長，噹噹網作為此次的研究對象，用來深入探討整個中國網路市場的生態與環境。 此篇論文探討中國網路公司噹噹網，如何在商業模式與亞馬遜相同，並且只擁有中國市場之下，仍然可以得到投資人很好的投資評價。中國的特殊環境造就了本土公司可以打敗全球跨國公司的現象。 最後此論文提到一些對投資中國網路股的建議，希望從噹噹網近一年的表現給予投資人一些投資啟示 / This article discusses Dangdang, the Chinese Amazon.com to demonstrate the characters of Chinese internet industry. I found out that Chinese internet industry is prospering due to the overall economy growth and improved internet penetration. Albeit Dangdang has a very similar business model with Amazon, the complicated Chinese market leads Dangdang to beat Joyo/Amazon.cn in online book sales in China. In the general merchandise Dangdang wants to aim for is a huge challenge and may lead the future instability to Dangdang. The stock price correction of Dangdang and other Chinese internet companies give investors some warnings that the sustainable and profitable business model should be more important than anything. It should be very careful to invest in Chinese internet stock even the growth rate is appealing.

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