The Photonic Crystal (PC) is a potential candidate for a compact optical integrated circuit on a solid state platform. The fabrication process of a PC is compatible with CMOS technology; thus, it could be potentially employed in hybrid optical and electrical integrated circuits. One of the main obstacles in the implementation of an integrated optical circuit is the polarization dependence of wave propagation. Our goal is to overcome this obstacle by implementing PC based polarization controlling devices. One of the crucial elements of polarization controlling devices is the polarization rotator. The polarization rotator is utilized to manipulate and rotate the polarization of light. In this thesis, we have proposed, designed and implemented an ultra-compact passive PC based polarization rotator. Passive polarization rotator structures are mostly composed of geometrically asymmetric structures. The polarization rotator structure consists of a single defect line PC slab waveguide. The geometrical asymmetry has been introduced on top of the defect line as an asymmetric loaded layer. The top loaded layer is asymmetric with respect to the z-axis propagation direction. To synchronize the power conversion and avoid power conversion reversal, the top loaded layer is alternated around the z-axis periodically. The structure is called periodic asymmetric loaded PC slab waveguide. Due to the compactness of the proposed structure, a rigorous numerical method, 3D-FDTD can be employed to analyze and simulate the final designed structure. For the quick preliminary design, an analytical method that provides good approximate values of the structural parameters is preferred. Coupled-mode theory is a robust and well-known method for such analyses of perturbed waveguide structures. Thus, a coupled-mode theory based on semi-vectorial modes was developed for propagation modeling on square hole PC structures. In essence, we wish to develop a simple yet closed form method to carry out the initial design of the device of interest. In the next step, we refined the design by using rigorous but numerically expensive 3D-FDTD simulations. We believe this approach leads to optimization of the device parameters easily, if desired. To extend the design to a more general shape PC based polarization rotator, a design methodology based on hybrid modes of asymmetric loaded PC slab waveguide was introduced. The hybrid modes of the structure were calculated utilizing the 3D-FDTD method combined with the Spatial Fourier Transform (SFT). The propagation constants and profile of the slow and fast modes of an asymmetric loaded PC slab waveguide were extracted from the 3D-FDTD simulation results. The half-beat length, which is the length of each loaded layer, and total number of the loaded layers are calculated using the aforementioned data. This method provides the exact values of the polarization rotator structure’s parameter. The square hole PC based polarization rotator was designed employing both coupled-mode theory and normal modal analysis for THz frequency applications. Both design methods led to the same results. The design was verified by the 3D-FDTD simulation of the polarization rotator structure. For a square hole PC polarization rotator, a polarization conversion efficiency higher than 90% over the propagation distance of 12 λ was achieved within the frequency band of 586.4-604.5 GHz corresponding to the normalized frequency of 0.258-0.267. The design was extended to a circular hole PC based polarization rotator. A polarization conversion efficiency higher than 75% was achieved within the frequency band of 600-604.5 GHz. The circular hole PC polarization rotator is more compact than the square-hole PC structure. On the other hand, the circular hole PC polarization rotator is narrow band in comparison with the square hole PC polarization rotator. In a circular hole PC slab structure, the Bloch modes (fast and slow modes) couple energy to the TM-like PC slab modes. In both square and circular hole PC slab structures with finite number of rows, and the TM-like PC slab modes are extended to the lower edge of the bandgap. In bandgap calculation using PWEM, it is assumed that the PC structure is extended to infinity, however in practice the number of rows is limited, which is the source of discrepancy between the bandgap calculation using PWEM and 3D-FDTD. In an asymmetric loaded circular hole PC slab waveguide, the leaky TM-like PC slab modes are extended deep inside the bandgap and overlapped with both the slow and fast Bloch modes; whereas, in an asymmetric loaded square hole PC slab waveguide, the leaky TM-like PC slab modes are below the frequency band of slow and fast modes. Therefore, TM-like PC slab modes have significantly more adverse effect on the performance of the circular-hole based polarization rotator leading to a narrow band structure. SOI based PC membrane technology for THz application was developed. The device layer is made of highly resistive silicon to maintain low loss propagation for THz wave. The PC slab waveguide and polarization rotators were fabricated employing this technology. Finally, an a-SiON PC slab waveguide structures were also fabricated at low temperature for optical applications. This technology has the potential to be implemented on any substrate or CMOS chips.

A measurement of J/\Psi polarization has been performed for 200 GeV proton+proton collisions with the PHENIX Muon Arms at RHIC. The results from the current data show no polarization within the PHENIX acceptance range. The results are consistent with the current model predictions and other experimental measurements.

Polymers are very attractive materials that can be tailored for specific needs and functionalities. Based on their chemical structure, they can for instance be made electrically insulating or semiconducting with specific mechanical properties. Polymers are often processable from a solution, which enables the use of conventional low-cost and high-volume manufacturing techniques to print electronic devices onto flexible substrates. A multitude of polymer-based electronic and electrochemical devices and sensors have been developed, of which some already has reached the consumer market. This thesis focuses on polarization characteristics in polyelectrolyte-based capacitor structures and their role in sensors, transistors and supercapacitors. The fate of the ions in these capacitor structures, within the polyelectrolyte and at the interfaces between the polyelectrolyte and various electronic conductors (a metal, a semiconducting polymer or a network of carbon nanotubes), is of outermost importance for the device function. The humidity-dependent polarization characteristics in a polyelectrolyte capacitor are used as the sensing probe for wireless readout of a passively operated humidity sensor circuit. This sensor circuit can be integrated into a printable low-cost passive sensor label. By varying the humidity level, limitations and possibilities are identified for polyelectrolyte-gated organic field-effect transistors. Further, the effect of the ionic conductivity is investigated for polyelectrolyte-based supercapacitors. Finally, by using an ordinary electrolyte instead of a polyelectrolyte and a high-surface area (supercapacitor) gate electrode, the device mechanisms proposed for electrolyte-gated organic transistors are unified.

The polarization behaviour for six species of Scarab beetles from the Chrysina genus is investigated with Mueller Matrix Spectroscopic Ellipsometer (MMSE). The m41 element of the matrix, which is related to the circular polarization behaviour, is analysed. The ellipticity, degree of polarization and azimuth angle are also presented to get a better understanding of the polarization effect. The measurements were done with a dual rotating compensator ellipsometer. The measured wavelength region was from 240 to 1000 nm and the angle of incidence from 25° to 75° in most of the cases. In general very high ellipticities (near circular) are reported. All specimens studied reflect both right- and left-handed polarized light. Depending on the species, two general types of polarization behaviour were observed. Chrysina macropus and Chrysina peruviana showed m41 values close to 0. Green stripes on Chrysina gloriosa showed similar polarization behaviour whereas gold stripes on the same beetle had much more pronounced m41 variations. Large m41 variations were also observed for Chrysina argenteola, Chrysina chrysargyrea and Chrysina resplendens. Four specimens of Chrysina resplendens show different m41 patterns suggesting differences in their structures.

Light reflected from the scarab beetles Cetonia aurata (C. aurata) and Chrysina gloriosa (C. gloriosa) has left-handed polarization. In this work the polarizing properties and structural characteristics of the cuticles of these two beetles are investigated with two different techniques: scanning electron microscopy (SEM) and Mueller-matrix spectroscopic ellipsometry (MMSE). SEM is used to get cross section images of the epicutucle and the endocuticle. Thicknesses around 18 μm were measured for both layers for C. aurata and between 12 and 16 μm for C. gloriosa. A layered structure is observed in both beetles. In addition, a cusp-like structure is also observed in C. gloriosa. MMSE showed left-handed near-circular polarization of light reflected on both beetles. For C. aurata this is observed in a narrow wavelength range (500-600 nm) and for C. gloriosa in a wider wavelength range (400-700 nm) when measured on golden areas of the cuticle. C. gloriosa also has green areas where the reflected light was linearly polarized. The results are used in regression modelling. A good model approximation was found for C. aurata for angles up to 60 whereas a good starting point for future work was reached for C. gloriosa.

This thesis describes the design, development, and implementation of a pulsed source of polarization-entangled photons using spontaneous parametric down-conversion in a Sagnac interferometer. A tangle of 0.9286 ± 0.0015, fidelity to the state (|10〉 + |01〉)/√2 of 0.9798 ± 0.0004 and a brightness of 597 pairs/s/mW were demonstrated. Spontaneous parametric down-conversion is a nonlinear optical process in which one photon is split into two lower-frequency photons while conserving momentum and energy, in this experiment nearly degenerate photons are produced. These photons are then interfered at the output beamsplitter of the interferometer, exchanging path entanglement for polarization entanglement and generating the desired polarization-entangled photon pairs.

The Photonic Crystal (PC) is a potential candidate for a compact optical integrated circuit on a solid state platform. The fabrication process of a PC is compatible with CMOS technology; thus, it could be potentially employed in hybrid optical and electrical integrated circuits. One of the main obstacles in the implementation of an integrated optical circuit is the polarization dependence of wave propagation. Our goal is to overcome this obstacle by implementing PC based polarization controlling devices. One of the crucial elements of polarization controlling devices is the polarization rotator. The polarization rotator is utilized to manipulate and rotate the polarization of light. In this thesis, we have proposed, designed and implemented an ultra-compact passive PC based polarization rotator. Passive polarization rotator structures are mostly composed of geometrically asymmetric structures. The polarization rotator structure consists of a single defect line PC slab waveguide. The geometrical asymmetry has been introduced on top of the defect line as an asymmetric loaded layer. The top loaded layer is asymmetric with respect to the z-axis propagation direction. To synchronize the power conversion and avoid power conversion reversal, the top loaded layer is alternated around the z-axis periodically. The structure is called periodic asymmetric loaded PC slab waveguide. Due to the compactness of the proposed structure, a rigorous numerical method, 3D-FDTD can be employed to analyze and simulate the final designed structure. For the quick preliminary design, an analytical method that provides good approximate values of the structural parameters is preferred. Coupled-mode theory is a robust and well-known method for such analyses of perturbed waveguide structures. Thus, a coupled-mode theory based on semi-vectorial modes was developed for propagation modeling on square hole PC structures. In essence, we wish to develop a simple yet closed form method to carry out the initial design of the device of interest. In the next step, we refined the design by using rigorous but numerically expensive 3D-FDTD simulations. We believe this approach leads to optimization of the device parameters easily, if desired. To extend the design to a more general shape PC based polarization rotator, a design methodology based on hybrid modes of asymmetric loaded PC slab waveguide was introduced. The hybrid modes of the structure were calculated utilizing the 3D-FDTD method combined with the Spatial Fourier Transform (SFT). The propagation constants and profile of the slow and fast modes of an asymmetric loaded PC slab waveguide were extracted from the 3D-FDTD simulation results. The half-beat length, which is the length of each loaded layer, and total number of the loaded layers are calculated using the aforementioned data. This method provides the exact values of the polarization rotator structure’s parameter. The square hole PC based polarization rotator was designed employing both coupled-mode theory and normal modal analysis for THz frequency applications. Both design methods led to the same results. The design was verified by the 3D-FDTD simulation of the polarization rotator structure. For a square hole PC polarization rotator, a polarization conversion efficiency higher than 90% over the propagation distance of 12 λ was achieved within the frequency band of 586.4-604.5 GHz corresponding to the normalized frequency of 0.258-0.267. The design was extended to a circular hole PC based polarization rotator. A polarization conversion efficiency higher than 75% was achieved within the frequency band of 600-604.5 GHz. The circular hole PC polarization rotator is more compact than the square-hole PC structure. On the other hand, the circular hole PC polarization rotator is narrow band in comparison with the square hole PC polarization rotator. In a circular hole PC slab structure, the Bloch modes (fast and slow modes) couple energy to the TM-like PC slab modes. In both square and circular hole PC slab structures with finite number of rows, and the TM-like PC slab modes are extended to the lower edge of the bandgap. In bandgap calculation using PWEM, it is assumed that the PC structure is extended to infinity, however in practice the number of rows is limited, which is the source of discrepancy between the bandgap calculation using PWEM and 3D-FDTD. In an asymmetric loaded circular hole PC slab waveguide, the leaky TM-like PC slab modes are extended deep inside the bandgap and overlapped with both the slow and fast Bloch modes; whereas, in an asymmetric loaded square hole PC slab waveguide, the leaky TM-like PC slab modes are below the frequency band of slow and fast modes. Therefore, TM-like PC slab modes have significantly more adverse effect on the performance of the circular-hole based polarization rotator leading to a narrow band structure. SOI based PC membrane technology for THz application was developed. The device layer is made of highly resistive silicon to maintain low loss propagation for THz wave. The PC slab waveguide and polarization rotators were fabricated employing this technology. Finally, an a-SiON PC slab waveguide structures were also fabricated at low temperature for optical applications. This technology has the potential to be implemented on any substrate or CMOS chips.

This thesis has two focuses. The major focus is an investigation of the nature of high-velocity ~2 km/s)ionospheric flows occasionally detected by the King Salmon SuperDARN radar at relatively low magnetic latitudes of 65^0. The second focus is a validation work on the quality of SuperDARN convection measurements. As an alternative convection-monitoring instrument, an ion drift meter onboard the DMSP satellite was chosen for comparison with SuperDARN. This study includes a broad range of velocities of up to ~1.5 km/s. Consideration of very large velocities is fundamentally important for successful research on the major topic of the thesis.<p>The validation work is performed first. Two approaches are undertaken. The first approach considers data at the raw level. SuperDARN F region line-of-sight velocities are directly compared with DMSP cross-track ion drifts in approximately the same directions. More than 200 satellite passes over the fields of view of five Northern Hemisphere and four Southern Hemisphere radars are considered. It is shown that all radars exhibit overall consistency with DMSP measurements and a linear fit line to the data has a slope of 0.8 with a tendency for SuperDARN velocities to be smaller. Radar echo range effects and the role of spatial inhomogeneity and temporal variations of the convection pattern are investigated. SuperDARN convection maps were generated for select events for which SuperDARN l-o-s data agree almost ideally with DMSP measurements.<p>Convection maps were obtained using all Northern Hemisphere SuperDARN radars. The full convection vectors were found to be in reasonable agreement with the DMSP ion drifts, although a small deterioration (~10%) was noticed. The overall agreement between SuperDARN and DMSP measurements implies SuperDARN observations are reliable for velocity magnitudes of up to ~1.5 km/s, and SuperDARN radars are suitable instruments for studying extremely fast ionospheric flows. These results also imply that radar measurements can be merged with DMSP measurements into a common data set to provide more reliable convection maps.<p>For the main focus of the thesis, a statistical investigation of the King Salmon radar echoes was performed to determine typical echo characteristics and compare them with data from other SuperDARN radars. It is shown that King Salmon regularly observes high-velocity echoes in the dusk sector at ~21:00 MLT and ~65^0 MLat. Individual events are presented with line-of-sight velocities (observed with the L-shell aligned beams) as high as 2 km/s. Statistically, the enhanced flows are the largest and cover the greatest area in the winter and are the smallest and cover the least area in the summer. Similar fast flows were discovered in the Unwin radar data (in the Southern Hemisphere, lowest magnetic latitude ~57^0) that became available near the completion time of this thesis. It is also shown that statistically, the Stokkseyri radar, which observes in the auroral zone and has a similar azimuthal orientation as King Salmon, does not observe similar high-velocity echoes. Geophysical conditions for the onset of high-velocity King Salmon flows in several individual events are then investigated. It is shown that fast flows are excited in close association with substorm progression near the King Salmon field of view. By comparing SuperDARN data with optical images obtained from the IMAGE satellite and particle data from the DMSP satellites it is shown that velocity enhancement begins at substorm onset and peaks 20-50 minutes later over a range of latitudes including the auroral and sub-auroral regions. During the substorm recovery phase, as bright aurora shifts poleward, exceptionally fast flows can be excited at the equatorial edge of the electron auroral oval and these flows can be classified as sub-auroral polarization stream (SAPS) flows. Variability of SAPS flows and their relationship to auroral oval processes are discussed. Finally, several suggestions for further research are presented.

I present numerical simulations of intensity and degree of polarization of light reflected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few different phase angles and a few different points on the planet. At this stage the aim is to show the working code and test a few different set ups of the star-planet system in order to find preferable configurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneficial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.

We study the spin polarization and conductance in infinitely long quasi one-dimensionalquantum wires under various conditions in an attempt to reproduce and to explain some of theanomalous conductance features as seen in various experiments. In order to accomplish thistask we create an idealized model of a quantum wire in a split-gate semiconductorheterostructure and we perform self-consistent Hartree-Fock calculations to determine theelectron occupation and spin polarization. Based on those results we calculate the currentthrough the wire as well as the direct and differential conductances. In the frame of theproposed model the results show a high degree of similarity to some of the experimentallyobserved conductance features, particularly the 0.25- and 0.85-plateaus. These results lead usto the conclusion that those conductance anomalies are in fact caused by the electronsspontaneously polarizing due to electron-electron interactions when an applied potentialdrives a current through the wire.