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This project successfully designed, fabricated and characterized two highly reflective distributed Bragg reflectors for use with long wavelength vertical cavity surface emitting lasers. The first reflector consisted of 20 pairs of alternating lnP/Ino.64Gao.36Aso.777Po.223 layers grown on an InP substrate with a theoretically predicted normal incident reflectivity of 96.6% at a center wavelength of 1550nm. The second DBR had 20 pairs of alternating GaAs/Ino.484Gao.5i6P layers grown on a GaAs substrate with a theoretically predicted reflectivity of 94.9% at a center wavelength of 1550nm for normal incident light. Experimental results obtained using a specially designed reflectivity measurement setup confirmed reflectivity models and predictions at both normal and variable incident light angles. However, these measurements revealed a discrepancy between theoretical and experimental layer thickness values for both DBR structures. Applying perturbations to the theoretical models, the actual layer thicknesses of the DBRs were determined. X-ray analysis was employed to examine the periodicity of the super-lattices along with the accuracy of lattice matching to the substrate. Transmission electron microscopy revealed that no detectable drift in layer thickness was apparent during growth of the DBR structures. Photoluminescence was used to investigate any compositional variations of the quaternary layers in the first DBR stack. / Thesis / Master of Applied Science (MASc)

The number of people who flee their countries because of armed conflicts increased dramatically. Recently, Sweden received a higher number of refugees than before. The issue of integration of these new refugees into the host society is a challenging process and still open for debate. The field of cross-cultural studies has paid great attention to post-migration experiences. Therefore, the integration of refugees into a new society is a complex process. It’s not limited to the receiving countries’ policies, several aspects such as social and cultural characteristics of the refugees have to be taken into consideration.  In this regard, the research aims to explore the acculturation process from the perspective of highly educated Arabic-speaking refugees who recently settled in Sweden. The data has been collected using semi-structured interviews. The research used Berry’s acculturation model and the related theoretical frameworks to discuss the integration of highly educated Arabic-speaking refugees. The results revealed that the participants adopted the integration strategy, they appreciate their home culture while they are highly interested to interact with the host society. Labor market entry and Swedish language proficiency were the major challenges faced by the participants to integrate into the Swedish society. The findings of this research can be used by policymakers, the labor market, and social workers to understand the refugees’ attitudes when designing integration tools and interventions for highly educated refugees.

In 2008, Sweden changed its labor migration legislation and allowed for labor migrants from non EU/EEA countries to migrate to Sweden, which had been heavily restricted since the 1970s. This shift in labor migration policy is mirrored in Swedish integration policy where the focus in recent years has been on labor market integration. This thesis aims to investigate the sociocultural integration of migrants who are employed and, in the Swedish context, assumed to be integrated. In addition, sociocultural integration is related to employment and length of stay. Sociocultural integration is measured by three indicators: knowledge of Swedish language, having Swedish friends, and membership in organizations. The data was collected through sixteen semi-structured interviews of highly educated migrants with employment in Sweden and analyzed using four integration theories.The study reveals that employed migrants are only partially socioculturally integrated. Respondents presented low levels of Swedish-language knowledge, which can be explained by their short stay in the country as well having international workplaces where mostly English is spoken. However, these workplaces also offer respondents opportunities to meet natives and most respondents met their Swedish friends through work. There is a need for further studies of integration, in particular those that would explore multiple dimensions of integration and incorporate migrants who are already economically integrated.

Silicones are industrially important polymers characterized by a wide spectrum of chemical and physical properties with a number of important applications including automotive components, construction materials, isolating parts in electronic devices, flexible electronics, and medical products. Development of additive manufacturing methods for silicones enable production of complex and custom designed shapes and structures at both the micro- and macro-scale, economically feasible. In general, such materials can be fabricated using stereolithographic, extrusion-based, or inkjet printing techniques, in which silicones are polymerized using either photo- or heat-initiators. Silicones can also be crosslinked based on chemical reactions. Although this approach is supposedly the simplest, it has not been widely applied in additive manufacturing, as suitable technology for mixing and curing reactive inks without clogging nozzles has not be developed yet. To address this issue, a new 3D printer, that enables the fabrication of highly reactive and low viscous materials, has been developed and tested experimentally. The proposed fabrication method involves the ejection of two reactive droplets simultaneously from individual dispensers, merging and mixing them in free space outside the nozzle followed by deposition of the merged drop in a patterned format on a substrate. It was shown that the printing process is robust and stable more than 4 hours and it can be used on demand. By incorporating an XYZ positioner, it was possible to deposit droplets in an overlapping fashion to print any programmable shape featuring homogeneous structure, with a small number of pores. Moreover, due to the almost instantaneous reaction between two components (< 10s), the fabrication of very high aspect ratio (AR > 50) objects is possible. Lastly, the presented method can be easily adapted to print in free space without the use of support materials. / Thesis / Master of Applied Science (MASc)

Yes / In this paper, we present the design of a compact and highly sensitive microwave sensor based on a metamaterial complementary split-ring resonator (CSRR), for liquid characterization at microwave frequencies. The design consists of a two-port microstrip-fed rectangular patch resonating structure printed on a 20 × 28 mm2 Roger RO3035 substrate with a thickness of 0.75 mm, a relative permittivity of 3.5, and a loss tangent of 0.0015. A CSRR is etched on the ground plane for the purpose of sensor miniaturization. The investigated liquid sample is put in a capillary glass tube lying parallel to the surface of the sensor. The parallel placement of the liquid test tube makes the design twice as efficient as a normal one in terms of sensitivity and Q factor. By bending the proposed structure, further enhancements of the sensor design can be obtained. These changes result in a shift in the resonant frequency and Q factor of the sensor. Hence, we could improve the sensitivity 10-fold compared to the flat structure. Subsequently, two configurations of sensors were designed and tested using CST simulation software, validated using HFSS simulation software, and compared to structures available in the literature, obtaining good agreement. A prototype of the flat configuration was fabricated and experimentally tested. Simulation results were found to be in good agreement with the experiments. The proposed devices exhibit the advantage of exploring multiple rapid and easy measurements using different test tubes, making the measurement faster, easier, and more cost-effective; therefore, the proposed high-sensitivity sensors are ideal candidates for various sensing applications. / This work was supported by the Moore4Medical project, funded within ECSEL JU in collaboration with the EU H2020 Framework Programme (H2020/2014–2020) under grant agreement H2020-ECSEL-2019-IA-876190, and the Fundação para a Ciência e Tecnologia (ECSEL/0006/2019). This project received funding in part from the DGRSDT (Direction Générale de la Recherche Scientifique et du Développement Technologique), MESRS (Ministry of Higher Education and Scientific Research), Algeria. This work was also supported by the General Directorate of Scientific Research and Technological Development (DGRSDT)–Ministry of Higher Education and Scientific Research (MESRS), Algeria, and funded by the FCT/MEC through national funds and, when applicable, co-financed by the ERDF, under the PT2020 Partnership Agreement under the UID/EEA/50008/2020 project.

An A2 + B3 polymerization for the synthesis of hyperbranched polymers was altered using oligomeric precursors in place of either one or both of the monomer pairs to synthesize highly branched macromolecules. Unique topologies that are intermediates between long-chain branched and hyperbranched structures were obtained and the term "highly branched" was used to define these novel architectures. Various types of highly branched polymers, such as polyurethanes, poly(urethane urea)s, poly(ether ester)s, and poly(arylene ether)s were synthesized using the oligomeric A2 + B3 strategy. The molar mass of the oligomeric precursor permitted the control of the molar mass between branch points, which led to interesting macromolecular properties, such as superior mechanical performance to conventional hyperbranched polymers, disrupted crystallinity, improved processibility, and a multitude of functional end groups. Highly branched poly(urethane urea)s and polyurethanes exhibited microphase-separated morphologies as denoted by dynamic mechanical analysis. The similarity in soft segment glass transition behavior and mechanical properties of the branched systems with that of the linear analogues suggested these materials have considerable promise for a variety of applications. When a polycaprolactone triol was utilized as the B3 oligomer for the synthesis of highly branched polyurethane elastomers, the high degree of branching resulted in a completely amorphous soft segment, whereas the linear analogue with equivalent soft segment molar mass retained the crystallinity of polycaprolactone segment. Oligomeric A2 + B3 methodology was further utilized to tailor the degree of branching of poly(ether ester)s that were developed based on slow addition of dilute solution of poly(ethylene glycol) (PEG) (A2) to a dilute solution of 1,3,5-benzenetricarbonyl trichloride (B3) at room temperature in the presence of triethylamine. A revised definition of the degree of branching was proposed to accurately describe the branched poly(ether ester)s and the degree of branching decreased as the molar mass of the PEG diols was increased. Moreover, branched poly(arylene ether)s were prepared via a similar oligomeric A2 + B3 polymerization of phenol endcapped telechelic poly(arylene ether sulfone) oligomers (A2) and tris(4-fluorophenyl) phosphine oxide (B3) in solution. Highly branched poly(ether ester)s were also synthesized in the melt phase using the oligomeric A2 + B3 polymerization strategy. Melt polymerization effectively limited the cyclization reactions, which are common in A2 + B3 polymerizations in solution, and overcame the need for large amounts of polymerization solvent typical of A2 + B3 systems. Finally, a new family of telechelic polyester ionomers was synthesized based on phosphonium bromide salt end groups and branching allowed the incorporation of higher levels of ionic end groups compared to linear analogues. / Ph. D.

This thesis presents a novel technique named "Core Suction" for fabricating optical fiber preforms for manufacturing highly doped fibers (HDFs) for optical amplification (Raman effect based or Erbium fiber based). The technique involves drawing the molten non-conventional core glass material into the silica cladding tube to form the preform. The developed technique is simple, inexpensive and shows great potential for fabricating preforms of highly nonlinear non-conventional multi-component glasses as the core material. Preforms were made with various core glasses such as Schott SF6, Lead-Tellurium-Germanate, Lead-Tellurium-Germanate- Neodymium -Erbium and MM2 in silica cladding tubes and then pulled into fibers. The fabricated fibers were measured for refractive index profile, loss spectrum and spontaneous Raman spectra. Elemental analysis of the fiber samples was also performed using an electron microprobe. Erbium doped fiber amplifiers (EDFAs) were setup using 30 cm, 5cm and 1 cm lengths of fabricated erbium doped fibers and their gain spectra measured. The distributed gain spectrum for an EDFA was also measured using an optical frequency domain reflectometery (OFDR) technique. Commercial dispersion compensated fiber (DCF) with very high GeO2 doping was used to setup a Raman amplifier and the gain spectrum measured. One of the needs of Raman amplification in optical fibers is to predict an accurate Raman gain, based on the fiber's refractive index profile. A method of predicting Raman gain in GeO2 doped fibers is presented and the predicted Raman gain values are compared with the measured ones in the same fibers. Raman gain issues like the dependence of the Raman gain on the GeO2 concentration, polarization dependence were taken into account for the gain calculations. An experimental setup for Raman gain measurements was made and measurement issues addressed. Polarization dependence of the Raman gain in one kilometer of polarization maintaining fiber was also measured. / Ph. D.

The increasing demand for high data rate devices and many applications in short range high speed communication, attract many RF IC designers to work on 24-GHz transceiver design. The Federal Communication Commission (FCC) also dedicates the unlicensed 24-GHz band for industrial, science, and medical applications to overcome the interference in overcrowded communications and have higher output signal power. LNA is the first building of the receiver and is a very critical building block for the overall receiver performance. The total NF and sensitivity of the receiver mainly depends on the LNAs NF that mandates a very low NF LNA design. Depending on its gain, the noise figure of the next stages can relax. However, the high gain of an LNA enforces the next stages to be more linear since they suffer from larger signal at their input stage and can get saturated easily. Apparently, designing high gain, low noise, and highly linear LNA is very stimulating. In this thesis, a wideband LNA with low noise figure and high linearity has been designed in 8XP 0.13-um SiGe BiCMOS IBM technology. The highlight of this design is proposing the peaking technique, which results in considerable linearity improvement. Loading the LNA with class AB amplifier, power gain experiences a peaking in high input signal swing levels. The next stager after the LNA is the buffer to provide isolation between the LNA and mixer, and also avoid loading of the LNA from the mixer. Instead of using popular emitter follower architecture, another circuit is proposed to have higher gain and linearity. This buffer has two separate out of phase inputs, coming from the LNA and are combined constructively at the output of the buffer. Since the frequency of this design is high, electromagnetic (EM) simulation for pads, interconnects, transmission lines, inductors, and coplanar transmission lines has been completed using Sonnet cad tool to consider all the parasitic and coupling effects. Considering all the EM effects, the LNA has 15 dB gain with 2.9 dB NF and -8.8 dBm input 1-dB compression point. The designed LNA is wideband, covering the frequency range of 12-GHz to 31-GHz. However, the designed LNA, has the capability of having higher gain at the expense of lower linearity and narrower frequency band using different control voltage. As an example peak gain of 29.3 dB at the 3-dB frequency range of 23.8 to 25.8-GHz can be achieved, having 2.3 dB noise figure and -17 dBm linearity. / Master of Science