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This thesis investigates the integration of planar antennas, such as Dielectric Resonator Antennas (DRAs) to the planar waveguide structure, specifically the Substrate Integrated Waveguide (SIW) for high radiation efficiency millimeter-wave (mm-wave) applications. The SIW is a low cost and low loss technology, since it almost keeps the guided wave inside the structure. Therefore, it is an excellent candidate feeding scheme compared to traditional planar (multi-conductor) structures, such as the Microstrip Line (MSL) and Co-planar Waveguide (CPW) for many planar antennas. It enhances the antenna???s overall radiation efficiency by minimizing the conduction loss, which dominates at the mm-wave frequency band. For this thesis, two different SIW-integrated DRA configurations operating at mm-wave frequency band are presented. The rectangular DRA is excited in its fundamental mode TE??11 for radiation through a narrow slot cut on the SIW broad wall. However, the coupling slot itself is excited by the SIW TE10 fundamental mode. In addition, the design guidelines, and a parametric study is also conducted on the proposed antenna parameters to investigate their impact on the antenna???s overall performance including the reflection coefficient and radiation pattern (gain). The results are provided within this thesis. The antenna is made of low cost and low loss materials that are available commercially. It is fabricated by using a novel and simple technique, which is compatible with the Printed Circuit Board (PCB) technology. The board is treated as multi-layers composed of the SIW-layer, and DRA element(s) layer, respectively. The fabricated antenna prototypes are tested to demonstrate their validity for real microwave/mm-wave applications. Their reflection coefficients and radiation patterns are measured, and the antenna shows a boresight gain of 5.51 dB and a radiation efficiency of more than 90 % over the operating frequency band of 33-40 GHz. Antenna arrays based on the SIW integrated DRA are investigated for high gain/radiation efficiency applications. Different array configurations such as, linear (series-fed and corporate-fed) and two-dimensional (2D) arrays are presented. The series-fed DRA array is characterized by a single SIW line loaded by DRA-slot pairs, whereas the SIW-power splitter is used to form the corporate-fed DRA array, when loaded by DRA-slot pairs. While the SIW hybrid-feeding scheme (series-feed combined with corporate-feed) is used to form 2D DRA arrays. In this design, the SIW-power splitter is used to split the power equally and in-phase among the sets (rows) of SIW series fed-DRA elements (columns). A simple and generic Transmission Line (T.L.) circuit model is proposed to simplify and expedite the antenna array design process. It is used to calculate the antenna reflection coefficient and radiation pattern (gain). The T.L. model does not take the mutual coupling between the DRA elements into account, since our study shows that its less than -20 dB over the operating bandwidth. However, it is useful and faster than full-wave solvers, such as HFSS, which consumes time and memory due to the huge generated mesh. The developed T.L. circuit model is used to design the antenna array and study the impact of its main designed parameters on the antenna performance. The developed antenna array T.L. model leads to a general design methodology (guidelines). It also allows for optimum array designs for a given set of performance requirements and to have more physical insight into the SIW technology based antenna systems for mm-wave bands. The designed antenna array samples are fabricated and tested within the operating frequency band 33-40 GHz. The series-fed antenna array shows a measured boresight gain of 11.70 dB, and high radiation efficiency, which is more than 90 % over an operating frequency band of 4%. Furthermore, the measured results are compared to these calculated by the proposed T.L. circuit model and full-wave solver. A good agreement between the measured and the HFSS results are observed, especially near the frequency at which the reflection coefficient is minimum. However, some deviation is noticed between the proposed circuit model and the measured results. This deviation is attributed to the discrete nature of the SIW structure that affects the Short Circuit (SC) performance (magnitude and phase), the T.L. lengths, and the mutual coupling between any two adjacent antenna elements. All these issues are handled efficiently and are taken into account by the full-wave solver. Therefore, the measured reflection coefficient agrees with that of the HFSS, except for a very small deviation, caused by the fabrication tolerances and measurement errors. However, the proposed T.L. circuit model is still valid and can easily predict and estimate the resonance behavior and the impedance bandwidth of the proposed antenna arrays in a very short time compared with the full-wave solver.

This thesis prompt a theoretical analysis of the hybrid plasmonic waveguide (HPWG) and a TE-pass polarizer based on HPWG has been designed, fabricated and characterized. A combination of low propagation loss, high power density, and large confinement is useful for many applications. The analysis results in this thesis show that the HPWG offers a better compromise between loss and confinement as compared to pure plasmonic waveguides. Another interesting property of the HPWG is its polarization diversity. In the HPWG the transverse electric and the transverse magnetic modes reside in different layers. We have designed a very compact hybrid TE-pass polarizer using this property. The polarizer was fabricated and characterized. The device shows low insertion loss for the TE mode with a high extinction ratio at telecommunication wavelength range for a 30 µm long HPWG section. Its performance compares favorably against previously reported silicon based integrated optic TE-pass polarizers.

This thesis prompt a theoretical analysis of the hybrid plasmonic waveguide (HPWG) and a TE-pass polarizer based on HPWG has been designed, fabricated and characterized. A combination of low propagation loss, high power density, and large confinement is useful for many applications. The analysis results in this thesis show that the HPWG offers a better compromise between loss and confinement as compared to pure plasmonic waveguides. Another interesting property of the HPWG is its polarization diversity. In the HPWG the transverse electric and the transverse magnetic modes reside in different layers. We have designed a very compact hybrid TE-pass polarizer using this property. The polarizer was fabricated and characterized. The device shows low insertion loss for the TE mode with a high extinction ratio at telecommunication wavelength range for a 30 µm long HPWG section. Its performance compares favorably against previously reported silicon based integrated optic TE-pass polarizers.

Amorphous and crystalline silicon nanocomposites have been shown to act as effective “sensitizers” for erbium ions. In the present work, a series of erbium-doped (0.2 at.%) SiOx:Er films (x = 1 - 1.8) were synthesized by physical vapor deposition and subsequently annealed at temperatures ranging from 400°C to 1100°C to induce phase separation and cluster growth. Silicon nanocluster (Si-NC) and Er3+ photoluminescence intensity spectra and dynamics were investigated as a function of SiOx composition, annealing temperature, pump wavelength and power, and specimen temperature in order to determine characteristic cross-sections and to map the efficiency of the energy transfer process between Si-NCs and Er3+ ions. Additionally, two types of optical waveguides based on SiOx:Er materials were fabricated using conventional CMOS compatible microfabrication processes. Waveguide propagation losses as well as signal absorption and enhancement were investigated under pumping conditions to evaluate the use of SiOx:Er materials as amplifying media. / Communications and Signal Processing

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abstract: This thesis summarizes modeling and simulation of plasmonic waveguides and nanolasers. The research includes modeling of dielectric constants of doped semiconductor as a potential plasmonic material, simulation of plasmonic waveguides with different configurations and geometries, simulation and design of plasmonic nanolasers. In the doped semiconductor part, a more accurate model accounting for dielectric constant of doped InAs was proposed. In the model, Interband transitions accounted for by Adachi's model considering Burstein-Moss effect and free electron effect governed by Drude model dominate in different spectral regions. For plasmonic waveguide part, Insulator-Metal-Insulator (IMI) waveguide, silver nanowire waveguide with and without substrate, Metal-Semiconductor-Metal (MSM) waveguide and Metal-Insulator-Semiconductor-Insulator-Metal (MISIM) waveguide were investigated respectively. Modal analysis was given for each part. Lastly, a comparative study of plasmonic and optical modes in an MSM disk cavity was performed by FDTD simulation for room temperature at the telecommunication wavelength. The results show quantitatively that plasmonic modes have advantages over optical modes in the scalability down to small size and the cavity Quantum Electrodynamics(QED) effects due to the possibility of breaking the diffraction limit. Surprisingly for lasing characteristics, though plasmonic modes have large loss as expected, minimal achievable threshold can be attained for whispering gallery plasmonic modes with azimuthal number of 2 by optimizing cavity design at 1.55µm due to interplay of metal loss and radiation loss. / Dissertation/Thesis / M.S. Electrical Engineering 2014

Semiconductor corrugated ridge waveguide (CRW) distributed feedback (DFB) lasers offer compelling advantages over standard DFB lasers. Indeed, the use of surface gratings etched on the ridge waveguide sidewalls in CRW-DFB devices avoids any epitaxial overgrowth. This provides a considerable simplification in the fabrication process, reducing cost and time of manufacturing, and ultimately increasing yield. It offers also the potential for monolithic integration with other devices, paving the way towards low-cost and mass-production of photonics integrated circuits. In recent years, the re-consideration of growth-free DFB lasers has drawn considerable attention, particularly with the current state-of-the-art photolithography machines. In this work, we present an experimental investigation on two generations of InGaAsP/InP multiple-quantum-well (MQW) CRW-DFB lasers that have been fabricated using stepper lithography. An early developed 1310 nm CRW-DFB laser showed stable single mode with high side-mode suppression ratios (SMSR) (>50 dB), albeit with thresholds higher than anticipated. A subsequent single-mode 1550 nm CRW-DFB laser showed stable operation with SMSR (>50 dB) and narrow spectral linewidths (≤250 kHz), observed for a wide range of current injection. Besides, novel multi-electrode CRW-DFB lasers have been tested. The experimental investigation showed that narrower linewidth (<150 kHz) and wide wavelength tunability (>3 nm) have been recorded using different multi-electrode current injection configurations. The application of a time-domain modeling approach for semiconductor CRW-DFB lasers is then described for the first time. We numerically studied the effect of the radiation modes on CRW-DFB laser properties by using time-domain coupled wave equations. High-order corrugated gratings with λ/4 phase-shit were analyzed, where the degree of longitudinal spatial hole burning (LSHB) can be effectively reduced by means of fine tuning of the grating duty cycle. Additionally, we showed how the side-mode suppression ratio can be predicted depending on the device geometry.

Electromagnetic waves in the terahertz spectral range have gained significant research focus due to their applications in various fields of science. To effectively generate and integrate terahertz waves in systems, appropriate waveguide design is critical. Conventionally waveguides have been used to control the propagation of electromagnetic waves. A waveguide with low loss and dispersion is always preferred. But achieving these characteristics is quite challenging especially if operating in the terahertz spectral range. There are inherent material and geometric limitations that exist for terahertz waveguides. It is therefore important to optimize the design to enable their use in applications efficiently. This thesis investigates the characteristics of three primary terahertz waveguides based on the underlying theory and results obtained from simulations. The three waveguides are parallel-plate waveguides, two-wire waveguides, and coplanar striplines. The work in this thesis mostly focuses on coplanar striplines, optimal for building a highly efficient commercial and portable terahertz system-on-chip (TSOC). The contribution of the thesis is around the use of different types of passive components mounted on a thin commercial Silicon Nitride membrane. A bias tee is introduced which is a combination of interdigitated electrodes and a meander inductor. The length of the interdigitated electrodes and the gap between them are 55 um and 5 um, respectively. The S21 parameter for this structure ranges from -24 dB/mm at near-zero frequencies to -0.8 dB/mm at 1 THz. This indicates that the designed bias tee can appropriately block low frequencies. Split-ring resonators are also used to act as band-stop filters. The resonant frequency of the resonator depends on the radii of the split-rings. In the optimized design, the internal radius of the outer ring is 25 um and the external radius of the inner ring is 20 um. This results in a narrowband band-stop filter with its resonant frequency centered at 701 GHz. The optimized final TSOC design discussed in this work uses these passive components placed on the Silicon Nitride membrane and is shown to have a total loss that is 3 dB/mm less than any of the previous work for terahertz frequencies. / Graduate