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One of the untapped energy sources is the thermal energy available either from solar irradiance which is still not fully utilized or from the ambient heat temperature. Both resources share the nature of infrared (IR) radiation but with different range of wavelengths. The rectenna (rectifying antenna) concept is presented to harvest these IR radiations. The rectenna is simply an antenna connected to a diode. The diode has to be able to follow and rectify the ultra-fast received AC signal. This condition promotes the use of metal-insulator-metal (MIM) diodes due to their ultra-fast tunneling mechanism. The impedance matching between the diode an antenna is to be considered. The resistance practical ranges of both nano-antenna and MIM diode are generally far. The diode responsivity determines the MIM rectification capability. By building MIM diodes with multiple insulator layers the trade-off between the resistance and responsivity can be resolved. An optimization algorithm to select the qualified materials to build an MIIM diode with high responsivity and low resistance is introduced. A Ti-TiO2/ZnO-Al MIIM diode with ultra-thin oxide layers is fabricated. Also, a global optimization approach is carried out to maximize the impedance matching between the diode and the nano-antenna while improving the capacitance effect on the device’s cut-off frequency. The optimal results reveal a maximum coupling efficiency of 5.5%, a responsivity of 6.4 A/W, and a cut-off frequency of ~34 THz. A symmetric MIM metamaterial perfect absorber is introduced. The design has larger resistance than conventional nano-antennas. The near unity absorptivity is achieved through an optimization approach. A novel Chand-Bali nano-antenna that supports dual polarization and wide angle of reception is presented. The rectenna based on this nano-antenna is expected to achieve more than one magnitude of efficiency higher than ones fabricated in literature. / Thesis / Doctor of Philosophy (PhD)

Silicon photonics provides an environmentally sustainable pathway to a more robust data infrastructure. To compensate for optical power losses, methods of amplification are required; specifically, amplifiers that can fit in a small footprint for applications in data centres. Semiconductor optical amplifiers (SOA) provide such a solution, and can be fabricated using III-V ternary or quaternary materials to enhance optical signals through a device on the scale of most CMOS components. This research sought to fabricate an InGaAsP multiple quantum well semiconductor optical amplifier using the facilities in McMaster University’s Centre for Emerging Device Technologies (CEDT). A ridge waveguide laser diode was first fabricated and validated, then altered by applying an anti-reflective coating to the waveguide facets to suppress reflections in the Fabry-Perot cavity in an attempt to create an SOA. The design process and fabrication methodology are explained, including an analysis of failed methodologies. Characterization measurement techniques are then detailed for the fabricated devices. Finally, the performance of the devices is presented, and future steps are suggested for improving the fabrication process to enhance device characteristics. The fabricated laser diodes produced an output power in excess of 20 mW at a peak wavelength near 1580 nm. The subsequently coated devices proved difficult to measure, displaying a maximum of 0 dB or 1 dB gain when checked for amplification, with suspicions that output loss (and therefore gain) was higher than measured. The coated devices exhibited gain saturation between -10 and 0 dBm of input power. Owing to the shapes of their characteristic curves, it was determined that SOA devices were successfully created. / Thesis / Master of Applied Science (MASc)

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23451号 / 理博第4745号 / 新制||理||1680(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 田中 耕一郎, 教授 佐々 真一, 教授 金光 義彦 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Yes / In this work, miniaturized tunable two-antenna MIMO systems composed of printed F-slot shaped is developed to operate in the GPS, PCS, DCS and UMTS bands. The two-element MIMO antenna occupies a volume of 50 × 37.5 ×1.6 mm3, and is printed on an FR4 substrate. Initially, the frequency tunability of the MIMO antennas was verified by lumped capacitors with values between 0.75 to 2.75 pF to achieve a tuning range from 1.55 to 2.07GHz while the low mutual coupling between the radiators was accomplished by adding an I-shaped branch to a cut-away ground plane. The two antennas are then loaded with varactors to simultaneously achieve miniaturization and tunability. Simulation and measurement results demonstrate the successful implementation of a tunable MIMO with coupling reduction mechanism for a portable handheld wireless transceiver. The channel capacity of the proposed antenna is investigated and found to be close to that of an un-correlated system with efficient diversity in which the mutual coupling across the full bandwidth was better than -13dB. Owing to the compact size and ease of manufacture, the proposed antennas can be a promising solution for adaptive MIMO systems in handheld devices. / This work has been performed in the framework of ARTEMOS project under work programme ENIAC JU 2010 and FCT (Fundação para a Ciência e Tecnologia) .The authors would like to thank Datong PLC (Leeds LS18 4EG, West Yorkshire, U.K.), for their financial support of the Knowledge Transfer Partnership (KTP No: 008734).

Yes / This paper presented a new circular polarization reconfigurable antenna for 5G wireless communications. The antenna, containing a semicircular slot, was compact in size and had a good axial ratio and frequency response. Two PIN diode switches controlled the reconfiguration for both the right-hand and left-hand circular polarization. Reconfigurable orthogonal polarizations were achieved by changing the states of the two PIN diode switches, and the reflection coefficient |S11| was maintained, which is a strong benefit of this design. The proposed polarization-reconfigurable antenna was modeled using the Computer Simulation Technology (CST) software. It had a 3.4 GHz resonance frequency in both states of reconfiguration, with a good axial ratio below 1.8 dB, and good gain of 4.8 dBic for both modes of operation. The proposed microstrip antenna was fabricated on an FR-4 substrate with a loss tangent of 0.02, and relative dielectric constant of 4.3. The radiating layer had a maximum size of 18.3 18.3 mm2, with 50 W coaxial probe feeding. / European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424.

The high-voltage SiC power semiconductor devices have been developed in recent years. They cause an urgent in the need for the power semiconductor packaging to have not only low interconnect resistance, less noise, less parasitic oscillations, improved reliability, and better thermal management, but also High-Voltage (HV) blocking capability. The existing power semiconductor packaging technologies includes wire-bonding interconnect, press pack, flip-chip technology, metal posts interconnected parallel plates structure (MIPPS), dimple array interconnection (DAI), power overlay (POL) technology, and embedded power (EP) technology. None of them meets the requirements of low profile and high voltage rating. The objective of the work in this dissertation is to propose and design a high-voltage power semiconductor device packaging method with low electric field stress and low profile to meet the requirments of high-voltage blocking capability. The main contributions of the work presented in this dissertation are: 1. Understanding the electric field distribution in the package. The power semiconductor packaging is simulated by using Finite Element Analysis (FEA) software. The electric field distribution is known and the locations of high electric field concentration are identified. 2. Development of planar high-voltage power semiconductor device packaging method With the proposed structure in the dissertation, the electric field distribution of a planar device package is improved and the high electric field intensity is relieved. 3. Development of design guidelines for the propsed planar high-voltage device packaging method. The influence of the structure dimensions and the material properties is studied. An optimal design is identified. The design guideline is given. 4. Fabrication and experimental verification of the proposed high-voltage device packaging method A detailed fabrication procedure which follows the design guideline is presented. The fabricated modules are tested by using a high power curve tracer. Test results verify the proposed method. 5. Simplification of the structure model of the proposed device package The package structure model is simplified through the elimination of power semiconductor device internal structure model. The simplified model can be simulated by a non-power device simulator. The simulation results of the simplified model match the simulation results of the complete model very well. / Ph. D.

Yes / A frequency tunable planar inverted F antenna (PIFA) is presented for use in the following bands: DCS, PCS, and UMTS. Initially, the tuning was achieved by placing a lumped capacitor, with values in the range of 1.5 to 4 pF, along the slot of the radiator. The final tuning circuit uses a varactor diode, and discrete lumped elements are fully integrated with the antenna. The antenna prototype is tunable over from 1850 MHz to 2200 MHz, with an associated volume of 21×13.5×5 mm3, making it suitable for potential integration in a commercial handset or mobile user terminal.