ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Yu, Hongbin
Description
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.
ContributorsWang, Haotong (Author) / Ning, Cunzheng (Thesis advisor) / Palais, Joseph (Committee member) / Yu, Hongbin (Committee member) / Arizona State University (Publisher)
Created2014
Description
Nanolasers represents the research frontier in both the areas of photonics and nanotechnology for its interesting properties in low dimension physics, its appealing prospects in integrated photonics, and other on-chip applications. In this thesis, I present my research work on fabrication and characterization of a new type of nanolasers: metallic cavity nanolasers. The last ten years witnessed a dramatic paradigm shift from pure dielectric cavity to metallic cavity in the research of nanolasers. By using low loss metals such as silver, which is highly reflective at near infrared, light can be confined in an ultra small cavity or waveguide with sub-wavelength dimensions, thus enabling sub-wavelength cavity lasers. Based on this idea, I fabricated two different kinds of metallic cavity nanolasers with rectangular and circular geometries with InGaAs as the gain material and silver as the metallic shell. The lasing wavelength is around 1.55 μm, intended for optical communication applications. Continuous wave (CW) lasing at cryogenic temperature under current injection was achieved on devices with a deep sub-wavelength physical cavity volume smaller than 0.2 λ3. Improving device fabrication process is one of the main challenges in the development of metallic cavity nanolasers due to its ultra-small size. With improved fabrication process and device design, CW lasing at room temperature was demonstrated as well on a sub-wavelength rectangular device with a physical cavity volume of 0.67 λ3. Experiments verified that a small circular nanolasers supporting TE¬01 mode can generate an azimuthal polarized laser beam, providing a compact such source under electrical injection. Sources with such polarizations could have many special applications. Study of digital modulation of circular nanolasers showed that laser noise is an important factor that will affect the data rate of the nanolaser when used as the light source in optical interconnects. For future development, improving device fabrication processes is required to improve device performance. In addition, techniques need to be developed to realize nanolaser/Si waveguide integration. In essence, resolving these two critical issues will finally pave the way for these nanolasers to be used in various practical applications.
ContributorsDing, Kang (Author) / Ning, Cun-Zheng (Thesis advisor) / Yu, Hongbin (Committee member) / Palais, Joseph (Committee member) / Zhang, Yong-Hang (Committee member) / Arizona State University (Publisher)
Created2014
Description
Nanowires are one-dimensional (1D) structures with diameter on the nanometer scales with a high length-to-diameter aspect ratio. Nanowires of various materials including semiconductors, dielectrics and metals have been intensively researched in the past two decades for applications to electrical and optical devices. Typically, nanowires are synthesized using the vapor-liquid-solid (VLS) approach, which allows defect-free 1D growth despite the lattice mismatch between nanowires and substrates. Lattice mismatch issue is a serious problem in high-quality thin film growth of many semiconductors and non-semiconductors. Therefore, nanowires provide promising platforms for the applications requiring high crystal quality materials.
With the 1D geometry, nanowires are natural optical waveguides for light guiding and propagation. By introducing feedback mechanisms to nanowire waveguides, such as the cleaved end facets, the nanowires can work as ultra-small size lasers. Since the first demonstration of the room-temperature ultraviolet nanowire lasers in 2001, the nanowire lasers covering from ultraviolet to mid infrared wavelength ranges have been intensively studied. This dissertation focuses on the optical characterization and laser fabrication of two nanowire materials: erbium chloride silicate nanowires and composition-graded CdSSe semiconductor alloy nanowires.
Chapter 1 – 5 of this dissertation presents a comprehensive characterization of a newly developed erbium compound material, erbium chloride silicate (ECS) in a nanowire form. Extensive experiments demonstrated the high crystal quality and excellent optical properties of ECS nanowires. Optical gain higher than 30 dB/cm at 1.53 μm wavelength is demonstrated on single ECS nanowires, which is higher than the gain of any reported erbium materials. An ultra-high Q photonic crystal micro-cavity is designed on a single ECS nanowire towards the ultra-compact lasers at communication wavelengths. Such ECS nanowire lasers show the potential applications of on-chip photonics integration.
Chapter 6 – 7 presents the design and demonstration of dynamical color-controllable lasers on a single CdSSe alloy nanowire. Through the defect-free VLS growth, engineering of the alloy composition in a single nanowire is achieved. The alloy composition of CdSxSe1-x uniformly varies along the nanowire axis from x=1 to x=0, giving the opportunity of multi-color lasing in a monolithic structure. By looping the wide-bandgap end of the alloy nanowire through nanoscale manipulation, the simultaneous two-color lasing at green and red colors are demonstrated. The 107 nm wavelength separation of the two lasing colors is much larger than the gain bandwidth of typical semiconductors. Since the two-color lasing shares the output port, the color of the total lasing output can be controlled dynamically between the two fundamental colors by changing the relative output power of two lasing colors. Such multi-color lasing and continuous color tuning in a wide spectral range would eventually enable color-by-design lasers to be used for lighting, display and many other applications.
With the 1D geometry, nanowires are natural optical waveguides for light guiding and propagation. By introducing feedback mechanisms to nanowire waveguides, such as the cleaved end facets, the nanowires can work as ultra-small size lasers. Since the first demonstration of the room-temperature ultraviolet nanowire lasers in 2001, the nanowire lasers covering from ultraviolet to mid infrared wavelength ranges have been intensively studied. This dissertation focuses on the optical characterization and laser fabrication of two nanowire materials: erbium chloride silicate nanowires and composition-graded CdSSe semiconductor alloy nanowires.
Chapter 1 – 5 of this dissertation presents a comprehensive characterization of a newly developed erbium compound material, erbium chloride silicate (ECS) in a nanowire form. Extensive experiments demonstrated the high crystal quality and excellent optical properties of ECS nanowires. Optical gain higher than 30 dB/cm at 1.53 μm wavelength is demonstrated on single ECS nanowires, which is higher than the gain of any reported erbium materials. An ultra-high Q photonic crystal micro-cavity is designed on a single ECS nanowire towards the ultra-compact lasers at communication wavelengths. Such ECS nanowire lasers show the potential applications of on-chip photonics integration.
Chapter 6 – 7 presents the design and demonstration of dynamical color-controllable lasers on a single CdSSe alloy nanowire. Through the defect-free VLS growth, engineering of the alloy composition in a single nanowire is achieved. The alloy composition of CdSxSe1-x uniformly varies along the nanowire axis from x=1 to x=0, giving the opportunity of multi-color lasing in a monolithic structure. By looping the wide-bandgap end of the alloy nanowire through nanoscale manipulation, the simultaneous two-color lasing at green and red colors are demonstrated. The 107 nm wavelength separation of the two lasing colors is much larger than the gain bandwidth of typical semiconductors. Since the two-color lasing shares the output port, the color of the total lasing output can be controlled dynamically between the two fundamental colors by changing the relative output power of two lasing colors. Such multi-color lasing and continuous color tuning in a wide spectral range would eventually enable color-by-design lasers to be used for lighting, display and many other applications.
ContributorsLiu, Zhicheng (Author) / Ning, Cun-Zheng (Thesis advisor) / Palais, Joseph (Committee member) / Yu, Hongbin (Committee member) / Yao, Yu (Committee member) / Arizona State University (Publisher)
Created2015
Description
Antenna arrays are widely used in wireless communication, radar, remote sensing, and other fields. Compared to traditional linear antenna arrays, novel nonlinear antenna arrays have fascinating advantages in terms of structural simplicity, lower cost, wider bandwidth, faster scanning speed, and lower side-lobe levels. This dissertation explores a novel design of a phased array antenna with an augmented scanning range, aiming to establish a clear connection between mathematical principles and practical circuitry. To achieve this goal, the Van der Pol (VDP) model is applied to a single-transistor oscillator to obtain the isolated limit cycle. The coupled oscillators are then integrated into a 1 times 7 coupled phased array, using the Keysight PathWave Advanced Design System (ADS) for tuning and optimization. The VDP model is used for analytic study of bifurcation, quasi-sinusoidal oscillation, quasi-periodic chaos, and oscillator death, while ADS schematics guide engineering implementation and physical fabrication. The coupled oscillators drive cavity-backed antennas, forming a one-dimensional scanning antenna array of 1 times 7. The approaches for increasing the scanning range performance are discussed.
ContributorsZhang, Kaiyue (Author) / Pan, George (Thesis advisor) / Yu, Hongbin (Committee member) / Aberle, James (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2023