Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Publication
- Publication Type
Articles 1 - 11 of 11
Full-Text Articles in Engineering
Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou
Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou
Graduate Theses and Dissertations
Si photonics is a fast-developing technology that impacts many applications such as data centers, 5G, Lidar, and biological/chemical sensing. One of the merits of Si photonics is to integrate electronic and photonic components on a single chip to form a complex functional system that features compact, low-cost, high-performance, and reliability. Among all building blocks, the monolithic integration of lasers on Si encountered substantial challenges. Si and Ge, conventional epitaxial material on Si, are incompetent for light emission due to the indirect bandgap. The current solution compromises the hybrid integration of III-V lasers, which requires growing on separate smaller size substrates …
Fully Analog Laser Driver With Robust Active Feedback Control, John Petrilli
Fully Analog Laser Driver With Robust Active Feedback Control, John Petrilli
Graduate Theses and Dissertations
The objective of this project was to go through a real life engineering development cycle, document and justify the design choices, and use background experience in electronic design and control systems to implement the best design possible. The laser driver implemented in this project is designed for the general use of a large variety of diodes in continuous wave mode, much like off the shelf laser drivers. The design goals included improving upon off the shelf laser drivers by decreasing steady state error, setting time, response time, and overshoot. Many different feedback control systems were evaluated, and a modified PID …
High Frequency Open Air Optical Communication System, Alexander C. Wolff
High Frequency Open Air Optical Communication System, Alexander C. Wolff
Electrical Engineering
The goal of this project is to create a wireless optical communication system that operates at high frequencies (up to 3 GHz). The system will function by taking a digital electric input signal, converting it to a photonic signal, recovering the signal at the other end of a short distance (~1 foot) and converting it back into a digital signal. Unlike the more common fiber-optic data transmission systems, this system will transmit light through air, instead of fiber, as its medium. Doing so will have the benefits of a wireless system combined with the benefits from an optical system, including …
Vision Based Real-Time Monitoring And Control Of Metal Transfer In Laser Enhanced Gas Metal, Yan Shao
Vision Based Real-Time Monitoring And Control Of Metal Transfer In Laser Enhanced Gas Metal, Yan Shao
Theses and Dissertations--Electrical and Computer Engineering
Laser enhanced gas metal arc welding (GMAW) is a novel welding process where a laser is applied to provide an auxiliary detaching force to help detach the droplet such that welds may be made in gas tungsten arc welding high quality at GMAW high speeds. The current needed to generate the electromagnetic (detaching) force is thus reduced. The reduction in the current helps reduce the impact on the weld pool and over-heat fumes/smokes. However, in the previous studies, a continuous laser is applied. Since the auxiliary is only needed each time the droplet needs to be detached and the detachment …
Ultrafast Laser Material Processing For Photonic Applications, Mark Ramme
Ultrafast Laser Material Processing For Photonic Applications, Mark Ramme
Electronic Theses and Dissertations
Femtosecond Laser Direct Writing (FLDW) is a viable technique for producing photonic devices in bulk materials. This novel manufacturing technique is versatile due to its full 3D fabrication capability. Typically, the only requirement for this process is that the base material must be transparent to the laser wavelength. The modification process itself is based on non-linear energy absorption of laser light within the focal volume of the incident beam. This thesis addresses the feasibility of this technique for introducing photonic structures into novel dielectric materials. Additionally, this work provides a deeper understanding of the lightmatter interaction mechanism occurring at high …
Laser-Induced Multi-Energy Processing In Diamond Growth, Zhiqiang Xie
Laser-Induced Multi-Energy Processing In Diamond Growth, Zhiqiang Xie
Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research
Laser-induced multi-energy processing (MEP) introduces resonant vibrational excitations of precursor molecules to conventional chemical vapor deposition methods for material synthesis. In this study, efforts were extended to explore the capability of resonant vibrational excitations for promotion of energy efficiency in chemical reactions, for enhancement of diamond deposition, and for control of chemical reactions. The research project mainly focused on resonant vibrational excitations of precursor molecules using lasers in combustion flame deposition of diamond, which led to: 1) promotion of chemical reactions; 2) enhancement of diamond growth with higher growth rate and better crystallizations; 3) steering of chemical reactions which lead …
A Laser Radar Employing Linearly Chirped Pulses From A Mode-Locked Laser For Long Range, Unambiguous, Sub-Millimeter Resolution Ranging And Velocimetry, Mohammad Umar Piracha
A Laser Radar Employing Linearly Chirped Pulses From A Mode-Locked Laser For Long Range, Unambiguous, Sub-Millimeter Resolution Ranging And Velocimetry, Mohammad Umar Piracha
Electronic Theses and Dissertations
Light detection and ranging (lidar) is used for various applications such as remote sensing, altimetry and imaging. In this talk, a linearly chirped pulse source is introduced that generates wavelength-swept pulses exhibiting ~6 nm optical bandwidth with > 20 km coherence length. The chirped pulses are used in an interferometric lidar setup to perform distance measurements with sub-millimeter resolution (using pulses that are a few meters long), at target distances > 10 km, with at least 25 dB signal-to-noise ratio at the receiver. A pulse repetition rate of 20 MHz provides fast update rates, while chirped pulse amplification allows easy amplification of …
Laser Cursor, Michael Liman
Laser Cursor, Michael Liman
Electrical Engineering
A user controls a cursor on a computer screen using a laser pointer. A camera picks up the laser pointer’s position and sends the data to the computer to move the cursor in the correct position.
Laser Plasma Radiation Studies For Droplet Sources In The Extreme Ultraviolet, Reuvani Kamtaprasad
Laser Plasma Radiation Studies For Droplet Sources In The Extreme Ultraviolet, Reuvani Kamtaprasad
Electronic Theses and Dissertations
The advancement of laboratory based Extreme Ultraviolet (EUV) radiation has escalated with the desire to use EUV as a source for semiconductor device printing. Laser plasmas based on a mass-limited target concept, developed within the Laser Plasma Laboratory demonstrate a much needed versatility for satisfying rigorous source requirements. This concept produces minimal debris concerns and allows for the attainment of high repetition rates as well as the accommodation of various laser and target configurations. This work demonstrates the generation of EUV radiation by creating laser plasmas from mass-limited targets with indium, tin, and antimony doped droplets. Spectral emission from the …
High-Intensity Ultra-Fast Laser Interaction Technologies, Robert Thomas Bernath
High-Intensity Ultra-Fast Laser Interaction Technologies, Robert Thomas Bernath
Electronic Theses and Dissertations
To our knowledge this is the first comprehensive study of laser-induced effects generated at intermediate distances using self-channeled femtosecond laser pulses. Studies performed were made both experimentally and theoretically with the use of novel modeling techniques. Peak laser pulse powers above 3 GW allow beam propagation without divergence for up to several kilometers. In this regime, experiments were performed at 30 meters from the laser system in a custom propagation and target range, utilizing the Laser Plasma Laboratory's Terawatt laser system. Experiments included investigations of laser ablation; electromagnetic pulsed (EMP) radiation generation over the 1-18 GHz region; shockwave formation in …
Debris Characterization And Mitigation Of Droplet Laser Plasma Sources For Euv Lithography, Kazutoshi Takenoshita
Debris Characterization And Mitigation Of Droplet Laser Plasma Sources For Euv Lithography, Kazutoshi Takenoshita
Electronic Theses and Dissertations
Extreme ultraviolet lithography (EUVL) is a next generation lithographic techniques under development for fabricating semiconductor devices with feature sizes smaller than 32 nm. The optics to be used in the EUVL steppers is reflective optics with multilayer mirror coatings on each surface. The wavelength of choice is 13.5 nm determined by the optimum reflectivity of the mirror coatings. The light source required for this wavelength is derived from a hot-dense plasma produced by either a gas discharge or a laser. This study concentrate only on the laser produced plasma source because of its advantages of scalability to higher repetition rates. …