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Full-Text Articles in Physics
Picosecond Yb-Doped Fiber Amplifier, Weibin Zhu
Picosecond Yb-Doped Fiber Amplifier, Weibin Zhu
Electronic Theses and Dissertations
Due to its versatility, rare earth doped fiber amplifier (RDFA) has attracted a lot of researchers worldwide in recent years. Depends on different kinds of rare earth ion, RDFA can be categorized into neodymium doped fiber amplifier (NDFA), erbium doped fiber amplifier (EDFA), thulium doped fiber amplifier (TDFA), and so forth. Among many kinds of RDFA, the ytterbium doped fiber amplifier (YDFA) has received even more interest, especially in high power application, mainly because of its broad gain bandwidth and high conversion efficiency which are due to its relatively simple electronic structure. The purpose of this research is to study …
Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah
Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah
Electronic Theses and Dissertations
Ultrashort pulse lasers are well-established in the scientific community due to the wide range of applications facilitated by their extreme intensities and broad bandwidth capabilities. This thesis will primarily present the design for the Mobile Ultrafast High Energy Laser Facility (MU-HELF) for use in outdoor atmospheric propagation experiments under development at the Laser Plasma Laboratory at UCF. The system is a 100fs 500 mJ Ti-Sapphire Chirped-Pulse Amplification (CPA) laser, operating at 10 Hz. Some background on the generation of very high intensity optical pulses is also presented, alongside an overview of the physics of filamentation. As part of the design …
High Performance Liquid Crystals For Displays And Spatial Light Modulators, Fenglin Peng
High Performance Liquid Crystals For Displays And Spatial Light Modulators, Fenglin Peng
Electronic Theses and Dissertations
Liquid crystals (LCs) are an amazing class of soft materials which have been widely used in the visible, infrared (IR), millimeter wave, and terahertz spectral regions. Both amplitude modulation (e.g. displays) and phase modulation (e.g. spatial light modulators (SLMs) for adaptive optics and adaptive lens) have been investigated extensively. Thin-film-transistor liquid crystal displays (TFT-LCDs) have become ubiquitous in our daily lives. Its widespread applications span from TVs, monitors, tablets, smartphones, augmented reality, virtual reality, to vehicle displays. LCD shows advantages in 1) high resolution, 2) long lifetime, 3) vivid colors using quantum dots backlight, and 4) high dynamic contrast ratio …
Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger
Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger
Electronic Theses and Dissertations
Quantum Cascade Lasers are a novel source of coherent infrared light, unique in their tunability over the mid-infrared and terahertz range of frequencies. Advances in bandgap engineering and semiconductor processing techniques in recent years have led to the development of highly efficient quantum cascade lasers capable of room temperature operation. Recent work has demonstrated power scaling with broad area quantum cascade lasers by increasing active region width beyond the standard ~10 ?m. Taking into account thermal effects caused by driving a device with electrical power, an experimentally fitted model is developed to predict the optical power output in both pulsed …
Photothermal Lensing In Mid-Infrared Materials, Justin Cook
Photothermal Lensing In Mid-Infrared Materials, Justin Cook
Electronic Theses and Dissertations
A thorough understanding of laser-materials interactions is crucial when designing and building optical systems. An ideal test method would probe both the thermal and optical properties simultaneously for materials under large optical loads where detrimental thermal effects emerge. An interesting class of materials are those used for infrared wavelengths due to their wide spectral transmission windows and large optical nonlinearities. Since coherent sources spanning the mid-wave and long-wave infrared wavelength regions have only become widely available in the past decade, data regarding their thermal and optical responses is lacking in literature. Photothermal Lensing (PTL) technique is an attractive method for …
High Dynamic Range Display Systems, Ruidong Zhu
High Dynamic Range Display Systems, Ruidong Zhu
Electronic Theses and Dissertations
High contrast ratio (CR) enables a display system to faithfully reproduce the real objects. However, achieving high contrast, especially high ambient contrast (ACR), is a challenging task. In this dissertation, two display systems with high CR are discussed: high ACR augmented reality (AR) display and high dynamic range (HDR) display. For an AR display, we improved its ACR by incorporating a tunable transmittance liquid crystal (LC) film. The film has high tunable transmittance range, fast response time, and is fail-safe. To reduce the weight and size of a display system, we proposed a functional reflective polarizer, which can also help …
Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei
Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei
Electronic Theses and Dissertations
In recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics- enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity …
Enhanced Ablation By Femtosecond And Nanoseond Pulses, Haley Kerrigan
Enhanced Ablation By Femtosecond And Nanoseond Pulses, Haley Kerrigan
Electronic Theses and Dissertations
Laser ablation of GaAs by a combination of femtosecond and nanosecond pulses is investigated as a means of enhancing material removal by a femtosecond pulse in the filamentation intensity regime. We demonstrate for the first time increased ablation of GaAs by ultrafast laser pulse plasmas augmented by nanosecond pulse radiation from a secondary laser. Material removal during laser ablation is a complex process that occurs via multiple mechanisms over several timescales. Due to different pulse durations, ablation by femtosecond and nanosecond pulses are dominated by different mechanisms. Ablation can be enhanced by optimally combining a femtosecond and nanosecond pulse in …
Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken
Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken
Electronic Theses and Dissertations
Glass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the resulting composite's optical properties including refractive index, transmission, dispersion, and thermo-optic coefficient. Optical property evolution was related to the type and amount of the crystal phases formed, since through control of the local …
Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen
Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen
Electronic Theses and Dissertations
Several metrics are commonly used to evaluate the performance of display devices. In this dissertation, we analyze three key parameters: fast response time, wide color gamut, and high contrast ratio, which affect the final perceived image quality. Firstly, we investigate how response time affects the motion blur, and then discover the 2-ms rule. With advanced low-viscosity materials, new operation modes, and backlight modulation technique, liquid crystal displays (LCDs) with an unnoticeable image blur can be realized. Its performance is comparable to an impulse-type display, like cathode ray tube (CRT). Next, we propose two novel backlight configurations to improve an LCD's …
Generation Of High-Flux Attosecond Pulses And Towards Attosecond-Attosecond Pump-Probe Experiments, Yang Wang
Generation Of High-Flux Attosecond Pulses And Towards Attosecond-Attosecond Pump-Probe Experiments, Yang Wang
Electronic Theses and Dissertations
At present, the energy of a single isolated attosecond pulse is limited to nanojoule levels. As a result, an intense femtosecond pulse has always been used in combination with a weak attosecond pulse in time-resolved experiments. To reach the goal of conducting true attosecond pump-attosecond probe experiments, a high flux laser source has been developed that can potentially deliver microjoule level isolated attosecond pulses in the 50 eV range, and a unique experimental end station has been fabricated and implemented that can provide precision control of the attosecond-attosecond pump-probe pulses. In order to scale up the attosecond flux, a unique …
Design Of A Hydrogen-Filled Hollow-Core Fiber Raman Laser, Yangyang Qin
Design Of A Hydrogen-Filled Hollow-Core Fiber Raman Laser, Yangyang Qin
Electronic Theses and Dissertations
The purpose of this study is to investigate the design of a Raman fiber laser based on a molecule hydrogen-filled hollow-core fiber with non-touching single ring of capillaries structure. O-hydrogen vibrational frequency shift of 4155 cm-1 and rotational frequency shift of 587 cm-1 were employed to generate Raman scattering from a 1064nm pump source. A thorough exploration was made to show how all Raman fiber laser components made up: gas chamber, hollow-core fibers, windows. The whole process of chamber design, modification and fabrication were demonstrated. Besides, two kinds of anti-resonant hollow-core fibers were studied and tested. The transmission and loss …
System For Metal Coated Fiber Fabrication, Da Zhang
System For Metal Coated Fiber Fabrication, Da Zhang
Electronic Theses and Dissertations
For many specific applications, such as sensors, aerospace, chemical industry, deep-well oil-field industry, metal-coated fiber shows strong abilities to satisfy people's requirement. With in-line coating technology, we are able to coat Aluminum on the fibers. Using electromagnetic induction, we can easily heat an electrically conducting thing such as a metal with the eddy current. This process is defined as Induction heating. And we will melt the Aluminum by this induction heating during drawing the fibers on the tower. Introduce the fiber tower system. The drawing process of in-line technology is formed of the following steps: Position, Melting, Forming into fibers, …
Noise, Stability, And Linewidth Performance Of 10-Ghz Optical Frequency Combs Generated From The Nested Cavity Architecture, Kristina Bagnell
Noise, Stability, And Linewidth Performance Of 10-Ghz Optical Frequency Combs Generated From The Nested Cavity Architecture, Kristina Bagnell
Electronic Theses and Dissertations
Optical frequency combs with wide mode spacing and low timing jitter are relied upon for both time domain and frequency domain applications. It has been previously demonstrated that surrounding a low-Q semiconductor laser chip with a long external fiber cavity and inserting a high finesse Fabry–Pérot etalon into this cavity can produce a mode-locked laser with the desired high repetition rate and narrow optical mode linewidths which are of benefit to applications like photonic analog-to-digital conversion and astronomical spectrograph calibration. With this nested cavity architecture, the quality factor of the resonator is effectively determined by the product of the individual …
Enhancement Of Bandwidth And Laser Deflection Angle Of Acousto-Optic Deflectors By Dynamic Two-Dimensional Refractive Index Modulation, Tiansi Wang
Electronic Theses and Dissertations
Acousto-Optic Deflectors (AODs) are inertialess optical solid state devices that have advantages over conventional mechanically controlled mirror-based deflectors in numerous scientific and industrial applications. These applications include fluorescence microscopy, sensing, variable-focus lens, photolithography and laser materials processing. AODs are currently operated with a single piezoelectric transducer that modulates the refractive index only in one direction. This operating principle limits the performance of AODs to a narrow acoustic bandwidth of the transducer and a small angle of laser deflection governed by the Bragg diffraction. To overcome these two limitations, the operation of AODs with phased array ultrasonic transducers is analyzed in …
Development Of A Compact Broadband Optical Parametric Oscillator For Ultra-Sensitive Molecular Detection, Sean O. Crystal
Development Of A Compact Broadband Optical Parametric Oscillator For Ultra-Sensitive Molecular Detection, Sean O. Crystal
Honors Undergraduate Theses
Every gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56µm pump laser and a never before used orientation patterned gallium-phosphide crystal. Periodically polled lithium niobate (PPLN), Gallium Arsenide (GaAs) and Gallium Phosphide are all crystals used to accomplish this task. GaP, in comparison to PPLN, has (i) a …
Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera
Micro-Spectroscopy Of Bio-Assemblies At The Single Cell Level, Jeslin Kera
Honors Undergraduate Theses
In this thesis, we investigate biological molecules on a micron scale in the ultraviolet spectral region through the non-destructive confocal absorption microscopy. The setup involves a combination of confocal microscope with a UV light excitation beam to measure the optical absorption spectra with spatial resolution of 1.4 μm in the lateral and 3.6 μm in the axial direction. Confocal absorption microscopy has the benefits of requiring no labels and only low light intensity for excitation while providing a strong signal from the contrast generated by the attenuation of propagating light due to absorption. This enables spatially resolved measurements of single …
Using Low-Coherence Interferometry To Monitor Cell Invasion In An In-Vitro Model System, Behnaz Davoudi Nasab
Using Low-Coherence Interferometry To Monitor Cell Invasion In An In-Vitro Model System, Behnaz Davoudi Nasab
Honors Undergraduate Theses
In an optically random system, such as naturally occurring and man-made media, light undergoes pronounced multiple scattering. This phenomenon has shown a remarkable potential in characterizing complex materials. In this regime, scattering occurs from each individual center of the scattering and independent scattering events lead to multiple light scattering. This phenomenon is often described as a random walk of photons and can be modeled in terms of a diffusion equation based on the radiative transfer theory. In this thesis, we used optical path-length spectroscopy (OPS), which is an experimental method to obtain the path-length probability density of the propagating light …
Filament Wavefront Evolution, Daniel Thul
Filament Wavefront Evolution, Daniel Thul
Electronic Theses and Dissertations
Filamentation is a complex process that gives rise to many nonlinear interactions. However, the fundamentals of filament formation and propagation can be explained in terms of two dominant mechanisms: Kerr self-focusing and plasma defocusing. The first to occur, self-focusing, is responsible for an increase in irradiance through beam collapse. This process requires sufficient initial peak power, on the order of gigawatts for near infrared beams in air. Plasma defocusing then arrests the collapse process once the irradiance reaches the ionization threshold of the medium. These two processes balance each other in an extended plasma channel known as a filament. A …
Mode Evolution In Fiber Based Devices For Optical Communication Systems, Bin Huang
Mode Evolution In Fiber Based Devices For Optical Communication Systems, Bin Huang
Electronic Theses and Dissertations
Space division multiplexing (SDM) is the most promising way of increasing the capacity of a single fiber. To enable the few mode fiber (FMF) or multi-mode fiber (MMF) transmission system, several major challenges have to be overcome. One is the urgent need of ideal mode multiplexer, the second is the perfect amplification for all spatial modes, another one is the modal delay spread (MDS) due to group velocity difference of spatial modes. The main subject of this dissertation is to model, fabricate and characterize the mode multiplexer for FMF transmission. First, we designed a novel resonant mode coupler (structured directional …
Harnessing Spatial Intensity Fluctuations For Optical Imaging And Sensing, Milad Akhlaghi Bouzan
Harnessing Spatial Intensity Fluctuations For Optical Imaging And Sensing, Milad Akhlaghi Bouzan
Electronic Theses and Dissertations
Properties of light such as amplitude and phase, temporal and spatial coherence, polarization, etc. are abundantly used for sensing and imaging. Regardless of the passive or active nature of the sensing method, optical intensity fluctuations are always present! While these fluctuations are usually regarded as noise, there are situations where one can harness the intensity fluctuations to enhance certain attributes of the sensing procedure. In this thesis, we developed different sensing methodologies that use statistical properties of optical fluctuations for gauging specific information. We examine this concept in the context of three different aspects of computational optical imaging and sensing. …