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- Title
- LASER METALLIZATION AND DOPING FOR SILICON CARBIDE DIODE FABRICATION AND ENDOTAXY.
- Creator
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Tian, Zhaoxu, Kar, Aravinda, University of Central Florida
- Abstract / Description
-
Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal...
Show moreSilicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal deposition and dope in silicon carbide without high temperature annealing, as an alternative to the conventional ion implantation, and find applications of this laser direct write metallization and doping technique on the fabrication of diodes, endotaxial layer and embedded optical structures on silicon carbide wafers. Mathematical models have been presented for the temperature distributions in the wafer during laser irradiation to optimize laser process parameters and understand the doping and metallization mechanisms in laser irradiation process. Laser irradiation of silicon carbide in a dopant-containing ambient allows to simultaneously heating the silicon carbide surface without melting and incorporating dopant atoms into the silicon carbide lattice. The process that dopant atoms diffuse into the bulk silicon carbide by laser-induced solid phase diffusion (LISPD) can be explained by considering the laser enhanced substitutional and interstitial diffusion mechanisms. Nitrogen and Trimethyaluminum (TMA) are used as dopants to produce n-type and p-type doped silicon carbide, respectively. Two laser doping methods, i.e., internal heating doping and surface heating doping are presented in this dissertation. Deep (800 nm doped junction for internal heating doping) and shallow (200 nm and 450 nm doped junction for surface heating doping) can be fabricated by different doping methods. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions by fitting the diffusion equation to the measured concentration profiles. The calculated diffusivities are at least 6 orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that laser doping process enhances the diffusion of dopants in silicon carbide significantly. No amorphization was observed in laser-doped samples eliminating the need for high temperature annealing. Laser direct metallization can be realized on the surface of silicon carbide by generating metal-like conductive phases due to the decomposition of silicon carbide. The ohmic property of the laser direct metallized electrodes can be dramatically improved by fabricating such electrodes on laser heavily doped SiC substrate. This laser-induced solid phase diffusion technique has been utilized to fabricate endolayers in n-type 6H-SiC substrates by carbon incorporation. X-ray energy dispersive spectroscopic analysis shows that the thickness of endolayer is about 100 nm. High resolution transmission electron microscopic images indicate that the laser endotaxy process maintains the crystalline integrity of the substrate without any amorphization. Rutherford backscattering studies also show no amorphization and evident lattice disorder occur during this laser solid phase diffusion process. The resistivity of the endolayer formed in a 1.55 omega•cm silicon carbide wafer segment was found to be 1.1E5 omega•cm which is sufficient for device fabrication and isolation. Annealing at 1000 oC for 10 min to remove hydrogen resulted in a resistivity of 9.4E4 omega•cm. Prototype silicon carbide PIN diodes have been fabricated by doping the endolayer and parent silicon carbide epilayer with aluminum using this laser-induced solid phase diffusion technique to create p-regions on the top surfaces of the substrates. Laser direct metallized contacts were also fabricated on selected PIN diodes to show the effectiveness of these contacts. The results show that the PIN diode fabricated on a 30 nm thick endolayer can block 18 V, and the breakdown voltages and the forward voltages drop at 100 A/cm2 of the diodes fabricated on 4H-SiC with homoepilayer are 420 ~ 500 V and 12.5 ~ 20 V, respectively. The laser direct metallization and doping technique can also be used to synthesize embedded optical structures, which can increase 40% reflectivity compared to the parent wafer, showing potential for the creation of optical, electro-optical, opto-electrical, sensor devices and other integrated structures that are stable in high temperature, high-pressure, corrosive environments and deep space applications.
Show less - Date Issued
- 2006
- Identifier
- CFE0001061, ucf:46803
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001061
- Title
- MONOLITHICALLY INTEGRATED WAVELENGTH TUNABLE LASER DIODE FOR INTEGRATED OPTIC SURFACE PLASMON RESONANCE SENSING.
- Creator
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Tabbakh, Thamer, Likamwa, Patrick, Batarseh, Issa, Fathpour, Sasan, Mikhael, Wasfy, Khajavikhan, Mercedeh, University of Central Florida
- Abstract / Description
-
In this work, we demonstrate an InGaAsP multiple quantum well tunable laser diode that amalgamates two gain sections with different bandgap energies. This is achieved using selective area intermixing of the multiple quantum wells, and impurity-free vacancy induced disordering. When different current combination is injected into each section, that leads to a laser wavelength peak whose position depends on the relative magnitudes of the two injected currents. The laser wavelength can be fine...
Show moreIn this work, we demonstrate an InGaAsP multiple quantum well tunable laser diode that amalgamates two gain sections with different bandgap energies. This is achieved using selective area intermixing of the multiple quantum wells, and impurity-free vacancy induced disordering. When different current combination is injected into each section, that leads to a laser wavelength peak whose position depends on the relative magnitudes of the two injected currents. The laser wavelength can be fine-tuned from 1538 nm to 1578 nm with relatively constant output power. The free spectral range FSR of the tunable laser found to be 0.25 nm. This tunable laser was launched into an optical surface plasmon resonance sensor head to provide an input light source for the SPR sensor.Using the tunable laser diode, we have demonstrated an optical surface plasmon resonance sensor head that is based on an inverted rib dielectric waveguide, in which the resonance wavelength of the surface plasmon excited at the gold metal-dielectric interface depends on the refractive index of the liquid in contact with it. The inverted-rib waveguide of the SPR sensor head is made of a layer of SU-8 polymer with a refractive index of 1.568. While the lower cladding layer consists of silicon oxynitride (SiOxNy) with a refractive index of 1.526. The top surface is coated with 20 nm of chromium followed by a 50 nm thick layer of gold or with 4 nm of titanium followed by a 25 nm thick layer of gold. The SPR sensor head was designed, to allow monitoring of analyte media with a refractive index, ranging from 1.43 to the 1.52. Using a set of reference liquids representing the analyte medium, the sensitivity of the SPR sensor was measured using the fabricated tunable laser, an optical spectrum analyzer, and a photodiode. It was found that with various calibrated sample liquids in contact with the gold metal, a sharp resonance dip in the transmission spectrum occurred, and its position shifted to a shorter wavelength when the refractive index of the sample liquids was increased. The average sensitivity of the SPR sensor devices was determined to be S = 334 nm/RIU.
Show less - Date Issued
- 2018
- Identifier
- CFE0007769, ucf:52390
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007769
- Title
- Broad Bandwidth Optical Frequency Combs from Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers.
- Creator
-
Klee, Anthony, Delfyett, Peter, Vanstryland, Eric, Schulzgen, Axel, DeSalvo, Richard, University of Central Florida
- Abstract / Description
-
Mode-locked lasers have numerous applications in the areas of communications, spectroscopy, and frequency metrology. Harmonically mode-locked semiconductor lasers with external ring cavities offer a unique combination of benefits in that they can produce high repetition rate pulse trains with low timing jitter, achieve narrow axial mode linewidths, have the potential for entire monolithic integration on-chip, feature high wall-plug efficiency due to direct electrical pumping, and can be...
Show moreMode-locked lasers have numerous applications in the areas of communications, spectroscopy, and frequency metrology. Harmonically mode-locked semiconductor lasers with external ring cavities offer a unique combination of benefits in that they can produce high repetition rate pulse trains with low timing jitter, achieve narrow axial mode linewidths, have the potential for entire monolithic integration on-chip, feature high wall-plug efficiency due to direct electrical pumping, and can be engineered to operate in different wavelength bands of interest. However, lasers based on InP/InGaAsP quantum well devices which operate in the important telecom C-band have thus far been relatively limited in bandwidth as compared to competing platforms. Broad bandwidth is critical for increasing information carrying capacity and enabling femtosecond pulse production for coherent continuum generation in offset frequency stabilization. The goal of the work in this dissertation is to maximize the bandwidth of semiconductor lasers, bringing them closer to reaching their full potential as all-purpose sources.Dispersion in the laser cavity is a primary limiter of the achievable bandwidth in the laser architectures covered in this dissertation. In the first part of this dissertation, an accurate self-referenced technique based on multi-heterodyne detection is developed for measuring the spectral phase of a mode-locked laser. This technique is used to characterize the dispersion in several semiconductor laser architectures. In the second part, this knowledge is applied to reduce the dispersion in a laser cavity using a programmable pulse shaper, and thus increase the laser's spectral bandwidth. We demonstrate a 10 GHz frequency comb with bandwidth spanning 5 THz, representing a twofold improvement over the previously achievable bandwidth. Finally, this laser is converted to a stand-alone system by reconfiguring it as a coupled opto-electronic oscillator and a novel stabilization scheme is presented.
Show less - Date Issued
- 2016
- Identifier
- CFE0006129, ucf:51184
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006129
- Title
- High flux isolated attosecond pulse generation.
- Creator
-
Wu, Yi, Chang, Zenghu, Richardson, Martin, Christodoulides, Demetrios, Rahman, Talat, University of Central Florida
- Abstract / Description
-
This thesis outlines the high intensity tabletop attosecond extreme ultraviolet laser source at the Institute for the Frontier of Attosecond Science and Technology Laboratory.First, a unique Ti:Sapphire chirped pulse amplifier laser system that delivers 14 fs pulses with 300 mJ energy at a 10 Hz repetition rate was designed and built. The broadband spectrum extending from 700 nm to 900 nm was obtained by seeding a two stage Ti:Sapphire chirped pulse power amplifier with mJ-level white light...
Show moreThis thesis outlines the high intensity tabletop attosecond extreme ultraviolet laser source at the Institute for the Frontier of Attosecond Science and Technology Laboratory.First, a unique Ti:Sapphire chirped pulse amplifier laser system that delivers 14 fs pulses with 300 mJ energy at a 10 Hz repetition rate was designed and built. The broadband spectrum extending from 700 nm to 900 nm was obtained by seeding a two stage Ti:Sapphire chirped pulse power amplifier with mJ-level white light pulses from a gas filled hollow core fiber. It is the highest energy level ever achieved by a broadband pulse in a chirped pulse amplifier up to the current date.Second, using this laser as a driving laser source, the generalized double optical gating method is employed to generate isolated attosecond pulses. Detailed gate width analysis of the ellipticity dependent pulse were performed. Calculation of electron light interaction dynamics on the atomic level was carried out to demonstrate the mechanism of isolated pulse generation.Third, a complete diagnostic apparatus was built to extract and analyze the generated attosecond pulse in spectral domain. The result confirms that an extreme ultraviolet super continuum supporting 230 as isolated attosecond pulses at 35 eV was generated using the generalized double optical gating technique. The extreme ultraviolet pulse energy was ~100 nJ at the exit of the argon gas target.
Show less - Date Issued
- 2013
- Identifier
- CFE0005075, ucf:49949
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005075
- Title
- External cavity mode-locked semiconductor lasers for the generation of ultra-low noise multi-gigahertz frequency combs and applications in multi-heterodyne detection of arbitrary optical waveforms.
- Creator
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Davila-Rodriguez, Josue, Delfyett, Peter, Likamwa, Patrick, Li, Guifang, Malocha, Donald, University of Central Florida
- Abstract / Description
-
The construction and characterization of ultra-low noise semiconductor-based mode-locked lasers as frequency comb sources with multi-gigahertz combline-to-combline spacing is studied in this dissertation. Several different systems were built and characterized. The first of these systems includes a novel mode-locking mechanism based on phase modulation and periodic spectral filtering. This mode-locked laser design uses the same intra-cavity elements for both mode-locking and frequency...
Show moreThe construction and characterization of ultra-low noise semiconductor-based mode-locked lasers as frequency comb sources with multi-gigahertz combline-to-combline spacing is studied in this dissertation. Several different systems were built and characterized. The first of these systems includes a novel mode-locking mechanism based on phase modulation and periodic spectral filtering. This mode-locked laser design uses the same intra-cavity elements for both mode-locking and frequency stabilization to an intra-cavity, 1,000 Finesse, Fabry-P(&)#233;rot Etalon (FPE). On a separate effort, a mode-locked laser based on a Slab-Coupled Optical Waveguide Amplifier (SCOWA) was built. This system generates a pulse-train with residual timing jitter of (<)2 fs and pulses compressible to (<)1 ps. Amplification of these pulse-trains with an external SCOWA lead to 390 mW of average optical power without evident degradation in phase noise and pulses that are compressible to the sub-picosecond regime. Finally, a new laser is built using a 10,000 Finesse Fabry-P(&)#233;rot Etalon held in a vacuum chamber. The fluctuations in the optical frequency of the individual comb-lines over time periods longer than 12 minutes are shown to be significantly reduced to (<)100 kHz in a measurement that is limited by the linewidth of the reference source.The use of these comb sources as local oscillators in multi-heterodyne detection of arbitrary optical waveforms is explored in three different cases. 1) Sampling of mode-locked pulses, 2) sampling of phase modulated continuous wave light and 3) periodically filtered white light. The last experiment achieves spectral interferometry with unprecedented resolution.
Show less - Date Issued
- 2013
- Identifier
- CFE0004669, ucf:49863
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004669
- Title
- Distribution of Laser Induced Heating in Multi-Component Chalcogenide Glass and its Associated Effects.
- Creator
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Sisken, Laura, Richardson, Kathleen, Richardson, Martin, Shah, Lawrence, University of Central Florida
- Abstract / Description
-
Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a...
Show moreChalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much greater precision by moving either the beam or the sample.The main properties of ChG glasses investigated in this study were the light-induced and thermally-induced modification of the glass through visible microscopy, white light interferometry, and Raman spectroscopy. Additionally computational models were developed in order to aid in determining what temperature rise should be occurring under the conditions used in experiments.It was seen that ablation, photo-expansion, crystallization, and melting could occur for some of the irradiation conditions that were used. The above bandgap energy simulations appeared to overestimate the maximum temperature that should have been reached in the sample, while the below bandgap energy simulations appeared to underestimate the maximum temperature that should have been reached in the sample. Ultimately, this work produces the ground work to be able to predict and control dose, and therefore heating, to induce localized crystallization and phase change.
Show less - Date Issued
- 2014
- Identifier
- CFE0005261, ucf:50606
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005261
- Title
- FEW-CYCLE PULSES AMPLIFICATION FOR ATTOSECOND SCIENCE APPLICATIONS: MODELING AND EXPERIMENTS.
- Creator
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Hemmer, Michael, Richardson, Martin, University of Central Florida
- Abstract / Description
-
The emergence of mode-locked oscillators providing pulses with durations as short as a few electric-field cycles in the near infra-red has paved the way toward electric-field sensitive physics experiments. In addition, the control of the relative phase between the carrier and the pulse envelope, developed in the early 2000's and rewarded by a Nobel price in 2005, now provides unprecedented control over the pulse behaviour. The amplification of such pulses to the millijoule level has been an...
Show moreThe emergence of mode-locked oscillators providing pulses with durations as short as a few electric-field cycles in the near infra-red has paved the way toward electric-field sensitive physics experiments. In addition, the control of the relative phase between the carrier and the pulse envelope, developed in the early 2000's and rewarded by a Nobel price in 2005, now provides unprecedented control over the pulse behaviour. The amplification of such pulses to the millijoule level has been an on-going task in a few world-class laboratories and has triggered the dawn of attoscience, the science of events happening on an attosecond timescale. This work describes the theoretical aspects, modeling and experimental implementation of HERACLES, the Laser Plasma Laboratory optical parametric chirped pulse amplifier (OPCPA) designed to deliver amplified carrier-envelope phase stabilized 8-fs pulses with energy beyond 1 mJ at repetition rates up to 10 kHz at 800 nm central wavelength. The design of the hybrid fiber/solid-state amplifier line delivering 85-ps pulses with energy up to 10 mJ at repetition rates in the multi-kHz regime tailored for pumping the optical parametric amplifier stages is presented. The novel stretcher/compressor design of HERACLES, suitable for handling optical pulses with spectra exceeding 300 nm of bandwidth with unprecedented flexibility, is fully modeled and also presented in the frame of this thesis. Finally, a 3D model of the multi-stage non-collinear optical parametric amplifier is also reported. The current and foreseen overall performances of HERACLES are presented. This facility is designed to enable attosecond physics experiments, high-harmonic generation and physics of plasma studies.
Show less - Date Issued
- 2011
- Identifier
- CFE0003576, ucf:48931
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003576
- Title
- FABRICATION OF INTEGRATED OPTOFLUIDIC CIRCUITS IN CHALCOGENIDE GLASS USING FEMTOSECOND LASER DIRECT WRITING.
- Creator
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Anderson, Troy, Richardson, Martin, University of Central Florida
- Abstract / Description
-
Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train...
Show moreFemtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. In this dissertation, the utility of femtosecond laser processing as a fabrication technique of optical and micro-fluidic elements in chalcogenide glasses is explored. The photo-induced modifications of optical and chemical parameters of new germanium-based Chalcogenide glasses in both bulk and thin-film form are characterized for the first time and the impact of material composition and laser fabrication parameters are discussed. The glasses are found to display an increase in volume, a decrease of the linear optical refractive index, and an increase of the nonlinear refractive index when exposed to femtosecond laser pulses. A model based on avalanche ionization and multi-photon ionization is used to describe the highly nonlinear absorption of laser light in the material and correlate the photo-induced modifications to the electron density generated during irradiation. The magnitude of the induced photo- modification is shown to be dependent on laser parameters such as laser dose and repetition rate. The fabrication of microfluidic elements through both direct ablation and the preferential etching of photo-modified regions is also explored. Finally, the integration of both optical elements and fluidic elements fabricated by FLDW into a single substrate is discussed.
Show less - Date Issued
- 2010
- Identifier
- CFE0002978, ucf:47965
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002978
- Title
- Detection of Gallium Arsenide Semiconductor Laser Pulses with Avalanche Detectors.
- Creator
-
Marshall, Albert H., Phillips, Ronald L., Engineering
- Abstract / Description
-
Florida Technological University College of Engineering Thesis
- Date Issued
- 1973
- Identifier
- CFR0011989, ucf:53090
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0011989
- Title
- Planar Laser Induced Fluorescence Experiments and Modeling Study of Jets in Crossflow at Various Injection Angles.
- Creator
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Thompson, Luke, Vasu Sumathi, Subith, Kassab, Alain, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
Planar Laser Induced Fluorescence (PLIF) with acetone seeding was applied to measure the scalar fields of an axisymmetric freejet and an inclined jet-in-crossflow as applicable to film cooling. From the scalar fields, jet-mixing and trajectory characteristics were obtained. In order to validate the technique, the canonical example of a nonreacting freejet of Reynolds Numbers 900-9000 was investigated. Desired structural characteristics were observed and showed strong agreement with...
Show morePlanar Laser Induced Fluorescence (PLIF) with acetone seeding was applied to measure the scalar fields of an axisymmetric freejet and an inclined jet-in-crossflow as applicable to film cooling. From the scalar fields, jet-mixing and trajectory characteristics were obtained. In order to validate the technique, the canonical example of a nonreacting freejet of Reynolds Numbers 900-9000 was investigated. Desired structural characteristics were observed and showed strong agreement with computational modeling. After validating the technique with the axisymmetric jet, the jet-in-crossflow was tested with various velocity ratios and jet injection angles. Results indicated the degree of wall separation for different injection angles and demonstrate both the time-averaged trajectories as well as select near-wall concentration results for varying jet momentum fluxes. Consistent with literature findings, the orthogonal jet trajectory for varying blowing ratios collapsed when scaled by the jet-to-freestream velocity ratio and hole diameter, rd. Similar collapsing was demonstrated in the case of a non-orthogonal jet. Computational Fluid Dynamic (CFD) simulations using the OpenFOAM software was used to compare predictions with select experimental cases, and yielded reasonable agreement. Insight into the importance and structure of the counter rotating vortex pair and general flow field turbulence was highlighted by cross validation between CFD and experimental results.
Show less - Date Issued
- 2015
- Identifier
- CFE0006057, ucf:50992
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006057
- Title
- LOW NOISE, HIGH REPETITION RATE SEMICONDUCTOR-BASED MODE-LOCKED LASERS FOR SIGNAL PROCESSING AND COHERENT COMMUNICATIONS.
- Creator
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Quinlan, Franklyn, Delfyett, Peter, University of Central Florida
- Abstract / Description
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This dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be...
Show moreThis dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be measured. Experimental results begin with an exploration of the consequences on the timing and amplitude jitter of the phase noise of an RF source used for mode-locking. These results lead to an ultralow timing jitter source, with 30 fs of timing jitter (1 Hz to 5 GHz, extrapolated). The focus of the work then shifts to generating a stabilized optical frequency comb. The first technique to generating the frequency comb is through optical injection. It is shown that not only can injection locking stabilize a mode-locked laser to the injection seed, but linewidth narrowing, timing jitter reduction and suppression of superfluous optical supermodes of a harmonically mode-locked laser also result. A scheme by which optical injection locking can be maintained long term is also proposed. Results on using an intracavity etalon for supermode suppression and optical frequency stabilization then follow. An etalon-based actively mode-locked laser is shown to have a timing jitter of only 20 fs (1Hz-5 GHz, extrapolated), optical linewidths below 10 kHz and optical frequency instabilities less than 400 kHz. By adding dispersion compensating fiber, the optical spectrum was broadened to 2 THz and 800 fs duration pulses were obtained. By using the etalon-based actively mode-locked laser as a basis, a completely self-contained frequency stabilized coupled optoelectronic oscillator was built and characterized. By simultaneously stabilizing the optical frequencies and the pulse repetition rate to the etalon, a 10 GHz comb source centered at 1550 nm was realized. This system maintains the high quality performance of the actively mode-locked laser while significantly reducing the size weight and power consumption of the system. This system also has the potential for outperforming the actively mode-locked laser by increasing the finesse and stability of the intracavity etalon. The final chapter of this dissertation outlines the future work on the etalon-based coupled optoelectronic oscillator, including the incorporation of a higher finesse, more stable etalon and active phase noise suppression of the RF signal. Two appendices give details on phase noise measurements that incorporate carrier suppression and the noise model for the coupled optoelectronic oscillator.
Show less - Date Issued
- 2008
- Identifier
- CFE0002252, ucf:47878
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002252
- Title
- Single Mode Wavelength-Tunable Thulium Fiber.
- Creator
-
Shin, Dong Jin, Richardson, Martin, Schulzgen, Axel, Amezcua Correa, Rodrigo, University of Central Florida
- Abstract / Description
-
Thulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75(&)#181;m and ends at around 2.15(&)#181;m, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them...
Show moreThulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75(&)#181;m and ends at around 2.15(&)#181;m, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them uniquely suited for applications such as remote sensing. At the moment, high power beam propagation of continuous wave laser through the atmosphere in the mid-infrared range is yet to be investigated anywhere. In particular, the effects of atmospheric water vapors on the thulium fiber laser propagation are unknown and are of great research interest. This dissertation identifies the stringent requirements in constructing a high power, single frequency, wavelength tunable, continuous wave thulium fiber laser with the aim of using it to study various atmospheric transmission effects. A fine spectral control scheme using diffraction gratings is explored and improvements are made. Moreover, a fiber numerical simulation model is presented and is used for designing and implementing the thulium fiber laser system. The current limitations of the implemented system are discussed and an improved system is proposed. This will lay the foundation for the future high power atmospheric propagation studies.
Show less - Date Issued
- 2018
- Identifier
- CFE0007372, ucf:52084
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007372
- Title
- High Energy, High Average Power, Picosecond Laser Systems to Drive Few-Cycle OPCPA.
- Creator
-
Vaupel, Andreas, Richardson, Martin, Delfyett, Peter, Schulzgen, Axel, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
-
The invention of chirped-pulse amplification (CPA) in 1985 led to a tremendous increase in obtainable laser pulse peak intensities. Since then, several table-top, Ti:sapphire-based CPA systems exceeding the 100 TW-level with more than 10 W average power have been developed and several systems are now commercially available. Over the last decade, the complementary technology of optical parametric chirped-pulse amplification (OPCPA) has improved in its performance to a competitive level. OPCPA...
Show moreThe invention of chirped-pulse amplification (CPA) in 1985 led to a tremendous increase in obtainable laser pulse peak intensities. Since then, several table-top, Ti:sapphire-based CPA systems exceeding the 100 TW-level with more than 10 W average power have been developed and several systems are now commercially available. Over the last decade, the complementary technology of optical parametric chirped-pulse amplification (OPCPA) has improved in its performance to a competitive level. OPCPA allows direct amplification of an almost-octave spanning bandwidth supporting few-cycle pulse durations at center wavelengths ranging from the visible to the mid-IR. The current record in peak power from a table-top OPCPA is 16 TW and the current record average power is 22 W. High energy, few-cycle pulses with stabilized carrier-envelope phase (CEP) are desired for applications such as high-harmonic generation (HHG) enabling attoscience and the generation keV-photon bursts.This dissertation conceptually, numerically and experimentally describes essential aspects of few-cycle OPCPA, and the associated pump beam generation. The main part of the conducted research was directed towards the few-cycle OPCPA facility developed in the Laser Plasma Laboratory at CREOL (University of Central Florida, USA) termed HERACLES. This facility was designed to generate few-cycle pulses in the visible with mJ-level pulse energy, W-level average power and more than 100 GW peak power. Major parts of the implementation of the HERACLES facility are presented.The pump generation beam of the HERACLES system has been improved in terms of pulse energy, average power and stability over the last years. It is based on diode-pumped, solid-state amplifiers with picosecond duration and experimental investigations are presented in detail. A robust system has been implemented producing mJ-level pulse energies with ~100 ps pulse duration at kHz repetition rates. Scaling of this system to high power ((>)30 W) and high peak power (50-MW-level) as well as ultra-high pulse energy ((>)160 mJ) is presented. The latter investigation resulted in the design of an ultra-high energy system for OPCPA pumping. Following this, a new OPCPA facility was designed termed PhaSTHEUS, which is anticipated to reach ultra-high intensities.Another research effort was conducted at CELIA (Univerist(&)#233; de Bordeaux 1, France) and aimed towards a previously unexplored operational regime of OPCPA with ultra-high repetition rates (10 MHz) and high average power. A supercontinuum seed beam generation has been established with an output ranging from 1.3 to 1.9 ?m and few ps duration. The pump beam generation has been implemented based on rod-type fiber amplifiers producing more than 37 W average power and 370 kW peak power. The utility of this system as an OPCPA pump laser is presented along with the OPA design.The discussed systems operate in radically different regimes in terms of peak power, average power, and repetition rate. The anticipated OPCPA systems with few-cycle duration enable a wide range of novel experimental studies in attoscience, ultrafast materials processing, filamentation, LIBS and coherent control.
Show less - Date Issued
- 2013
- Identifier
- CFE0004952, ucf:49570
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004952
- Title
- NEW LASER TECHNOLOGIES: ANALYSIS OF QUANTUM DOT ANDLITHOGRAPHIC LASER DIODES.
- Creator
-
Demir, Abdullah, Deppe, Dennis, University of Central Florida
- Abstract / Description
-
The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the...
Show moreThe first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold temperature dependence of a QD laser diode. The second part is on the experimental demonstration of lithographic lasers. Today's vertical-cavity surface-emitting lasers (VCSELs) based on oxide-aperture suffer from serious problems such as heat dissipation, internal strain, reliability, uniformity and size scaling. The lithographic laser provides solutions to all these problems. The transverse mode and cavity are defined using only lithography and epitaxial crystal growth providing simultaneous mode- and current-confinement. Eliminating the oxide aperture is shown to reduce the thermal resistance of the device and leading to increased power density in smaller lasers. When it is combined with better mode matching to gain for smaller devices, high output power density of 58 kW/cm2 is possible for a 3 micron VCSEL with threshold current of 260 microamperes. These VCSELs also have grating-free single-mode single-polarization emission. The demonstration of lithographic laser diodes with good scaling properties is therefore an important step toward producing ultra-small size laser diodes with high output power density, high speed, high manufacturability and high reliability. Lithographic VCSELs ability to control size lithographically in a strain-free, high efficiency device is a major milestone in VCSEL technology.
Show less - Date Issued
- 2010
- Identifier
- CFE0003304, ucf:48494
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003304
- Title
- Noise, Stability, and Linewidth Performance of 10-GHz Optical Frequency Combs Generated from the Nested Cavity Architecture.
- Creator
-
Bagnell, Kristina, Delfyett, Peter, Likamwa, Patrick, Schulzgen, Axel, DeSalvo, Richard, University of Central Florida
- Abstract / Description
-
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(-)P(&)#233;rot 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...
Show moreOptical 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(-)P(&)#233;rot 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 quality factors of the long fiber cavity and the short etalon cavity. Passive cavity Q and intracavity power both influence mode-locked laser mode linewidth, optical frequency stability, and the phase noise of the photodetected output. The nested cavity architecture has been demonstrated at 10-GHz mode spacing a few times with increasing etalon finesse and once with a high saturation power semiconductor gain medium to increase intracavity power. No one system has been fully characterized for long term optical frequency stability, phase noise and timing jitter, and optical mode linewidth. As a result, the trade-offs involved with advancing any one element (e.g. increasing cavity Q by adding fiber length and maintaining a broad spectral region of low dispersion for broad-bandwidth operation) have not been fully examined. In this work, three cavity elements are identified for study to influence cavity Q, effective noise spur suppression, and intracavity power, and the trade-offs of pushing those parameters to new limits are experimentally demonstrated. In the process, we also demonstrate nested cavity systems with fractional frequency instability on the order of 10^-13, timing jitter as low as 20 fs, and Hz-level linewidths.
Show less - Date Issued
- 2017
- Identifier
- CFE0006717, ucf:51883
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006717
- Title
- Phase-locking Stability of a Quasi-single-cycle Pulse.
- Creator
-
Bodnar, Nathan, Richardson, Martin, Chang, Zenghu, Delfyett, Peter, University of Central Florida
- Abstract / Description
-
There is increasing interest in the generation of very short laser pulses, even down to attosecond (10-18 s) durations. Laser systems with femtosecond pulse durations are needed for these applications. For many of these applications, positioning of the maximum electric field within the pulse envelope can affect the outcome. The peak of the electric field relative to the peak of the pulse is called the Carrier Envelope Phase (CEP). Controlling the position of the electric field becomes more...
Show moreThere is increasing interest in the generation of very short laser pulses, even down to attosecond (10-18 s) durations. Laser systems with femtosecond pulse durations are needed for these applications. For many of these applications, positioning of the maximum electric field within the pulse envelope can affect the outcome. The peak of the electric field relative to the peak of the pulse is called the Carrier Envelope Phase (CEP). Controlling the position of the electric field becomes more important when pulse duration approaches single-cycle.This thesis focuses on the stabilization of a quasi-single-cycle laser facility. Improvements to this already-established laser facility, HERACLES (High Energy, Repetition rate Adjustable, Carrier-Locked-to-Envelope System) described in this thesis include a stabilized pump line and the improvement in CEP stabilization electronics. HERACLES is built upon an Optical Parametric Chirped Pulse Amplification (OPCPA) architecture. This architecture uses Optical Parametric Amplification (OPA) as the gain material to increase the output energy of the system. OPA relies on a nonlinear process to generate high gain (106) with ultra-wide bandwidth. Instabilities in the OPA driving pump energy can create dynamically fluctuations in the final OPCPA output energy. To reduce these fluctuations two key upgrades were implemented on the pump beam. Both were major improvements in the stability. Firstly, an improved regenerative amplifier design reduced beam pointing fluctuations. Secondly, the addition of a pump monitoring system with feedback-control eliminated long-term power drifts. Both enhanced the OPA pulse-to-pulse and long-term stability.To improve the stability in measuring CEP drifts, modification of the feedback electronics was needed. The modification consisted of integrating noise reduction electronics. This novel noise reducer uses a similar process to a super-heterodyne receiver. The noise reducer resulted in 60 dB reduction of out-of-band noise. This led to increased signal quality with cleaner amplification of weaker signals. The enhanced signal quality led to more reliable long-term locking. The synthetically increased signal-to-noise ratio allows locking of the CEP frequency below the typically requirements. This integration allows relaxed constraints on the laser systems.The optics and electronics of a high-power, quasi-single cycle laser facility were improved. This thesis included the stabilization of the pump line and the stabilization of the CEP. This work allows for new long-duration experiments.
Show less - Date Issued
- 2013
- Identifier
- CFE0004654, ucf:49908
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004654
- Title
- Enhanced Ablation by Femtosecond and Nanoseond Laser Pulses.
- Creator
-
Kerrigan, Haley, Richardson, Martin, Baudelet, Matthieu, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
-
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...
Show moreLaser 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 time. In this work, the craters generated by combinations of pulses are investigated for inter-pulse delays ranging from -50ns to +1?s, with the fs pulse preceding the ns pulse corresponding to a positive delay. The Ti:Sapph Multi-Terawatt Femtosecond Laser (MTFL) in the Laser Plasma Laboratory (LPL) provides 50fs pulses at 800nm with intensities of 1014W/cm^2 at the sample. An Nd:YAG laser (Quantel CFR200) provides 8ns pulses at 1064nm with intensities of 109W/cm^2. Crater profilometry with white-light interferometry and optical microscopy determine the structure and surface features of the craters and the volume of material removed. Ultrafast shadowgraphy of the ejected plasma provides insight to the dual-pulse ablation dynamics. Sedov-Taylor analysis of the generated shockwave reveals the energy coupled to the sample or preceding plasma. It was found that inter-pulse delays between +40 and +200ns yielded craters 2.5x greater in volume than that of the femtosecond pulse alone, with a maximum enhancement of 2.7x at +100ns. Shadowgraphy of -40 to +40ns delays revealed that enhancement occurs when the nanosecond pulse couples to plasma generated by the fs pulse. This work provides a possible means of enhancing ablation by femtosecond filaments, which propagate long distances with clamped intensity, advancing long-range stand-off ablation
Show less - Date Issued
- 2017
- Identifier
- CFE0006889, ucf:51734
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006889
- Title
- Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points.
- Creator
-
Hodaeiesfahani, Seyedhossein, Khajavikhan, Mercedeh, Christodoulides, Demetrios, Likamwa, Patrick, Abdolvand, Reza, University of Central Florida
- Abstract / Description
-
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...
Show moreIn 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 of micro-resonators.In the first part of this work, I will describe how stable single mode lasing can be readily achieved in longitudinally and transversely multi-moded microring cavities through the systematic utilization of abrupt phase transitions at exceptional points. This technique will be first demonstrated in a parity-time laser that is comprised of a gain cavity coupled to an identical but lossy counterpart. A detailed study of the behavior of this system around the exceptional point will be presented. Furthermore, we report the first experimental realization of a dark state laser in which by strategically designing the spectral locations of exceptional points, widely tunable single-mode lasing can be attained even at high pump levels. Despite the presence of loss in such open laser systems, the slope efficiency remains virtually intact. Our results demonstrate the potential of exceptional points as a versatile design tool for mode management in on-chip laser configurations.In the second part of my dissertation, I will show how the exceptional points and their underlying degeneracies can be used to significantly boost the intrinsic sensitivity of microcavities. I will demonstrate the enhanced sensitivity in a binary PT-symmetric coupled cavity arrangement that is biased at an exceptional point. Then I will report the first observation of higher-order exceptional points in a ternary parity-time symmetric microring laser system with a judiciously tailored gain-loss distribution. The enhanced response associated with this ternary system follows a cubic root dependence on externally introduced perturbation, which can in turn be detected in the spectral domain. Using such arrangements, more than one order of magnitude enhancement in the sensitivity is observed experimentally. These results can pave the way towards improving the performance of current on-chip micro-cavity sensors.
Show less - Date Issued
- 2017
- Identifier
- CFE0006947, ucf:51627
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006947
- Title
- Injection Locking of Semiconductor Mode-Locked Lasers for Long-Term Stability of Widely Tunable Frequency Combs.
- Creator
-
Williams, Charles, Delfyett, Peter, Hagan, David, Likamwa, Patrick, Vanstryland, Eric, DeSalvo, Richard, University of Central Florida
- Abstract / Description
-
Harmonically mode-locked semiconductor lasers with external ring cavities offer high repetition rate pulse trains while maintaining low optical linewidth via long cavity storage times. Single frequency injection locking generates widely-spaced and tunable frequency combs from these harmonically mode-locked lasers, while stabilizing the optical frequencies. The output is stabilized long-term with the help of a feedback loop utilizing either a novel technique based on Pound-Drever-Hall...
Show moreHarmonically mode-locked semiconductor lasers with external ring cavities offer high repetition rate pulse trains while maintaining low optical linewidth via long cavity storage times. Single frequency injection locking generates widely-spaced and tunable frequency combs from these harmonically mode-locked lasers, while stabilizing the optical frequencies. The output is stabilized long-term with the help of a feedback loop utilizing either a novel technique based on Pound-Drever-Hall stabilization or by polarization spectroscopy. Error signals of both techniques are simulated and compared to experimentally obtained signals. Frequency combs spaced by 2.5 GHz and ~10 GHz are generated, with demonstrated optical sidemode suppression of unwanted modes of 36 dB, as well as RF supermode noise suppression of 14 dB for longer than 1 hour. In addition to the injection locking of actively harmonically mode-locked lasers, the injection locking technique for regeneratively mode-locked lasers, or Coupled Opto-Electronic Oscillators (COEOs), is also demonstrated and characterized extensively.
Show less - Date Issued
- 2013
- Identifier
- CFE0004774, ucf:49805
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004774
- Title
- DEBRIS CHARACTERIZATION AND MITIGATION OF DROPLET LASER PLASMA SOURCES FOR EUV LITHOGRAPHY.
- Creator
-
Takenoshita, Kazutoshi, Richardson, Martin, University of Central Florida
- Abstract / Description
-
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...
Show moreExtreme 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. The design of a the laser plasma EUVL light source consists of a plasma produced from a high-intensity focused laser beam from a solid/liquid target, from which radiation is generated and collected by a large solid angle mirror or array of mirrors. The collector mirrors have the same reflectivity characteristics as the stepper mirrors. The EUVL light source is considered as the combination of both the hot-dense plasma and the collector mirrors. The EUVL light sources required by the stepper manufacturers must have sufficient EUV output power and long operational lifetimes to meet market-determined chip production rates. The most influential factor in achieving the required EUV output power is the conversion efficiency (CE) of laser input energy relative to the EUV radiation collected. A high CE is demonstrated in a separate research program by colleagues in the Laser Plasma laboratory at CREOL. Another important factor for the light source is the reflectivity lifetime of the collection optics as mirror reflectivity can be degraded by deposition and ablation from the plasma debris. Realization of a high CE but low debris plasma source is possible by reducing the mass of the target, which is accomplished by using tin-doped droplet targets. These have sufficient numbers of tin atoms for high CE, but the debris generation is minimal. The first part of this study investigates debris emissions from tin-doped droplet targets, in terms of aerosols and ions. Numerous tin aerosols can be created during a single laser-target interaction. The effects these interactions are observed and the depositions are investigated using SEM, AFM, AES, XPS, and RBS techniques. The generation of aerosols is found to be the result of incomplete ionization of the target material, corresponding to non-optimal laser coupling to the target for maximum CE. In order to determine the threats of the ion emission to the collector mirror coatings from an optimal, fully ionized target, the ion flux is measured at the mirror distance using various techniques. The ion kinetic energy distributions obtained for individual ion species are quantitatively analyzed. Incorporating these distributions with Monte-Carlo simulations provide lifetime estimation of the collector mirror under the effect of ion sputtering. The current estimated lifetime the tin-doped droplet plasma source is only a factor of 500 less than the stepper manufacturer requirements, without the use of any mitigation schemes to stop these ions interacting with the mirror. The second part of this investigation explores debris mitigation schemes. Two mitigation schemes are applied to tin-doped droplet laser plasmas; electrostatic field mitigation, and a combination of a foil trap with a magnetic field. Both mitigation schemes demonstrate their effectiveness in suppressing aerosols and ion flux. A very small number of high-energy ions still pass through the combination of the two mitigation schemes but the sputtering caused by these ions is too small to offer a threat to mirror lifetime. It is estimated that the lifetime of the collector mirror, and hence the source lifetime, will be sufficient when tin-doped targets are used in combination with these mitigation schemes.
Show less - Date Issued
- 2006
- Identifier
- CFE0001289, ucf:46920
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001289
