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Title: High Average Power Nanosecond Pulsed Tm:Fiber Laser for Pumping an Optical Parametric Oscillator.
Creator: Abdulfattah, Ali, Richardson, Martin, Shah, Lawrence, Delfyett, Peter, University of Central Florida
Abstract / Description: Thulium-doped fiber lasers operating with wavelengths in the vicinity of 2 (&)#181;m are useful for several emerging applications including generating mid-IR light via nonlinear frequency conversion. In this study we describe the design and construction of a thulium fiber laser system comprising a master oscillator and a power amplifier. The first stage is a Q-switched, thulium-doped photonic crystal fiber oscillator utilizing an acousto-optic modulator to produce 65-80 nanosecond pulses. A...
Show moreThulium-doped fiber lasers operating with wavelengths in the vicinity of 2 (&)#181;m are useful for several emerging applications including generating mid-IR light via nonlinear frequency conversion. In this study we describe the design and construction of a thulium fiber laser system comprising a master oscillator and a power amplifier. The first stage is a Q-switched, thulium-doped photonic crystal fiber oscillator utilizing an acousto-optic modulator to produce 65-80 nanosecond pulses. A diffraction grating in the cavity provides wavelength tunability from 1.8 (-) 2?m. The oscillator produced up to 3 W of average power and 150 (&)#181;J pulse energies, corresponding to 2.3 kW peak powers. The amplifier stage consists of a large mode area, thulium-doped, step-index fiber seeded with powers up to 2 W from the oscillator. An output energy of 700 (&)#181;J with 81 ns pulse width, was achieved at a wavelength of 1.9 (&)#181;m. The effect of the fiber holder temperature on the amplifier performance relative to output pulse energy and seed wavelength was also studied. As a part of this thesis, a methodology has been developed to thoroughly characterize Tm:fiber amplifier performance. This has been the subject of prior work by several research groups, however, this work explicitly focuses on the precise characterization of absorbed pump power, pump bleaching, and extracted amplified energy for a range of input seeds power, pulse energy, and wavelength in order to better understand amplifier performance.
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Date Issued: 2016
Identifier: CFE0006240, ucf:51065
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006240

Title: Design of a hydrogen-filled hollow-core Raman fiber laser.
Creator: Qin, Yangyang, Amezcua Correa, Rodrigo, Schulzgen, Axel, Shah, Lawrence, University of Central Florida
Abstract / Description: 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...
Show moreThe 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 spectrum of these fibers were measured thus it's easier to make a choice. Through the whole thesis a Raman fiber laser can be set up and tested very soon.
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Date Issued: 2017
Identifier: CFE0006645, ucf:51213
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006645

Title: POWER SCALING OF LARGE MODE AREA THULIUM FIBER LASERS IN VARIOUS SPECTRAL AND TEMPORAL REGIMES.
Creator: McComb, Timothy, Richardson, Martin, University of Central Florida
Abstract / Description: High power thulium fiber lasers are interesting for a myriad of applications due to their potential for high average output power, excellent beam quality, compactness, portability, high operating efficiency and broad, eye-safe spectral range from 1.8-2.1 microns. Currently, the majority of thulium laser research effort is being invested into scaling average output powers; however, such output powers are being scaled with no degree of control on laser system output spectrum or temporal...
Show moreHigh power thulium fiber lasers are interesting for a myriad of applications due to their potential for high average output power, excellent beam quality, compactness, portability, high operating efficiency and broad, eye-safe spectral range from 1.8-2.1 microns. Currently, the majority of thulium laser research effort is being invested into scaling average output powers; however, such output powers are being scaled with no degree of control on laser system output spectrum or temporal behavior. Thulium fiber laser technology is not useful for many of its most important applications without implementation of techniques enabling tunable, narrow spectral widths with appropriate pulse durations for particular applications. This work outlines several techniques for spectral control of thulium fiber lasers and investigates scaling of average laser powers while using these techniques to maintain a desired spectral output. In addition, an examination of operation in both nanosecond and picosecond pulsed regimes and scaling of average powers and pulse energies in these regimes to useful power levels is conducted. The demonstration of thulium fiber laser systems for applications in frequency conversion and spectral beam combination is also discussed. In addition to the experimental results, theoretical modeling of thulium fiber amplifier operation, simple thermal management analysis, as well as practical fiber and system design considerations for future power scaling are presented. Experimental and theoretical results of this work will enable the successful design of future extremely high power spectrally and temporally controlled thulium fiber laser systems.
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Date Issued: 2009
Identifier: CFE0002885, ucf:48045
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002885

Title: High power fiber lasers and fiber devices.
Creator: Sanjabieznaveh, Zeinab, Amezcua Correa, Rodrigo, Chang, Zenghu, Argenti, Luca, Richardson, Martin, Schulzgen, Axel, University of Central Florida
Abstract / Description: Fiber lasers and fiber amplifiers have experienced considerable improvements in recent years and demonstrated remarkable power scalability. However, due to high optical intensity in the core, the performance of high power fiber lasers is limited by detrimental nonlinear processes, such as four-wave mixing, self-phase modulation, stimulated Brillouin scattering, and stimulated Raman scattering. To mitigate nonlinear effects, very large mode area (LMA) fibers, which exhibit a mode field...
Show moreFiber lasers and fiber amplifiers have experienced considerable improvements in recent years and demonstrated remarkable power scalability. However, due to high optical intensity in the core, the performance of high power fiber lasers is limited by detrimental nonlinear processes, such as four-wave mixing, self-phase modulation, stimulated Brillouin scattering, and stimulated Raman scattering. To mitigate nonlinear effects, very large mode area (LMA) fibers, which exhibit a mode field diameter larger than 30 ?m have been developed. However, for larger core sizes the discrimination capabilities of conventional fiber designs decrease, consequently, LMA fibers are not strictly single mode which ultimately at high average powers results in sudden degradation of the output beam of a fiber laser or amplifier, namely, modal instability (MI). To suppress higher order modes (HOMs) in LMA fibers, various techniques have been proposed such as large pitch fibers (LPFs), differential bend loss for HOMs, leakage channel fibers, mode filtering with tapers, and chirally coupled cores. This thesis is divided into two parts. In the first two chapters, I focus on simulation, design and characterization of advanced high power fiber amplifiers. In the first chapter, I study the numerical modeling of the MI in active LMA fibers. Using a high fidelity time dependent computer model based on beam propagation method (BPM), taking laser gain and thermal effects into account, I show that engineering pump scheme is a promising technique leading to an appreciable threshold increase in a fiber amplifier. As an example I demonstrate that bi-directional pump scheme increases the instabilities threshold by a factor of ~30% with respect to the forward pump configuration. In the second chapter, I present a novel design of microstructured large pitch, LMA asymmetric rod-type fiber to achieve higher MI threshold. By eliminating mirror symmetries in the cladding of the LPF through six high refractive index germanium-doped silica inclusions, we reduce the overlap of the LP1m-like modes with the core region, which leads to strong HOM delocalization and enhanced preferential gain for the fundamental mode in active fibers. The third and fourth chapters of this thesis are focused on all-fiber mode multiplexers for communication applications. In the third chapter, I present an all-fiber mode selective photonic lantern mode multiplexer designed for launching into few-mode multicore fibers (FM-MCFs). This device is capable of selectively exciting LP01, LP11a and LP11b modes in a seven core configuration resulting in 21 spatial channels, with less than 38 dB crosstalk and with insertion loss below 0.4 dB. This device can be a critical component for the evolution of high capacity, high-density space division multiplexing (SDM) transmission networks based on MCFs.In the fourth chapter, I demonstrate for the first time, an all-fiber orbital angular momentum (OAM) mode multiplexer to efficiently generate and simultaneously multiplex multiple OAM modes within a broad spectral range of at least 550 nm. This innovative all-fiber passive design provides simultaneous multiplexing of multiple orthogonal OAM modes in a single fiber device with low loss and at low design complexity, therefore, it is of grand utility in variety of applications in classical and modern optical studies.
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Date Issued: 2017
Identifier: CFE0006956, ucf:51632
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006956

Title: 2 micron fiber lasers: power scaling concepts and limitations.
Creator: Sincore, Alex, Richardson, Martin, Amezcua Correa, Rodrigo, Schulzgen, Axel, Shah, Lawrence, University of Central Florida
Abstract / Description: Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin...
Show moreThulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses is developed. Measuring the SBS threshold versus pulse duration enables the Brillouin gain coefficient and gain bandwidth to be determined at 2 micron. Second, a 23 W spectrally-broadband, nanosecond pulsed laser is constructed for materials processing applications. The temporally incoherent multi-kW peak power pulses can also efficiently produce MI and supercontinuum generation by adjusting the input spectral linewidth. Third, the measured performance of in-band pumped TDF and HDF lasers are compared with simulations. HDF displays low efficiencies, which is explained by including ion clustering in the simulations. The TDF operates with impressive (>)90% slope efficiencies. Based on this result, a system design for (>)1 kW average power TDF amplifier is described. The designed final amplifier will be in-band pumped to enable high efficiency and low thermal load. The amplifier efficiency, operating bandwidth, thermal load, and nonlinear limits are modeled and analyzed to provide a framework for execution. Overall, this dissertation provides further insight and understanding on the various processes that limit power scaling of 2 micron fiber lasers.
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Date Issued: 2018
Identifier: CFE0007374, ucf:52105
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007374

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.
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Date Issued: 2018
Identifier: CFE0007372, ucf:52084
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007372

Title: THE DEVELOPMENT OF SCALABLE PUMP TECHNIQUES FOR GG IAG FIBER LASERS AND PASSIVE ATHERMALIZATION TECHNIQUES FOR SOLID STATE LASERS.
Creator: Hageman, William, Bass, Michael, University of Central Florida
Abstract / Description: This dissertation consists of two parts: research pertaining to the development of scalable pump techniques for gain guided index-antiguided fiber lasers and research relating to the development of passive athermalization schemes for solid state lasers. The first section primarily details the development of a side pump scheme that allows for power scaling of gain-guided index anti-guided fibers. While these fibers have been demonstrated in past research, none have used a pump technology...
Show moreThis dissertation consists of two parts: research pertaining to the development of scalable pump techniques for gain guided index-antiguided fiber lasers and research relating to the development of passive athermalization schemes for solid state lasers. The first section primarily details the development of a side pump scheme that allows for power scaling of gain-guided index anti-guided fibers. While these fibers have been demonstrated in past research, none have used a pump technology capable of pumping with the efficiencies, uniformity, and necessary length to allow for scaling of the fiber lasers to high output powers. The side pumped scheme developed in this section demonstrates a 6 W output power fiber laser with room for improvement in efficiency and beam quality. The second section details work done on the development of technologies for passively athermalizing the output of solid state laser systems. Techniques for passively removing the dependence of laser output power/energy on the operating temperature of the laser system promise to reduce the weight, power consumption, and cost of fielded laser systems. Methods for achieving passive athermalization are discussed, as well as prior research in laser athermalization, background theory, enabling technologies, and experimental results. This work provides the basis for continued research of passive athermalization and the eventual demonstration of this technology.
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Date Issued: 2010
Identifier: CFE0002993, ucf:47938
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002993

Title: Transverse mode selection and brightness enhancement in laser resonators by means of volume Bragg gratings.
Creator: Anderson, Brian, Glebov, Leonid, Zeldovich, Boris, Schulzgen, Axel, Rahman, Talat, University of Central Florida
Abstract / Description: The design of high power lasers requires large mode areas to overcome various intensity driven nonlinear effects. Increasing the aperture size within the laser can overcome these effects, but typically result in multi-transverse mode output and reduced beam quality, limiting the brightness of the system. As one possible solution, the angular selectivity of a diffractive optical element is proposed as a spatial filter, allowing for the design of compact high brightness sources not possible...
Show moreThe design of high power lasers requires large mode areas to overcome various intensity driven nonlinear effects. Increasing the aperture size within the laser can overcome these effects, but typically result in multi-transverse mode output and reduced beam quality, limiting the brightness of the system. As one possible solution, the angular selectivity of a diffractive optical element is proposed as a spatial filter, allowing for the design of compact high brightness sources not possible with conventional methods of transverse mode selection. This thesis explores the angular selectivity of volume Bragg gratings (VBGs) and their use as spatial transverse mode filters in a laser resonator. Selection of the fundamental mode of a resonator is explored using transmission Bragg gratings (TBGs) as the spatial filter. Simulations and experimental measurements are made for a planar, 1 cm long resonator demonstrating near diffraction limited output (M2 (<) 1.4) for aperture sizes as large as 2.0 mm. Applications to novel fiber laser designs are explored. Single mode operation of a multi-mode Yb3+ doped ribbon fiber laser (core dimensions of 107.8 ?m x 8.3 ?m) is obtained using a single transmission VBG as the filter in an external cavity resonator. Finally, a novel method of selecting a pure higher order mode to oscillate within the gain medium while simultaneously converting this higher order mode to a fundamental mode at an output coupler is proposed and demonstrated. A multiplexed transmission VBG is used as the mode converting element, selecting the 12th higher order mode for amplifications in an Yb3+ doped ribbon fiber laser, while converting the higher order mode of a laser resonator to a single lobed output beam with diffraction limited divergence.
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Date Issued: 2015
Identifier: CFE0005754, ucf:50103
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005754

Title: Picosecond Yb-Doped Fiber Amplifier.
Creator: Zhu, Weibin, Amezcua Correa, Rodrigo, Schulzgen, Axel, Fathpour, Sasan, University of Central Florida
Abstract / Description: 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...
Show moreDue 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 the YDFA by developing a model and building a YDFA setup in free space configuration. The active fiber used in the setup is a few modes, polarization-maintaining double-cladding ytterbium-doped large mode area (LMA) fiber and the length is 1m. The pump used is a tunable 975nm laser diode and a 1064nm laser diode was used as the seed which has 630 ps pulse duration time and 9.59 kHz repetition rate. This setup produces 2.514W average power, corresponding to a pulse peak power of 423kW, with 15W absorbed pump power. The spectrum of the output power has also been investigated.
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Date Issued: 2017
Identifier: CFE0006678, ucf:51214
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006678

Title: Peak Power Scaling of Nanosecond Pulses in Thulium based Fiber Lasers.
Creator: Gaida, Christian, Richardson, Martin, Shah, Lawrence, Amezcua Correa, Rodrigo, University of Central Florida
Abstract / Description: Thulium based fiber lasers represent a promising alternative for pulse energy scaling and highpeak power generation with ytterbium based systems at 1 micrometer. Advantages of thulium arise fromthe operation at longer wavelengths and a large gain bandwidth (1.8-2.1 micrometer). Nonlinear effects,such as self phase modulation, stimulated Raman scattering and stimulated Brillouin scattering generally limit peak power scaling in fiber lasers. The longer wavelength of thulium fiber lasersand...
Show moreThulium based fiber lasers represent a promising alternative for pulse energy scaling and highpeak power generation with ytterbium based systems at 1 micrometer. Advantages of thulium arise fromthe operation at longer wavelengths and a large gain bandwidth (1.8-2.1 micrometer). Nonlinear effects,such as self phase modulation, stimulated Raman scattering and stimulated Brillouin scattering generally limit peak power scaling in fiber lasers. The longer wavelength of thulium fiber lasersand large mode field areas can significantly increase the nonlinear thresholds. Compared to 1 micrometer systems, thulium fiber lasers enable single mode guidance for two times larger mode field diameterin step index fibers. Similar behavior is expected for index guiding thulium doped photonic crystalfibers.In this work a novel thulium doped rod type photonic crystal fiber design with large mode field diameter (>50 micrometer) was first characterized in CW-lasing configuration and then utilized as finalamplifier in a two stage master oscillator power amplifier. The system generated MW-level peakpower at 6.5ns pulse duration and 1kHz repetition rate. This world record performance exemplifiesthe potential of thulium fiber lasers to supersede ytterbium based systems for very high peak powergeneration in the future.As part of this work a computer model for the transient simulation of pulsed amplification inthulium based fiber lasers was developed. The simulations are in good agreement with the experimentalresults. The computer model can be used for efficient optimization of future thulium basedfiber amplifier designs.
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Date Issued: 2013
Identifier: CFE0004845, ucf:49699
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004845

Title: Specialty Fiber Lasers and Novel Fiber Devices.
Creator: Jollivet, Clemence, Schulzgen, Axel, Moharam, Jim, Richardson, Martin, Mafi, Arash, University of Central Florida
Abstract / Description: At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled...
Show moreAt the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the recurring needs for in-depth fiber characterization. The first part of this dissertation details a novel experiment that was demonstrated to achieve modal decomposition with extended capabilities, reaching beyond the limits set by the existing mode analysis techniques. As a result, individual transverse modes carrying between ~0.01% and ~30% of the total light were resolved with unmatched accuracy. Furthermore, this approach was employed to decompose the light guided in Large-Mode Area (LMA) fiber, Photonic Crystal Fiber (PCF) and Leakage Channel Fiber (LCF). The single-mode performances were evaluated and compared. As a result, the suitability of each specialty fiber design to be implemented for power-scaling applications of fiber laser systems was experimentally determined.The second part of this dissertation is dedicated to novel specialty fiber laser systems. First, challenges related to the monolithic integration of novel and complex specialty fiber designs in all-fiber systems were addressed. The poor design and size compatibility between specialty fibers and conventional fiber-based components limits their monolithic integration due to high coupling loss and unstable performances. Here, novel all-fiber Mode-Field Adapter (MFA) devices made of selected segments of Graded Index Multimode Fiber (GIMF) were implemented to mitigate the coupling losses between a LMA PCF and a conventional Single-Mode Fiber (SMF), presenting an initial 18-fold mode-field area mismatch. It was experimentally demonstrated that the overall transmission in the mode-matched fiber chain was increased by more than 11 dB (the MFA was a 250 ?m piece of 50 ?m core diameter GIMF). This approach was further employed to assemble monolithic fiber laser cavities combining an active LMA PCF and fiber Bragg gratings (FBG) in conventional SMF. It was demonstrated that intra-cavity mode-matching results in an efficient (60%) and narrow-linewidth (200 pm) laser emission at the FBG wavelength.In the last section of this dissertation, monolithic Multi-Core Fiber (MCF) laser cavities were reported for the first time. Compared to existing MCF lasers, renown for high-brightness beam delivery after selection of the in-phase supermode, the present new generation of 7-coupled-cores Yb-doped fiber laser uses the gain from several supermodes simultaneously. In order to uncover mode competition mechanisms during amplification and the complex dynamics of multi-supermode lasing, novel diagnostic approaches were demonstrated. After characterizing the laser behavior, the first observations of self-mode-locking in linear MCF laser cavities were discovered.
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Date Issued: 2014
Identifier: CFE0005354, ucf:50491
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005354

Title: Applications of Volume Holographic Elements in High Power Fiber Lasers.
Creator: Jain, Apurva, Glebov, Leonid, Zeldovich, Boris, Schulzgen, Axel, Likamwa, Patrick, Rahman, Talat, University of Central Florida
Abstract / Description: The main objective of this thesis is to explore the use of volume holographic elements recorded in photo-thermo-refractive (PTR) glass for power scaling of narrow linewidth diffraction-limited fiber lasers to harness high average power and high brightness beams. Single fiber lasers enable kW level output powers limited by optical damage, thermal effects and non-linear effects. Output powers can be further scaled using large mode area fibers, however, at the cost of beam quality and...
Show moreThe main objective of this thesis is to explore the use of volume holographic elements recorded in photo-thermo-refractive (PTR) glass for power scaling of narrow linewidth diffraction-limited fiber lasers to harness high average power and high brightness beams. Single fiber lasers enable kW level output powers limited by optical damage, thermal effects and non-linear effects. Output powers can be further scaled using large mode area fibers, however, at the cost of beam quality and instabilities due to the presence of higher order modes. The mechanisms limiting the performance of narrow-linewidth large mode area fiber lasers are investigated and solutions using intra-cavity volume Bragg gratings (VBG) proposed. Self-pulsations-free, completely continuous-wave operation of a VBG-stabilized unidirectional fiber ring laser is demonstrated with quasi single-frequency ((<) 7.5 MHz) output. A method for transverse mode selection in multimode fiber lasers to reduce higher order mode content and stabilize the output beam profile is developed using angular selectivity of reflecting VBGs. By placing the VBG output coupler in a convergent beam, stabilization of the far-field beam profile of a 20 ?m core large mode area fiber laser is demonstrated.Beam combining techniques are essential to power scale beyond the limitations of single laser sources. Several beam combining techniques relevant to fiber lasers were compared in this study and found to be lacking in one or more of the following aspects: the coherence of the individual sources is compromised, the far-field beam quality is highly degraded with significant power in side lobes, spectrally broad and unstable, and uncertainty over scaling to larger arrays and higher power. Keeping in mind the key requirements of coherence, good far-field beam quality, narrow and stable spectra, and scalability in both array size and power, a new passive coherent beam combining technique using multiplexed volume Bragg gratings (M-VBGs) is proposed.In order to understand the mechanism of radiation exchange between multiple beams via these complex holographic optical elements, the spectral and beam splitting properties a 2nd order reflecting M-VBG recorded in PTR glass is experimentally investigated using a tunable single frequency seed laser. Two single-mode Yb-doped fiber lasers are then coherently combined using reflecting M-VBGs in both linear and unidirectional-ring resonators with (>)90% combining efficiency and diffraction-limited beam quality. It is demonstrated that the combining bandwidth can be controlled in the range of 100s of pm to a few pm by angular detuning of the M-VBG. Very narrow-linewidth ((<) 210 MHz) operation in a linear cavity and possibility of single-frequency operation in a unidirectional ring cavity of the coherently combined system is demonstrated using this technique. It is theoretically derived and experimentally demonstrated that high combining efficiency can be achieved even by multiplexing low-efficiency VBGs, with the required diffraction efficiency of individual VBGs decreasing as array size increases. Scaling of passive coherent beam combining to four fiber lasers is demonstrated using a 4th order transmitting M-VBG. Power scaling of this technique to 10 W level combined powers with 88% combining efficiency is demonstrated by passively combining two large mode area fiber lasers using a 2nd order reflecting M-VBG in a unidirectional ring resonator. High energy compact single-frequency sources are highly desired for several applications (-) one of which is as a seed for high power fiber amplifiers. Towards achieving the goal of a monolithic solid-state laser, a new gain medium having both photosensitive and luminescence properties is investigated (-) rare-earth doped PTR glass. First lasing is demonstrated in this new gain element in a VBG-stabilized external cavity.
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Date Issued: 2012
Identifier: CFE0004553, ucf:49230
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004553

Title: Development of Thulium Fiber Lasers for High Average Power and High Peak Power Operation.
Creator: Sims, Robert, Richardson, Martin, Schulzgen, Axel, Delfyett, Peter, Chow, Louis, University of Central Florida
Abstract / Description: High power thulium fiber lasers are useful for a number of applications in both continuous-wave and pulsed operating regimes. The use of thulium as a dopant has recently gained interest due to its large bandwidth, possibility of high efficiency, possibility of high power and long wavelength ~1.8 (-) 2.1 ?m. The longer emission wavelength of Tm-doped fiber lasers compared to Yb- and/or Er-doped fiber lasers creates the possibility for higher peak power operation due to the larger nonlinear...
Show moreHigh power thulium fiber lasers are useful for a number of applications in both continuous-wave and pulsed operating regimes. The use of thulium as a dopant has recently gained interest due to its large bandwidth, possibility of high efficiency, possibility of high power and long wavelength ~1.8 (-) 2.1 ?m. The longer emission wavelength of Tm-doped fiber lasers compared to Yb- and/or Er-doped fiber lasers creates the possibility for higher peak power operation due to the larger nonlinear thresholds and reduced nonlinear phase accumulation. One primary interest in Tm-doped fiber lasers has been to scale to high average powers; however, the thermal and mechanical constraints of the fiber limit the average power out of a single-fiber aperture. One method to overcome the constraints of a single laser aperture is to spectrally combine the output from multiple lasers operating with different wavelengths into a single beam. In this thesis, results will be presented on the development of three polarized 100 W level laser systems that were wavelength stabilized for SBC. In addition to the development of the laser channels, the beams were combined using bandpass filters to achieve a single near diffraction-limited output.Concurrently, with the development of high average power systems there is an increasing interest in femotosecond pulse generation and amplification using Tm- doped fiber lasers. High peak power sources operating near 2 (&)#181;m have the potential to be efficient pump sources to generate mid-infrared light through supercontinuum generation or optical parametric oscillators. This thesis focuses on the development of a laser system utilizing chirped pulse amplification (CPA) to achieve record level energies and peak powers for ultrashort pulses in Tm-doped fiber. A mode-locked oscillator was built to generate femtosecond pulses operating with pJ energy. Pulses generated in the mode-locked oscillator were limited to low energies and contained spectral modulation due to the mode-locking mechanism, therefore, a Raman-soliton self-frequency shift (Raman-SSFS) amplifier was built to amplify pulses, decrease the pulse duration, and spectrally clean pulses. These pulses were amplified using chirped pulse amplification (CPA) in which, limiting factors for amplification were examined and a high peak power system was built. The primary limiting factors of CPA in fibers include the nonlinear phase accumulation, primarily through self-phase modulation (SPM), and gain narrowing. Gain narrowing was examined by temporally stretching pulses in a highly nonlinear fiber that both stretched the pulse duration and broadened the spectrum. A high peak power CPA system amplified pulses to 1 (&)#181;J energy with 300 fs compressed pulses, corresponding to a peak power (>)3 MW. High peak power pulses were coupled into highly nonlinear fibers to generate supercontinuum.
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Date Issued: 2012
Identifier: CFE0004752, ucf:49768
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004752

Title: Properties of High Energy Laser Light Transmission through Large Core Optical Cables.
Creator: Kennedy, Christopher, Schulzgen, Axel, Bass, Michael, Soileau, Marion, Gordon, Ali, University of Central Florida
Abstract / Description: Laser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica...
Show moreLaser induced damage is of interest in studying the transmission of large amounts of optical energy through step-index, large core multimode fibers. Optical fibers often have to be routed around objects when laser light is being transmitted between two locations which require the fiber to bend into a curve. Depending on how tight the bend is, this can result in transmission losses or even catastrophic damage when the energy density of the laser pulse exceeds the damage threshold of silica glass. Waveguide theory predicts that light traveling through a bend will form whispering-gallery modes that propagate through total internal reflection bounces along the inside of the outer edge of the bend. This is critical since in these locations the energy density of the light will increase significantly, raising the potential of laser damage, nonlinear effects, and transmission losses. This loss is especially problematic when two 90(&)deg; bends going in opposite directions are in close proximity to each other, forming an 'S-bend'. Light that is grouped along the outer edge going through the first bend will enter the second bend at a sharper angle which causes much high transmission losses and raises the possibility of failure.Models using R-Soft BeamProp and Zemax were developed to study transmission losses, investigate light interactions at critical areas, and predict under which conditions laser damage would occur. BeamProp presents a clearer view of the modal distribution of light within the core of the fiber and is used to analyze how a plane wave with a Gaussian intensity distribution excites the fiber modes. Zemax provides a tool to perform non-sequential ray tracing through the fiber cable and stray light analysis within the core and once the light exits the fiber. Intensity distributions of the cross sectional area of the fiber shows the whispering gallery modes forming as the light propagates around bends and disburses as it propagates afterwards. It was discovered using R-Soft that if the separation distance between bends in an S-bend is approximately 3 mm there exists a condition where maximum transmission occurs. For 365 (&)#181;m diameter core fiber it was calculated that the difference in output power could be as high as 150%. This was initially completely unexpected; however ray tracing using Zemax was able to verify that this distance allows the light to transition so that it enters the 2nd bend at the optimal angle to enter the whispering gallery mode. Experiments were performed that validated the models' predictions and images were captured clearly showing the spatial distribution shift of the light within the core of the fiber.Experiments were performed to verify light grouping together to form whispering gallery modes as predicted by Zemax. Microscope images were taken as a function of distance from various bends to observe the periodic nature in which the laser light fills up the fiber. Additionally, a configuration was setup to examine stimulated Brillioun scattering and determine the onset of laser damage in the fiber. Fibers were tested as a function of bend radius and number of shots and recommendations for future systems were made. Lastly, mechanical failure tests were performed to determine the relationship between stress placed on the fiber through bending and fiber lifetime in a static environment. This allowed a minimum safe bend radius to be calculated for a 30 year lifetime that agreed with previous calculated values.
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Date Issued: 2013
Identifier: CFE0004871, ucf:49668
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004871

Title: Pulsed Tm-Fiber Laser for Mid-IR Generation.
Creator: Kadwani, Pankaj, Richardson, Martin, Abouraddy, Ayman, Schulzgen, Axel, Peale, Robert, University of Central Florida
Abstract / Description: Thulium fiber lasers have attracted interest based on their long emission wavelength and large bandwidth (~1.8 (-) 2.1 (&)#181;m) relative to more established ytterbium and erbium fiber lasers. In addition, Tm:fiber lasers offer the potential for high efficiencies (~60 %) and high output power levels both in cw as well as pulsed regimes. These attributes are useful particularly in applications such as remote sensing, materials processing and mid-infrared generation. This dissertation...
Show moreThulium fiber lasers have attracted interest based on their long emission wavelength and large bandwidth (~1.8 (-) 2.1 (&)#181;m) relative to more established ytterbium and erbium fiber lasers. In addition, Tm:fiber lasers offer the potential for high efficiencies (~60 %) and high output power levels both in cw as well as pulsed regimes. These attributes are useful particularly in applications such as remote sensing, materials processing and mid-infrared generation. This dissertation describes the development of novel nanosecond pulsed thulium fiber laser systems with record high peak power levels in order to pump nonlinear mid-infrared generation. The peak power scaling in thulium fiber lasers requires new fiber designs with ultra large mode field area (MFA). Two different classes of prototype thulium doped photonic crystal fibers (PCF) were investigated for high peak power generation. The first prototype is a flexible-PCF with 50 ?m core diameter, and the second is a rod-type PCF with 80 ?m diameter core. A robust single stage master oscillator power amplifier (MOPA) source based on flexible-PCF was developed. This source provided narrow linewidth, tunable wavelength, variable pulse duration, high peak power, and high energy nanosecond pulses. The PCF-rod was implemented as a second stage power amplifier. This system generated a record level of ~1 MW peak power output with 6.4 ns pulse-duration at 1 kHz repetition rate. This thulium doped PCF based MOPA system is a state of the art laser source providing high quality nanosecond pulses. The single stage MOPA system was successfully implemented to pump a zinc germanium phosphide (ZGP) crystal in an optical parametric oscillator (OPO) cavity to generate 3 - 5 (&)#181;m wavelengths. The MOPA source was also used to demonstrate backside machining in silicon wafer. The PCF based laser system demonstrated an order of magnitude increase in the peak power achievable in nanosecond thulium doped fiber laser systems, and further scaling appears possible. Further increases in the peak power will enable additional capabilities for mid-IR generation and associated applications.
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Date Issued: 2013
Identifier: CFE0005100, ucf:50739
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005100

Title: Dynamic feedback pulse shaping for high power chirped pulse amplification system.
Creator: Nguyen, Dat, Delfyett, Peter, Rahman, Talat, Richardson, Martin, Schulzgen, Axel, Li, Guifang, University of Central Florida
Abstract / Description: The topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic...
Show moreThe topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic pulse shaping approaches. The experimental research addresses the topic of parabolic pulse generation in two distinct ways. First, pulse shaping technique involving a time domain approach is presented, that results in stretched pulses with parabolic profiles with temporal duration of 15 ns. After pulse is shaped into a parabolic intensity profile, the pulse is compressed with DCF fiber spool by 100 times to 80 ps duration at FWHM. A different approach of pulse shaping in frequency domain is performed, in which a spectral processor based on Liquid Crystal on Silicon technology is used. The pulse is stretched to 1.5 ns before intensity mask is applied, resulting in a parabolic intensity profile. Due to frequency to time mapping, its temporal profile is also parabolic. After pulse shaping, the pulse is compressed with a bulk compressor, and subsequently analyzed with a Frequency Resolved Optical Gating (FROG). The spectral content of the compressed pulse is feedback to the spectral processor and used to adjust the spectral phase mask applied on the pulse. The resultant pulse after pulse shaping with feedback mechanism is a Fourier transform, sub-picosecond ultrashort pulse with 5 times increase in peak power.The appendices in this dissertation provide additional material used for the realization of the main research focus of the dissertation. Specification and characterization of major components of equipment and devices used in the experiment are present. The description of Matlab algorithms that was used to calculate required signals for pulse shaping are shown. A brief description of the Labview code used to control the spectral processor will also be illustrated.
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Date Issued: 2013
Identifier: CFE0004899, ucf:49642
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004899

Title: DENSE SPECTRAL BEAM COMBINING WITH VOLUME BRAGG GRATINGS IN PHOTO-THERMO-REFRACTIVE GLASS.
Creator: Andrusyak, Oleksiy, Zeldovich, Boris, University of Central Florida
Abstract / Description: Beam combining techniques have become an important tool in the design of high-power high-brightness laser systems. Spectral beam combining (SBC) is an incoherent combining technique that does not require phase control of sources, allowing for a stable and robust system. Using SBC, beams from an array of lasers with each element operated at a different wavelength are combined into a single near-diffraction-limited beam with the same aperture using dispersive optical elements. SBC by means of...
Show moreBeam combining techniques have become an important tool in the design of high-power high-brightness laser systems. Spectral beam combining (SBC) is an incoherent combining technique that does not require phase control of sources, allowing for a stable and robust system. Using SBC, beams from an array of lasers with each element operated at a different wavelength are combined into a single near-diffraction-limited beam with the same aperture using dispersive optical elements. SBC by means of volume Bragg gratings (VBGs) utilizes unique spectral response of VBGs: diffraction efficiency is close to unity when the Bragg condition is satisfied and is close to zero at multiple points corresponding to particular wavelength offsets from Bragg condition. High-efficiency VBGs can be recorded in UV-sensitive photo-thermo-refractive (PTR) glass. Narrow-band reflecting VBGs allow multi-channel SBC with high spectral density of channels. In this dissertation, experimental results of SBC with high spectral density of combined channels in two spectral regions of interest (1064 and 1550 nm) are reported. The behavior of narrow-band VBGs under high-power laser radiation is investigated. A laser system with kW-level output power and near-diffraction-limited divergence of spectrally-combined output beam is demonstrated. The system combines five randomly-polarized Yb-doped fiber lasers with 0.5 nm spectral separation in central wavelengths using narrow-band reflecting VBGs with absolute efficiency of combining > 90%. A novel design of a multi-channel high-power SBC system is suggested. In this approach, a common-cavity is created for all channels such that wavelengths of the sources are passively controlled by the combination of a common output coupler and intra-cavity VBGs which also act as combining elements. Laser wavelengths are automatically selected to match resonant wavelengths of respective VBGs. We report successful demonstration of a passively-controlled SBC system consisting of two amplifiers in a common cavity configuration. A compact and rugged monolithic SBC module based on multiplexed VBGs is introduced. Experimental results of a four-channel implementation of such module are discussed. Modular design of high-power laser systems is suggested with multiple modules arranged in a series. We show that with basic combining parameters achieved up to date, laser systems with 10 kW output power can be constructed using this arrangement. Further scaling to 100 kW power level is discussed.
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Date Issued: 2009
Identifier: CFE0002662, ucf:48189
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002662

Title: ALL-SEMICONDUCTOR HIGH POWER MODE-LOCKED LASER SYSTEM.
Creator: Kim, Kyungbum, Delfyett, Peter, University of Central Florida
Abstract / Description: The objective of this dissertation is to generate high power ultrashort optical pulses from an all-semiconductor mode-locked laser system. The limitations of semiconductor optical amplifier in high energy, ultrashort pulse amplification are reviewed. A method to overcome the fundamental limit of small stored energy inside semiconductor optical amplifier called "eXtreme Chirped Pulse Amplification (X-CPA)" is proposed and studied theoretically and experimentally. The key benefits of the...
Show moreThe objective of this dissertation is to generate high power ultrashort optical pulses from an all-semiconductor mode-locked laser system. The limitations of semiconductor optical amplifier in high energy, ultrashort pulse amplification are reviewed. A method to overcome the fundamental limit of small stored energy inside semiconductor optical amplifier called "eXtreme Chirped Pulse Amplification (X-CPA)" is proposed and studied theoretically and experimentally. The key benefits of the concept of X-CPA are addressed. Based on theoretical and experimental study, an all-semiconductor mode-locked X-CPA system consisting of a mode-locked master oscillator, an optical pulse pre-stretcher, a semiconductor optical amplifier (SOA) pulse picker, an extreme pulse stretcher/compressor, cascaded optical amplifiers, and a bulk grating compressor is successfully demonstrated and generates >kW record peak power. A potential candidate for generating high average power from an X-CPA system, novel grating coupled surface emitting semiconductor laser (GCSEL) devices, are studied experimentally. The first demonstration of mode-locking with GCSELs and associated amplification characteristics of grating coupled surface emitting SOAs will be presented. In an effort to go beyond the record setting results of the X-CPA system, a passive optical cavity amplification technique in conjunction with the X-CPA system is constructed, and studied experimentally and theoretically.
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Date Issued: 2006
Identifier: CFE0001069, ucf:46767
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001069

Title: MICRO-OPTIC-SPECTRAL-SPATIAL-ELEMENTS (MOSSE).
Creator: Mehta, Alok, Johnson, Eric, University of Central Florida
Abstract / Description: Over a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization...
Show moreOver a wide range of applications, optical systems have utilized conventional optics in order to provide the ability to engineer the properties of incident infra-red fields in terms of the transmitted field spectral, spatial, amplitude, phase, and polarization characteristics. These micro/nano-optical elements that provide specific optical functionality can be categorized into subcategories of refractive, diffractive, multi-layer thin film dichroics, 3-D photonic crystals, and polarization gratings. The feasibility of fabrication, functionality, and level of integration which these elements can be used in an optical system differentiate which elements are more compatible with certain systems than others. With enabling technologies emerging allowing for a wider range of options when it comes to lithographic nano/micro-patterning, dielectric growth, and transfer etching capabilities, optical elements that combine functionalities of conventional optical elements can be realized. Within this one class of optical elements, it is possible to design and fabricate components capable of tailoring the spectral, spatial, amplitude, phase, and polarization characteristics of desired fields at different locations within an optical system. Optical transmission filters, polarization converting elements, and spectrally selective reflecting components have been investigated over the course of this dissertation and have been coined MOSSE,' which is an acronym for micro-optic-spectral-spatial-elements. Each component is developed and fabricated on a wafer scale where the thin film deposition, lithographic exposure, and transfer etching stages are decoupled from each other and performed in a sequential format. This facilitates the ability to spatially vary the optical characteristics of the different MOSSE structures across the surface of the wafer itself.
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Date Issued: 2007
Identifier: CFE0001962, ucf:47457
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001962

Title: Broad Bandwidth, All-fiber, Thulium-doped Photonic Crystal Fiber Amplifier for Potential Use in Scaling Ultrashort Pulse Peak Powers.
Creator: Sincore, Alex, Richardson, Martin, Shah, Lawrence, Amezcua Correa, Rodrigo, University of Central Florida
Abstract / Description: Fiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be...
Show moreFiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be simultaneously attained using photonic crystal fibers.Thulium-doped fiber lasers are attractive for high peak power ultrashort pulse systems. They offer a broad gain bandwidth, capable of amplifying sub-100 femtosecond pulses. The longer center wavelength at 2 ?m theoretically enables higher peak powers relative to 1 ?m systems since nonlinear effects inversely scale with wavelength. Also, the 2 ?m emission is desirable to support applications reaching further into the mid-IR.This work evaluates the performance of a novel all-fiber pump combiner that incorporates a thulium-doped photonic crystal fiber. This fully integrated amplifier is characterized and possesses a large gain bandwidth, essentially single-mode propagation, and high degree of polarization. This innovative all-fiber, thulium-doped photonic crystal fiber amplifier has great potential for enabling high peak powers in 2 ?m fiber systems; however the current optical-to-optical efficiency is low relative to similar free-space amplifiers. Further development and device optimization will lead to higher efficiencies and improved performance.
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Date Issued: 2014
Identifier: CFE0005260, ucf:50611
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005260

fiber laser (5)	+ -
fiber lasers (4)	+ -
laser (4)	+ -
Fiber Laser (3)	+ -
Thulium (3)	+ -

PCF (2)	+ -
high power lasers (2)	+ -
thulium (2)	+ -
thulium fiber laser (2)	+ -
volume Bragg gratings (2)	+ -
2 ?m (1)	+ -
2 micron (1)	+ -
2 micron fiber laser (1)	+ -
2um (1)	+ -
Chirped Pulse Amplification (1)	+ -
Diffractive Optics (1)	+ -
Fiber (1)	+ -
Fiber Amplifier (1)	+ -
Fiber Lasers (1)	+ -
GG IAG (1)	+ -
High Power Laser (1)	+ -
Laser (1)	+ -
Lasers (1)	+ -
MOPA (1)	+ -
Master Oscillator Power Amplifier (1)	+ -
Nano-Optics (1)	+ -
OPO (1)	+ -
Optical Filters (1)	+ -
Optical fiber (1)	+ -
PCF rod (1)	+ -

University of Central Florida (20)	+ -
Schulzgen, Axel (12)	+ -
Richardson, Martin (11)	+ -
Amezcua Correa, Rodrigo (7)	+ -
Shah, Lawrence (5)	+ -

Delfyett, Peter (4)	+ -
Rahman, Talat (3)	+ -
Zeldovich, Boris (3)	+ -
Bass, Michael (2)	+ -
Glebov, Leonid (2)	+ -
Sincore, Alex (2)	+ -
Abdulfattah, Ali (1)	+ -
Abouraddy, Ayman (1)	+ -
Anderson, Brian (1)	+ -
Andrusyak, Oleksiy (1)	+ -
Argenti, Luca (1)	+ -
Chang, Zenghu (1)	+ -
Chow, Louis (1)	+ -
Fathpour, Sasan (1)	+ -
Gaida, Christian (1)	+ -
Gordon, Ali (1)	+ -
Hageman, William (1)	+ -
Jain, Apurva (1)	+ -
Johnson, Eric (1)	+ -
Jollivet, Clemence (1)	+ -
Kadwani, Pankaj (1)	+ -
Kennedy, Christopher (1)	+ -
Kim, Kyungbum (1)	+ -
Li, Guifang (1)	+ -
Likamwa, Patrick (1)	+ -

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