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- Title
- High Average Power Nanosecond Pulsed Tm:Fiber Laser for Pumping an Optical Parametric Oscillator.
- Creator
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Abdulfattah, Ali, Richardson, Martin, Shah, Lawrence, Delfyett, Peter, University of Central Florida
- Abstract / Description
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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.
Show less - Date Issued
- 2016
- Identifier
- CFE0006240, ucf:51065
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006240
- Title
- On-Chip Optical Stabilization of High-Speed Mode-locked Quantum Dot Lasers for Next Generation Optical Networks.
- Creator
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Ardey, Abhijeet, Delfyett, Peter, Chow, Lee, Peale, Robert, Likamwa, Patrick, University of Central Florida
- Abstract / Description
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Monolithic passively mode-locked colliding pulse semiconductor lasers generating pico- to sub-picosecond terahertz optical pulse trains are promising sources for future applications in ultra-high speed data transmission systems and optical measurements. However, in the absence of external synchronization, these passively mode-locked lasers suffer from large amplitude and timing jitter instabilities resulting in broad comb linewidths, which precludes many applications in the field of coherent...
Show moreMonolithic passively mode-locked colliding pulse semiconductor lasers generating pico- to sub-picosecond terahertz optical pulse trains are promising sources for future applications in ultra-high speed data transmission systems and optical measurements. However, in the absence of external synchronization, these passively mode-locked lasers suffer from large amplitude and timing jitter instabilities resulting in broad comb linewidths, which precludes many applications in the field of coherent communications and signal processing where a much narrower frequency line set is needed. In this dissertation, a novel quantum dot based coupled cavity laser is presented, where for the first time, four-wave mixing (FWM) in the monolithically integrated saturable absorber is used to injection lock a monolithic colliding pulse mode-locked (CPM) laser with a mode-locked high-Q ring laser. Starting with a passively mode-locked master ring laser, a stable 30 GHz optical pulse train is generated with more than 10 dB reduction in the RF noise level at 20 MHz offset and close to 3-times reduction in the average optical linewidth of the injection locked CPM slave laser. The FWM process is subsequently verified experimentally and conclusively shown to be the primary mechanism responsible for the observed injection locking. Other linear scattering effects are found to be negligible, as predicted in the orthogonal waveguide configuration. The novel injection locking technique is further exploited by employing optical hybrid mode-locking and increasing the Q of the master ring cavity, to realize an improved stabilization architecture. Dramatic reduction is shown with more than 14-times reduction in the photodetected beat linewidth and almost 5-times reduction in the optical linewidth of the injection locked slave laser with generation of close to transform limited pulses at ~ 30 GHz. These results demonstrate the effectiveness of the novel injection locking technique for an all-on-chip stability transfer and provides a new way of stabilizing monolithic optical pulse sources for applications in future high speed optical networks.
Show less - Date Issued
- 2014
- Identifier
- CFE0005299, ucf:50518
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005299
- Title
- LP fiber mode converters using holographic phase mask in photo-thermo-refractive glass.
- Creator
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Patil, Aniket, Schulzgen, Axel, Delfyett, Peter, Amezcua Correa, Rodrigo, University of Central Florida
- Abstract / Description
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In this study, an investigation was undertaken to research the use of holographic phase masks (HPMs) in photo-thermo-refractive (PTR) glass as mode converters for linearly polarized (LP) fiber modes. A Spatial Light Modulator (SLM) was used to generate higher-order transverse fiber modes LPm,n. Under proper incidence condition on the holographic device, LPm,n modes are diffracted and simultaneously converted into higher order or lower order LP modes. The process was analyzed by imaging the...
Show moreIn this study, an investigation was undertaken to research the use of holographic phase masks (HPMs) in photo-thermo-refractive (PTR) glass as mode converters for linearly polarized (LP) fiber modes. A Spatial Light Modulator (SLM) was used to generate higher-order transverse fiber modes LPm,n. Under proper incidence condition on the holographic device, LPm,n modes are diffracted and simultaneously converted into higher order or lower order LP modes. The process was analyzed by imaging the far field on a CCD camera. It is demonstrated that using this novel method of converting transverse fiber modes several combinations of LP modes can be converted to each other with mode conversion efficiencies up to 70%. Mode purities were found to be around 85% for up conversion and around 90% for down conversion, respectively. It is noticed that this approach has several promising applications such as mode multiplexing, beam cleaning and power scaling of higher-order mode fiber lasers and amplifiers by combining mode conversion and beam combining.
Show less - Date Issued
- 2014
- Identifier
- CFE0005396, ucf:50459
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005396
- Title
- Generation and characterization of sub-70 isolated attosecond pulses.
- Creator
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Zhang, Qi, Chang, Zenghu, Delfyett, Peter, Gaume, Romain, Saha, Haripada, University of Central Florida
- Abstract / Description
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Dynamics occurring on microscopic scales, such as electronic motion inside atoms and molecules, are governed by quantum mechanics. However, the Schr(&)#246;dinger equation is usually too complicated to solve analytically for systems other than the hydrogen atom. Even for some simple atoms such as helium, it still takes months to do a full numerical analysis. Therefore, practical problems are often solved only after simplification. The results are then compared with the experimental outcome in...
Show moreDynamics occurring on microscopic scales, such as electronic motion inside atoms and molecules, are governed by quantum mechanics. However, the Schr(&)#246;dinger equation is usually too complicated to solve analytically for systems other than the hydrogen atom. Even for some simple atoms such as helium, it still takes months to do a full numerical analysis. Therefore, practical problems are often solved only after simplification. The results are then compared with the experimental outcome in both the spectral and temporal domain. For accurate experimental comparison, temporal resolution on the attosecond scale is required. This had not been achieved until the first demonstration of the single attosecond pulse in 2001. After this breakthrough, (")attophysics(") immediately became a hot field in the physics and optics community. While the attosecond pulse has served as an irreplaceable tool in many fundamental research studies of ultrafast dynamics, the pulse generation process itself is an interesting topic in the ultrafast field. When an intense femtosecond laser is tightly focused on a gaseous target, electrons inside the neutral atoms are ripped away through tunneling ionization. Under certain circumstances, the electrons are able to reunite with the parent ions and release photon bursts lasting only tens to hundreds of attoseconds. This process repeats itself every half cycle of the driving pulse, generating a train of single attosecond pulses which lasts longer than one femtosecond. To achieve true temporal resolution on the attosecond time scale, single isolated attosecond pulses are required, meaning only one attosecond pulse can be produced per driving pulse.Up to now, there are only a few methods which have been demonstrated experimentally to generate isolated attosecond pulses. Pioneering work generated single attosecond pulse using a carrier-envelope phase-stabilized 3.3 fs laser pulse, which is out of reach for most research groups. An alternative method termed as polarization gating generated single attosecond pulses with 5 fs driving pulses, which is still difficult to achieve experimentally. Most recently, a new technique termed as Double Optical Gating (DOG) was developed in our group to allow the generation of single attosecond pulse with longer driving pulse durations. For example, isolated 150 as pulses were demonstrated with a 25 fs driving laser directly from a commercially-available Ti:Sapphire amplifier. Isolated attosecond pulses as short as 107 as have been demonstrated with the DOG scheme before this work. Here, we employ this method to shorten the pulse duration even further, demonstrating world-record isolated 67 as pulses. Optical pulses with attosecond duration are the shortest controllable process up to now and are much faster than the electron response times in any electronic devices. In consequence, it is also a challenge to characterize attosecond pulses experimentally, especially when they feature a broadband spectrum. Similar challenges have previously been met in characterizing femtosecond laser pulses, with many schemes already proposed and well-demonstrated experimentally. Similar schemes can be applied in characterizing attosecond pulses with narrow bandwidth. The limitation of these techniques is presented here, and a method recently developed to overcome those limitations is discussed. At last, several experimental advances toward the characterization of the isolated 25 as pulses, which is one atomic unit time, are discussed briefly.
Show less - Date Issued
- 2014
- Identifier
- CFE0005450, ucf:50375
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005450
- Title
- Photonic Filtering for Applications in Microwave Generation and Metrology.
- Creator
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Bagnell, Marcus, Delfyett, Peter, Schoenfeld, Winston, Li, Guifang, Peale, Robert, University of Central Florida
- Abstract / Description
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This work uses the photonic filtering properties of Fabry-Perot etalons to show improvements in the electrical signals created upon photodetection of the optical signal. First, a method of delay measurement is described which uses multi-heterodyne detection to find correlations in white light signals at 20 km of delay to sub millimeter resolution. By filtering incoming white light with a Fabry-Perot etalon, the pseudo periodic signal is suitable for measurement by combining and photodetecting...
Show moreThis work uses the photonic filtering properties of Fabry-Perot etalons to show improvements in the electrical signals created upon photodetection of the optical signal. First, a method of delay measurement is described which uses multi-heterodyne detection to find correlations in white light signals at 20 km of delay to sub millimeter resolution. By filtering incoming white light with a Fabry-Perot etalon, the pseudo periodic signal is suitable for measurement by combining and photodetecting it with an optical frequency comb. In this way, optical data from a large bandwidth can be downconverted and sampled on low frequency electronics. Second, a high finesse etalon is used as a photonic filter inside an optoelectronic oscillator (OEO). The etalon's narrow filter function allows the OEO loop length to be extremely long for a high oscillator quality factor while still suppressing unwanted modes below the noise floor. The periodic nature of the etalon allows it to be used to generate a wide range of microwave and millimeter wave tones without degradation of the RF signal.
Show less - Date Issued
- 2014
- Identifier
- CFE0005457, ucf:50396
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005457
- Title
- Injection-Locked Vertical Cavity Surface Emitting Lasers (VCSELs) for Optical Arbitrary Waveform Generation.
- Creator
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Bhooplapur, Sharad, Delfyett, Peter, Li, Guifang, Christodoulides, Demetrios, Malocha, Donald, University of Central Florida
- Abstract / Description
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Complex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse?shaping, with the goal of making non?periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance...
Show moreComplex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse?shaping, with the goal of making non?periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance of LADAR systems, high?capacity optical telecommunications and ultra wideband signals processing.In this work, an array of Vertical Cavity Surface Emitting Lasers (VCSELs) are used as modulators, by injection-locking each VCSEL to an individual combline from an optical frequency comb source. Injection-locking ensures that the VCSELs' emission is phase coherent with the input combline, and modulating its current modulates mainly the output optical phase. The multi-GHz modulation bandwidth of VCSELs updates the output optical pulse shape on a pulse-to-pulse time scale, which is an important step towards true OAWG. In comparison, it is about a million times faster than the liquid-crystal modulator arrays typically used for pulse shaping! Novel components and subsystems of Optical Arbitrary Waveform Generation (OAWG) are developed and demonstrated in this work. They include:1.Modulators An array of VCSELs is packaged and characterized for use as a modulator for rapid?update pulse?shaping at GHz rates. The amplitude and phase modulation characteristics of an injection?locked VCSEL are simultaneously measured at GHz modulation rates.2.Optical Frequency Comb SourcesAn actively mode?locked semiconductor laser was assembled, with a 12.5 GHz repetition rate, ~ 200 individually resolvable comblines directly out of the laser, and high frequency stability. In addition, optical frequency comb sources are generated by modulation of a single frequency laser.3.High-resolution optical spectral demultiplexersThe demultiplexers are implemented using bulk optics, and are used to spatially resolve individual optical comblines onto the modulator array. 4.Optical waveform measurement techniques Several techniques are used to measure generated waveforms, especially for spectral phase measurements, including multi-heterodyne phase retrieval. In addition, an architecture for discriminating between ultrashort encoded optical pulses with record high sensitivity is demonstrated.
Show less - Date Issued
- 2014
- Identifier
- CFE0005466, ucf:50402
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005466
- Title
- Phase-locking Stability of a Quasi-single-cycle Pulse.
- Creator
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Bodnar, Nathan, Richardson, Martin, Chang, Zenghu, Delfyett, Peter, University of Central Florida
- Abstract / Description
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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
- Reduced Susceptibility of Deformation due to Vibrational and Gravitational Effects on a Focus Variable Adaptive Lens.
- Creator
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Relina, Victoriya, Wu, Shintson, Likamwa, Patrick, Delfyett, Peter, University of Central Florida
- Abstract / Description
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Orthodox optical devices, such as lenses, mirrors, and prisms, are composed of solid-state materials, which although well studied and implemented ubiquitously are severely limited in their adaptable properties. An arguably new field of adaptive optics has emerged to further expand photonic manipulation competences of optical components. Fluid-based adaptive optical components were introduced as early as 1968; such components have the ability to change the shape of their interface surface,...
Show moreOrthodox optical devices, such as lenses, mirrors, and prisms, are composed of solid-state materials, which although well studied and implemented ubiquitously are severely limited in their adaptable properties. An arguably new field of adaptive optics has emerged to further expand photonic manipulation competences of optical components. Fluid-based adaptive optical components were introduced as early as 1968; such components have the ability to change the shape of their interface surface, thus allowing for a variable curvature profile. The method of manipulation varies greatly, as does the range of surface deformations. A solid-state optical component is affected by system vibration variation only (difference in vibration from one component to the other due to damping effect). By comparison, two large limiting factors of a fluid-based adaptive optical component are the effect of local vibrations on the surface of the device and gravitational effect (when the optical axis of a lens is positioned parallel to gravitational pull). Such a gravitational effect has been mitigated by the invention of the mechanical electrowetting lens, which uses density matching of two liquids that make up an adaptive lens. However, this configuration creates an extra limiting factor of density matching two optically clear fluids with a desirable transmission spectrum. This method can also become bulky when a large aperture is needed. In this thesis, two adaptive lens systems are explored. Principles of operation, performance, limitations, as well as future improvements are studied and theorized. The first lens uses an optically clear elastomer as the substrate of an adaptive lens and a primitive mechanical manipulation to turn a plano(-)plano lens into a plano(-)convex lens. The second lens is composed of an optically clear gel rather than a fluid. Both methods exhibit excellent optical properties regardless of the orientation about the gravitational pull and significantly limit local vibration affects simply by the physical nature of the chosen materials.
Show less - Date Issued
- 2013
- Identifier
- CFE0004739, ucf:49841
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004739
- Title
- True linearized intensity modulation for photonic analog to digital conversion using an injection-locked mode-locked laser.
- Creator
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Sarailou, Edris, Delfyett, Peter, Likamwa, Patrick, Fathpour, Sasan, Malocha, Donald, University of Central Florida
- Abstract / Description
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A true linearized interferometric intensity modulator for pulsed light has been proposed and experimentally presented in this thesis. This has been achieved by introducing a mode-locked laser into one of the arms of a Mach-Zehnder interferometer and injection-locking it to the input light (which is pulsed and periodic). By modulating the injection-locked laser, and combining its output light with the light from the other arm of interferometer in quadrature, one can achieve true linearized...
Show moreA true linearized interferometric intensity modulator for pulsed light has been proposed and experimentally presented in this thesis. This has been achieved by introducing a mode-locked laser into one of the arms of a Mach-Zehnder interferometer and injection-locking it to the input light (which is pulsed and periodic). By modulating the injection-locked laser, and combining its output light with the light from the other arm of interferometer in quadrature, one can achieve true linearized intensity modulator. This linearity comes from the arcsine phase response of the injection-locked mode-locked laser (as suggested by steady-state solution of Adler's equation) when it is being modulated. Mode-locked lasers are fabricated using a novel AlGaInAs-InP material system. By using the BCB for planarization and minimizing the metal pad size and directly modulating the laser, we have achieved very effective fundamental hybrid mode-locking at the repetition rate of ~ 23 GHz. This laser also provided the short pulses of 860 fs and 280 fs timing jitter integrated from 1 Hz- 100 MHz.The linearized intensity modulator has been built by using two identical two-section mode-locked lasers with the same length, one as the slave laser in one of the arms of the Mach-Zehnder interferometer injection-locked to the other one as the master which is the input light to the modulator. A low V? of 8.5 mV is achieved from this modulator. Also the current of the gain section or the voltage of the saturable absorber section of the slave laser has been used to apply the modulation signal. A spur free dynamic range of 70 dB.Hz2/3 is achieved when modulating the modulator through the saturable absorber. Modulating the saturable absorber provides a reduced third-order intermodulation tone with respect to modulating the gain. This is simply because of the unwanted amplitude modulation created when modulating the gain section current.Finally an improved design is proposed and demonstrated to improve the modulator performance. This is achieved by introducing a third section to the laser. Using the impurity free vacancy disordering technique the photoluminescence peak of this section is blue-shifted selectively and therefore there would not be any absorption in that passive section. By applying the modulation signal to this passive section rather than applying it to the gain section or saturable absorber section, the amplitude and phase modulation could be decoupled. The experimental results have presented here and an almost six-fold reduction in V? and 5 dB improvement in spur free dynamic range have been achieved. The proposed and demonstrated configuration as an analog optical link has the potential to increase the performance and resolution of photonic analog-to-digital converters.
Show less - Date Issued
- 2015
- Identifier
- CFE0005707, ucf:50118
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005707
- Title
- Imaging through Glass-air Anderson Localizing Optical Fiber.
- Creator
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Zhao, Jian, Schulzgen, Axel, Amezcua Correa, Rodrigo, Pang, Sean, Delfyett, Peter, Mafi, Arash, University of Central Florida
- Abstract / Description
-
The fiber-optic imaging system enables imaging deeply into hollow tissue tracts or organs of biological objects in a minimally invasive way, which are inaccessible to conventional microscopy. It is the key technology to visualize biological objects in biomedical research and clinical applications. The fiber-optic imaging system should be able to deliver a high-quality image to resolve the details of cell morphology in vivo and in real time with a miniaturized imaging unit. It also has to be...
Show moreThe fiber-optic imaging system enables imaging deeply into hollow tissue tracts or organs of biological objects in a minimally invasive way, which are inaccessible to conventional microscopy. It is the key technology to visualize biological objects in biomedical research and clinical applications. The fiber-optic imaging system should be able to deliver a high-quality image to resolve the details of cell morphology in vivo and in real time with a miniaturized imaging unit. It also has to be insensitive to environmental perturbations, such as mechanical bending or temperature variations. Besides, both coherent and incoherent light sources should be compatible with the imaging system. It is extremely challenging for current technologies to address all these issues simultaneously. The limitation mainly lies in the deficient stability and imaging capability of fiber-optic devices and the limited image reconstruction capability of algorithms. To address these limitations, we first develop the randomly disordered glass-air optical fiber featuring a high air-filling fraction (~28.5 %) and low loss (~1 dB per meter) at visible wavelengths. Due to the transverse Anderson localization effect, the randomly disordered structure can support thousands of modes, most of which demonstrate single-mode properties. By making use of these modes, the randomly disordered optical fiber provides a robust and low-loss imaging system which can transport images with higher quality than the best commercially available imaging fiber. We further demonstrate that deep-learning algorithm can be applied to the randomly disordered optical fiber to overcome the physical limitation of the fiber itself. At the initial stage, a laser-illuminated system is built by integrating a deep convolutional neural network with the randomly disordered optical fiber. Binary sparse objects, such as handwritten numbers and English letters, are collected, transported and reconstructed using this system. It is proved that this first deep-learning-based fiber imaging system can perform artifact-free, lensless and bending-independent imaging at variable working distances. In real-world applications, the gray-scale biological subjects have much more complicated features. To image biological tissues, we re-design the architecture of the deep convolutional neural network and apply it to a newly designed system using incoherent illumination. The improved fiber imaging system has much higher resolution and faster reconstruction speed. We show that this new system can perform video-rate, artifact-free, lensless cell imaging. The cell imaging process is also remarkably robust with regard to mechanical bending and temperature variations. In addition, this system demonstrates stronger transfer-learning capability than existed deep-learning-based fiber imaging system.
Show less - Date Issued
- 2019
- Identifier
- CFE0007746, ucf:52405
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007746
- Title
- Design and Engineering Criteria for Optical Parametric Chirped Pulse Amplifier Systems.
- Creator
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Bodnar, Nathan, Richardson, Martin, Delfyett, Peter, Likamwa, Patrick, Baudelet, Matthieu, Shah, Lawrence, University of Central Florida
- Abstract / Description
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The generation of a quasi-single-cycle laser light pulse is a goal in many laser applications experiments. Some involve in High Harmonic Generation (HHG) and Attosecond Sciences. The demand for ultrafast laser facilities has grown; the techniques and availability of materials have changed; thereby posing new design challenges in building Optical Parametric Chirped Pulse Amplification (OPCPA) laser facilities. The concepts and challenges are discussed in detail in the development of two laser...
Show moreThe generation of a quasi-single-cycle laser light pulse is a goal in many laser applications experiments. Some involve in High Harmonic Generation (HHG) and Attosecond Sciences. The demand for ultrafast laser facilities has grown; the techniques and availability of materials have changed; thereby posing new design challenges in building Optical Parametric Chirped Pulse Amplification (OPCPA) laser facilities. The concepts and challenges are discussed in detail in the development of two laser systems within the Laser Plasma Laboratory, HERACLES and PhaSTHEUS. This dissertation also gives insight to the challenges that are encountered in other cutting edge OPCPA laser facilities. An overview of the design challenges that need to be addressed in any OPCPA laser facility either high energy or high average power that is suitable for high intensity laser physics is discussed in this dissertation.
Show less - Date Issued
- 2018
- Identifier
- CFE0007158, ucf:52300
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007158
- Title
- Ytterbium-doped fiber-seeded thin-disk master oscillator power amplifier laser system.
- Creator
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Willis-Ott, Christina, Richardson, Martin, Schulzgen, Axel, Delfyett, Peter, Chow, Louis, University of Central Florida
- Abstract / Description
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Lasers which operate at both high average power and energy are in demand for a wide range of applications such as materials processing, directed energy and EUV generation. Presented in this dissertation is a high-power 1 ?m ytterbium-based hybrid laser system with temporally tailored pulse shaping capability and up to 62 mJ pulses, with the expectation the system can scale to higher pulse energies. This hybrid system consists of a low power fiber seed and pre-amplifier, and a solid state thin...
Show moreLasers which operate at both high average power and energy are in demand for a wide range of applications such as materials processing, directed energy and EUV generation. Presented in this dissertation is a high-power 1 ?m ytterbium-based hybrid laser system with temporally tailored pulse shaping capability and up to 62 mJ pulses, with the expectation the system can scale to higher pulse energies. This hybrid system consists of a low power fiber seed and pre-amplifier, and a solid state thin-disk regenerative amplifier. This system has been designed to generate high power temporally tailored pulses on the nanosecond time scale. Temporal tailoring and spectral control are performed in the low power fiber portion of the system with the high pulse energy being generated in the regenerative amplifier. The seed system consists of a 1030 nm fiber-coupled diode, which is transmitted through a Mach-Zehnder-type modulator in order to temporally vary the pulse shape. Typical pulses are 20-30 ns in duration and have energies of ~0.2 nJ from the modulator. These are amplified in a fiber pre-amplifier stage to ~100 nJ before being used to seed the free-space Yb:YAG thin-disk regenerative amplifier. Output pulses have maximum demonstrated pulse energies of 62 mJ with 20 ns pulse after ~250 passes in the cavity. The effects of thermal distortion in laser and passive optical materials are also. Generally the development of high power and high energy lasers is limited by thermal management strategies, as thermally-induced distortions can degrade laser performance and potentially cause catastrophic damage. Novel materials, such as optical ceramics, can be used to mitigate thermal distortions; however, thorough analysis is required to optimize their fabrication and minimize thermal distortions. Using a Shack-Hartmann wavefront sensor (SHWFS), it is possible to analyze the distortion induced in passive and doped optical elements by high power lasers. For example, the thin-disk used in the regenerative amplifier is examined in-situ during CW operation (up to 2 kW CW pump power). Additionally, passive oxide-based optical materials and Yb:YAG optical ceramics are also examined by pumping at 2 and 1 ?m respectively to induce thermal distortions which are analyzed with the SHWFS. This method has been developed as a diagnostic for the relative assessment of material quality, and to grade differences in ceramic laser materials associated with differences in manufacturing processes and/or the presence of impurities. In summation, this dissertation presents a high energy 1 ?m laser system which is novel in its combination of energy level and temporal tailoring, and an analysis of thermal distortions relevant to the development of high power laser systems.
Show less - Date Issued
- 2013
- Identifier
- CFE0004961, ucf:49588
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004961
- Title
- Wavelength scale resonant structures for integrated photonic applications.
- Creator
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Weed, Matthew, Schoenfeld, Winston, Moharam, M., Likamwa, Patrick, Delfyett, Peter, Leuenberger, Michael, University of Central Florida
- Abstract / Description
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An approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled...
Show moreAn approach to integrated frequency-comb filtering is presented, building from a background in photonic crystal cavity design and fabrication. Previous work in the development of quantum information processing devices through integrated photonic crystals consists of photonic band gap engineering and methods of on-chip photon transfer. This work leads directly to research into coupled-resonator optical waveguides which stands as a basis for the primary line of investigation. These coupled cavity systems offer the designer slow light propagation which increases photon lifetime, reduces size limitations toward on-chip integration, and offers enhanced light-matter interaction. A unique resonant structure explained by various numerical models enables comb-like resonant clusters in systems that otherwise have no such regular resonant landscape (e.g. photonic crystal cavities). Through design, simulation, fabrication and test, the work presented here is a thorough validation for the future potential of coupled-resonator filters in frequency comb laser sources.
Show less - Date Issued
- 2013
- Identifier
- CFE0004957, ucf:49568
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004957
- Title
- Sensing with Specialty Optical Fibers.
- Creator
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Van Newkirk, Amy, Schulzgen, Axel, Delfyett, Peter, Amezcua Correa, Rodrigo, Raghavan, Seetha, University of Central Florida
- Abstract / Description
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Fiber optic based sensing is a growing field with many applications in civil and aerospace engineering, oil and gas industries, and particularly in harsh environments where electronics are not able to function. Optical fibers can be easily integrated into structures, are immune to electromagnetic interference, can be interrogated from remote distances, and can be multiplexed for distributed measurements. Because of these properties, specialty fiber designs and devices are being explored for...
Show moreFiber optic based sensing is a growing field with many applications in civil and aerospace engineering, oil and gas industries, and particularly in harsh environments where electronics are not able to function. Optical fibers can be easily integrated into structures, are immune to electromagnetic interference, can be interrogated from remote distances, and can be multiplexed for distributed measurements. Because of these properties, specialty fiber designs and devices are being explored for sensing temperature, strain, pressure, curvature, refractive index, and more. Here we show a detailed analysis of a multicore fiber (MCF) for sensing, including its design and optimization in simulation, as well as experimental operation when used as sensor. The multicore fiber sensor's performance as a function of temperature, strain, bending, and acoustic waves are all explored. The MCF sensors are shown to be able to withstand temperatures up to 1000(&)deg;C, making them suitable to be harsh environment sensors. Additionally, a simple method for increasing the sensitivity of the MCF to longitudinal force is shown to multiple the sensitivity of the MCF sensor by a factor of seven. Also, a configuration for decoupling force and temperature will be presented. Finally, a developing all-fiber device, a photonic lantern, will be shown in conjunction with the MCF in order to increase sensitivity, add directional sensitivity, and lower the cost of the sensor interrogation for bending measurements. In addition to the multicore fiber, an analysis of anti-resonant hollow core fiber (ARHCF) is also presented. The fibers' design-dependent propagation losses are explored, as well as their higher order mode content. Also, a potential application of an ARHCF for an in-fiber Raman air sensor is introduced, and the design optimization in simulation is shown.
Show less - Date Issued
- 2016
- Identifier
- CFE0006409, ucf:51490
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006409
- Title
- Monolithically Integrated InP-based Unidirectional Circulators Utilizing non-Hermiticity and Nonlinearity.
- Creator
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Aleahmad, Parinaz, Christodoulides, Demetrios, Delfyett, Peter, Likamwa, Patrick, Moya Cessa, Hector Manual, University of Central Florida
- Abstract / Description
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The need to integrate critical optical components on a single chip has been an ongoing quest in both optoelectronics and optical communication systems. Among the possible devices, elements supporting non-reciprocal transmission are of great interest for applications where signal routing and isolation is required. In this respect, breaking reciprocity is typically accomplished via Faraday rotation through appropriate magneto-optical arrangements. Unfortunately, standard light emitting...
Show moreThe need to integrate critical optical components on a single chip has been an ongoing quest in both optoelectronics and optical communication systems. Among the possible devices, elements supporting non-reciprocal transmission are of great interest for applications where signal routing and isolation is required. In this respect, breaking reciprocity is typically accomplished via Faraday rotation through appropriate magneto-optical arrangements. Unfortunately, standard light emitting optoelectronic materials like for example III-V semiconductors, lack magneto-optical properties and hence cannot be directly used in this capacity. To address these issues, a number of different tactics have been attempted in the last few years. These range from directly bonding garnets on chip, to parametric structures and unidirectional nonlinear arrangements involving ring resonators, to mention a few. Clearly, of importance will be to realize families of non-reciprocal devises that not only can be miniaturized and readily integrated on chip but they also rely on physical processes that are indigenous to the semiconductor wafer itself. Quite recently we have theoretically shown that such unidirectional systems can be implemented, provided one simultaneously exploits the presence of gain/loss processes and optical nonlinearities. In principle, these all-dielectric structures can be broadband, polarization insensitive, color-preserving, and can display appreciable isolation ratios provided they are used under pulsed conditions. In this study, we experimentally demonstrate a compact, monolithically integrated unidirectional 4(&)#215;4 optical circulator, based on non-reciprocal optical transmission through successive amplification/attenuation stages and elements with very large resonance nonlinearities associated with InGaAsP quantum wells. Our results indicate that isolation ratios over 20dB can be experimentally achieved in pulse-mode operation. Our design can be effortlessly extended to other existing optoelectronic device systems beyond InP.
Show less - Date Issued
- 2016
- Identifier
- CFE0006522, ucf:51373
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006522
- Title
- Design and Engineering of Ultrafast Amplifier Systems.
- Creator
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Webb, Benjamin, Richardson, Martin, Chang, Zenghu, Delfyett, Peter, Gaume, Romain, Shah, Lawrence, Klemm, Richard, University of Central Florida
- Abstract / Description
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Recently, the design and engineering of ultrafast laser systems have led to an extraordinary increase in laser power and performance which have brought about advances in many fields such as medicine, material processing, communications, remote sensing, spectroscopy, nonlinear optics, and atomic physics. In this work, several ultrafast amplification techniques -- including chirped-pulse amplification (CPA), optical parametric chirped-pulse amplification (OPCPA), and divided-pulse amplification...
Show moreRecently, the design and engineering of ultrafast laser systems have led to an extraordinary increase in laser power and performance which have brought about advances in many fields such as medicine, material processing, communications, remote sensing, spectroscopy, nonlinear optics, and atomic physics. In this work, several ultrafast amplification techniques -- including chirped-pulse amplification (CPA), optical parametric chirped-pulse amplification (OPCPA), and divided-pulse amplification (DPA) -- are described and demonstrated in the design and construction of two ultrafast laser facilities. An existing Ti:Sapphire laser system was completely redesigned with an increased power of 10 TW for experiments capable of generating hundreds of laser filaments in ordered arrays. The performance of DPA above the Joule-level was investigated in a series of experiments utilizing various DPA schemes with gain-saturated amplifiers at high pulse energy. A new high energy OPCPA facility has been designed and its pump laser system constructed, utilizing the technique of DPA for the first time in a flashlamp-pumped amplifier chain and with a record combined energy of 5 Joules in a 230 ps pulse duration. The demonstrated OPCPA pump performance will allow for the generation of 50 TW quasi-single cycle 5 fs pulses at 2.5 Hz from a table-top OPCPA system.
Show less - Date Issued
- 2016
- Identifier
- CFE0006547, ucf:51349
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006547
- Title
- Noise, Stability, and Linewidth Performance of 10-GHz Optical Frequency Combs Generated from the Nested Cavity Architecture.
- Creator
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Bagnell, Kristina, Delfyett, Peter, Likamwa, Patrick, Schulzgen, Axel, DeSalvo, Richard, University of Central Florida
- Abstract / Description
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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
- Broad Bandwidth Optical Frequency Combs from Low Noise, High Repetition Rate Semiconductor Mode-Locked Lasers.
- Creator
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Klee, Anthony, Delfyett, Peter, Vanstryland, Eric, Schulzgen, Axel, DeSalvo, Richard, University of Central Florida
- Abstract / Description
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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
- Injection Locking of Semiconductor Mode-Locked Lasers for Long-Term Stability of Widely Tunable Frequency Combs.
- Creator
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Williams, Charles, Delfyett, Peter, Hagan, David, Likamwa, Patrick, Vanstryland, Eric, DeSalvo, Richard, University of Central Florida
- Abstract / Description
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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
- Development of Thulium Fiber Lasers for High Average Power and High Peak Power Operation.
- Creator
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Sims, Robert, Richardson, Martin, Schulzgen, Axel, Delfyett, Peter, Chow, Louis, University of Central Florida
- Abstract / Description
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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.
Show less - Date Issued
- 2012
- Identifier
- CFE0004752, ucf:49768
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004752
