Physical Sciences and Mathematics Commons^™

Developing A Femtosecond Stimulated Raman Spectroscopy Experiment For Solid State Materials, Daniel Hammerland

Electronic Theses and Dissertations

Femtosecond Stimulated Raman Spectroscopy (FSRS) is a ultrafast spectroscopy technique first implemented by chemists to understand isomerization and other ultrafast molecular morphology changes by resolving vibrational dynamics[1, 2, 3]. FSRS has an unparalleled temporal and spectral resolution [4, 1, 5, 6] that arises as a result of a clever combination of picosecond and femtosecond pulses. However, despite this capability, FSRS has yet to be applied to modern materials in condensed matter physics. This thesis explores the design and implementation of FSRS to study two-dimensional materials in order to measure their quantum confined vibrational dynamics on utlrafast time scales.

Diffraction Of Laguerre Gaussian Vortex Beams, Anindya Ambuj

Graduate Theses and Dissertations

The natural phenomenon of waves bending around obstacles is diffraction. Spatial characteristics of the diffraction pattern depends on the incident wave field, the shape, and size of the aperture. The diffraction of a plane wave of light by a slit and a circular aperture produce the sinc-squared and the Airy intensity patterns, respectively. On the contrary, the diffraction of Laguerre-Gauss vortex (LGV) beams by simple apertures such as a slit, circular apertures, and polygons show many unexpected features.

LGV beams have ρ ` e i`φ transverse spatial dependence, where ρ is the distance from the beam axis, φ the azimuthal …

A Confocal Fabry Perot Etalon For Laser Frequency Analysis, Theodore Arsenault

Physics Student Scholarship

No abstract provided.

Mobile Free-Electron Laser For Remote Atmospheric Survey, S. Johnson, Balša Terzić, Geoffrey A. Krafft

Physics Faculty Publications

Reliable atmospheric surveys for carbon distributions will be essential to building an understanding of the Earth's carbon cycle and the role it plays in climate change. One of the core needs of NASA 's Active Sensing of CO2 Over Nights, Days and Seasons (ASCENDS) Mission is to advance the range and precision of current remote atmospheric survey techniques. The feasibility of using accelerator-based sources of infrared light to improve current airborne lidar systems has been explored. A literary review has been conducted to asses the needs of ASCENDS versus the current capabilities of modern atmospheric survey technology, and the parameters …

Production Of Magnetized Electron Beam From A Dc High Voltage Photogun, M.A. Mamun, P.A. Adderly, J. Benesch, B. Bullard, J. Delayen, J. Grames, J. Guo, F. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey Krafft, M. Poelker, R. Suleiman, M. Tiefenback, Y. Wang, Sajini Wijethunga, S. Zhang

Physics Faculty Publications

Bunched-beam electron cooling is a key feature of all proposed designs of the future electron-ion collider, and a requirement for achieving the highest promised collision luminosity. At the Jefferson Lab Electron Ion Collider (JLEIC), fast cooling of ion beams will be accomplished via so-called 'magnetized cooling' implemented using a recirculator ring that employs an energy recovery linac. In this contribution, we describe the production of magnetized electron beam using a compact 300 kV DC high voltage photogun with an inverted insulator geometry, and using alkali-antimonide photocathodes. Beam magnetization was assessed using a modest diagnostic beamline that includes YAG view screens …

300 Kv Dc High Voltage Photogun With Inverted Insulator Geometry And Csk₂Sb Photocathode, Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F. E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, Geoffrey A. Krafft, M. A. Mamun, G. G. Palacios Serrano, M. Poelker, R. Suleiman, M. G. Tiefenback, S.A.K. Wijethunga

Physics Faculty Publications

A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.

Bessel And Bessel Vortex Beams Generated By Blunt-Tip Axicon, Ramazan Şahi̇n

Turkish Journal of Physics

A theoretical prediction of the propagation characteristics of Laguerre--Gaussian beams after passing through a blunt-tip axicon is presented. An ideal axicon generates theoretically perfect diffraction-free and smooth-on-axis intensity Bessel beams, while experiments and calculations show that a zeroth-order Bessel beam deviates from its perfect behavior. Strong intensity modulation occurs due to interference around the center of the beam. The origin of these oscillations should be explored to increase the quality of beam shaping. This research shows that these oscillations can be reduced by stopping the beam center for a small portion or by optimizing input beam parameters. On the other …

Harmonically Resonant Cavity As A Bunch Length Monitor, B. Roberts, M. Pablo, E. Forman, J. Grames, F. Hannon, R.Kazimi W. Moore, M. M. Ali

Physics Faculty Publications

A compact, harmonically-resonant cavity with a fundamental resonant frequency of 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). The cavity’s antenna was attached directly to a sampling oscilloscope that detected the electron bunches as they passed through the cavity bore with a sensitivity of ~ mV/ μA. The oscilloscope wave-forms are a superposition of the harmonic modes excited by …

Development Of A Compact Broadband Optical Parametric Oscillator For Ultra-Sensitive Molecular Detection, Sean O. Crystal

Honors Undergraduate Theses

Every gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56µm pump laser and a never before used orientation patterned gallium-phosphide crystal. Periodically polled lithium niobate (PPLN), Gallium Arsenide (GaAs) and Gallium Phosphide are all crystals used to accomplish this task. GaP, in comparison to PPLN, has (i) a …

Cavity Ringdown Spectroscopy In Nitrogen/Oxygen Mixtures In The Presence Of Alpha Radiation, Sidney John Gautrau

Master's Theses

This research was part of an effort to experimentally validate computational models under development for radiation-induced atmospheric effects. Cavity Ringdown Spectroscopy (CRDS) was used to measure the concentration of chemical products generated as a result of radiation interactions in a controlled atmosphere. Experiments were conducted in a vacuum chamber interfaced with a gas introduction system that controlled the initial atmospheric composition. A quadrupole mass spectrometer and tunable dye laser were integrated to confirm initial atmospheric composition, and provide wavelength flexibility for detecting a variety of chemical products generated by radiation interactions. CRDS measurements were made for ozone production resulting from …

Hybrid Spatiotemporal Coherent Pulse Addition Of A Picosecond Flashlamp-Pumped Ndyag Laser.Pdf, Ahmad Azim

Ahmad Azim

Transmission Of Focused Picosecond Light Pulse Through Multimode Fibers, Yin Cen

Dissertations, Theses, and Capstone Projects

This thesis focuses on a technique of delivering spatially focused and temporally compressed picosecond laser pulses through multimode fibers. This study was inspired by recent success in focusing light through optically diffusive media of which multimode fibers were a special case in terms of causing scrambled phase distribution in the transmitted light. The approach involved controlling the phase distribution of incoming beam using a deformable mirror prior to its entry into the multimode fiber in order to achieve constructive interference at selected spots in the output. With phase control, the intensity of the focused light at the output can be …

Divided-Pulse Amplification To The Joule Level.Pdf, Ahmad Azim, Benjamin Webb, Nathan Bodnar, Michael Chini, Lawrence Shah, Martin Richardson

Ahmad Azim

Coherent Beam Combining Of Ultrashort Laser Pulses.Pdf, Ahmad Azim

Ahmad Azim

Coherent Beam Combining Of Ultrashort Laser Pulses, Ahmad Azim

Honors Undergraduate Theses

Ultrashort pulsed lasers have become critical to understanding light-matter interactions in new regimes such as generation of attosecond pulses, laser filamentation, and intense relativistic processes. Development of more powerful and energetic ultrafast lasers is required for advancing these fields of study. Several petawatt class systems now exist with more in development to further scale peak power and extend the frontier of ultrafast laser technology. Another relevant solution to the scaling of energy and power of ultrashort pulses is coherent beam combining (CBC). CBC is useful for not only scaling of laser parameters but also to mitigate parasitic nonlinear processes associated …

Shielded Radiography With A Laser-Driven Mev-Energy X-Ray Source, Shouyuan Chen, Grigory V. Golovin, Cameron Miller, Daniel Haden, Sudeep Banerjee, Ping Zhang, Cheng Liu, Jun Zhang, Baozhen Zhao, Shaun Clarke, Sara Pozzi, Donald Umstadter

Donald Umstadter Publications

We report the results of experimental and numerical-simulation studies of shielded radiography using narrowband MeVenergy X-rays from a compact all-laser-driven inverse-Compton-scattering X-ray light source. This recently developed Xray light source is based on a laser-wakefield accelerator with ultra-high-field gradient (GeV/cm). We demonstrate experimentally high-quality radiographic imaging (image contrast of 0.4 and signal-to-noise ratio of 2:1) of a target composed of 8-mm thick depleted uranium shielded by 80-mm thick steel, using a 6-MeV X-ray beam with a spread of 45% (FWHM) and 107 photons in a single shot. The corresponding dose of the X-ray pulse measured in front of the target …

Increasing The Sensitivity Of The Michelson Interferometer Through Multiple Reflection, Woonghee Youn

Graduate Theses - Physics and Optical Engineering

Michelson interferometry has been one of the most famous and popular optical interference system for analyzing optical components and measuring optical metrology properties. Typical Michelson interferometer can measure object displacement with wavefront shapes to one half of the laser wavelength. As testing components and devices size reduce to micro and nano dimension, Michelson interferometer sensitivity is not suitable. The purpose of this study is to design and develop the Michelson interferometer using the concept of multiple reflections. This thesis proposes a new and novel design for a multiple reflection interferometer, where the number of reflections does not affect the quality …

Toward Quantum Analog Computing: Simulating Designer Atomic Systems, Veronica L. Sanford, Jacob L. Bigelow

Physics and Astronomy Summer Fellows

We use a magneto-optical trap to cool rubidium atoms to temperatures in the _µK range. On the _µs timescales of our experiment, the atoms are moving slowly enough that they appear stationary. We then excite them to a Rydberg state, where the outer electron is loosely bound. In these high energy states, the atoms can exchange energy with each other. Since the energy exchange depends on the separation and the relative orientation of the atoms, we can potentially control their interactions by controlling the spatial arrangements of the atoms. We model this system using simulations on a supercomputer …

Mathematical Model: Comparative Study Of Thermal Effects Of Laser In Corneal Refractive Surgeries, Gokul Kc, Dil B. Gurung, Pushpa R. Adhikary

Applications and Applied Mathematics: An International Journal (AAM)

Lasers have been widely used in ophthalmology. Refractive errors are some of the most common ophthalmic abnormalities worldwide. Laser refractive surgery was developed to correct refractive errors myopia, hyperopia and astigmatism. Two types of laser surgical techniques: lamellar and thermal are available to reshape the corneal curvature. Ultraviolet (UV) emitting argon fluoride (ArF) excimer laser is used to sculpt cornea in lamellar procedures, whereas, infrared (IR) emitting holmium yttrium aluminum garnet (Ho: YAG) laser is used to shrink cornea in thermal procedure. Tissue heating is common in all types of laser surgical techniques. Hence, in this paper, a finite element …

Imaging An Aligned Polyatomic Molecule With Laser-Induced Electron Diffraction, Michael G. Pullen, Benjamin Wolter, Anh-Thu Le, Matthias Baudisch, Michael Hemmer, Arne Senftleben, Claus Dieter Schroeter, Joachim Ullrich, Robert Moshammer, C. D. Lin, Jens Biegert

Physics Faculty Research & Creative Works

Laser-induced electron diffraction is an evolving tabletop method that aims to image ultrafast structural changes in gas-phase polyatomic molecules with sub-Ångström spatial and femtosecond temporal resolutions. Here we demonstrate the retrieval of multiple bond lengths from a polyatomic molecule by simultaneously measuring the C-C and C-H bond lengths in aligned acetylene. Our approach takes the method beyond the hitherto achieved imaging of simple diatomic molecules and is based on the combination of a 160kHz mid-infrared few-cycle laser source with full three-dimensional electron-ion coincidence detection. Our technique provides an accessible and robust route towards imaging ultrafast processes in complex gas-phase molecules …

Barium Concentrations In Rock Salt By Laser Induced Breakdown Spectroscopy, Kiley J. Spirito

Dissertations, Master's Theses and Master's Reports - Open

Time-REsolved Laser Induced Breakdown Spectroscopy (TRELIBS) was used to determine the elemental concentration of barium in Texas Dome rock salt. TRELIBS allows for an efficient and in situ concentration analysis technique that detects a wide range of elements with no sample preparation.

TRELIBS measurements were made in the 545nm to 594nm wavelength range. The proximity of a strong barium emission line (553.5481 nm) to the sodium doublet (588.9950 nm and 589.5924 nm) allowed for measurement within a single frame of the spectrograph.

This barium emission line was compared to the sodium doublet for relative intensity. A homemade calibration sample containing …

Construction And Optimization Of A Tapered Amplifier System For Applications In Ultra-Cold Plasma Research, Ryan Cole

Honors Theses

The number density of cold atoms confined in a magneto-optical trap (MOT) is critically dependent on the intensity of the lasers used to cool the sample. To generate large optical powers while retaining the practicality of homemade external cavity diode lasers (ECDLs), a tapered amplifier (TA) system was designed and constructed to amplify the output of an existing 780 nm, continuous-wave ECDL. The amplifier’s performance is discussed in terms of its gain and power output. Under standard operating conditions, optical amplification of 12 dB is achieved, with a maximum power output of 0.75 W. The completed amplifier is installed into …

Laser-Induced Breakdown Spectroscopy For Analysis Of High Density Methane-Oxygen Mixtures, Matthew Dackman

Masters Theses

The applicability of laser-induced breakdown spectroscopy (LIBS) toward greater than atmospheric density combustion diagnostics is examined. Specifically, this involves ascertaining the feasibility of measuring chemical equivalence ratios directly from atomic emission spectra at high density. The need for such measurement arises from the desire to quantify real time, localized combustion performance in weakly mixed flows. Insufficiently mixed flows generally result in unwanted byproducts, possess the propensity for overall combustion instability, and are increasingly likely to experience localized flame extinction.

We simulate methane/oxygen combustion in ambient pressures ranging 1 to 4 atmospheres, demonstrating these results to be analogous to what would …

Universality Of Returning Electron Wave Packet In High-Order Harmonic Generation With Midinfrared Laser Pulses, Anh-Thu Le, Hui Wei, Cheng Jin, Vu Ngoc Tuoc, Toru Morishita, C. D. Lin

Physics Faculty Research & Creative Works

We show that a returning electron wave packet in high-order harmonic generation (HHG) with midinfrared laser pulses converges to a universal limit for a laser wavelength above about 3µm. The results are consistent among the different methods: a numerical solution of the time-dependent Schrödinger equation, the strong-field approximation, and the quantum orbits theory. We further analyze how the contribution from different electron "trajectories" survives the macroscopic propagation in the medium. Our result thus provides a new framework for investigating the wavelength scaling law for the HHG yields.

Waveforms For Optimal Sub-Kev High-Order Harmonics With Synthesized Two- Or Three-Colour Laser Fields, Cheng Jin, Guoli Wang, Hui Wei, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

High-order harmonics extending to the X-ray region generated in a gas medium by intense lasers offer the potential for providing tabletop broadband light sources but so far are limited by their low conversion efficiency. Here we show that harmonics can be enhanced by one to two orders of magnitude without an increase in the total laser power if the laser's waveform is optimized by synthesizing two- or three-colour fields. The harmonics thus generated are also favourably phase-matched so that radiation is efficiently built up in the gas medium. Our results, combined with the emerging intense high-repetition MHz lasers, promise to …

The Quest For High Power Lasers: Forcing Mutual Coherence In Broad Area Diode Lasers, Jonathan R. Wurtz

Student Research Projects

This poster explains efforts to improve spatial beam quality of diode array stacks using an external optical feedback system to force coherence of individual diodes.

Integration Of Instrumentation And Processing Software Of A Laser Speckle Contrast Imaging System, Jacob James Carrick

Dissertations, Master's Theses and Master's Reports - Open

Laser speckle contrast imaging (LSCI) has the potential to be a powerful tool in medicine, but more research in the field is required so it can be used properly. To help in the progression of Michigan Tech's research in the field, a graphical user interface (GUI) was designed in Matlab to control the instrumentation of the experiments as well as process the raw speckle images into contrast images while they are being acquired. The design of the system was successful and is currently being used by Michigan Tech's Biomedical Engineering department. This thesis describes the development of the LSCI GUI …

The Talbot Effect, Malia Kawamura

Honors Theses

The goal of this project is to experimentally investigate the optical Talbot effect and the electron Talbot effect. The Talbot effect is a near-field diffraction effect which occurs when plane waves are incident upon a grating. The Talbot effect creates full grating revivals at integral Talbot lengths and revivals with greater spatial periodicity at fractional Talbot lengths. We use a green helium neon laser and Ronchi rulings to take CCD camera images of the fractional Talbot revivals directly. Additionally, a photodiode records light intensity as a function of time as a second identical grating is moved to verify the presence …

Forcing Mutual Coherence In Diode Laser Stacks, Jonathan R. Wurtz

Honors Theses and Capstones

This paper will discuss both theoretical and experimental attempts to improve the spatial beam quality of diode laser stacks using an external optical system. An overview and derivation of the mathematics of both the optical system and diode lasers will be discussed. The experimental setup will be presented, as well as the fundamental theoretical and experimental results that suggest the external optical system used for this thesis fails to improve the beam quality of a diode laser stack.

Design And Construction Of An Optical Tweezers, Pavel Aprelev

Honors Theses

We constructed an optical tweezers apparatus, used it to trap transparent micron-sized particles, and moved those particles within a sample by moving the sample relative to the focal point of the trapping beam. The optical trap was based on the fact that focused coherent light creates forces on dielectric objects that point towards the focal point. The magnitude and the span of the force are dependent on the size of the focal point of the beam - generally around 1µm - and the intensity of light. We used an 808 nm 200 mW laser and a piezoelectric stage to trap …