Optics Commons^™

Measuring The Pulse Duration Of A Femtosecond Laser Using Intensity Autocorrelation, Ross N. Relic

Macalester Journal of Physics and Astronomy

In this experiment, an intensity autocorrelator is set up in order to measure the pulse duration of a passively mode-locked Titanium-Sapphire laser with a power of 267mW producing femtosecond pulses. Then this measurement, as well as a measurement of the laser’s spectrum, is used to test the Uncertainty Principle. Intensity autocorrelation is a well-established technique for measuring pulse duration, and is among the more intuitive techniques for this purpose, which is why it was selected for this experiment. The experimental setup was computerized. The delay of one half of the pulse was controlled by a motorized translation stage which was …

Characterization Of Boreal-Arctic Vegetation Growth Phases And Active Soil Layer Dynamics In The High-Latitudes Of North America: A Study Combining Multi-Year In Situ And Satellite-Based Observations, Michael G. Brown

Dissertations, Theses, and Capstone Projects

This dissertation examined the seasonal freeze/thaw activity in boreal-Arctic soils and vegetation physiology in Alaska, USA and Alberta, Canada, using in situ environmental measurements and passive microwave satellite observations. The boreal-Arctic high-latitudes have been experiencing ecosystem changes more rapidly in comparison to the rest of Earth due to the presently warming climatic conditions having a magnified effect over Polar Regions. Currently, the boreal-Arctic is a carbon sink; however, recent studies indicate a shift over the next century to become a carbon source. High-latitude vegetation and cold soil dynamics are influenced by climatic shifts and are largely responsible for the regions …

Tardys Quantifiers: Extracting Temporal And Reversible Dynamical Symmetries, Nhat Vu Minh Nguyen, Arjendu K. Pattanayak, Andres Aragoneses

2023 Symposium

One of the great challenges in complex and chaotic dynamics is to reveal the details of its underlying determinism. This can be manifest in the form of temporal correlations or structured patterns in the dynamics of a measurable variable. These temporal dynamical structures are sometimes a consequence of hidden global symmetries. Here we identify the temporal (approximate) symmetries of a semiconductor laser with external optical feedback, based on which we define the Temporal And Reversible DYnamical Symmetry (TARDYS) quantifiers to evaluate the relevance of specific temporal correlations in a time series. We show that these symmetries are also present in …

Effective Non-Hermiticity And Topology In Markovian Quadratic Bosonic Dynamics, Vincent Paul Flynn

Dartmouth College Ph.D Dissertations

Recently, there has been an explosion of interest in re-imagining many-body quantum phenomena beyond equilibrium. One such effort has extended the symmetry-protected topological (SPT) phase classification of non-interacting fermions to driven and dissipative settings, uncovering novel topological phenomena that are not known to exist in equilibrium which may have wide-ranging applications in quantum science. Similar physics in non-interacting bosonic systems has remained elusive. Even at equilibrium, an "effective non-Hermiticity" intrinsic to bosonic Hamiltonians poses theoretical challenges. While this non-Hermiticity has been acknowledged, its implications have not been explored in-depth. Beyond this dynamical peculiarity, major roadblocks have arisen in the search …

Method Of Evanescently Coupling Whispering Gallery Mode Optical Resonators Using Liquids [U.S. Patent Us11650370b2], Hengky Chandrahalim, Kyle T. Bodily

Faculty Publications

The present invention relates to evanescently coupling whispering gallery mode optical resonators having a liquid coupling as well as methods of making and using same. The aforementioned evanescently coupling whispering gallery mode optical resonators having a liquid couplings provide increased tunability and sensing selectivity over current same. The aforementioned. Applicants’ method of making evanescent-wave coupled optical resonators can be achieved while having coupling gap dimensions that can be fabricated using standard photolithography. Thus economic, rapid, and mass production of coupled WGM resonators-based lasers, sensors, and signal processors for a broad range of applications can be realized.

Photonic Sensors Based On Integrated Ring Resonators, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis investigates the application of integrated ring resonators to different sensing applications. The sensors proposed here rely on the principle of optical whispering gallery mode (WGM) resonance shifts of the resonators. Three distinct sensing applications are investigated to demonstrate the concept: a photonic seismometer, an evanescent field sensor, and a zero-drift Doppler velocimeter. These concepts can be helpful in developing lightweight, compact, and highly sensitive sensors. Successful implementation of these sensors could potentially address sensing requirements for both space and Earth-bound applications. The feasibility of this class of sensors is assessed for seismic, proximity, and vibrational measurements.

Microscopic And Spectroscopic Analysis Of Nordihydroguaiaretic Acid Effect On Astrocytes, Lizbeth Vanessa Martinez Lopez

Open Access Theses & Dissertations

Astrocytes, one of the most abundant cell components in the central nervous system (CNS), have been a research target in the last few years. Several studies have found that astrocytes are not only mere supporters of neurons but also of essential processes developed in the CNS. Their malfunction could induce neurodegenerative diseases and brain tumors. Thus, further understanding of astrocytes and their role is of high interest to develop possible new treatments and methods of disease diagnosis, especially in brain cancer. The plant Larrea tridentata (La Gobernadora in Mexico or Creosote bush in the United States) is known to have …

Investigating Properties Of Commercially Available Ir Detector Technology, Ethan Taylor

ATU Research Symposium

With the ability to transcode valuable information from light emitting objects, infrared (IR) detector technology has begun to find recreational use in the form of non-contact thermometers and home insulation tools. Research and industry have long been using IR technology in the form of high-altitude balloons, CubeSats, and UAV cameras, but the technology remains a niche market, and thus, a burdensome financial investment. As such, given general consumer products recently introduced as more economically viable, we sought to design an affordable IR camera capable of effective and meaningful data collection. To do so, we utilized a Raspberry Pi 4 and …

Optical Fiber Tip Micro Anemometer [U.S. Patent Us11635315b2], Hengky Chandrahalim, Jeremiah C. Williams

Faculty Publications

A passive microscopic flow sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fiber. The three-dimensional microscopic optical structure includes a post attached off-center to and extending longitudinally from the cleaved tip of the optical fiber. A rotor of the three-dimensional microscopic optical structure is received for rotation on the post. The rotor has more than one blade. Each blade has a reflective undersurface that reflects a light signal back through the optical fiber when center aligned with the optical fiber, the blades of the rotor shaped to rotate at a rate related to …

Fourth Order Dispersion In Nonlinear Media, Georgios Tsolias

Doctoral Dissertations

In recent years, there has been an explosion of interest in media bearing quartic
dispersion. After the experimental realization of so-called pure-quartic solitons, a
significant number of studies followed both for bright and for dark solitonic struc-
tures exploring the properties of not only quartic, but also setic, octic, decic etc.
dispersion, but also examining the competition between, e.g., quadratic and quartic
dispersion among others.
In the first chapter of this Thesis, we consider the interaction of solitary waves in
a model involving the well-known φ⁴ Klein-Gordon theory, bearing both Laplacian and biharmonic terms with different prefactors. As a …

"In The Beginning, God Created Atoms", Samiya L. Henry

Undergraduate Research and Scholarship Symposium

Genesis 1:1 states “In the beginning, God created the heavens and the earth.” This is the defining statement in the Bible and acts as the foundation of creation and God’s power in the Christian faith. On the other hand, many scientists believe the Big Bang Theory and the discoveries made in other fields of science solely define the creation of the universe and explain life as we know it, also disproving the Christian creation story and the overall existence of God. However, the exact opposite is true; God is science.

Alone, neither of these concepts (faith and science) fully solve …

Diffractive Imaging Of Laser Induced Molecular Reactions With Kiloelectron-Volt Ultrafast Electron Diffraction, Yanwei Xiong

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

Capturing the structural changes during a molecular reaction with ultrafast electron diffraction (UED) requires a high spatiotemporal resolution and sufficiently high signal-to-noise to record the signals with high fidelity. In this dissertation, I have focused on the development of a tabletop gas phase keV-UED setup with a femtosecond temporal resolution. A DC electron gun was employed to generate electron pulses with a high repetition rate of 5 kHz. The space charge effect in the electron pulse was ameliorated by compressing the 90 keV electron pulse longitudinally with a time varying electric field in an RF cavity. The velocity mismatch between …

Computational Design Of Fiber-Optic Probes For Biosensing, Suwarna Karna

Electrical Engineering Theses

This thesis presents a study on the optical characteristics of hollow-core photonic crystal fibers (HC-PCFs) with a band gap cladding structure and their applications in optical fiber sensing. This 800B HC-PCF exhibited excellent optical properties and has a flexible structure, which makes them suitable for a wide range of industrial applications. Finite element simulations and structural optimization designs were conducted using the surface plasmon resonance (SPR) technique to determine the optimal performance parameters of the 800B HC-PCF. The fiber was further modified using the SPR technique to improve its practical detection capabilities. The performance of the modified fiber was observed …

Novel As-S-Se Compositions Of Solution-Processed Chalcogenide Thin Films For Infrared Optics, Annabella Orsini

Physics and Astronomy Honors Papers

Chalcogenide glasses (ChGs) have a wide range of interdisciplinary applications. In industry, ChGs are used to vastly improve infrared sight abilities. There are, however, improvements that can be made to the films’ stability, cost, and flexibility. Our project seeks to produce thin films that have these improvements, with capabilities comparable or better than what is widely used in the field. Thin films created through solution-based processes have proven to be much more flexible in comparison to bulk glass versions. Other elements in Group 16, such as Sulfur and Selenium have shown across literature to be a cost-effective alternative to Tellurium …

Fano-Type Resonance Structures Based On Combination Of Fiber Bragg Grating With Fabry-Perot Interferometer, A.Zh. Sakhabutdinov, T.A. Agliullin, S.M.R.H. Hussein, A.A. Kuznetsov, V.I. Anfinogentov, B.I. Valeev

Karbala International Journal of Modern Science

The work is dedicated to the mathematical modeling of the combined fiber-optic structure, which consists of a Fabry-Perot interferometer in the form of a thin polymer film at the end of an optical fiber and a fiber Bragg grating formed near it. The simulation results obtained using the proposed rigorous mathematical model are in good agreement with the reflectance spectrum of the experimental fiber-optic structure. It is shown that the combination of two resonant wave processes in the optical fiber leads to the asymmetric Fano-type resonance. The spectral shape of the resonance depends on the parameters of the structure, in …

Design, Construction, And Stabilization Of An Adjustable Repetition Rate Frequency Comb For Precision Spectroscopy, Matthew Carter

Physics, Astronomy and Geophysics Honors Papers

Optical frequency combs have numerous applications across the sciences. One of the most powerful applications is in molecular spectroscopy, which takes advantage of both the coherence of lasers and combs’ inherent broad bandwidth. One well-established design is the erbium fiber comb, which is popular due to its low cost and relative ease of construction. I have modified the traditional all-fiber design by introducing an adjustable free-space section which allows for adjustments to the path length, and thus the comb’s repetition rate. This low-cost addition allows for repetition rate matching, a necessity for dual-comb spectroscopy, and active repetition rate stabilization, which …

Emission Spectroscopy Of Ingaas Quantum Dots Via High-Resolution Fabry-Perot Interferometer, Raju Bhai Kc

Graduate Theses, Dissertations, and Problem Reports

Single photons emitted from self-assembled quantum dots have been widely studied to use as a promising qubit for quantum information processing. Therefore, it is critical to fully understand the emission spectra from the quantum dot's excitation if we want to use a single photon as a quantum bit. It is almost impossible to produce rotationally symmetric quantum dots due to various growth conditions and restrictions. So the real quantum dots do not have a perfectly symmetric structure. A broken rotational symmetry causes an asymmetric exchange interaction between electron and hole, leading to a fine structure splitting between two excited states. …

An Analysis Of Tidal Mixing Front Dynamics And Frontal Biophysical Interaction In The Harpswell Sound Shelf Sea, Lemona Yingzhuo Niu

Honors Projects

Tidal Mixing Fronts (TMFs) are prominent hydrographic features of tidally energetic shallow shelf seas, representing the transition from mixed to stratified waters. These frontal boundaries often host enhanced phytoplankton primary productivity, as complete vertical mixing exhumes nutrients from depth to the light-lit surface. Existing observational programs for locating TMFs include infra-red satellite imagery of sea surface temperature (SST) and vertical profiling of temperature and density. However, challenges in observationally distinguishing mixed from mixing using only conservatively mixed hydrographic properties persist. A novel approach based on phytoplankton in-situ oxygen production response to light is proposed in this paper to distinguish stable …

Optical Tweezers: Exerting Force With Light, Gabriella Seifert

Scripps Senior Theses

Photons carry momentum. When a tightly-focused beam of photons hit a particle, they transfer some of their momentum to the particle, exerting a force. Optical tweezers take advantage of this phenomenon to trap (or “tweeze”) a spherical bead just after the focus of a diverging laser beam, creating a potential well that pulls in beads. In this thesis, I predict the force exerted on trapped beads and measure the actual force using an optical tweezers setup that I built. To predict the force, I follow the path of all possible rays from a diverging beam incident on a spherical bead …

The Behavior Of Partially Coherent Twisted Space-Time Beams In Atmospheric Turbulence, Milo W. Hyde Iv

Faculty Publications

We study how atmospheric turbulence affects twisted space-time beams, which are non-stationary random optical fields whose space and time dimensions are coupled with a stochastic twist. Applying the extended Huygens–Fresnel principle, we derive the mutual coherence function of a twisted space-time beam after propagating a distance z through atmospheric turbulence of arbitrary strength. We specialize the result to derive the ensemble-averaged irradiance and discuss how turbulence affects the beam’s spatial size, pulse width, and space-time twist. Lastly, we generate, in simulation, twisted space-time beam field realizations and propagate them through atmospheric phase screens to validate our analysis.