Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session A47: Undergraduate Research IIUndergrad Friendly
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Sponsoring Units: SPS Chair: Farah Dawood, APS Room: Room 313 |
Monday, March 6, 2023 8:00AM - 8:12AM |
A47.00001: Cooled atomic force microscope for undergraduate research Cody Graves Recent advances in quantum materials have attracted research on new local imaging techniques to investigate physics at the atomic scale. Our motivation is to design a low-cost low temperature portable atomic force microscope (AFM) suitable for implementing scanning probe techniques on quantum materials and devices. The AFM is intended to be made affordable so that small colleges and high school students have access to such imaging research. One of the first applications of the microscope is to image electron flow in two-dimensional materials such as graphene. |
Monday, March 6, 2023 8:12AM - 8:24AM |
A47.00002: Design and Construction of an Inverted Microscope to be Used in IR Optical Tweezers Gabriel Andres ISLAND CURE is a new research collaboration with a focus on using physics techniques and apparatuses to make biochemical measurements. Within the larger scope of the ISLAND CURE, there are many different aspects of research, all of which involve undergraduate students. One of our goals will be to create tools that are low-cost to share with other departments and researchers with a limited budget. One of our objectives is to build an infrared optical tweezing system to study DNA. For this, we will need to design and construct a relatively inexpensive inverted microscope. This talk will be focused on the microscopy calculations we made for the design as well as the material design and construction. This demonstrates a cost-effective method using undergraduate students to move towards more complicated biochemical measurements. |
Monday, March 6, 2023 8:24AM - 8:36AM |
A47.00003: Design and Application of Wide-Angle Ultraviolet Stop Filter for Semi-transparent Organic Photovoltaics Alyssa L Miller, Hafiz K Sheriff, Stephen R Forrest The threat of global warming can be mitigated by converting from fossil fuels to green energy sources to power our economies. Semi-transparent organic photovoltaics (ST-OPVs) provide an opportunity to do so. These devices present a unique solution to the clean energy challenge from their capabilities of being transparent, lightweight, flexible, and easily producible for window integrated applications. However, there are concerns about their operational longevity. Research has shown that one of the failure modes that lessens the lifetime of these devices is degradation of the active layer1 by high energy ultraviolet (UV) radiation. Radiation in this band breaks the bonds within organic molecules that form the device photoactive layers. We report on the design and implementation of a modified substrate that serves the dual functions of blocking UV radiation and reducing Fresnel reflections at the light incident side of the device to extend the lifetime and reduce losses in the power conversion efficiency (PCE). |
Monday, March 6, 2023 8:36AM - 8:48AM |
A47.00004: Developing dielectric-metal hybrid nanomaterials for solar cells Aries Martinez, Dongheon Ha Dielectric resonating materials are useful in solar cells as they excite strong optical coupling to underlying solar cells.[1] We present the method to further enhance the optoelectronic responses of solar cells with the application of plasmonic nanoparticles (e.g., Au, Ag, Al). When placed atop dielectric resonators, the plasmonic particles strongly capture incident light by localized surface plasmon effect at visible wavelengths, further increasing optical coupling between dielectric resonators and solar cells. From our simulations and analytical calculations, it is found that the photo-response of solar cells can further be enhanced as much as > 5 % with hybrid nanomaterials. With the strong excited optical modes, we also found that the light absorbed in underlying solar cells can be increased close to 100 % at resonant peaks, demonstrating the potential of developing high-performing optical sensors. To realize the full potential of using hybrid nanomaterials, we also discuss how to optimize the geometry (e.g., size, periodicity) and materials (e.g., metal alloys) of plasmonic particles. |
Monday, March 6, 2023 8:48AM - 9:00AM |
A47.00005: Solar cell photoresponse enhancement with perovskite quantum dots and plasmonic particles David Whatcott, Luis M Torres Cantu, Dominic Torrepalma, Aries Martinez, Dongheon Ha We present the method to improve silicon solar cells through the application of nanomaterials such as perovskite quantum dots and plasmonic particles. We utilized an external quantum efficiency measurement system to test the enhancement of the silicon cells with these nanomaterials. First, we measured bare cells, then tested the same cells with the quantum dots applied to the surface and compared the results. We were able to see clear improvement in the external quantum efficiency of the cells at shorter wavelengths due to the quantum dots' photon down-conversion effect, as well as slight broadband improvement due to the applied material's antireflective ability. We then tested the effect of gold and silver plasmonic particles applied to silicon cells. Enhancement was seen at longer wavelengths for gold particles, and midrange wavelengths for silver particles. We then added both quantum dots and plasmonic particles to further enhance the characteristic of the silicon cells. We discuss the effect of the added nanomaterials, as well as the ways to optimize the effect of applied nanomaterials. |
Monday, March 6, 2023 9:00AM - 9:12AM |
A47.00006: Nanoscale imaging of solar cells using Kelvin probe force microscopy Luis M Torres Cantu, David Whatcott, Dominic Torrepalma, Aries Martinez, Dongheon Ha In the search for renewable energy, solar cells have become the prevailing alternative; however, the main drawback to consider in solar cells is their limited efficiency. To identify the causes of limiting factors, we investigated the fundamental interaction between photons and electrons of polysilicon solar cells at the nanoscale using a Kelvin probe force microscopy (KPFM) technique. With this technique, we imaged nanoscale surface potential of polycrystalline silicon solar cells. In this presentation, we discuss how influential the defects at grain boundaries affect electrical properties of solar cells. To improve photo responses, we employed nanophotonic materials such as quantum dots and plasmonic nanostructures atop polycrystalline solar cells. We also present how these nanomaterials enhance surface potential of solar cells at the nanoscale using the same measurement technique. Lastly, we discuss the potential and limitations of a KPFM technique.
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Monday, March 6, 2023 9:12AM - 9:24AM |
A47.00007: Simulating the Influence of Birefringence for CentrosymmetricPoint Groups using Rotational Anisotropy Second HarmonicGeneration (RA-SHG) Alex V Landry Birefringence is an optical property of crystals with a refractive index that varies with the polarization and propagation direction of light. A crystal's birefringence is determined by its anisotropic and symmetric properties, and by utilizing rotational anisotropy second harmonic generation (RA-SHG) the symmetry information of crystals that incident light interacts with can be observed. This results in outgoing radiation that is highly dependent on the symmetry properties of the crystal. By using RA-SHG we can simulate nonlinear induced polarization for higher-rank multipolar densities in crystals at a given distance from the sample's surface. This project focuses on developing an interactive interface that allows for the manipulation of the simulated RA-SHG process for birefringent centrosymmetric (inversely symmetric) point groups. In the future, this program can be expanded to magnetic symmetry groups undergoing additional physical transformations. This project was developed in part in collaboration with Dr. Liuyan Zhao of the University of Michigan. |
Monday, March 6, 2023 9:24AM - 9:36AM |
A47.00008: On the Importance of the Direct Measurements of the Specific Refractive Index for Microgels and Micelles Patrick Herron Specific refractive index (dn/dc) is the change in solutions' index of refraction as concentration of a solution changes. When static light scattering (SLS) is used to determine structural properties of scatterers in a solution, a separate measurement of dn/dc on the same solutions is crucial to obtain dependable results for molecular weight as a 5% dn/dc error causes a 10% Mw error according to scattering theory. This project is focused on dn/dc measurements for microgels of various crosslinking density, ELP micelles of various composition, and polystyrene spherical standards of various sizes using a Brice-Phoenix Refractometer. The dn/dc values measured were shown to depend on size and concentration of particles, composition of microgels and micelles, and temperature of solutions tested. Here we present how dn/dc results affect Mw values deduced from SLS for microgels and ELP micelles highlighting the critical importance of direct dn/dc measurements for solutions of interest in light scattering. |
Monday, March 6, 2023 9:36AM - 9:48AM |
A47.00009: Effect of Hydrogen Content on Rare Earth Fluorescence in Lithium Niobate Michael W Dixon, Steven Rehbein, Thomas Rust, Rufus L Cone, Charles W Thiel The unique properties of the rare earth ions make them attractive optoelectronic dopants whose electronic structure varies little by host material. Ubiquitous hydrogen impurities can, however, affect photodynamic processes such a fluorescence. Due to difficulties in material characterization the role and mechanism of rare earth fluorescence quenching by hydrogen remains unclear. We have studied the quenching of erbium(III) and thulium(III) fluorescence in lithium niobate as a function of hydrogen content. By varying the hydrogen content in LiNbO3 by indiffusion processes we were able to control the concentration of hydrogen and the proximity of hydroxyl impurities to the rare earth ions to probe the quenching mechanism. This increased understanding of the relationship between rare earth ion performance and hydrogen will allow for the tailoring of fluorescence lifetimes and selective quenching of individual electronic transitions. |
Monday, March 6, 2023 9:48AM - 10:00AM |
A47.00010: Exploring Cathodoluminescence Evident Features of Tungsten Disulfide, Molybdenum Disulfide, and Tungsten-Sulfide-Selenide Nathan Mayer Cathodoluminescence (CL) microscopy can be used to characterize the quantum optical behaviors of two-dimensional nanostructures. To investigate this behavior, we mounted flakes of tungsten disulfide (WS2), molybdenum disulfide (MoS2), and tungsten-sulfide-selenide Janus structures (WSSe) on a SiO2 substrate and analyzed these samples under both high vacuum and low H2O vacuum conditions using a scanning electron microscope. We then captured CL and secondary-electron images of the samples at multiple electron-beam energies and currents (5 keV to 30 keV, and 0.5 nA to 5 nA, respectively). We used a range of beam currents and energies to maximize image resolution while minimizing beam-induced sample damage. The images we secured were subjected to nonnegative matrix factorization and principal component analysis processing to identify and isolate areas of unique quantum optical behavior across various wavelengths. Artifacts in the CL images exposed flaws in this analysis methodology which prevented proper quantization of this behavior. Nevertheless, preliminary raw data showed evidence of non-uniform CL emission across flakes of WSSe and WS2. |
Monday, March 6, 2023 10:00AM - 10:12AM |
A47.00011: Measuring photon correlation using laser feedback interferometry with time-correlated coherence measurements Avery A Gilson, Ben Ovryn In Paul Dirac's "The principles of quantum mechanics", he explains the basis for intensity fringes when a light beam is split into 2 beams and then made to interfere by stating: "Each photon then interferes only with itself. Interference between two different photons never occurs". Dirac's famous statement forms the basis for the presentation of optical interferometry in undergraduate modern physics courses. Regarding this quote, Roy J. Glauber said, during his Nobel Prize Lecture (awarded for contributions to the quantum theory of optical coherence in 2005), "Forgive me, this is quantum mechanical scripture, but it is also nonsense". Glauber then elaborates to explain the Hanbury Brown-Twiss photon correlation experiment and in his published Nobel Prize Lecture he writes: "It is not the photons that interfere physically, it is their probability amplitudes that interfere – and probability amplitudes can be defined equally well for arbitrary numbers of photons. "Of course, the contemporary importance of these ideas was highlighted with the 2022 Nobel Prize in Physics awarded to 3 scientists "... for experiments with entangled photons ...". We are exploring photon correlations using a unique setup based upon electro-optic, phase-modulated HeNe laser feedback interferometry. We have shown that the laser feedback interferometer is a dynamic instrument that responds to dc and oscillatory changes in the optical path that can be measured with nanometer precision. This approach enables photon interference as well as time-correlated coherence measurements. |
Monday, March 6, 2023 10:12AM - 10:24AM |
A47.00012: Strain engineering effects on the optical properties of bilayer MoS2 Charanjot Singh, Biswajit Datta, Vinod M Menon Two-dimensional (2D) materials like transitional metal dichalcogenides (TMDs) exhibit interesting optical, mechanical, and electronic properties. These properties can be manipulated in several ways, one of them being strain engineering. By applying strain to very thin layers of TMDs, we can change properties like photoluminescence and absorption for these materials by causing their bandgap to change under strain. In our experiment, we prepared Al2O3 pillars on a silicon substrate. Then a MoS2 bilayer, encapsulated in hBN, was transferred on the pillars via dry transfer technique. Photoluminescence and white light absorption measurements were carried out at low temperature (5K) to understand the effect of strain on the excitonic properties. |
Monday, March 6, 2023 10:24AM - 10:36AM |
A47.00013: 4-level ladder electromagnetic induced transparency quantum antenna: theory Lee E Harrell, David O Kashinski, Brian C Holloway, Nathon L Segovia, William Kaiser, Samantha C Damonte, Kirk A Ingold Quantum Information Science & Technologies (QIST) is a topic of national priority. QIST has the potential to enable a new generation of transformative sensors similar to the transformative impact that the Global Positioning System (GPS), nuclear spin control for magnetic resonance imaging (MRI), and atomic clocks had in the last century. Researchers in the Photonics Researcher Center's Atomic, Molecular, and Optical Physics program (PRC-AMO) at the United States Military Academy are working to establish an education-centered QIST research laboratory with an initial focus on Quantum Sensors. Our immediate research objective is the demonstration of an operational Rydberg-atom (rubidium-based) Radio Frequency (RF) antenna capable of quantitative E-field meteorology, achieved through two parallel lines of effort: developing the theoretical model of a 4-level ladder system coupled with noise and the sharp absorption features in the electromagnetic induced transparency (EIT) spectra, and the provisioning of the QIST laboratory, to include all necessary optical accessories and lasers. We report on our progress in modeling the 4-level ladder EIT-based antenna signals using the three-level lambda system as a baseline. |
Monday, March 6, 2023 10:36AM - 10:48AM |
A47.00014: 4-level ladder electromagnetic induced transparency quantum antenna: experiment Lee E Harrell, Samantha C Damonte, William Kaiser, Nathon L Segovia, Kirk A Ingold, David O Kashinski, Brian C Holloway Quantum Information Science & Technologies (QIST) is a topic of national priority. QIST has the potential to enable a new generation of transformative sensors similar to the transformative impact that the Global Positioning System (GPS), nuclear spin control for magnetic resonance imaging (MRI), and atomic clocks had in the last century. Researchers in the Photonics Researcher Center's Atomic, Molecular, and Optical Physics program (PRC-AMO) at the United States Military Academy are working to establish an education-centered QIST research laboratory with an initial focus on Quantum Sensors. Our immediate research objective is the demonstration of an operational Rydberg-atom (rubidium-based) Radio Frequency (RF) antenna capable of quantitative E-field meteorology, achieved through two parallel lines of effort: developing the theoretical model of a 4-level ladder system coupled with noise and the sharp absorption features in the electromagnetic induced transparency (EIT) spectra, and the provisioning of the QIST laboratory, to include all necessary optical accessories and lasers. We report on our progress demonstrating an EIT-based quantum antenna. |
Monday, March 6, 2023 10:48AM - 11:00AM |
A47.00015: Converting Radio Frequency waves to Electrical Energy using Metamaterials Jordan Wilhelm We designed a high-efficiency radio frequency (RF) energy harvesting device using a metamaterials perfect absorber (MPA). With the embedded Schottky diodes, the device converts RF waves to DC electricity. The MPA design greatly improves the amount of RF energy captured by the device. The Fabry-Perot (FP) cavity resonance of the MPA further increases the voltage across the Schottky diodes significantly, allowing the diodes to turn on at a very low intensity of the incident waves. Therefore our device can harvest low-intensity RF waves, such as ambient RF waves of cell phone networks or WiFi networks. Numerical simulations were performed to improve the device performance by investigating different design parameters. The optimized design consists of a 4x4 array of split-ring resonators (SRR) and a metal plate separated by a small cavity of 4 cm. The resulting design is 21x19 cm in size with each SRR having 3.75 cm side lengths and an 8 mm gap. |
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