Bulletin of the American Physical Society
Fall 2019 Meeting of the Ohio-Region Section and the Michigan Section of the American Association of Physics Teachers
Volume 64, Number 15
Friday–Saturday, October 11–12, 2019; Flint, Michigan
Session B02: Optics, Photonics, Spectroscopy and Imaging |
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Chair: Gregory Hassold, Kettering University Room: Kettering University Academic Building 4501 |
Saturday, October 12, 2019 8:00AM - 8:12AM |
B02.00001: Verdet Constant Measurements for Terbium Gallium Garnet and Potassium Terbium Fluoride Michael Mueller, Said Elhamri, David Zelmon, Kevin Stevens, Greg Foundos Terbium Gallium Garnet (TGG) and Potassium Terbium Fluoride (KTF) are materials used as optical isolators which prevent feedback to the pump laser via the Faraday effect. The Verdet constant is a measure of the strength of the Faraday Effect which is the rotation of the plane of polarization of light in a magnetic field. The Verdet constant was measured by exposing samples of TGG and KTF to a magnetic field as a linearly polarized He-Ne laser beam passed through the samples. To determine the Verdet constant, the change of direction of the linear polarization was measured as a function of the magnetic field and determined the Verdet coefficients of TGG and KTF. [Preview Abstract] |
Saturday, October 12, 2019 8:12AM - 8:24AM |
B02.00002: Optical Properties of Photo-thermo-refractive Glass for Volume Bragg Gratings Zayne Parsons, Said Elhamri, David Zelmon, Vadim Smirnov, Dan Perlov Photo-thermo-refractive (PTR) glass is used to fabricate volume Bragg gratings. The gratings are formed by exposing PTR glass to UV light interference patterns and then annealing the glass. This produces a grating by locally modulating the refractive index. The diffraction efficiency of these gratings is dependent on the refractive index modulation amplitude. We report the refractive indices of unprocessed and processed PTR glass at wavelengths from 0.4 to 4.6 microns and discuss their uses in specifying VBGs for laser beam combining. [Preview Abstract] |
Saturday, October 12, 2019 8:24AM - 8:36AM |
B02.00003: GeSn thin film alloys for infrared optoelectronics Jay Mathews, Zairui Li, Yining Liu GeSn alloys are attractive for infrared emission due to the tunable band gap in the infrared and the quasi-direct or direct nature of the gap. Epitaxial growth of GeSn on Si has been demonstrated using multiple growth techniques and is now being incorporated into commercial device fabrication. Photodetectors covering a wide range of near- to mid-IR wavelengths have been realized. Recently, laser emission from GeSn waveguides on Si has been demonstrated at temperatures up to 240 K, but the search for room temperature Si-based laser continues. In this talk, I will discuss the recent results of optical characterization of GeSn alloys grown using a new remote plasma-enhanced chemical vapor deposition. [Preview Abstract] |
Saturday, October 12, 2019 8:36AM - 8:48AM |
B02.00004: Instrumentation of a low-cost Raman spectroscopy module to study MoS2 monolayers Gavin Trevorrow, Lyall Alwafi, Biplob Barman Raman scattering provides important information, via vibrational changes, about a molecule's response to electromagnetic radiation. In this work, we discuss the basic operating principle and instrumentation of a low-cost Raman spectroscopy module which uses a 532 nm CW laser as the excitation source. We demonstrate the capabilities of our set-up along with theoretical underpinnings and as an example, bearing testimony to our successful instrumentation, we compare our Raman spectrum (from toluene) to that of previously published results. We follow it up with modifying the module to perform micro-Raman measurements on mechanically exfoliated monolayer MoS2 flakes including imaging capabilities (using a CCD) for samples as small as 6-10 microns. [Preview Abstract] |
Saturday, October 12, 2019 8:48AM - 9:00AM |
B02.00005: Impact of finite sample dimensions on calculated reflectance and transmittance of thin turbid samples: numerical comparisons of Monte Carlo vs. Adding-Doubling Vinoin Devpaul Vincely, Karthik Vishwanath Accurate estimations of wavelength-dependent scattering and absorption coefficients are needed to describe photon propagation in multiply-scattering media. Experimentally measured reflectance and transmittance are fit by theoretical photon-migration models to estimate sample optical properties. Modeled solutions to the equation of radiative transport (RTE) (or its approximation such as diffusion theory) express the measured quantities as functions of the optical properties of the sample. The adding doubling (AD) algorithm is a commonly used method that reduces the RTE to one-dimension (1-D), to calculate solutions. For this 1-D approximation to be valid, samples are modelled to have infinite extent in two spatial dimensions (orthogonal to the incident beam direction). Experimentally this condition may not be valid, especially for large beam diameters. Alternatively, 3D photon migration dictated by RTE can be directly simulated using Monte-Carlo (MC) methods. Here, we compare total reflectance and transmittance of samples with varying optical properties and finite spatial dimensions obtained from MC to AD predictions. [Preview Abstract] |
Saturday, October 12, 2019 9:00AM - 9:12AM |
B02.00006: The Cutting Edge of Mirror Design -- Optimizing Hemispherical Mirrors for Fourier Transform Microwave Spectroscopy Brendan Beaver, Christopher Dewberry Microwave spectroscopy has been looking at molecular structures for years but little has been done on mirror design. More and more interest has been growing for studying larger molecules to aid in the study of species of medical and biomedical interests. Here we will present our findings from experiments conducted on aluminum hemispherical mirrors of varying geometries with the same radius of curvature. These tests were conducted using hornless chirp pulse FTMW, a broadband technique. The recently designed hornless chirp FTMW exceeds beyond the limitations of normal chirp pulse techniques, and this study seeks to optimize the collection of electromagnetic radiation for this new lower frequency region. Discussions on these results and future applications to study will be given. [Preview Abstract] |
Saturday, October 12, 2019 9:12AM - 9:24AM |
B02.00007: Hornless Chirped Pulse Fourier Transform Microwave Spectrometer Christopher Dewberry, John Kopp, Emily Dunkel, Brendan Beaver, Nicholas Knowles Broadband horn antennas have been used for Fourier transform microwave spectroscopy for a little over a decade. In this presentation, we will show a more cost effective alternative as well as describe several improvements done to the tandem cavity / chirped pulse FTMW to expand its capabilities. These improvements include 3D printed fractal antenna designs, a double-bladed iris for absorbing microwaves, and mirror design optimized for the low frequency region. Discussions will be made for making FTMW an analytical tool that could be incorporated in university teaching labs. [Preview Abstract] |
Saturday, October 12, 2019 9:24AM - 9:36AM |
B02.00008: Computer Generated Binary Fraunhofer Holograms Teresa Jeffrey, Marian Shih A computer algorithm is useful when generating mathematical representations of physical objects. In this case, this research project demonstrated the accuracy and viability of computer generated holograms using the Fraunhofer diffraction formula. This was done by way of mathematically representing a physical object as a matrix, generating the Binary Fraunhofer Hologram, and computing said hologram. The holograms generated by computer were printed and photographically reduced onto film, then successfully reconstructed optically to view the preconceived virtual object. The algorithm was written using Matlab. The algorithm contained a computational stage, followed by a representational stage. The computational stage calculated the complex scalar field by means of a 2-dimensional Discrete Fourier Transform, which was the numerical equivalent of the process of recording a hologram using an analog optical method. The representational stage created a binary pattern using information from the computed complex scalar field, by encoding cells using the detour-phase method invented by Brown and Lohmann {\&} Lohmann and Paris. [Preview Abstract] |
Saturday, October 12, 2019 9:36AM - 9:48AM |
B02.00009: Qubit-based optical nonreciprocity in hybrid optomechanical spinning resonators Imran Mirza, Wenchao Ge We study the transmission of probe light in a hybrid optomechanical spinning resonator coupled with a single two-level emitter (qubit). Applying the weak atomic excitation condition, we find that the presence of a single qubit can alter the probe light transmission considerably by introducing a spinning rate-dependent reflection channel. [Preview Abstract] |
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