Bulletin of the American Physical Society
2019 Annual Spring Meeting of the APS Ohio-Region Section
Volume 64, Number 7
Friday–Saturday, March 29–30, 2019; The College of Wooster in Wooster, Ohio
Session F03: Condensed Matter and AMO |
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Chair: Susan Y. Lehman, The College of Wooster Room: Ruth W. Williams Hall 260 |
Saturday, March 30, 2019 9:30AM - 9:45AM |
F03.00001: Spontaneous Emission of GeSn via Thin Film Alloys and Quantum Wells Elaheh Ghanati, Jay Mathews The microelectronics industry is based on silicon. Si has mechanically rigid crystalline structure and has reasonable electrical characteristics, however its optical properties do not make it the best choice for photonics. The band gap does not allow for absorption in the 1.2-2 um range and the indirect band gap means that no lasers can be produced from silicon.silicon compatible material which responds actively and efficiently to light, with the ability to emit or receive in the infrared region, could be used to achieve infrared photonic devices on silicon. Ge is a promising candidate due to its lower band gap and its ability for direct band gap emission. It has been reported that alloying Ge with Sn helps to change the band structure of Ge by lowering the band gap, and increasing the efficiency of optical absorption and emission. In this work, we explore the tunability of optical emission by measuring photoluminescence from GeSn thin films with varying concentrations of Sn and comparing experimental data with the theoretical data (generic perturbation model). [Preview Abstract] |
Saturday, March 30, 2019 9:45AM - 10:00AM |
F03.00002: Optical non-reciprocity and slow light propagation in coupled spinning optomechanical resonators Imran Mirza, Wenchao Ge, Hui Jing Recently [Nature 558, 7711, 569 (2018)] architectures based on fiber coupled spinning micro-ring optomechanical resonators have shown ability to perform non-reciprocal light propagation without using traditional means such as magneto-optical based Faraday rotation. Motivated by these studies, we investigate the optical transmission of pump-probe driven spinning optomechanical micro-ring resonators coupled in a series configuration [arXiv:1810.03709]. The main focus of our work is to analyze how changing optical Sagnac effect due to same or opposite spinning directions of resonators can provide means to non-reciprocal and delayed transmission of the probe light. We expect the results to be relevant to the problem of photon transport in quantum networks and quantum communications. [Preview Abstract] |
Saturday, March 30, 2019 10:00AM - 10:15AM |
F03.00003: Large and realistic models of amorphous silicon Dale Igram, Bishal Bhattarai, Parthaparatim Biswas, David Drabold Amorphous silicon (a-Si) models are analyzed for structural, electronic and vibrational characteristics. Several models of various sizes have been computationally fabricated for this analysis. It is shown that a recently developed structural modeling algorithm known as force-enhanced atomic refinement (FEAR) provides results in agreement with experimental neutron and X-ray diffraction data while producing a total energy below conventional schemes. We also show that a large model ($\sim $500 atoms) and a complete basis is necessary to properly describe vibrational and thermal properties. We compute the density for a-Si, and compare with experimental results. [Preview Abstract] |
Saturday, March 30, 2019 10:15AM - 10:30AM |
F03.00004: Size, Shape and Aspect Ratio Effect on the LSPR Sensitivity of Hollow-Gold Nanoshells Masoud Shabaninezhad Navrood, Guda Ramakrishna The changing refractive index of the surrounding medium of the plasmonic nanoparticles due to binding biomolecules is routinely used in localized surface plasmon resonance (LSPR) based biosensors. In this work, the influence of the shape, size, shell thickness and aspect ratio on the plasmon sensitivity, defined as change in LSPR peak wavelength per unit refractive index, of the hollow-gold nanoshells is studied using theoretical modeling. Different shapes of hollow Au nanoshells are studied that include: sphere, disk, triangular prism, rod, ellipsoid, and rectangular block. We used multi-layered Mie theory and discrete dipole approximation (DDA) to determine the LSPR peak position and LSPR sensitivity of the spherical and non-spherical nanoparticles, respectively. The rectangular block and rod-shaped Au nanoshells have shown maximum LSPR sensitivity when compared to other shaped Au nanoshells. In addition, increased sensitivity was observed for higher aspect ratio as well as for smaller shell thicknesses. The results are rationalized based on the inner and outer surface plasmonic coupling. [Preview Abstract] |
Saturday, March 30, 2019 10:30AM - 10:45AM |
F03.00005: A Three Phase Model for Weathering Via Stochastic Fragmentation Donald Priour Through abrasion (e.g. collisions among neighboring rocks in a river or stream) stones lose mass while also changing shape. To model the evolution of the profile of rocks over the course of an extensive stochastically driven mechanical weathering process, we consider a scenario in which randomly oriented planes successively cleave away portions of a stone's volume. To take into consideration the aggressiveness of the weathering, the probability of the removal of a prospective fragment is considered to be proportional to $e^{-\gamma N_{v}}$, where $N_{v}$ is the number of vertices in the fragment while $\gamma$ is inversely related to the intensity of the abrasive collisions. With standard quantitative tools for identifying second order phase transitions, we find three distinct phases in the limit of many successful or sustained abrasive events. For very small $\gamma$, many sustained slices yield angular stones with clean planar facets. In the extreme $\gamma = 0$ case, the mean number of facets quickly tends to 8.50(2). On the other hand, for large $\gamma$, highly weathered stones have flat faces with rounded corners and edges. In the regime of intermediate $\gamma$ values, initially angular polyhedral shapes are weathered into round stones with smooth surfaces. [Preview Abstract] |
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