Bulletin of the American Physical Society
2014 Annual Meeting of the Mid-Atlantic Section of the APS
Volume 59, Number 9
Friday–Sunday, October 3–5, 2014; University Park, Pennsylvania
Session E8: Atomic, Molecular and Optical Physics II |
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Chair: Charles Jaffe, West Virginia University Room: Life Sciences Building 013 |
Saturday, October 4, 2014 3:30PM - 3:42PM |
E8.00001: Optical beam imaging studies on high power lasers Julia Yang SLAC National Accelerator Laboratory hosts the unique Linac Coherent Light Source, a free electron x-ray laser (FEL) with high peak brightness, tunability, and narrow bandwidth. Matter in Extreme Conditions (MEC) end station at SLAC investigates the behavior of states in extreme environments of high pressure (several megabars) and temperatures (millions of Kelvin) produced by powerful class 4 lasers using the FEL to probe transient states. Recent experiments in warm dense matter at MEC have required relativistic laser intensities greater than 10$^{\mathrm{19}}$ W/cm$^{\mathrm{2}}$ to create hot electrons. The aim of this study is to characterize the beam spot per pulse to establish high intensity values within 10{\%} accuracy. This will indicate if enough peak intensity has impacted the sample. A numerical code in MATLAB is developed to find spatial and intensity jitter, spot size measurements for four profiles, average peak intensity, and error propagation. This procedure automates previous methods done with imaging software for characterizing beam profile. The implemented code leads to faster and more accurate beam size characterization to eventually enable live pulse-by-pulse measurement, a valuable capability yet to be achieved in laser studies. [Preview Abstract] |
Saturday, October 4, 2014 3:42PM - 3:54PM |
E8.00002: Transmission Spectra for 1D Disordered Photonic Crystals Donald Priour With a recursive technique which accounts for disorder in a rigorous fashion without a need for averaging over multiple configurations of disorder, we calculate transmission spectra (for normal and oblique incidence in the optical range) for disordered nanoscale photonic crystals comprised of layers of alternating composition (i.e. Zinc Oxide and Chromium). Our theoretical results are in accord with recent experimental data obtained for a ZnO/Cr system. For the latter, we discuss the unusually high transmitted intensity of the photonic crystals, with theoretical predictions (calculated using the bulk attenuation coefficient for Chromium) several orders of magnitude lower. Nevertheless, by using a modified and considerably reduced attenuation coefficient for the nanoscale chromium layers, we obtain excellent agreement with the experimental data. [Preview Abstract] |
Saturday, October 4, 2014 3:54PM - 4:06PM |
E8.00003: Coherent spectroscopy of excitons in strained bulk GaAs Brian Wilmer, Ashley Batesole, Daniel Webber, Kimberly Hall, Edward Flagg, Richard Mirin, Alan Bristow Two-dimensional Fourier transform spectroscopy is used to measure bulk excitons in GaAs. The degeneracy of heavy and light hole excitons is lifted due to biaxial strain. This allows for observation of coherent coupling features between exciton resonances in rephasing spectra. This system differs from quantum wells, due to lack of inhomogeneity, and is a model system for isolating many-body interactions without quantum confinement. Low power and low temperature excitation reveals excitation-induced dephasing in the real-part of spectra. Excitation dependence shows an increase in spectral linewidths due to increasing excitation induced dephasing. Increasing temperature also increases dephasing, but reduces signal strength, due to increased interactions with the phonon bath. At low temperature there is also asymmetry in the strength of the off-diagonal coupling features, with downhill energy transfer being favored. The degree of asymmetry indicates that there are the same number of quantum pathways transferring spectral weight from the uphill coherence to the lower energy eigenstate and the higher energy eigenstate to the downhill coherence. At higher excitation density there is a swap in the strength of the coherences possibly due to saturation of the lower energy feature. [Preview Abstract] |
Saturday, October 4, 2014 4:06PM - 4:18PM |
E8.00004: Structure and Symmetry in Coherent Perfect Polarization Rotation Michael Crescimanno, Chuanhong Zhou, James Andrews, Michael Baker Theoretical investigation of different routes to coherent perfect polarization rotation illustrates its phenomenological connection with coherent perfect absorption, a.k.a. The anti-laser. Analysis of the effects of parity breaking, layering, combining Faraday rotation and optical activity, and a rotator-loaded optical cavity serve to sharpen the contrast between these phenomena. These comparisons may be useful in suggesting new approaches to common optical devices and identifying promising routes to their miniaturization. [Preview Abstract] |
Saturday, October 4, 2014 4:18PM - 4:30PM |
E8.00005: Near-analytic solutions to the PMD equations in Periodically Spun Fiber using Differential Transform Method Vinod Mishra Periodically spun optical fibers have been found to reduce Polarization Mode Dispersion (PMD) in propagating optical modes [1]. The resulting coupled ordinary differential equations are usually solved numerically. To gain better physical understanding and dependence of PMD on relevant parameters, analytical solutions are to be preferred. The current work uses Differential Transform Method to derive analytical solutions to the original equations as a series and investigates their properties. \\[4pt] [1] ``Analytical Treatment of Randomly Birefringent Periodically Spun Fibers'': Anna Pizzinat, Luca Palmieri, Brian S. Marks, Curtis R. Menyuk, and Andrea Galtarossa, J. Lightw. Techn., V. 21, No. 12, (2003) 3355 [Preview Abstract] |
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