Bulletin of the American Physical Society
Fall 2015 Joint Meeting of the Texas Section of the AAPT, Texas Section of the APS and Zone 13 of the Society of Physics Students
Volume 60, Number 15
Thursday–Saturday, October 29–31, 2015; Waco, Texas
Session J2: Optics II and Nanoscience |
Hide Abstracts |
Chair: Charley Myles, Texas Tech University Room: A.108 |
Friday, October 30, 2015 3:30PM - 3:42PM |
J2.00001: Electrically tunable conducting oxide metasurfaces Ho Wai Howard Lee, Harry Atwater Metasurfaces composed of planar arrays of sub-wavelength artificial structures show promise for light manipulation, and have yielded novel ultrathin optical components such as flat lenses, holographic surfaces and orbital angular momentum manipulation. However the optical properties of metasurfaces developed to date do not allow for versatile tunability of wave amplitude and phase after fabrication, thus limiting their use in many applications. We experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface in the near-IR. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna which are configured in a reflectarray geometry. We measure a phase shift of $\pi $ and \textasciitilde 30{\%} change in the reflectance at 1550 nm by applying 2.5 V gate bias. Additionally, we demonstrate modulation at frequencies exceeding 10 MHz, and electrical switching of $+$/-1 order diffracted beams, a basic requirement for electrically tunable beam-steering phased array metasurfaces. These structures have potential applications for future ultrathin optical components, such as dynamic holograms, tunable ultrathin lens, and reconfigurable beam steering devices. [Preview Abstract] |
Friday, October 30, 2015 3:42PM - 3:54PM |
J2.00002: Linear actuators based on nano-energetic active materials Mkhitar Hobosyan, Patricia Martinez, Anvar Zakhidov, Karen Martirosyan The nanoenergetic materials (NM) are nano-structured mixtures of fuel (metal nanoparticles, usually Al or Mg) and non-metal or metal oxides (Bi$_{\mathrm{2}}$O$_{\mathrm{3}}$, CuO, I$_{\mathrm{2}}$O$_{\mathrm{5}}$, Fe$_{\mathrm{2}}$O$_{\mathrm{3}}$ etc). In this report we implanted NMs in multi-walled carbon nanotube (MWCNT) yarns to produce linear actuators for various applications. The actuation force can be tuned by using various atmospheres (ambient, inert, and vacuum) and by adjusting the NM loading density, MWCNT/NM weight ratio, yarn type and rotation number, as well as the type of NM utilized for yarn preparation. The combustion wave speed can reach up to 10 m/s to achieve adjustable actuation effective force up to 22 N/g. Although the combustion temperature is above 700 \textordmasculine C, the MWCNTs yarn is well preserved after the actuation. The proof of concept actuation of loading different mass demonstrated the possibility to apply this method in ambient, inert and vacuum environment, where other actuation methods can be difficult to apply. [Preview Abstract] |
Friday, October 30, 2015 3:54PM - 4:06PM |
J2.00003: Variation of optical properties of single-walled carbon nanotubes with length Anton Naumov, Dmitri Tsyboulski, Sergei Bachilo, R. Bruce Weisman The length dependence of the optical properties of single-walled carbon nanotubes (SWCNTs) was studied in bulk dispersions length-fractionated by electrophoretic separation or ultrasonication-induced scission. Fractions ranged from 120 to 760 nm in mean length. After shortening SWCNTs by timed ultrasonic treatment, their absorption was found constant within 11 percent as average nanotube length changed by a factor of 3.8. This indicates that the absorption cross-section per carbon atom is not length-dependent. By contrast, in length fractions prepared by both fractionation methods, the fluorescence efficiency and average quantum yield increased with average SWCNT length, approaching an asymptotic limit of 1 micrometer. This is interpreted as reflecting the combined contributions of exciton quenching by sidewall defects and by the ends of shorter nanotubes. Mathematical modeling of the quantum yield based on the experimentally found parameters and only nanotube end defects suggested a mean exciton excursion range of 50 nm. This is significantly below the 90-200 nm exciton excursion ranges found previously for individual, nearly-pristine SWCNTs that are expected to have lower defect density than typical processed SWCNTs. [Preview Abstract] |
Friday, October 30, 2015 4:06PM - 4:18PM |
J2.00004: Biological Quantum Nanoimaging. Dmitri Voronine, Marlan Scully Recent progress in nanoscale bioimaging has led to a better understanding of biological systems and processes. Development of new microscopic tools for faster imaging with better spatial resolution can help developing new medical treatments and more efficient devices. We investigate quantum limits to optical signal enhancement in biological systems and develop improved imaging techniques. Raman spectroscopy signals are enhanced by plasmonic nanostructures and reveal nanoscale chemical signatures of biomolecules. [Preview Abstract] |
Friday, October 30, 2015 4:18PM - 4:30PM |
J2.00005: Digital Holographic Microscopy for Dispersed Flows. Khaled Sallam Measuring the velocity field of a dispersed flow (e.g. bubbly flows, sprays, particle-laden flows) is of major importance in many industrial applications. Particle Image Velocimetry techniques are limited to 2-dimensional measurements. The present study involved extension of the existing holographic PIV method to two-phase flow velocimetry. The objective of the present study was to conduct velocity measurements using in-line holographic microscopy arrangement to analyze dispersed flows including an air bubble rising through stagnant water in a rectangular column, and spray injected in gaseous crossflow. Seeding particles (hollow glass spheres) are scattered uniformly in the continuous phase and are used as seed particles for the case of bubbly flow. Double-pulsed holograms recorded on 2K by 2K pixels CCD sensor capture the three-dimensional motion of the particles (in the continuous phase) and that of the dispersed phase itself. The holograms are reconstructed into `slices' and analyzed using image-processing algorithms to yield information about the sizes and velocities of the particles. [Preview Abstract] |
Friday, October 30, 2015 4:30PM - 4:42PM |
J2.00006: Raman Spectroscopic study of drought/saline stressed tobacco plants in vivo Narangerel Altangerel, Connor Gorman, Ariunbold Gombojav, Marlan Scully Raman spectroscopy is a valuable tool to analyze of plant substances and quality parameters in horticultural and agricultural crops. This spectroscopic technique allows to obtain spectra which present some characteristic key bands of the photosynthetic pigments. In our experiment, we study Raman spectra of water and saline stressed tobacco plants in vivo. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700