Bulletin of the American Physical Society
2014 Annual Spring Meeting of the APS Ohio-Region Section
Volume 59, Number 3
Friday–Saturday, April 4–5, 2014; Youngstown, Ohio
Session E2: Optical Phenomena and Photonic Crystals |
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Chair: Michael Crescimanno, Youngstown State University Room: Williamson Hall 3418 |
Saturday, April 5, 2014 8:00AM - 8:12AM |
E2.00001: Forster Resonance Energy Transfer in PbS Quantum Dot Films Matthew Leopold Forster resonance energy transfer (FRET) is a phenomenon which occurs when an excited fluorophore loses its energy to a nearby fluorophore with lower excitation energy through dipole-dipole coupling. We observed FRET between large PbS Quantum dots and small quantum dots when they were close to each other in a film. The photoluminescence intensity of the large quantum dots is enhanced by a factor of ten. This technique may help to improve the efficiency of light emission of quantum dots in thin films. [Preview Abstract] |
Saturday, April 5, 2014 8:12AM - 8:24AM |
E2.00002: Exciton Dynamics in Organic/Plasmonic polytype WZ/ZB InP Nanowires Masoud Kaveh-Baghbadorani, Qiang Gao, Chaennupati Jagadish, Gerd Duscher, Hans-Peter Wagner We investigate the exciton dynamics in bare and organic/metal coated wurzite/zincblende (WZ/ZB) InP nanowires (NW) by temperature-dependent time-integrated (TI) and time-resolved (TR) photoluminescence (PL). Aluminum quinoline (Alq$_{3})$ as well as Alq$_{3}$/Mg:Ag covered NW heterostructures are fabricated by organic molecular beam deposition. PL measurements on bare InP nanowires at 15 K reveal two emission bands at 1.45, and 1.48 eV originating from indirect WZ/ZB and point-defect (PD) trapped excitons, respectively. TR PL traces show an approximately single exponential decay for PD trapped excitons with a lifetime of 2 ns and biexponential decay for indirect WZ/ZB excitons with lifetimes of 5 ns and 24 ns. In Alq$_{3}$ covered NWs we observe a stronger emission from both exciton transitions and longer decay times for indirect excitons indicating surface state passivation at the Alq$_{3}$/NW interface. In Alq$_{3}$/Mg:Ag NWs the PD trapped exciton emission is notably reduced which is attributed to a fast energy-transfer from free excitons in the WZ segments to plasmon oscillations in the metal film. [Preview Abstract] |
(Author Not Attending)
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E2.00003: Topological insulators driven by an electron spin Maxim Dzero The application of ideas developed in topology to the electronic band structure led to an intriguing discovery: materials can conduct electricity at the surface while remaining insulating at the bulk. These materials, called topological insulators, will have transformative impact on spintronics, low-power transport, and quantum computing. The search for a true topological insulator took years because even best candidates exhibited significant bulk conductivity. Only recently, literally in the past few months, several experimental groups established that samarium hexaboride, discovered in 1969 in Bell Labs, is a first topological insulator in its bulk form. In my talk, I review the theory which paved the way for this discovery. I will explain how crystalline symmetry, electron-electron interactions, and orbital degeneracy contribute to protecting the topological states in SmB6. In addition, I will discuss the experimental signatures of metallic surface states. [Preview Abstract] |
Saturday, April 5, 2014 8:36AM - 8:48AM |
E2.00004: Simulation of Optical Topological Edge States in Ring Resonator Lattices Guanquan Liang, Yidong Chong Several recent studies have reported on photonic analogs of the quantum Hall effect and topological insulators. The most striking property of these systems is the existence of topologically protected photonic one-way edge states. However, the systems thus far proposed either have non-optical operating frequencies or are difficult to fabricate. In this talk, we describe an optical topological insulator realized by a periodic lattice of coupled ring resonators. This system uses only periodic elements made of ordinary dielectric material, and should be simple to design and fabricate. The working frequency is scalable up to the optical range. The system consists of a ring resonator on each lattice (square or honeycomb) site, whose modes are coupled to modes on neighboring resonators having the same ``spin'' (clockwise or anti-clockwise direction of propagation). Using finite-difference time-domain (FDTD) simulations, we demonstrate the band structure and the existence of robust edge states. We demonstrate also that a transition between topological and conventional insulator behaviors can be achieved by tuning the inter-ring coupling strength. [Preview Abstract] |
Saturday, April 5, 2014 8:48AM - 9:00AM |
E2.00005: Superhigh resolution microscopy using microlenses Chuanhong Zhou, P. Kohli We report a new super-resolution microscope for optical imaging which attains an upmost resolution \textless 100nm with a broad-band white light source. The noninvasive microscope uses liquid plano-convex microlens (ML) to collect diffractive light from specimen. The deliquescent salt added in the liquid maintains the atomic smooth surface and the high refractive index of microlens. The microlens works in the near proximate to the objects and picks up both propagation and evanescent light diffracted from the objects. The produced super-resolution and enlarged images are then magnified by the conventional microscope. We also demonstrate that the microscope provides superior for fluorescence imaging where a resolution of $\sim$ 90 nm and $\sim$ 4 enhanced emission intensity was obtained. This microlens based microscope is easy to fabricate and use, inexpensive and no special requirement to illumination. It has potential applications in diverse fields of life-, bio-, and nano- sciences. [Preview Abstract] |
Saturday, April 5, 2014 9:00AM - 9:12AM |
E2.00006: Artificial Brownian Ratchets on the Nanoscale Using Ultra-cold Rubidium Atoms Andrew Hachtel, Matthew Gillette, Ethan Clements, Samir Bali It has been proposed that we may be able to harness, or direct, Brownian motion to create useful energy out of background thermal noise (without violating the laws of Physics) given that the system is being operated outside of equilibrium conditions. Recently, the field of nanotechnology has exploded with scientists trying to fabricate nanomachines that achieve efficiencies similar to that of the molecular motors, but with little success. Ultra-cold Rubidium atoms, which have been arranged into a periodic three-dimensional nanoscale crystalline structure created by the interference of counter-propagating laser beams, have been proposed as a promising testbed for simulating molecular motors. This is because such ``designer crystals'' are entirely defect-free and important crystal properties (such as lattice spacing and well depth) can be freely varied -- this is obviously not the case for crystals found in nature. The ratcheting effect is created by introducing an asymmetry into the wells of the lattice, thus instigating directed transport. This ratcheting phenomenon, which allows for the direct control of atomic dynamics on the nanoscale, is of great interest in fundamental as well as applied science, for example in the new and exciting field of nanolithography. [Preview Abstract] |
Saturday, April 5, 2014 9:12AM - 9:24AM |
E2.00007: Contributed Session Abstract |
Saturday, April 5, 2014 9:24AM - 9:36AM |
E2.00008: Dispersion and Conversion: Coherent Perfect Rotation in 1-d Photonic Crystals Michael Baker, Chaunhong Zhou, Michael Crescimanno, James Andrews We describe theory we use to investigate the role that group velocity modulation plays in the coherent perfect rotation (CPR). CPR is the conservative, reversible analogue of the antilaser. Beyond simple band effects, we study the CPR threshold at so-called ``phase slip'' in-band defect modes. [Preview Abstract] |
Saturday, April 5, 2014 9:36AM - 9:48AM |
E2.00009: New optical settings contrast Coherent Perfect Phenomena Michael Crescimanno, Chuanhong Zhou, Michael Baker, James Andrews Studying the two most popular coherent perfect phenomenon (the anti-laser and CPR) in diverse optical settings highlights the distinct role that reversibility plays in the underlying physical process. We report recent theoretical results that test these differences and suggest technology opportunities for improving optical devices and sensors. [Preview Abstract] |
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