Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session S6: Focus Session: Nanostructures and Metamaterials III |
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Sponsoring Units: DMP DCMP Chair: Rashid Zia, Brown University Room: 006A |
Thursday, March 5, 2015 8:00AM - 8:36AM |
S6.00001: Self-Configuring Universal Linear Optics Invited Speaker: David Miller Until recently, it was not clear whether we could make or even design arbitrary linear optical devices or transforms on light fields. A single thin dielectric structure or meta material layer is not sufficiently general, for example [1]. The canonical arbitrary linear problem is to separate and separately modulate arbitrary overlapping orthogonal light beams at a given wavelength without fundamental loss and then transform them into other arbitrary orthogonal beams; such a mode conversion corresponds to multiplying by an arbitrary matrix, so solving this problem in general enables arbitrary linear transforms (unitary or non-unitary) [2]. Recently we showed constructively how to implement any such linear transform [3,4], thereby solving the design problem in principle. Furthermore, we showed that this could be done entirely by training a mesh of interferometers and modulators with desired inputs and outputs, without any calculations and without any calibration of components [3,4]. This approach relies on simple single-parameter feedback loops that minimize power on detectors, in completely progressive algorithms, and could be implemented in silicon photonics. It could solve practical problems such as separating spatial modes in telecommunications [5], automatically aligning beams [3], and finding optimal channels through scatterers [6]. It offers new possibilities for self-configuring and self-stabilizing optical systems, and could enable complicated optics, such as for quantum networks and information, well beyond current capabilities. One interesting open question is how to exploit such approaches with nanoscale optics. \\[4pt] [1] D. A. B. Miller, J. Opt. Soc. Am. A 30, 238-251 (2013)\\[0pt] [2] D. A. B. Miller, Opt. Express 20, 23985-23993 (2012)\\[0pt] [3] D. A. B. Miller, Opt. Express 21, 6360-6370 (2013)\\[0pt] [4] D. A. B. Miller, Photon. Res. 1, 1-15 (2013) \\[0pt] [5] D. A. B. Miller, Opt. Express 21, 20220-20229 (2013)\\[0pt] [6] D. A. B. Miller, J. Lightwave Technol. 31, 3987 -- 3994 (2013) [Preview Abstract] |
Thursday, March 5, 2015 8:36AM - 8:48AM |
S6.00002: Surface plasmon decay dynamics in nanostructured systems: A Feynman diagram approach Prineha Narang, Ravishankar Sundararaman, Adam S. Jermyn, William A. Goddard III, Harry A. Atwater The decay of surface plasmon resonances is usually a detriment in the field of plasmonics, but the possibility to capture the energy normally lost to heat would open new opportunities in photon sensors and energy conversion devices. In the context of hot-electron devices, the large extinction cross-section at a surface plasmon resonance enables nanostructures to absorb a significant fraction of the solar spectrum in very thin films. Despite the significant experimental work in this direction, a complete theoretical understanding of plasmon-driven hot carrier generation with electronic structure details has been evasive. Recently we analyzed the quantum decay of surface plasmon polaritons and found that the prompt distribution of generated carriers is extremely sensitive to the energy band structure of the plasmonic material. In this context, we use a Feynman diagram approach to describe processes involving plasmons, electrons and phonons in plasmonic hot carrier generation. Built upon this general theoretical and computational framework, we present results on higher order processes such as multi-plasmon decays in metals which are critical for plasmon-driven upconversion. [Preview Abstract] |
Thursday, March 5, 2015 8:48AM - 9:00AM |
S6.00003: Photonic pulling force in one-way waveguides Danlu Wang, Chengwei Qiu, Peter Rakich, Zheng Wang Light can apply pulling force on dielectric particles through forward scattering, i.e, scattering that increases photon momentum. The forward scattering typically requires delicate conditions in free space, e.g. large incident angle, excitation of dipole-quadrapole interaction on spherically shaped particles. Here we demonstrate photonic pulling forces on dielectric particles in photonic crystal defect waveguides supporting one-way chiral edge modes. Intuitively, momentum discrepancy between two co-existing one-way modes facilitate forward scattering on arbitrarily configured particles inside the waveguide, over a broad frequency range, upon proper choice of incident mode. The pulling forces are also topologically protected against bending of the waveguide. Moreover, we rigorously related the direction and amplitude of photonic forces to the phase response of output modes versus the particle's displacement. While the phase response of output modes is determined by wave functions of the involved modes. [Preview Abstract] |
Thursday, March 5, 2015 9:00AM - 9:36AM |
S6.00004: PT symmetry in optics Invited Speaker: Demetrios Christodoulides Interest in complex Hamiltonians has been rekindled after the realization that a wide class of non-Hermitian Hamiltonians can have entirely real spectra as long as they simultaneously respect parity and time reversal operators. In non-relativistic quantum mechanics, governed by the Schr\"{o}dinger equation, a necessary but not sufficient condition for PT symmetry to hold is that the complex potential should involve real and imaginary parts which are even and odd functions of position respectively. As recently indicated, optics provides a fertile ground to observe and utilize notions of PT symmetry. In optics, the refractive index and gain/loss profiles play the role of the real and imaginary parts of the aforementioned complex potentials. As it has been demonstrated in several studies, PT-symmetric optical structures can exhibit peculiar properties that are otherwise unattainable in traditional Hermitian (conservative) optical settings. Among them, is the possibility for breaking this symmetry through an abrupt phase transition, band merging effects and unidirectional invisibility. Here we review recent developments in the field of $\mathcal{PT}$-symmetric optics. [Preview Abstract] |
Thursday, March 5, 2015 9:36AM - 9:48AM |
S6.00005: Parity-Time Symmetric Nonlocal Metamaterials for Focusing and Image Processing Francesco Monticone, Constantinos Valagiannopoulos, Silvio Savoia, Romain Fleury, Andrea Alu Parity-Time (PT) symmetry refers to the invariance of a physical system upon reflection of space and time. An intriguing property of PT-symmetric quantum systems is the fact that they can have entirely real eigenvalue spectra, despite being non-Hermitian. Although the application of these concepts in quantum mechanics remains speculative, in classical optics non-Hermitian PT-symmetric systems can be readily realized with spatially balanced gain and loss. These systems have been shown to exhibit exotic responses, e.g., unidirectional invisibility, or anomalous scattering. Recently, negative refraction and planar focusing have been achieved by pairing a perfectly coherent absorbing metasurface with its time-reversed counterpart, i.e., a coherently lasing metasurface. Here, we generalize this idea to any pair of PT-symmetric structures, characterized by their scattering matrix, to put forward a realistic venue to PT-symmetric metamaterials for imaging. This approach allows us to design realistic structures based, e.g., on multilayered slabs, which implement the necessary nonlocality and spatial dispersion to achieve ideal all-angle negative refraction and planar focusing. We will also discuss how these concepts may realize arbitrary magnifying, focusing and image processing systems. [Preview Abstract] |
Thursday, March 5, 2015 9:48AM - 10:00AM |
S6.00006: Single-mode laser by parity-time symmetry breaking Liang Feng, Zi Jing Wong, Ren-Min Ma, Yuan Wang, Xiang Zhang Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and applications. Using the concept of parity-time symmetry to exploit the interplay between gain and loss (i.e. light amplification and absorption), we demonstrate a parity-time synthetic laser with resonant modes that can be controlled at will. In contrast to conventional ring cavity lasers with multiple competing modes, our parity-time microring laser exhibits robust broadband single-mode lasing regardless of the gain spectral bandwidth. Thresholdless parity-time symmetry breaking due to the rotationally symmetric structure leads to stable single-mode operation with the selective whispering-gallery mode order. Exploration of parity-time symmetry in laser physics may develop a new paradigm of strategically utilizing optical losses and open a door to next-generation optoelectronic devices for optical communications and computing. [Preview Abstract] |
Thursday, March 5, 2015 10:00AM - 10:12AM |
S6.00007: Hybrid chiral metamaterials by dynamic shadowing growth John Gibbs, Peer Fischer, Andrew Mark, Sahand Eslami, Tung-Chun Lee Coupling optical and magnetic properties is possible in metamaterials and in higher-order magnetic field induced optical activities. Here, we show that these two mechanisms can be combined in nanostructures that are simultaneously ferromagnetic, chiral, and plasmonically resonant. In this talk, a short description of the fabrication of optically active helical metamaterials will first be given, followed by the highlighting of the materials' enhanced optical properties. Giant circular dichroism (CD) and optical rotatory dispersion (ORD) in the visible arise from helical plasmonic modes within the individual structures and can be tuned by altering the material composition, i.e. nanoalloys or nanocomposites, and/or by changing the structures' morphologies. By fabricating metamaterials which exhibit both strong CD and are ferromagnetic at room temperature, higher order terms in the generalized dielectric function in the presence of a B-field can be measured easily. In particular, magnetochiral dichroism (MChD) is a cross-term between chirality and an applied external B-field which has only been measured in crystals and molecules, but never in a metamaterial. We show that arrays of helical Ni nanostructures, due to the plasmonic nature of Ni, their chirality, as well as the fact they retain their ferromagnetism even at scales comparable to the average ferromagnetic domain size, exhibit an MChD signal that is much more pronounced in a metamaterial and can therefore be easily measured in the laboratory. [Preview Abstract] |
Thursday, March 5, 2015 10:12AM - 10:24AM |
S6.00008: Chiral Quantum Dots Milan Balaz Chiral optically active semiconductor quantum dots (chiral QDs) represent appealing building blocks for assembly of nanomaterials with modular structural, electronic and chiroptical properties. Chirality in QDs can originate from several distinct phenomena that can concurrently modulate the observed chiroptical and optical properties (e.g. chiral surface, orbital hybridization). We will use our experimental and theoretical data to elaborate on the origin of capping ligand induced chirality in achiral colloidal QDs [1]. We will present a simple method to prepare chiral QDs by post-synthetic chiral ligand functionalization of achiral QDs. Importantly, capping ligands can be used not only to induce but also to control chiroptical activity of QDs. Enantiomers of chiral ligands induce mirror-image chirality in QDs, and chiroptical properties of QDs can be further modulated by the chemical structure of capping ligands as well as the size of QDs.\\[4pt] [1] U. Tohgha, K. K. Deol, A. G. Porter, S. G. Bartko, J. K. Choi, B. M. Leonard, K. Varga, J. Kubelka, G. Muller, M. Balaz, Ligand induced circular dichroism and circularly polarized luminescence in CdSe quantum dots, ACS Nano, 2013, 7, 11094-11102 [Preview Abstract] |
Thursday, March 5, 2015 10:24AM - 10:36AM |
S6.00009: Generating Optical Vortex Arrays with Rectangular Hole Arrays Miao Jiang, Yu-Bing Guo, Qi-Huo Wei Paraxial optical beams are known to carry angular momentums which contain both spin and orbital components. Light carrying orbital angular momentum promise applications in information transfer and new spinoptic devices. In this paper we study optical transmission through rectangular hole arrays in metal films, and discuss their interactions with the angular momentum of light and applications in the generations of optical vortex arrays with different topological charges. [Preview Abstract] |
Thursday, March 5, 2015 10:36AM - 10:48AM |
S6.00010: Manipulating the polarization state of light with a metallic stereostructured layer Xiang Xiong, Shang-Chi Jiang, Yuan-Sheng Hu, Mu Wang, Ru-Wen Peng Without introducing dielectric material, we report here for the first time a wave plate constructed merely by metallic stereostructured layer. With an assembly of metallic L-shaped stereostructures (LSSs), the polarization state of the reflected light can be freely manipulated within a broad frequency band. The amplitude ratio of light in two orthogonal directions and the phase difference in these two directions can be tuned accurately and independently. We suggest that our design provides a new approach in realizing broadband wave plate device to manipulate the polarization state of light. [Preview Abstract] |
Thursday, March 5, 2015 10:48AM - 11:00AM |
S6.00011: Polarisation singularities in photonic crystals for an on-chip spin-photon interface Daryl M. Beggs, Andrew B. Young, Arthur C. T. Thijssen, Ruth Oulton Integrated quantum photonic chips are a leading contender for future quantum technologies, which aim to use the entanglement and superposition properties of quantum physics to speed up the manipulation of data. Quantum information may be stored and transmitted in photons, which make excellent flying qubits. Photons suffer little from decoherence, and single qubit gates performed by changing photon phase, are straightforward. Less straightforward is the ability to create two qubit gates, where one photon is used to switch another's state; inherently difficult due to the extremely small interaction cross-section between photons. The required deterministic two-qubit interactions will likely need a hybrid scheme with the ``flying'' photonic qubit interacting with a ``static'' matter qubit. Here we present the design of a photonic crystal waveguide structure that can couple electron-spin to photon path, thus providing an interface between a static and a flying qubit. We will show that the complex polarization properties inherent in the photonic crystal eigenmodes supports polarization singularities -- positions in the electric field vector where one of the parameters describing the local polarization ellipse is singular -- and that these singularities are ideal for a range of quantum information applications. In particular, we will show that by placing a quantum dot at one of these singularities, the electron-spin becomes correlated with the photon emission direction, creating an in-plane spin-photon interface that can transfer quantum information from static to flying qubits. [Preview Abstract] |
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