Modeling and Computational Techniques II

14:00 : Quantum vacuum photon modes tuning: a new route towards multifunctional surfaces

L. Dellieu, O. Deparis, J. Muller, M. Sarrazin

University of Namur (Belgium)

While wettability phenomena have been extensively studied over the last decade, the alteration of van der Waals forces via vacuum photon modes tuning has been unnoticed in theoretical models. Using first-principles calculations, we show that superhydrophibicity of nanostructured surfaces is dramatically enhanced by properly designed vacuum photon-mode modifications. As a case study, wetting contact angles of a water droplet above a polyethylene nanostructured surface are obtained from the potential energy calculated as a function of the droplet-surface separation distance.
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14:15 : Simulation and Observation of Enhanced Emission from Patterned Hyperbolic Metamaterials

Daniel Fullager (1),Ravi Hegde (2),Michael Fiddy (1)

(1)University of North Carolina (USA) , (2)A*STAR (Singapore)

Hyperbolic metamaterials (HMMs) are known to possess an unbounded range of wave vectors to which radiation can couple due to the hyperbolic shape of the HMM isofrequency surface. Thus, there exists a large range of modes that can be excited by thermal fluctuations which can then reradiate by coupling to high spatial frequency features. Herein we show predicted transmission in an alternating GZO/ZnO HMM using CST microwave studio and actual observation of enhanced emission in the infrared
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14:30 : Vertical Mode Expansion Method for Analyzing Metallic Nanoparticles

Xun Lu, Hualiang Shi, Ya Yan Lu

City University of Hong Kong (Hong Kong)

For analyzing cylindrical metallic nanoparticles, we present an efficient method based on expanding the electromagnetic field in one-dimensional (1D) vertical modes and solving related two-dimensional (2D) Helmholtz equations by boundary integral equations or cylindrical wave expansions. The method effectively reduces the original three-dimensional (3D) problems to 2D problems.
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14:45 : Unidirectional Light Propagation Through Two-Layer Nanostructures by Momentum Transfer via Optical Near-Fields

Makoto Naruse (1),Hirokazu Hori (2),Satoshi Ishii (3),Aurelien Drezet (4),Serge Huant (4),Morihisa Hoga (5),Yasuyuki Ohyagi (5),Tsutomu Matsumoto (6),Naoya Tate (7),Motoichi Ohtsu (8)

(1)National Institute of Information and Communications Technology (Japan) , (2)University of Yamanashi (Japan) , (3)National Institute for Materials Science (Japan) , (4)Institut Neel (France) , (5)Dai Nippon Printing Co. Ltd. (Japan) , (6)Yokohama National University (Japan) , (7)Kyushu University (Japan) , (8)The University of Tokyo (Japan)

We theoretically demonstrate direction-dependent polarization conversion efficiency, yielding unidirectional light transmission, through a two-layer nanostructure by using the angular spectrum representation of optical near-fields. The direction-dependent efficiency is characterized based on the momentum of near-field light, which is much larger than that of propagating light. The theory provides results that are consistent with electromagnetic numerical simulations. This study offers a design principle for metamaterials in realizing optical properties, such as the unidirectionality observed here.
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15:00 : An improvement over the effective index method for photonic crystal simulations

Sebastian Andreas Schulz, Anthony Park, Israel De Leon, Jeremy Upham, Robert W. Boyd

University of Ottawa (Canada)

We show that the effective index method in its current form is not appropriate for the calculation of slow light behavior in photonic crystal waveguides. It consistently underestimates the group index of devices under investigation and consequently also predicts a wrong propagation loss behavior. Instead we demonstrate that 2D simulations performed using the bulk refractive index, with appropriate renormalization of the results, yield a more accurate description of device performance for the same simulation complexity.
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15:15 : Efficient treatment and optimization of stacked, complex shaped homogeneous metasurfaces by an 4x4 S-Matrix formalism

Jan Sperrhake, Christoph Menzel, Thomas Pertsch

Friedrich-Schiller Universitat Jena (Germany)

We propose a 4x4 S-Matrix formalism for efficient design and optimization of stacked homogeneous metasurfaces (MS). Based on the S-Matrices of the individual MS layers arbitrary stacks with rotated or flipped layers even of incommensurable periods can be treated analytically. By choosing arbitrary layers as well as intermediate spacer layers the method provides additional degrees of freedom for optimizing optical systems with full polarization and dispersion control.
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15:30 : Efficient Computation of the Spontaneous Decay Rate of Arbitrarily Shaped 3D Nanosized Resonators - A Krylov Model-Order Reduction Approach

Jorn T. Zimmerling, Lei Wei, Paul Urbach, Rob Remis

Delft University of Technology (Netherlands)

We present a Krylov model-order reduction approach to efficiently compute the spontaneous decay(SD) rate of arbitrarily shaped 3D nanosized resonators. We exploit the symmetry of Maxwell's equations to efficiently construct so-called reduced-order models that approximate the SD rate of a quantum emitter embedded in a resonating nanostructure. The models allow for frequency sweeps meaning that a single model provides SD rate approximations over an entire spectral interval. Field approximations and dominant quasinormal modes can be determined at low cost.
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15:45 : Efficiency Improvement in Organic Solar Cells with Nano-structured ITO Electrodes

C. D. Wang (1),U. Hajime (2),P. Ruankham (3),T. Sagawa (2),M. J. Cryan (1)

(1)University of Bristol (United Kingdom) , (2)Kyoto University (Japan) , (3)Chiang Mai University (Thailand)

This paper uses the Finite Difference Time Domain (FDTD) method to show that the efficiency of an Organic PhotoVoltaic (OPV) cell can be significantly improved by nano-structuring the Indium Tin Oxide (ITO) electrode with a periodic arrays of holes. With air filling of the ITO structure, the number of absorbed photons is increased by 24.8 percent. Preliminary experimental results show that the power conversion efficiency (PCE) of this OPV cell can been improved by up to 14.0 percent.
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