Abstracts of Publications
This page features a more exhaustive list of publications including their abstracts.
Refereed journal articles
Note: This list also includes recent preprints.
- Electron beam lithography for high density meta fish scale operational at optical frequency
Y. Chen, A. S. Schwanecke, V. A. Fedotov, V. V. Khardikov, P. L. Mladyonov, S. L. Prosvirnin, A. V. Rogacheva, N. I. Zheludev, and E. Huq
Microelectron. Eng. 86 (4-6), 1081–1084 (2009)<pdf> <doi:10.1016/j.mee.2008.11.094>
[presented at International Conference on Micro and Nano Engineering 2008 (MNE)]This paper reports our recent progress in electron beam lithography for high resolution and highly dense metallic structures such as fish scale on both silicon and quartz. To observe photonic property in optical frequency, the pitch of 500 nm with both linewidth and gap of 50 nm gap in Al is demanded. For reliable lift-off process, adequate undercut in bilayer layer of resists is essential. Three different bilayers, PMMA/LOR, PMMA/copolymer and PMMA/PMMA (with different molecular weights) were compared and the most suitable bilayer was found to be the PMMA/PMMA with a difference in molecular weight between the top and bottom layer. With such a bilayer stack, dense fish scale pattern with minimum linewidth of 50 nm in Al were fabricated for both transparent and reflective configurations. Astonishing optical properties such as magnetic wall and asymmetric propagating waves through the chiral fish scale were observed. - Nanostructured metal film with asymmetric optical transmission
A. S. Schwanecke, V. A. Fedotov, V. V. Khardikov, S. L. Prosvirnin, Y. Chen, and N. I. Zheludev
Nano Lett. 8 (9), 2940–2943 (2008)<pdf> <doi:10.1021/nl801794d>We demonstrate for the first time a nanostructured planar photonic metamaterial transmitting light differently in forward and backward directions. - Enhanced microwave transmission through quasicrystal hole arrays
N. Papasimakis, V. A. Fedotov, A. S. Schwanecke, N. I. Zheludev, and F. J. Garcia de Abajo
Appl. Phys. Lett. 91 (8), 081503 (2007)The authors report on the observation of enhanced microwave transmission through quasiperiodic hole arrays in metal films. The fraction of transmitted light reaches 50 % in a self-standing metal film and approaches 90% when the film is sandwiched between thin dielectric slabs, while the holes occupy only 10 % of the sample area. The maximum transmission exhibits a Breit-Wigner resonance behavior, accompanied by zero phase change and rendering the film almost invisible over a wide frequency range. The extraordinary transmission phenomenon is interpreted in terms of resonances in the self-consistent interaction between holes, which are represented by effective electric and magnetic dipoles. - Asymmetric transmission of light and enantiomerically sensitive plasmon resonance in planar chiral nanostructures
V. A. Fedotov, A. S. Schwanecke, N. I. Zheludev, V. V. Khardikov, and S. L. Prosvirnin
Nano Lett. 7 (7), 1996-1999 (2007)<pdf> <doi:10.1021/nl0707961>We show that in the visible to near-IR part of the spectrum, normal incidence transmission of circularly polarized light through a nanostructured anisotropic planar chiral metamaterial is asymmetric in the opposite directions. The new effect is fundamentally different from the conventional gyrotropy of bulk chiral media and the Faraday effect. It has a resonance nature associated with a new type of excitation in the metal nanostructure: the enantiomerically sensitive plasmon. - Giant optical gyrotropy due to electromagnetic coupling
E. Plum, V. A. Fedotov, A. S. Schwanecke, Y. Chen, and N. I. Zheludev
Appl. Phys. Lett. 90 (22), 223113 (2007)<pdf> <doi:10.1063/1.2745203>
[additionally part of the Virtual Journal of Nanoscale Science & Technology 15(23) (2006), link]The authors demonstrate a chiral photonic metamaterial with chirality provided by electromagnetic coupling between mutually twisted unconnected layers. In the visible and near-IR spectral ranges, the material exhibits polarization rotatory power of up to 2500 °/mm and shows relatively low losses and negligible circular dichroism, making it a promising candidate for the development of chiral negative index media. - Optical magnetic mirrors
A. S. Schwanecke, V. A. Fedotov, V. V. Khardikov, S. L. Prosvirnin, Y. Chen, and N. I. Zheludev
J. Opt. A 9 (1), L1-L2 (2007)<pdf> <doi:10.1088/1464-4258/9/1/L01>We report the first demonstration of an optical magnetic mirror achieved by nanostructuring a metal surface. It reverses the magnetic field of an incident wave upon reflection, acting as an 'optical frequency superconductor'. - Giant gyrotropy due to electromagnetic-field coupling in a bilayered chiral structure
A. V. Rogacheva, V. A. Fedotov, A. S. Schwanecke, and N. I. Zheludev
Phys. Rev. Lett. 97 (17), 177401 (2006)<pdf> <doi:10.1103/PhysRevLett.97.177401> <arXiv:physics/0604105>
[additionally part of the Virtual Journal of Nanoscale Science & Technology 14(19) (2006), link]We report experimental evidence that electromagnetic coupling between physically separated planar metal patterns located in parallel planes provides for extremely strong polarization rotatory power if one pattern is twisted with respect to the other, creating a chiral object. In terms of a rotary power per sample thickness equal to one wavelength, the bilayered structure rotates 5 orders of magnitude stronger than a gyrotropic crystal of quartz in the visible spectrum. - Multiplicative measure of planar chirality for 2D meta-materials
S. P. Boruhovich, S. L. Prosvirnin, A. S. Schwanecke, and N. I. Zheludev
Proc. Eur. Microw. Assoc. 2 (1), 89-93 (2006)<pdf>
[part of special issue: 'Microwave Metamaterials']We describe a new efficient continuous geometrical measure of two-dimensional chirality for photonic and microwave planar meta-materials. Its properties include integrability, scale-independence, boundedness to a well defined interval and flexibility as well as applicability towards an extensive number of chiral geometries. The chirality measures of various arrangements of standard chiral and achiral template structures are evaluated and a method for the characterization of (infinite) periodic structures is suggested. - Gallium/Aluminium nano-composite material for nonlinear optics and nonlinear plasmonics
K. F. MacDonald, A. V. Krasavin, A. S. Schwanecke, and N. I. Zheludev
Appl. Phys. Lett. 89 (3), 031118 (2006)<pdf> <doi:10.1063/1.2234276>
[additionally part of the Virtual Journal of Nanoscale Science & Technology 14(6) (2006), link]We report on a new type of composite metallic structure for nonlinear optics and nonlinear plasmonics, created by grain boundary penetration of gallium into an aluminum film. These composite films form mirrorlike interfaces with silica and show an exceptionally broadband phase-transition-based nonlinear response to optical excitation. - Broken enantiomeric symmetry for electromagnetic waves interacting with planar chiral nanostructures
M. Reichelt, S. W. Koch, A. V. Krasavin, J. V. Moloney, A. S. Schwanecke, T. Stroucken, E. M. Wright, and N. I. Zheludev
Appl. Phys. B 84 (1-2), 97-101 (2006)<pdf> <doi:10.1007/s00340-006-2211-4>
[part of special issue: 'Optics on the Nanoscale: Principles, Instrumentation and Applications']Simulations of Maxwell's equations for electromagnetic waves interacting with planar chiral structures are shown to depend on the polarization state of the exciting light field. These results illustrate generic features of light interaction with planar chiral structures and imply broken enantiomeric symmetry for excitation with circularly polarized light. - Extraordinary properties of light transmission through a small chiral hole in a metallic screen
A. V. Krasavin, A. S. Schwanecke, and N. I. Zheludev
J. Opt. A 8 (4), S98-S105 (2006)<pdf> <doi:10.1088/1464-4258/8/4/S08>
[part of 'Special Issue on Fundamental Aspects of Nanophotonics']The true three-dimensional finite element numerical solution of Maxwell's equations shows that the propagation of light through a thin flat free-standing metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The intensity map and polarization state of light are dramatically changed depending on the mutual direction of the hole's twist and the incident light's wave polarization handedness. We also observed a strong concentration of the transmitted field at the centre of the chiral hole when light in the object plane rotates against the twist of the investigated gammadion type structure. - Polarization conversion and "focusing" of light propagating through a small chiral hole in a metallic screen
A. V. Krasavin, A. S. Schwanecke, N. I. Zheludev, M. Reichelt, T. Stroucken, S. W. Koch, and E. M. Wright
Appl. Phys. Lett. 86 (20), 201105 (2005)Propagation of light through a thin flat metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The transmitted light accrues a component with handedness opposite to the incident wave. The efficiency of polarization conversion depends on the mutual direction of the hole's twist and the incident light's wave polarization handedness and peaks at a wavelength close to the hole overall size. We also observed a strong transmitted field concentration at the center of the chiral hole when the handedness of the chiral hole and the wave's polarization state are the same. - Nanoimprint lithography for planar chiral photonic meta-materials
Y. Chen, J. Tao, X. Zhao, Z. Cui, A. S. Schwanecke, and N. I. Zheludev
Microelectron. Eng. 78-79, 612-617 (2005)<pdf> <doi:10.1016/j.mee.2004.12.078>
[presented at International Conference on Micro and Nano Engineering 2004 (MNE)]Room temperature nanoimprint lithography has successfully been applied to the fabrication of planar chiral photonic meta-materials. For dielectric chiral structures a single layer of thick HSQ was used while for metallic chiral structures a bi-layer technique using PMMA/hydrogen silsequioxane (HSQ) was applied. The polarization conversion capabilities of planar chiral structures imprinted in dielectric materials have experimentally been observed. This indicates that the developed processes in this work have the prospect of manufacturing planar photonic meta media in high volume at low cost. - Broken time reversal of light interaction with planar chiral nanostructures
A. S. Schwanecke, A. Krasavin, D. M. Bagnall, A. Potts, A. V. Zayats, and N. I. Zheludev
Phys. Rev. Lett. 91 (24), 247404 (2003)<pdf> <doi:10.1103/PhysRevLett.91.247404> <arXiv:cond-mat/0307056>
[additionally part of the Virtual Journal of Nanoscale Science & Technology 8(5) (2003), link]
[press article in LaserFocusWorld (Feb 2004), link]We report unambiguous experimental evidence of broken time-reversal symmetry for the interaction of light with an artificial nonmagnetic material. Polarized color images of planar chiral gold-on-silicon nanostructures consisting of arrays of gammadions show intriguing and unusual symmetry: structures, which are geometrically mirror images, lose their mirror symmetry in polarized light. The symmetry of images can be described only in terms of antisymmetry (black-and-white symmetry) appropriate to a time-odd process. The effect results from a transverse chiral nonlocal electromagnetic response of the structure and has some striking resemblance with the expected features of light scattering on anyon matter. - Noninvasive myocardial contractility monitoring with seismocardiography during simulated dives
A. Koch, P. McCormack, A. Schwanecke, P. Schnoor, C. Buslaps, K. Tetzlaff, and H. Rieckert
Undersea Hyperb. Med. 30 (1), 19-27 (2003)<pdf>Objective: To determine if bradycardia during hyperbaric exposure is accompanied by a negative influence on myocardial contractility. Methods: Accelerometer-based registration of myocardial compression waves with Seismocardiography (SCG) for noninvasive contractility monitoring. Comparative pulmonary artery (PA) catheter study (9 ICU-patients, mean = 67ys) with ejection-fraction (EF) equivalent versus sum of g-values of contraction phase in SCG, and Preload (leg-positioning). Test with monitoring of changes in Contractility Index (ContrI) derived from the SCG-power spectrum (contraction phases, area under curve). Hyperbaric chamber study (0.6MPa dive-simulation) in 14 healthy divers. Quantitative SCG(ContrI, power spectra) and ECG-recording. Results: Correlation between changes in EF (PA catheter) and in the g-values (SCG) was r(SP)=0.87 (p < 0.0001). ContrI increased in the leg-positioning test parallel to preload increase, heart rate remained stable. During hyperbaric exposure (0.6MPa) heart rate decrease was highly significant (68 to 58 min(-1); p < 0.001), Contrl and power spectra remained nearly unchanged, SCG registration was noise free. Conclusions: Hyperoxic bradycardia during simulated dives is not accompanied by impaired contractility measured with SCG, which is concordant to findings with invasive methods in current literature. SCG is suitable for noninvasive and stress free contractility monitoring and patient surveillance in a hyperbaric chamber.
Other entries
- Novel phenomena in planar and layered, photonic and microwave metamaterials
Alexander S. Schwanecke
Thesis for the degree of Doctor of Philosophy (PhD), University of Southampton, UK (2009) (viva pending)
<link>(Submitted / awaiting viva.) - Application of planar chirality to nanophotonics, astronomy and image analysis
A. S. Schwanecke
Thesis for the degree of Master of Philosophy (MPhil), School of Physics and Astronomy, University of Southampton (2004)
<link>The concept of geometrical chirality has been improved introducing a unit of planar chirality and dedicated normalisation factors which facilitate the analysis of various complex chiral objects. On the basis of these improvements a highly efficient Monte Carlo computer algorithm for calculation of the planar chirality measure has been developed.
I have investigated the planar chirality of characteristic planar chiral objects such as triangles, gammadions and round gammadions and established the configurations for various parameter fields for which their chirality is maximised.
For the first time I have explored the aggregated chirality of ensembles of 2, 3 and more planar chiral structures including their regular grids. The chirality of ensembles is found to be a strong function of the mutual positions of the individual elements to an extent that the ensemble chirality can change its sign. It has furthermore been established that the chirality of regular square grids may be nonzero when constituting of achiral objects.
For the first time I have investigated the chirality and rotational and mirror symmetries of diffraction field patterns and microscopic images created by different enantiomeric forms of various planar chiral structures. I have established that the chirality of the diffraction patterns is inherited from the chiral object itself while the rotational symmetries are lower than in the underlying design.
For the first time a geometrical chirality measure has been applied to quantify the geometry of star distributions in 113 nearby galaxies. A quantitative parameter has been suggested for classification of galaxies which is based on the chirality measure. - Numerische Integration: Adaptive Verfahren und Extrapolation
A. Schwanecke
Seminar über numerische Mathematik für Studierende der Oberstufenlehrämter und Proseminar für Naturwissenschaftler (Plön, Germany; 2001)
<pdf>Bei näherungsweisen Integrationen war es uns bisher nur möglich, anhand von einer immer genauer werdenden äquidistanten Maschenstruktur die Genauigkeit zu erhöhen. Dabei wurde aber immer außer acht gelassen, daß eine Funktion sich in unterschiedlichen Bereichen unterschiedlich stark ändert. Ziel dieses Vortrags ist es, das Prinzip der sogenannten adaptiven Verfahren und schließlich auch der Extrapolation vorzustellen. Hierfür werden die Grundlagen und Bezeichnungen der numerischen Integration wiederholt, um dann hieraus das sog. adaptive Simpson-Verfahren herzuleiten. Zur Erläuterung werden Bedeutung und Wirkung anhand von Grafiken und Programmierbeispiele aufgeführt. Abschließend wird das Romberg-Verfahren kurz erläutert.