86 research outputs found
A fundamental relation between phase and group velocity, and application to the failure of perfectly matched layers in backward-wave structures
http://link.aps.org/doi/10.1103/PhysRevE.79.065601We demonstrate that the ratio of group to phase velocity has a simple relationship to the orientation of the electromagnetic field. In nondispersive materials, opposite group and phase velocity corresponds to fields that are mostly oriented in the propagation direction. More generally, this relationship (including the case of dispersive and negative-index materials) offers a perspective on the phenomena of backward waves and left-handed media. As an application of this relationship, we demonstrate and explain an irrecoverable failure of perfectly matched layer absorbing boundaries in computer simulations for constant cross-section waveguides with backward-wave modes and suggest an alternative in the form of adiabatic isotropic absorbers
Photon Management in Two-Dimensional Disordered Media
Elaborating reliable and versatile strategies for efficient light coupling
between free space and thin films is of crucial importance for new technologies
in energy efficiency. Nanostructured materials have opened unprecedented
opportunities for light management, notably in thin-film solar cells. Efficient
coherent light trapping has been accomplished through the careful design of
plasmonic nanoparticles and gratings, resonant dielectric particles and
photonic crystals. Alternative approaches have used randomly-textured surfaces
as strong light diffusers to benefit from their broadband and wide-angle
properties. Here, we propose a new strategy for photon management in thin films
that combines both advantages of an efficient trapping due to coherent optical
effects and broadband/wide-angle properties due to disorder. Our approach
consists in the excitation of electromagnetic modes formed by multiple light
scattering and wave interference in two-dimensional random media. We show, by
numerical calculations, that the spectral and angular responses of thin films
containing disordered photonic patterns are intimately related to the in-plane
light transport process and can be tuned through structural correlations. Our
findings, which are applicable to all waves, are particularly suited for
improving the absorption efficiency of thin-film solar cells and can provide a
novel approach for high-extraction efficiency light-emitting diodes
Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes
Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared (NIR) dye (Alexa Fluor 790). Extensive fluorescence enhancement of âŒ2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield (7.8 fold for Alexa Fluor 488, quantum efficiency (Qy) = 0.92). A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement (MIFE) substrates for dyes in the NIR âbiological windowâ as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications
Femtogram Doubly Clamped Nanomechanical Resonators Embedded in a High-Q Two-Dimensional Photonic Crystal Nanocavity
We demonstrate a new optomechanical device system which allows highly
efficient transduction of femtogram nanobeam resonators. Doubly clamped
nanomechanical resonators with mass as small as 25 fg are embedded in a
high-finesse two-dimensional photonic crystal nanocavity. Optical transduction
of the fundamental flexural mode around 1 GHz was performed at room temperature
and ambient conditions, with an observed displacement sensitivity of 0.94
fm/Hz^(1/2). Comparison of measurements from symmetric and asymmetric
double-beam devices reveals hybridization of the mechanical modes where the
structural symmetry is shown to be the key to obtain a high mechanical quality
factor. Our novel configuration opens the way for a new category of
"NEMS-in-cavity" devices based on optomechanical interaction at the nanoscale.Comment: Nano Lett. 201
Resonances On-Demand for Plasmonic Nano-Particles
A method for designing plasmonic particles with desired resonance spectra is
presented. The method is based on repetitive perturbations of an initial
particle shape while calculating the eigenvalues of the various quasistatic
resonances. The method is rigorously proved, assuring a solution exists for any
required spectral resonance location. Resonances spanning the visible and the
near-infrared regimes, as designed by our method, are verified using
finite-difference time-domain simulations. A novel family of particles with
collocated dipole-quadrupole resonances is designed, demonstrating the unique
power of the method. Such on-demand engineering enables strict realization of
nano-antennas and metamaterials for various applications requiring specific
spectral functions
Outlook for inverse design in nanophotonics
Recent advancements in computational inverse design have begun to reshape the
landscape of structures and techniques available to nanophotonics. Here, we
outline a cross section of key developments at the intersection of these two
fields: moving from a recap of foundational results to motivation of emerging
applications in nonlinear, topological, near-field and on-chip optics.Comment: 13 pages, 6 figure
Lateral forces on circularly polarizable particles near a surface
Optical forces allow manipulation of small particles and control of nanophotonic structures
with light beams. While some techniques rely on structured light to move particles using field intensity gradients, acting locally, other optical forces can push particles on a wide area of
illumination but only in the direction of light propagation. Here we show that spin orbit
coupling, when the spin of the incident circularly polarized light is converted into lateral
electromagnetic momentum, leads to a lateral optical force acting on particles placed above a substrate, associated with a recoil mechanical force. This counterintuitive force acts in a direction in which the illumination has neither a field gradient nor propagation. The force direction is switchable with the polarization of uniform, plane wave illumination, and its magnitude is comparable to other optical forces.This work has been supported, in part, by EPSRC (UK). A.V.Z. acknowledges support from the Royal Society and the Wolfson Foundation. N.E. acknowledges partial support from the US Office of Naval Research Multidisciplinary University Research Initiative Grant No. N00014-10-1-0942. A.M. acknowledges support from the Spanish Government (contract Nos TEC2011-28664-C02-02 and TEC2014-51902-C2-1-R).RodrĂguez Fortuño, FJ.; Engheta, N.; MartĂnez Abietar, AJ.; Zayats, AV. (2015). Lateral forces on circularly polarizable particles near a surface. Nature Communications. 6(8799):1-7. https://doi.org/10.1038/ncomms9799S1768799Novotny, L. & Hecht, B. Principles of Nano-Optics Cambridge University Press (2011).Jackson, J. D. Classical Electrodynamics Wiley (1998).Ashkin, A. & Dziedzic, J. M. Optical levitation by radiation pressure. Appl. Phys. Lett. 19, 283 (1971).Ashkin, A. Acceleration and trapping of particles by radiation pressure. Phys. Rev. Lett. 24, 156â159 (1970).Omori, R., Kobayashi, T. & Suzuki, A. Observation of a single-beam gradient-force optical trap for dielectric particles in air. Opt. Lett. 22, 816â818 (1997).Ashkin, A., Dziedzic, J. M., Bjorkholm, J. E. & Chu, S. Observation of a single-beam gradient force optical trap for dielectric particles. Opt. Lett. 11, 288â290 (1986).Ashkin, A., Dziedzic, J. M. & Yamane, T. Optical trapping and manipulation of single cells using infrared laser beams. Nature 330, 769â771 (1987).Bagnato, V. S. et al. Continuous stopping and trapping of neutral atoms. Phys. Rev. Lett. 58, 2194â2197 (1987).Phillips, W. D. Nobel lecture: laser cooling and trapping of neutral atoms. Rev. Mod. Phys. 70, 721â741 (1998).Wang, M. M. et al. Microfluidic sorting of mammalian cells by optical force switching. Nat. Biotechnol. 23, 83â87 (2005).Dholakia, K. & ÄiĆŸmĂĄr, T. Shaping the future of manipulation. Nat. Photon. 5, 335â342 (2011).Zhao, R., Zhou, J., Koschny, T., Economou, E. N. & Soukoulis, C. M. Repulsive Casimir force in chiral metamaterials. Phys. Rev. Lett. 103, 103602 (2009).Leonhardt, U. & Philbin, T. G. Quantum levitation by left-handed metamaterials. New J. Phys. 9, 254â254 (2007).Ginis, V., Tassin, P., Soukoulis, C. M. & Veretennicoff, I. Enhancing optical gradient forces with metamaterials. Phys. Rev. Lett. 110, 057401 (2013).RodrĂguez-Fortuño, F. J., Vakil, A. & Engheta, N. Electric levitation using É-near-zero metamaterials. Phys. Rev. Lett. 112, 033902 (2014).Grier, D. G. A revolution in optical manipulation. Nature 424, 810â816 (2003).Yang, X., Liu, Y., Oulton, R. F., Yin, X. & Zhang, X. Optical forces in hybrid plasmonic waveguides. Nano Lett. 11, 321â328 (2011).Oskooi, A., Favuzzi, P. A., Kawakami, Y. & Noda, S. Tailoring repulsive optical forces in nanophotonic waveguides. Opt. Lett. 36, 4638 (2011).Shalin, A. S., Ginzburg, P., Belov, P. A., Kivshar, Y. S. & Zayats, A. V. Nano-opto-mechanical effects in plasmonic waveguides. Laser Photon. Rev. 8, 131â136 (2014).Abajo, F. J. G., de, Brixner, T. & Pfeiffer, W. Nanoscale force manipulation in the vicinity of a metal nanostructure. J. Phys. B At. Mol. Opt. Phys. 40, S249âS258 (2007).Juan, M. L., Righini, M. & Quidant, R. Plasmon nano-optical tweezers. Nat. Photon. 5, 349â356 (2011).Beth, R. Mechanical detection and measurement of the angular momentum of light. Phys. Rev. 50, 115â125 (1936).Padgett, M. & Bowman, R. Tweezers with a twist. Nat. Photon. 5, 343â348 (2011).Liu, M., Zentgraf, T., Liu, Y., Bartal, G. & Zhang, X. Light-driven nanoscale plasmonic motors. Nat. Nanotechnol. 5, 570â573 (2010).Marston, P. L. & Crichton, J. H. Radiation torque on a sphere caused by a circularly-polarized electromagnetic wave. Phys. Rev. A 30, 2508â2516 (1984).Sokolov, I. V. The angular momentum of an electromagnetic wave, the Sadovski effect, and the generation of magnetic fields in a plasma. Phys. Uspekhi 34, 925â932 (1991).Wang, S. B. & Chan, C. T. Lateral optical force on chiral particles near a surface. Nat. Commun. 5, 3307 (2014).Hayat, A., MĂŒller, J. P. B. & Capasso, F. Lateral chirality-sorting optical forces. doi:10.1073/pnas.1516704112 (2015).Bliokh, K. Y., Bekshaev, A. Y. & Nori, F. Extraordinary momentum and spin in evanescent waves. Nat. Commun. 5, 3300 (2014).Antognozzi, M. et al. Direct measurement of the extraordinary optical momentum using a nano-cantilever. Preprint at http://arxiv.org/abs/1506.04248 (2015).Bekshaev, A. Y., Bliokh, K. Y. & Nori, F. Transverse spin and momentum in two-wave interference. Phys. Rev. X 5, 011039 (2015).Bliokh, K. Y., Smirnova, D. & Nori, F. Quantum spin Hall effect of light. Science 348, 1448â1451 (2015).RodrĂguez-Fortuño, F. J. et al. Near-field interference for the unidirectional excitation of electromagnetic guided modes. Science 340, 328â330 (2013).Kapitanova, P. V. et al. Photonic spin Hall effect in hyperbolic metamaterials for polarization-controlled routing of subwavelength modes. Nat. Commun. 5, 3226 (2014).Bliokh, K. Y., RodrĂguez-Fortuño, F. J., Nori, F. & Zayats, A. V. Spin-orbit interactions of light. Preprint at http://arxiv.org/abs/1505.02864 (2015).OâConnor, D., Ginzburg, P., RodrĂguez-Fortuño, F. J., Wurtz, G. A. & Zayats, A. V. Spinâorbit coupling in surface plasmon scattering by nanostructures. Nat. Commun. 5, 5327 (2014).Neugebauer, M., Bauer, T., Banzer, P. & Leuchs, G. Polarization tailored light driven directional optical nanobeacon. Nano Lett. 14, 2546â2551 (2014).Mueller, J. P. B. & Capasso, F. Asymmetric surface plasmon polariton emission by a dipole emitter near a metal surface. Phys. Rev. B 88, 121410 (2013).Xi, Z. et al. Controllable directive radiation of a circularly polarized dipole above planar metal surface. Opt. Express 21, 30327 (2013).Carbonell, J. et al. Directive excitation of guided electromagnetic waves through polarization control. Phys. Rev. B 89, 155121 (2014).Young, A. B. et al. Polarization engineering in photonic crystal waveguides for spin-photon entanglers. Phys. Rev. Lett. 115, 153901 (2015).Mitsch, R., Sayrin, C., Albrecht, B., Schneeweiss, P. & Rauschenbeutel, A. Quantum state-controlled directional spontaneous emission of photons into a nanophotonic waveguide. Nat. Commun. 5, 5713 (2014).Le Kien, F. & Rauschenbeutel, A. Anisotropy in scattering of light from an atom into the guided modes of a nanofiber. Phys. Rev. A 90, 023805 (2014).Luxmoore, I. J. et al. Interfacing spins in an InGaAs quantum dot to a semiconductor waveguide circuit using emitted photons. Phys. Rev. Lett. 110, 037402 (2013).RodrĂguez-Fortuño, F. J. et al. Universal method for the synthesis of arbitrary polarization states radiated by a nanoantenna. Laser Photon. Rev. 8, L27âL31 (2014).RodrĂguez-Fortuño, F. J., Barber-Sanz, I., Puerto, D., Griol, A. & Martinez, A. Resolving light handedness with an on-chip silicon microdisk. ACS Photon. 1, 762â767 (2014).Petersen, J., Volz, J. & Rauschenbeutel, A. Chiral nanophotonic waveguide interface based on spin-orbit interaction of light. Science 346, 67â71 (2014).Xi, Z., Lu, Y., Yu, W., Wang, P. & Ming, H. Unidirectional surface plasmon launcher: rotating dipole mimicked by optical antennas. J. Opt. 16, 105002 (2014).Frisch, R. Experimental demonstration of Einsteinâs radiation recoil. Zeitschrift fĂŒr Phys. 86, 42â45 (1933).Wylie, J. M. & Sipe, J. E. Quantum electrodynamics near an interface. II. Phys. Rev. A 32, 2030â2043 (1985).Fichet, M., Schuller, F., Bloch, D. & Ducloy, M. van der Waals interactions between excited-state atoms and dispersive dielectric surfaces. Phys. Rev. A 51, 1553â1564 (1995).Failache, H., Saltiel, S., Fichet, M., Bloch, D. & Ducloy, M. Resonant van der Waals repulsion between excited Cs atoms and sapphire surface. Phys. Rev. Lett. 83, 5467â5470 (1999).Gordon, J. P. & Ashkin, A. Motion of atoms in a radiation trap. Phys. Rev. A 21, 1606â1617 (1980).Chaumet, P. C. & Nieto-Vesperinas, M. Time-averaged total force on a dipolar sphere in an electromagnetic field. Opt. Lett. 25, 1065â1067 (2000).Ishimaru, A. Electromagnetic Wave Propagation, Radiation, and Scattering Prentice Hall (1990).Söllner, I., Mahmoodian, S., Javadi, A. & Lodahl, P. A chiral spin-photon interface for scalable on-chip quantum-information processing. Preprint at http://arxiv.org/abs/1406.4295 (2014).Rotenberg, N. et al. Magnetic and electric response of single subwavelength holes. Phys. Rev. B Condens. Matter Mater. Phys. 88, 241408 (2013).Sukhov, S., Kajorndejnukul, V. & Dogariu, A. Dynamic Consequences of Optical Spin-Orbit Interaction. Preprint at http://arxiv.org/abs/1504.01766 (2015).Scheel, S., Buhmann, S. Y., Clausen, C. & Schneeweiss, P. Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber. Preprint at http://arxiv.org/abs/1505.01275 (2015).RodrĂguez-Fortuño, F. J., Engheta, N., MartĂnez, A. & Zayats, A. V. Lateral Forces Acting on Particles Near a Surface Under Circularly Polarized Illumination. in 5th Inte rnational Topical Meeting on Nanophotonics and Metamaterials (Nanometa) (2-914771-91-6, Seefeld, Austria 2015).Bochenkov, V. et al. Applications of plasmonics: general discussion. Faraday Discuss. 178, 435â466 (2015).Dogariu, A. & Schwartz, C. Conservation of angular momentum of light in single scattering. Opt. Express 14, 8425â8433 (2006).Haefner, D., Sukhov, S. & Dogariu, A. Spin hall effect of light in spherical geometry. Phys. Rev. Lett. 102, 123903 (2009).Bliokh, K. Y. et al. Spin-to-orbit angular momentum conversion in focusing, scattering, and imaging systems. Opt. Express 19, 26132â26149 (2011)
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