We show how to obtain optical fields possessing superoscillatory features by superposing the evanescent tails of waves undergoing total internal reflection at a plane dielectric interface. In doing so, we essentially extend the definition of superoscillations to functions expressed as a continuum of slowly decaying exponentials, while not necessarily being bandlimited in the standard (Fourier) sense. We obtain such functions by complexifying the argument of standard bandlimited superoscillatory functions with a strictly positive spectrum. Combined with our recent method for superoscillations with arbitrary polynomial shape, the present approach offers flexibility for locally shaping the evanescent field near dielectric interfaces for applications such as particle or atom trapping. (C) 2015 Elsevier B.V. All rights reserved.
Curved singular beams for three-dimensional particle manipulation
Juanying Zhao,
Ioannis D. Chremmos,
Daohong Song,
Demetrios N. Christodoulides,
Nikolaos K. Efremidis,
Zhigang Chen
For decades, singular beams carrying angular momentum have been a topic of considerable interest. Their intriguing applications are ubiquitous in a variety of fields, ranging from optical manipulation to photon entanglement, and from microscopy and coronagraphy to free-space communications, detection of rotating black holes, and even relativistic electrons and strong-field physics. In most applications, however, singular beams travel naturally along a straight line, expanding during linear propagation or breaking up in nonlinear media. Here, we design and demonstrate diffraction-resisting singular beams that travel along arbitrary trajectories in space. These curved beams not only maintain an invariant dark "hole" in the center but also preserve their angular momentum, exhibiting combined features of optical vortex, Bessel, and Airy beams. Furthermore, we observe three-dimensional spiraling of microparticles driven by such fine-shaped dynamical beams. Our findings may open up new avenues for shaped light in various applications.
3D Printing of Reduced Graphene Oxide Nanowires
Jung Hyun Kim,
Won Suk Chang,
Daeho Kim,
Jong Ryul Yang,
Joong Tark Han,
Geon-Woong Lee,
Ji Tae Kim,
Seung Kwon Seol
Nondiffracting chirped Bessel waves in optical antiguides
Ioannis Chremmos,
Melpomeni Giamalaki
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND
VISION
32
(5)
867-876
(2015)
| Journal
Chirped Bessel waves are introduced as stable (nondiffracting) solutions of the paraxial wave equation in optical antiguides with a power-law radial variation in their index of refraction. Through numerical simulations, we investigate the propagation of apodized (finite-energy) versions of such waves, with or without vorticity, in antiguides with practical parameters. The new waves exhibit a remarkable resistance against the defocusing effect of the unstable index potentials, outperforming standard Gaussians with the same full width at half-maximum. The chirped profile persists even under conditions of eccentric launching or antiguide bending and is also capable of self-healing like standard diffraction-free beams in free space. (C) 2015 Optical Society of America
Light microscopy: an ongoing contemporary revolution
The optical microscope is one of the oldest scientific instruments that is still used in forefront research. Ernst Abbe's nineteenth century formulation of the resolution limit in microscopy let generations of scientists believe that optical studies of individual molecules and resolving subwavelength structures were not feasible. The Nobel Prize in 2014 for super-resolution fluorescence microscopy marks a clear recognition that the old beliefs have to be revisited. In this article, we present a critical overview of various recent developments in optical microscopy. In addition to the popular super-resolution fluorescence methods, we discuss the prospects of various other techniques and imaging contrasts and consider some of the fundamental and practical challenges that lie ahead.
Spectroscopic detection of single Pr3+ ions on the H-3(4)-D-1(2)
transition
Emanuel Eichhammer,
Tobias Utikal,
Stephan Goetzinger,
Vahid Sandoghdar
Rare earth ions in crystals exhibit narrow spectral features and hyperfine-split ground states with exceptionally long coherence times. These features make them ideal platforms for quantum information processing in the solid state. Recently, we reported on the first high-resolution spectroscopy of single Pr3+ ions in yttrium orthosilicate nanocrystals via the H-3(4)-P-3(0) transition at a wavelength of 488 nm. Here we show that individual praseodymium ions can also be detected on the more commonly studied H-3(4)-D-1(2) transition at 606 nm. In addition, we present the first measurements of the second-order autocorrelation function, fluorescence lifetime, and emission spectra of single ions in this system as well as their polarization dependencies on both transitions. Furthermore, we demonstrate that by a proper choice of the crystallite, one can obtain narrower spectral lines and, thus, resolve the hyperfine levels of the excited state. We expect our results to make single-ion spectroscopy accessible to a larger scientific community.
Enhancing the radiative emission rate of single molecules by a plasmonic
nanoantenna weakly coupled with a dielectric substrate
X. W. Chen,
K. G. Lee,
H. Eghlidi,
Stephan Götzinger,
Vahid Sandoghdar
Enhancing the spontaneous emission of single emitters has been an important subject in nano optics in the past decades. For this purpose, plasmonic nanoantennas have been proposed with enhancement factors typically larger than those achievable with optical cavities. However, the intrinsic ohmic losses of plasmonic structures also introduce an additional nonradiative decay channel, reducing the quantum yield. Here we report on experimental studies of a weakly coupled dielectric substrate and a plasmonic nanoantenna for enhancing the radiative decay rate of single terrylene molecules embedded in an ultrathin organic film. We systematically investigate how the refractive index of the dielectric substrate affects the lifetime and the quantum efficiency and show that the coupled structure could moderately enhance the radiative decay rate while maintaining a high quantum efficiency. (C)2015 Optical Society of America
Squeezed Light from Entangled Nonidentical Emitters via Nanophotonic
Environments
We propose a scheme in which broadband nanostructures allow for an enhanced two-photon nonlinearity that generates squeezed light from far-detuned quantum emitters via collective resonance fluorescence. To illustrate the proposal, we consider a pair of two-level emitters detuned by 400 line widths that are coupled by a plasmonic nanosphere. It is shown that the reduced fluctuations of the electromagnetic field arising from the interaction between the emitters provide a means to detect their entanglement. Due to the near-field enhancement in the proposed hybrid systems, these nonclassical effects can be encountered outside both the extremely close separations limiting the observation in free space and narrow frequency bands in high-Q cavities. Our approach permits overcoming the fundamental limitations to the generation of squeezed light from noninteracting single emitters and is more robust against phase decoherence induced by the environment.
Nano-Quantenoptik
Tobias Utikal,
Emanuel Eichhammer,
Benjamin Gmeiner,
Andreas Maser,
Daqing Wang,
Pierre Türschmann,
Hrishikesh Kelkar,
Nir Rotenberg,
Stephan Götzinger,
Vahid Sandoghdar
Nanoskopische Quantensysteme in einem Festkörper finden in der Quantenoptik zunehmend an Bedeutung. Deren Integrierbarkeit in photonische Nanostrukturen machen sie zu aussichtsreichen Kandidaten zur Realisierung von zukünftigen Quantennetzwerken. Als Grundbaustein konnte kürzlich die effiziente Kopplung von einzelnen Molekülen an photonische Wellenleiterstrukturen gezeigt werden. Mit neuartigen Mikroresonatoren ist es möglich, die optische Kopplung zwischen einzelnen Quantensystemen zu untersuchen. Unterdessen kommen sogar einzelne Ionen in einem Kristall in der Nano-Quantenoptik zum Einsatz.
Sensing Nanoparticles with a Cantilever-Based Scannable Optical Cavity
of Low Finesse and Sub-lambda(3) Volume
Hrishikesh Kelkar,
Daqing Wang,
Diego Martin-Cano,
Bjoern Hoffmann,
Silke Christiansen,
Stephan Goetzinger,
Vahid Sandoghdar
We report on the realization of an open plane-concave Fabry-Perot resonator with a mode volume below lambda(3) at optical frequencies. We discuss some of the less-common features of this microcavity regime and show that the ultrasmall mode volume allows us to detect cavity resonance shifts induced by single nanoparticles even at quality factors as low as 100. Being based on low-reflectivity micromirrors fabricated on a silicon cantilever, our experimental arrangement provides broadband operation, tunability of the cavity resonance, and lateral scanning. These features are interesting for a range of applications including biochemical sensing, modification of photophysics, and optomechanical studies.
Superoscillations with arbitrary polynomial shape
Ioannis Chremmos,
George Fikioris
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
48
(26)
265204
(2015)
| Journal
We present a method for constructing superoscillatory functions the superoscillatory part of which approximates a given polynomial with arbitrarily small error in a fixed interval. These functions are obtained as the product of the polynomial with a sufficiently flat, bandlimited envelope function whose Fourier transform has at least N - 1 continuous derivatives and an Nth derivative of bounded variation, N being the order of the polynomial. Polynomials of arbitrarily high order can be approximated if the Fourier transform of the envelope is smooth, i.e. a bump function.
When excitons and plasmons meet: Emerging function through synthesis and assembly
Jennifer A. Hollingsworth,
Han Htoon,
Andrei Piryatinski,
Stephan Goetzinger,
Vahid Sandoghdar
To meet the challenge of precise nanoscale arrangement of emitter and plasmonic nanoantenna, synthesis and assembly methods continue to evolve in accuracy and reproducibility. This article reviews some of the many strategies being developed for "soft" chemical approaches to precision integration and assembly. We also discuss investigations of the Purcell effect, emission directionality control, and near-unity collection efficiency of photons, emitter emitter coupling, and higher-order emission processes that have been most deeply explored using individual-emitter- (or several-emitter-) nanoantenna pairs fabricated using traditional lithographic methods or dynamically and controllably manipulated using scanning probe methods. Importantly, these results along with theoretical analyses inspire and motivate continued advancements in large-scale synthesis and assembly. We emphasize assembly approaches that have been used to create nanosemiconductor-nanometal hybrids and, in particular, those that have afforded specific plasmonic effects on excitonic properties. We also review direct-synthesis and chemical-linker strategies to creating discrete, though less spatially extended, semiconductor-metal interactions.
Modified and controllable dispersion interaction in a one-dimensional
waveguide geometry
Dispersion interactions such as the van derWaals interaction between atoms or molecules derive from quantum fluctuations of the electromagnetic field and can be understood as the exchange of virtual photons between the interacting partners. Any modification of the environment in which those photons propagate will thus invariably lead to an alteration of the van der Waals interaction. Here we show how the two-body dispersion interaction inside a cylindrical waveguide can be made to decay asymptotically exponentially and how this effect sensitively depends on the material properties and the length scales of the problem, eventually leading to the possibility of controllable interactions. Further, we discuss the possibility to detect the retarded van der Waals interaction by resonant enhancement of the interaction between Rydberg atoms in the light of long-range potentials due to guided modes.
Specially shaped Bessel-like self-accelerating beams along predesigned
trajectories
Juanying Zhao,
I. D. Chremmos,
Ze Zhang,
Yi Hu,
Daohong Song,
Peng Zhang,
N. K. Efremidis,
Zhigang Chen
Over the past several years, spatially shaped self-accelerating beams along different trajectories have been studied extensively. Due to their useful properties such as resistance to diffraction, self-healing, and self-bending even in free space, these beams have attracted great attention with many proposed applications. Interestingly, some of these beams could be designed with controllable spatial profiles and thus propagate along various desired trajectories such as parabolic, snake-like, hyperbolic, hyperbolic secant, three-dimensional spiraling, and even self-propelling trajectories. Experimentally, such beams are realized typically by using a spatial light modulator so as to imprint a desired phase distribution on a Gaussian-like input wave front propagating under paraxial or nonparaxial conditions. In this paper, we provide a brief overview of our recent work on specially shaped self-accelerating beams, including Bessel-like, breathing Bessel-like, and vortex Bessel-like beams. In addition, we propose and demonstrate a new type of dynamical Bessel-like beams that can exhibit not only self-accelerating but also self-propelling during propagation. Both theoretical and experimental results are presented along with a brief discussion of potential applications.
Effective medium theory for two-dimensional non-magnetic metamaterial
lattices up to quadrupole expansions
Ioannis Chremmos,
Efthymios Kallos,
Melpomeni Giamalaki,
Vassilios Yannopapas,
Emmanuel Paspalakis
We present a formulation for deriving effective medium properties of infinitely periodic two-dimensional metamaterial lattice structures beyond the conventional static and quasi-static limits. We utilize the multipole expansions, where the polarization currents associated with the supported Bloch modes are expressed via the electric dipole, magnetic dipole, and electric quadrupole moments per unit length. We then propose a method to calculate the Bloch modes based on the lattice geometry and individual unit element structure. The results revert to well-known formulas in the traditional quasistatic limit and are useful for the homogenization of nanorod-type metamaterials which are frequently used in optical applications.
Fabrication and characterization of plasmonic nanocone antennas for
strong spontaneous emission enhancement
Bjoern Hoffmann,
Simon Vassant,
Xue-Wen Chen,
Stephan Goetzinger,
Vahid Sandoghdar,
Silke Christiansen
Plasmonic antennas are attractive nanostructures for a large variety of studies ranging from fundamental aspects of light-matter interactions at the nanoscale to industry-relevant applications such as ultrasensitive sensing, enhanced absorption in solar cells or solar fuel generation. A particularly interesting feature of these antennas is that they can enhance the fluorescence properties of emitters. Theoretical calculations have shown that nanocone antennas provide ideal results, but a high degree of manufacturing precision and control is needed to reach optimal performance. In this study, we report on the fabrication of nanocones with base diameters and heights in the range of 100 nm with variable aspect ratios using focused ion beam milling of sputtered nano-crystalline gold layers. The controlled fabrication process allows us to obtain cones with tailored plasmon resonances. The measured plasmon spectra show very good agreement with finite-difference time-domain calculations. Theoretical investigations predict that these nanocones can enhance the spontaneous emission rate of a quantum emitter by several hundred times while keeping its quantum efficiency above 60%.
Contact
Nano-Optics Division Prof. Vahid Sandoghdar
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
