Riccardo Sapienza

Subwavelength, high–refractive index semiconductor nanostructures support optical resonances that endow them with valuable antenna functions. Control over the intrinsic properties, including their complex refractive index, size, and geometry, has been used to manipulate fundamental light absorption, scattering, and emission processes in nanostructured optoelectronic devices. In this study, we harness the electric and magnetic resonances of such antennas to achieve a very strong dependence of the optical properties on the external environment. Specifically, we illustrate how the resonant scattering wavelength of single silicon nanowires is tunable across the entire visible spectrum by simply moving the height of the nanowires above a metallic mirror. We apply this concept by using a nanoelectromechanical platform to demonstrate active tuning.

Clinton Cahall, Kathryn L. Nicolich, Nurul T. Islam, Gregory P. Lafyatis, Aaron J. Miller, Daniel J. Gauthier, Jungsang Kim
We present the first evidence of multi-photon detection using a conventional superconducting nanowire single-photon detector, indicating number resolution up to four photons. The observed multi-photon detection statistics are consistent with the predictions of our model. [Optica 4, 1534-1535 (2017)]

Author(s): Mikhail V. Rybin, Kirill L. Koshelev, Zarina F. Sadrieva, Kirill B. Samusev, Andrey A. Bogdanov, Mikhail F. Limonov, and Yuri S. Kivshar

Recent progress in nanoscale optical physics is associated with the development of a new branch of nanophotonics exploring strong Mie resonances in dielectric nanoparticles with a high refractive index. The high-index resonant dielectric nanostructures form building blocks for novel photonic metadev...

[Phys. Rev. Lett. 119, 243901] Published Wed Dec 13, 2017

Amma Safdar, Yue Wang, Thomas F. Krauss
Following the very promising results obtained by the solar cell community, metal halide perovskite materials are increasingly attracting the attention of other optoelectronics researchers, especially for light emission applications. Lasing with both engineered and self-assembled resonator ... [Opt. Express 26, A75-A84 (2018)]

The emerging field of optical nanoantennas has been extending the reach of traditional antenna technology to the realms of photonics, nanotechnology, and quantum electrodynamics. In this article, we review the basic concepts of nanoantennas while highlighting similarities and differences with their low-frequency counterparts. We discuss how several concepts from traditional antenna technology, e.g., the antenna input impedance, can be translated to optical frequencies, and examine the new phenomena and engineering opportunities enabled by the material platform available at these frequencies. In this article, particular attention is devoted to different kinds of plasmonic nanoantennas (nanodipoles, nanoloops, and nanopatches) and to systematic approaches to control and enhance their performances, especially for impedance matching and directivity enhancement. We also show how linear and nonlinear plasmonic nanoantennas represent an ideal platform to realize anomalous and extreme forms of classical and quantum light-matter interactions, including artificial optical magnetism, spontaneous emission enhancement, and anomalous coupling between quantum emitters. As antenna concepts are increasingly appreciated and used in the design of nanophotonic devices and systems, we believe that the exciting field of optical antennas holds promise for large technological and scientific impact in the coming years.

Dielectric resonator antennas (DRAs) represent a well established concept for microwave frequencies. In recent years, DRAs and related counterparts have been embraced as structures for higher frequencies, including visible optics. This research trend is facilitated by advances in nanofabrication techniques and motivated by two prominent advantages of DRAs: 1) DRAs are highly efficient because their operation is based on displacement currents in low-loss dielectrics, and 2) DRAs are versatile radiating elements that can support multiple resonance modes when made of medium- or highpermittivity materials. In this article, we review our recent work on optical DRAs for high-efficiency beam control and reconfigurability. This review includes theoretical background and design examples as well as prospects and challenges of optical DRAs that we hope will be of interest to a broad audience in the antenna community.

The articles included in this special section focus on several recent advances in the field of passive and active nanoantennas that employ not only traditional based realizations but also their new frontiers.

Author(s): Pai Peng ((彭湃)), Yong-Chun Liu, Da Xu, Qi-Tao Cao, Guowei Lu, Qihuang Gong, and Yun-Feng Xiao

Quantum manipulation is challenging in localized-surface plasmon resonances (LSPRs) due to strong dissipations. To enhance quantum coherence, here we propose to engineer the electromagnetic environment of LSPRs by placing metallic nanoparticles (MNPs) in optical microcavities. An analytical quantum ...

[Phys. Rev. Lett. 119, 233901] Published Mon Dec 04, 2017

Author(s): Antonios Papaioannou, Dmitry S. Novikov, Els Fieremans, and Gregory S. Boutis

We report on an experimental observation of classical diffusion distinguishing between structural universality classes of disordered systems in one dimension. Samples of hyperuniform and short-range disorder were designed, characterized by the statistics of the placement of micrometer-thin parallel ...

[Phys. Rev. E 96, 061101(R)] Published Fri Dec 01, 2017

Mohsen Kamandar Dezfouli, Christos Tserkezis, N. Asger Mortensen, Stephen Hughes
Nonlocal effects have been shown to be responsible for a variety of nontrivial optical effects in small-size plasmonic nanoparticles, beyond classical electrodynamics. However, it is not clear whether optical mode descriptions can be applied to such extreme confinement regimes. Here, we present a ... [Optica 4, 1503-1509 (2017)]

Efficient optical frequency mixing typically must accumulate over large interaction lengths because nonlinear responses in natural materials are inherently weak. This limits the efficiency of mixing processes owing to the requirement of phase matching. Here, we report efficient four-wave mixing (FWM) over micrometer-scale interaction lengths at telecommunications wavelengths on silicon. We used an integrated plasmonic gap waveguide that strongly confines light within a nonlinear organic polymer. The gap waveguide intensifies light by nanofocusing it to a mode cross-section of a few tens of nanometers, thus generating a nonlinear response so strong that efficient FWM accumulates over wavelength-scale distances. This technique opens up nonlinear optics to a regime of relaxed phase matching, with the possibility of compact, broadband, and efficient frequency mixing integrated with silicon photonics.

Author(s): A. Dareau, E. Levy, M. Bosch Aguilera, R. Bouganne, E. Akkermans, F. Gerbier, and J. Beugnon

An arrangement of lasers and mirrors is used to map the topology patterns of quasicrystals.

[Phys. Rev. Lett. 119, 215304] Published Wed Nov 22, 2017

Author(s): L. De Angelis, F. Alpeggiani, A. Di Falco, and L. Kuipers

Phase singularities are locations where light is twisted like a corkscrew, with positive or negative topological charge depending on the twisting direction. Among the multitude of singularities arising in random wave fields, some can be found at the same location, but only when they exhibit opposite...

[Phys. Rev. Lett. 119, 203903] Published Thu Nov 16, 2017

F. Peragut, L. Cerutti, A. Baranov, J. P. Hugonin, T. Taliercio, Y. De Wilde, J. J. Greffet
Hyperbolic materials can sustain propagating modes with very large wave vectors and are thus characterized by a very large density of states. In practice, it is possible to mimic a hyperbolic material using a periodic stack of metallic and dielectric layers that can support surface plasmons with ... [Optica 4, 1409-1415 (2017)]

Yair Rivenson, Zoltán Göröcs, Harun Günaydin, Yibo Zhang, Hongda Wang, Aydogan Ozcan
We demonstrate that a deep neural network can significantly improve optical microscopy, enhancing its spatial resolution over a large field of view and depth of field. After its training, the only input to this network is an image acquired using a regular optical microscope, without any changes to ... [Optica 4, 1437-1443 (2017)]

Title: Resonant transport and near-field effects in photonic glasses
Author(s): Aubry, Geoffroy J.; Schertel, Lukas; Chen, Mengdi; et al.
Source: PHYSICAL REVIEW A, 96 (4): OCT 31 2017
Document Type: Article

In advanced field theories, there can be more than four dimensions to space, the excess dimensions described as compacted and unobservable on everyday length scales. We report a simple model, unconnected to field theory, for a compacted dimension realized in a metallic metasurface periodically structured in the form of a grating comprising a series of singularities. An extra dimension of the grating is hidden, and the surface plasmon excitations, though localized at the surface, are characterized by three wave vectors rather than the two of typical two-dimensional metal grating. We propose an experimental realization in a doped graphene layer.

On-chip optoelectronic and all-optical information processing paradigms require compact implementation of signal transfer for which nanoscale surface plasmons circuitry offers relevant solutions. This work demonstrates the directional signal transmittance mediated by 2D plasmonic eigenmodes supported by crystalline cavities. Channel devices comprising two mesoscopic triangular input and output ports and sustaining delocalized, higher-order plasmon resonances in the visible to infra-red range are shown to enable the controllable transmittance between two confined entry and exit ports coupled over a distance exceeding 2 $\mu$m. The transmittance is attenuated by > 20dB upon rotating the incident linear polarization, thus offering a convenient switching mechanism. The optimal transmittance for a given operating wavelength depends on the geometrical design of the device that sets the spatial and spectral characteristic of the supporting delocalized mode. Our approach is highly versatile and opens the way to more complex information processing using pure plasmonic or hybrid nanophotonic architectures.

Photonic Neural Network implementations have been gaining considerable attention as a potentially disruptive future technology. Demonstrating learning in large scale neural networks is essential to establish photonic machine learning substrates as viable information processing systems. Realizing photonic Neural Networks with numerous nonlinear nodes in a fully parallel and efficient learning hardware was lacking so far. We demonstrate a network of up to 2500 diffractively coupled photonic nodes, forming a large scale Recurrent Neural Network. Using a Digital Micro Mirror Device, we realize reinforcement learning. Our scheme is fully parallel, and the passive weights maximize energy efficiency and bandwidth. The computational output efficiently converges and we achieve very good performance.

Author(s): Akbar Safari, Robert Fickler, Miles J. Padgett, and Robert W. Boyd

Experiments show that the nonlinear response of an optical system can enhance localization of energy, leading to the formation of rogue waves.

[Phys. Rev. Lett. 119, 203901] Published Mon Nov 13, 2017

The microstructure of a medium strongly influences how light propagates through it. The amount of disorder it contains determines whether the medium is transparent or opaque. Theory predicts that exciting such a medium homogeneously and isotropically makes some of its optical properties depend only on the medium’s outer geometry. Here, we report an optical experiment demonstrating that the mean path length of light is invariant with respect to the microstructure of the medium it scatters through. Using colloidal solutions with varying concentration and particle size, the invariance of the mean path length is observed over nearly two orders of magnitude in scattering strength. Our results can be extended to a wide range of systems—however ordered, correlated, or disordered—and apply to all wave-scattering problems.

Thomas Chaigne, Bastien Arnal, Sergey Vilov, Emmanuel Bossy, Ori Katz
In deep-tissue photoacoustic imaging, optical-contrast images of deep-lying structures are formed by recording acoustic waves that are generated by optical absorption. Although photoacoustics is perhaps the leading technique for high-resolution deep-tissue optical imaging, its spatial resolution is ... [Optica 4, 1397-1404 (2017)]