Recent years have seen a rapid expansion of research into nanophotonics based on surface plasmon–polaritons. These electromagnetic waves propagate along metal–dielectric interfaces and can be guided by metallic nanostructures beyond the diffraction limit. This remarkable capability has unique prospects for the design of highly integrated photonic signal-processing systems, nanoresolution optical imaging techniques and sensors. This Review summarizes the basic principles and major achievements of plasmon guiding, and details the current state-of-the-art in subwavelength plasmonic waveguides, passive and active nanoplasmonic components for the generation, manipulation and detection of radiation, and configurations for the nanofocusing of light. Potential future developments and applications of nanophotonic devices and circuits are also discussed, such as in optical signals processing, nanoscale optical devices and near-field microscopy with nanoscale resolution.

Plasmonics beyond the diffraction limit

In 1873, Ernst Abbe discovered what was to become a well-known paradigm: the inability of a lens-based optical microscope to discern details that are closer together than half of the wavelength of light. However, for its most popular imaging mode, fluorescence microscopy, the diffraction barrier is crumbling. Here, I discuss the physical concepts that have pushed fluorescence microscopy to the nanoscale, once the prerogative of electron and scanning probe microscopes. Initial applications indicate that emergent far-field optical nanoscopy will have a strong impact in the life sciences and in other areas benefiting from nanoscale visualization.

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Far-Field Optical Nanoscopy

Artificially engineered metamaterials are now demonstrating unprecedented electromagnetic properties that cannot be obtained with naturally occurring materials. In particular, they provide a route to creating materials that possess a negative refractive index and offer exciting new prospects for manipulating light. This review describes the recent progress made in creating nanostructured metamaterials with a negative index at optical wavelengths, and discusses some of the devices that could result from these new materials.

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Optical negative-index metamaterials

Metamaterials, or engineered materials with rationally designed, subwavelength-scale building blocks, allow us to control the behavior of physical fields in optical, microwave, radio, acoustic, heat transfer, and other applications with flexibility and performance that are unattainable with naturally available materials. In turn, metasurfaces-planar, ultrathin metamaterials-extend these capabilities even further. Optical metasurfaces offer the fascinating possibility of controlling light with surface-confined, flat components. In the planar photonics concept, it is the reduced dimensionality of the optical metasurfaces that enables new physics and, therefore, leads to functionalities and applications that are distinctly different from those achievable with bulk, multilayer metamaterials. Here, we review the progress in developing optical metasurfaces that has occurred over the past few years with an eye toward the promising future directions in the field.

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Planar Photonics with Metasurfaces

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

We demonstrate that nonlocal nanowire metamaterials can help to alleviate one of the main limitations of Salisbury screens, their dependence on the incident angle.

Angle-independent Salisbury screens based on nonlocal nanowire metamaterials

We present a detailed study of optical properties of recently introduced nonmagnetic, nonperiodic planar materials with negative refractive index and demonstrate the possibility of achieving far-field resolution below the free-space diffraction limit in these systems.

Imaging properties of anisotropy-based negative index composites

We propose a non-magnetic system with negative refraction index for terahertz applications. The system is based on a planar metallic waveguide with bismuth core, and uses strong anisotropy of bismuth permittivity and its ultra-low losses

Non-magnetic System with Negative Index of Refraction for Terahertz Application

We consider the formation of highly directional beams from a subwavelength aperture surrounded by surface corrugations through a high-index superstrate and show that the beaming pattern strongly depends on the distance to the aperture.

Evolution of beaming pattern in corrugated mid-IR plasmonic structures

Generalized Ohm's Law is used to model the phenomenon of broadband asymmetric reflectance recently observed in semicontinuous metal-dielectric films in the proximity of the percolation threshold. Qualitative agreement with experiment is achieved.

Viktor A. Podolskiy

Papers

Angle-independent Salisbury screens based on nonlocal nanowire metamaterials

Imaging properties of anisotropy-based negative index composites

Non-magnetic System with Negative Index of Refraction for Terahertz Application

Evolution of beaming pattern in corrugated mid-IR plasmonic structures

Modeling asymmetric reflectance in semicontinuous metal films using generalized Ohm's Law