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 present numerically stable expansion basis for diffraction-based far-field computational imaging systems and demonstrate the capabilities of reconstructing wavelength-scale objects with wavelength/20 resolution.

Numerically Stable Reconstruction of Wavelength-Scale Objects with Sub-Wavelength Resolution

We have demonstrated stimulated emission in microring cavity formed by dye-doped polymer deposited on a gold wire. The mode structure suggests that the stimulated emission originates from surface plasmon polaritons propagating at the gold-polymer interface.

Stimulated Emission in Microring Cavity with Gold Core

We demonstrate that relatively weak material gain can be utilized as an effective tool to manipulate dispersion of negative index materials achieving, in particular, broadband impedance- or index-matching. Finite-size and unbounded media are discussed.

Gain-assisted dispersion management in negative-index materials

We demonstrate reduced reflectance and a corresponding enhancement of transmittance in lamellar hyperbolic
metamaterials, with scatterers deposited on the top. The effect is much more significant in curvilinear hyperbolic
metamaterials. We also show that absorption strengths of dyes on the top of hyperbolic metamaterials can be tuned and
enhanced (nearly threefold). The effect can be controlled by interplay of the substrate geometry, composition and
location of the absorbing medium. Our observations pave the way for a variety of applications, including broadband
enhancements of light trapping and absorption in solar cells.

Hyperbolic metamaterials platforms for tuning reflectance, transmittance and absorption

We develop a new approach to build left-handed material (LHM). In contrast to conventional resonance-based LHM designs, our material is non magnetic, and is based on anisotropic dielectric permittivity. We develop theory of its right- and left-handed response, and suggest a number of feasible systems for infrared and optical LHMs.

Viktor A. Podolskiy

Papers

Numerically Stable Reconstruction of Wavelength-Scale Objects with Sub-Wavelength Resolution

Stimulated Emission in Microring Cavity with Gold Core

Gain-assisted dispersion management in negative-index materials

Hyperbolic metamaterials platforms for tuning reflectance, transmittance and absorption

Non-magnetic left handed nanostructured material