"Considered one of the major fields of photonics of the beginning 21st century, plasmonics offers the potential to confine and guide light below the diffraction limit and promises a new generation of ...highly miniaturized photonic devices. Offering both a comprehensive introduction to the field and an extensive overview of the current state of the art,""Plasmonics Fundamentals and Applications""should be of great value to the newcomer and to the experienced researcher.The first part of the book describes the fundamentals of this research area, starting with a review of Maxwell s equations in a form suited to the description of metals. Subsequent chapters introduce the two major ingredients of plasmonics, surface plasmon polaritons at metallic interfaces and localized plasmons in nanostructures. The mathematics of their description, excitation and imaging of the modes are discussed. This part closes with a presentation of electromagnetic surface waves at lower frequencies in the THz and microwave regime, comprising both spoof or designer plasmons and surface phonon polaritons.Building on the fundamentals, the second part discusses some of the most prominent applications of plasmons: Plasmon waveguides, extraordinary transmission through aperturearrays, sensing and surface enhanced Raman scattering, spectroscopy as well as metamaterials. Exemplary studies in each of these fields taken from the original literature are presented."
Semiconducting two-dimensional (2D) crystals such as MoS2 and WSe2 exhibit unusual optical properties that can be exploited for novel optoelectronics ranging from flexible photovoltaic cells to ...harmonic generation and electro-optical modulation devices. Rapid progress of the field, particularly in the growth area, is beginning to enable ways to implement 2D crystals into devices with tailored functionalities. For practical device performance, a key challenge is to maximize light–matter interactions in the material, which is inherently weak due to its atomically thin nature. Light management around the 2D layers with the use of plasmonic nanostructures can provide a compelling solution.
Nanophotonic devices, which control light in subwavelength volumes and enhance light-matter interactions, have opened up exciting prospects for biosensing. Numerous nanophotonic biosensors have ...emerged to address the limitations of the current bioanalytical methods in terms of sensitivity, throughput, ease-of-use and miniaturization. In this Review, we provide an overview of the recent developments of label-free nanophotonic biosensors using evanescent-field-based sensing with plasmon resonances in metals and Mie resonances in dielectrics. We highlight the prospects of achieving an improved sensor performance and added functionalities by leveraging nanostructures and on-chip and optoelectronic integration, as well as microfluidics, biochemistry and data science toolkits. We also discuss open challenges in nanophotonic biosensing, such as reducing the overall cost and handling of complex biological samples, and provide an outlook for future opportunities to improve these technologies and thereby increase their impact in terms of improving health and safety.
Color is a ubiquitous perceptual stimulus that is often considered in terms of aesthetics. Here we review theoretical and empirical work that looks beyond color aesthetics to the link between color ...and psychological functioning in humans. We begin by setting a historical context for research in this area, particularly highlighting methodological issues that hampered earlier empirical work. We proceed to overview theoretical and methodological advances during the past decade and conduct a review of emerging empirical findings. Our empirical review focuses especially on color in achievement and affiliation/attraction contexts, but it also covers work on consumer behavior as well as food and beverage evaluation and consumption. The review clearly shows that color can carry important meaning and can have an important impact on people's affect, cognition, and behavior. The literature remains at a nascent stage of development, however, and we note that considerable work on boundary conditions, moderators, and real-world generalizability is needed before strong conceptual statements and recommendations for application are warranted. We provide suggestions for future research and conclude by emphasizing the broad promise of research in this area.
We compute the static contribution to the gravitational interaction potential of two point masses in the velocity-independent five-loop (and 5th post-Newtonian) approximation to the harmonic ...coordinates effective action in a direct calculation. The computation is performed using effective field methods based on Feynman diagrams in momentum-space in d=3−2ε space dimensions. We also reproduce the previous results including the 4th post-Newtonian order.
Allowing subwavelength-scale-digitization of optical wavefronts to achieve complete control of light at interfaces, metasurfaces are particularly suited for the realization of planar phase-holograms ...that promise new applications in high-capacity information technologies. Similarly, the use of orbital angular momentum of light as a new degree of freedom for information processing can further improve the bandwidth of optical communications. However, due to the lack of orbital angular momentum selectivity in the design of conventional holograms, their utilization as an information carrier for holography has never been implemented. Here we demonstrate metasurface orbital angular momentum holography by utilizing strong orbital angular momentum selectivity offered by meta-holograms consisting of GaN nanopillars with discrete spatial frequency distributions. The reported orbital angular momentum-multiplexing allows lensless reconstruction of a range of distinctive orbital angular momentum-dependent holographic images. The results pave the way to the realization of ultrahigh-capacity holographic devices harnessing the previously inaccessible orbital angular momentum multiplexing.
Molecular mechanics is powerful for its speed in atomistic simulations, but an accurate force field is required. The Amber ff99SB force field improved protein secondary structure balance and dynamics ...from earlier force fields like ff99, but weaknesses in side chain rotamer and backbone secondary structure preferences have been identified. Here, we performed a complete refit of all amino acid side chain dihedral parameters, which had been carried over from ff94. The training set of conformations included multidimensional dihedral scans designed to improve transferability of the parameters. Improvement in all amino acids was obtained as compared to ff99SB. Parameters were also generated for alternate protonation states of ionizable side chains. Average errors in relative energies of pairs of conformations were under 1.0 kcal/mol as compared to QM, reduced 35% from ff99SB. We also took the opportunity to make empirical adjustments to the protein backbone dihedral parameters as compared to ff99SB. Multiple small adjustments of φ and ψ parameters were tested against NMR scalar coupling data and secondary structure content for short peptides. The best results were obtained from a physically motivated adjustment to the φ rotational profile that compensates for lack of ff99SB QM training data in the β-ppII transition region. Together, these backbone and side chain modifications (hereafter called ff14SB) not only better reproduced their benchmarks, but also improved secondary structure content in small peptides and reproduction of NMR χ1 scalar coupling measurements for proteins in solution. We also discuss the Amber ff12SB parameter set, a preliminary version of ff14SB that includes most of its improvements.
Metals support surface plasmons at optical wavelengths and have the ability to localize light to subwavelength regions. The field enhancements that occur in these regions set the ultimate limitations ...on a wide range of nonlinear and quantum optical phenomena. We found that the dominant limiting factor is not the resistive loss of the metal, but rather the intrinsic nonlocality of its dielectric response. A semiclassical model of the electronic response of a metal places strict bounds on the ultimate field enhancement. To demonstrate the accuracy of this model, we studied optical scattering from gold nanoparticles spaced a few angstroms from a gold film. The bounds derived from the models and experiments impose limitations on all nanophotonic systems.
Metasurfaces based on quasi‐bound states in the continuum (quasi‐BICs) constitute an emerging toolkit in nanophotonic sensing as they sustain high quality factor resonances and substantial near‐field ...enhancements. It is demonstrated that silicon metasurfaces composed of crescent shaped meta‐atoms provide tailored light‐matter interaction controlled by the crescent geometry. Significantly, this metasurface not only exhibits a fundamental quasi‐BIC resonance, but also supports a higher‐order resonance with tunable electromagnetic field enhancement and advantageous properties for sensing. The higher‐order resonance shows twice the sensitivity of the fundamental one for bulk refractive index sensing. It is further demonstrated that both the fundamental and higher‐order resonances can be exploited for sensing ultrathin layers of biomolecules in air and buffer solutions. Specifically, when measuring in buffer solution, the figure of merit of the sensor, defined as the change in the spectral position of the resonance normalized to its full width at half maximum, is a factor of 2.5 larger for the higher‐order resonance when compared to the fundamental one. Due to its high sensitivity and potential for straightforward microfluidic integration, the silicon crescent metasurface is ideally suited for real‐time and in situ biosensing, enabling compact sensing devices for a wide range of diagnostic applications.
An all‐dielectric crescent silicon metasurface serving as an efficient optical sensor is achieved. This sensing platform is driven by quasi‐bound states in the continuum with well‐tailored high quality factors of excited resonances and enhanced near‐fields, thus enabling refractive index sensing and ultrathin biomolecular detection both in air and buffer with high sensitivity and a low detection limit.
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