1,300 research outputs found
Duality Symmetry, Strong Coupling Expansion and Universal Critical Amplitudes in 2D Phi-4 Field Models
No full textNanostructures + light = 'new optics'
No full textSuddenly, at the end of the last century, classical optics and classical electrodynamics became fashionable again. Fields that several generations of researchers thought were comprehensively covered by the famous Born and Wolf textbook and were essentially dead as research subjects were generating new excitement. In accordance with Richard Feynman's famous quotation on nano-science, the optical community suddenly discovered that 'there is plenty of room at the bottom'—mixing light with small, meso- and nano-structures could generate new physics and new mind-blowing applications. This renaissance began when the concept of band structure was imported from electronics into the domain of optics and led to the development of what is now a massive research field dedicated to two- and three-dimensional photonic bandgap structures. The field was soon awash with bright new ideas and discoveries that consolidated the birth of the 'new optics'. A revision of some of the basic equations of electrodynamics led to the suspicion that we had overlooked the possibility that the triad of wave vector, electric field and magnetic field, characterizing propagating waves, do not necessarily form a right-handed set. This brought up the astonishing possibilities of sub-wavelength microscopy and telescopy where resolution is not limited by diffraction. The notion of meta-materials, i.e. artificial materials with properties not available in nature, originated in the microwave community but has been widely adopted in the domain of optical research, thanks to rapidly improving nanofabrication capabilities and the development of sub-wavelength scanning imaging techniques. Photonic meta-materials are expected to open a gateway to unprecedented electromagnetic properties and functionality unattainable from naturally occurring materials. The structural units of meta-materials can be tailored in shape and size; their composition and morphology can be artificially tuned, and inclusions can be designed and placed at desired locations to achieve new functionality. Among important developments in the new optics was the discovery that a metal film with arrays of small holes in it could be transparent to light beyond any intuitive expectations and that a properly designed metallic structure could be made completely 'invisible' at certain wavelengths. A strong technological drive towards device miniaturization (or, perhaps we should say 'nanoturization'?) has breathed new life into plasmonics—a field many thought had matured some time ago. Surface plasmon polarition waves have come to be seen as potential broadband information carriers for highly integrated photonic devices with research now concentrating on routing and controlling plasmon–polariton signals. Among other new topics in optical electrodynamics are frequency selective surfaces, optical effects of low-dimensional chirality and electrodynamics of toroidal structures.This Special Issue of Journal of Optics A: Pure and Applied Optics on 'Nanostructured Optical Meta-Materials: Beyond Photonic Bandgap Effects' is a very representative cross-section of research in 'new optics', with papers covering essential issues in meta-materials research, surface plasmons, nanostructured surfaces, sub-wavelength imaging, nanostructured and random laser media and nonlinearities in nanostructured films.As the Guest Editors of this Special Issue, we are deeply grateful to all contributing authors for their efforts and their willingness to share recent results within the framework of what promises to be a landmark collection of papers in the field of 'new optics'. We are especially proud that the authorship includes pioneers and newcomers to this intriguing and fertile field of research
Challenges and prospects of plasmonic metasurfaces for photothermal catalysis
No full textSolar-thermal technologies for converting chemicals using thermochemistry require extreme light concentration. Exploiting plasmonic nanostructures can dramatically increase the reaction rates by providing more efficient solar-to-heat conversion by broadband light absorption. Moreover, hot-carrier and local field enhancement effects can alter the reaction pathways. Such discoveries have boosted the field of photothermal catalysis, which aims at driving industrially-relevant chemical reactions using solar illumination rather than conventional heat sources. Nevertheless, only large arrays of plasmonic nano-units on a substrate, i.e., plasmonic metasurfaces, allow a quasi-unitary and broadband solar light absorption within a limited thickness (hundreds of nanometers) for practical applications. Through moderate light concentration (similar to 10 Suns), metasurfaces reach the same temperatures as conventional thermochemical reactors, or plasmonic nanoparticle bed reactors reach under similar to 100 Suns. Plasmonic metasurfaces, however, have been mostly neglected so far for applications in the field of photothermal catalysis. In this Perspective, we discuss the potentialities of plasmonic metasurfaces in this emerging area of research. We present numerical simulations and experimental case studies illustrating how broadband absorption can be achieved within a limited thickness of these nanostructured materials. The approach highlights the synergy among different enhancement effects related to the ordered array of plasmonic units and the efficient heat transfer promoting faster dynamics than thicker structures (such as powdered catalysts). We foresee that plasmonic metasurfaces can play an important role in developing modular-like structures for the conversion of chemical feedstock into fuels without requiring extreme light concentrations. Customized metasurface-based systems could lead to small-scale and low-cost decentralized reactors instead of large-scale, infrastructure-intensive power plants
Challenges and prospects of plasmonic metasurfaces for photothermal catalysis
No full textSolar-thermal technologies for converting chemicals using thermochemistry require extreme light concentration. Exploiting plasmonic nanostructures can dramatically increase the reaction rates by providing more efficient solar-to-heat conversion by broadband light absorption. Moreover, hot-carrier and local field enhancement effects can alter the reaction pathways. Such discoveries have boosted the field of photothermal catalysis, which aims at driving industrially-relevant chemical reactions using solar illumination rather than conventional heat sources. Nevertheless, only large arrays of plasmonic nano-units on a substrate, i.e., plasmonic metasurfaces, allow a quasi-unitary and broadband solar light absorption within a limited thickness (hundreds of nanometers) for practical applications. Through moderate light concentration (∼10 Suns), metasurfaces reach the same temperatures as conventional thermochemical reactors, or plasmonic nanoparticle bed reactors reach under ∼100 Suns. Plasmonic metasurfaces, however, have been mostly neglected so far for applications in the field of photothermal catalysis. In this Perspective, we discuss the potentialities of plasmonic metasurfaces in this emerging area of research. We present numerical simulations and experimental case studies illustrating how broadband absorption can be achieved within a limited thickness of these nanostructured materials. The approach highlights the synergy among different enhancement effects related to the ordered array of plasmonic units and the efficient heat transfer promoting faster dynamics than thicker structures (such as powdered catalysts). We foresee that plasmonic metasurfaces can play an important role in developing modular-like structures for the conversion of chemical feedstock into fuels without requiring extreme light concentrations. Customized metasurface-based systems could lead to small-scale and low-cost decentralized reactors instead of large-scale, infrastructure-intensive power plants
Nanophotonics & Metamaterials
No full textThis course, instructed by Vlad Shalaev of Purdue University, aims to "cover nanoscale processes and devices and their applications for manipulating light on the nanoscale." The topics covered in this course are: Photonic crystals, Photonic crystal fibers, Photonic nanocircuits, Metal optics, Manipulating light with plasmonic nanostructures, Plasmonic nano-sensors, Near-field optics, and Metamaterials and negative refractive index and super-resolution. Here, visitors will find the course outline and syllabus, recommended readings, homework assignments, and weekly lecture notes. There is also a link to two online textbooks. This resource has plenty of assignment ideas and lecture materials to draw on for any educator's own nanotechnology classroom
Bianisotropic Effective Parameters of Optical Metamagnetics and Negative-Index Materials
No full textApproaches to the adequate homogenization of optical metamaterials are becoming more and more complex, primarily due to an increased understanding of the role of asymmetric electrical and magnetic responses, in addition to the nonlocal effects of the surrounding medium, even in the simplest case of plane-wave illumination. The current trend in developing such advanced homogenization descriptions often relies on utilizing bianisotropic models as a base on top of which novel optical characterization techniques can be built. In this paper, we first briefly review general principles for developing a bianisotropic homogenization approach. Second, we present several examples validating and illustrating our approach using single-period passive and active optical metamaterials. We also show that the substrate may have a significant effect on the bianisotropic characteristics of otherwise symmetric passive and active metamaterials
Laser assisted modification of poled silver-doped nanocomposite soda-lime glass
No full textThermal poling assisted homogenization of polydisperse Ag nanoparticles embedded in the soda-lime glass is demonstrated. The homogenization leads to the narrowing of the localized surface plasmon resonance. The subsequent irradiation with linearly polarized ultrashort laser pulses induces spectrally defined and three times larger dichroism than in non-poled sample
Optical Metamaterials: Fundamentals and Applications
No full textMetamaterials—artificially structured materials with engineered electromagnetic properties—have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. In just a few years, the field of optical metamaterials has emerged as one of the most exciting topics in the science of light, with stunning and unexpected outcomes that have fascinated scientists and the general public alike. This volume details recent advances in the study of optical metamaterials, ranging from fundamental aspects to up-to-date implementations, in one unified treatment. Important recent developments and applications such as superlenses and cloaking devices are also treated in detail and made understandable. Optical Metamaterials will serve as a very timely book for both newcomers and advanced researchers in this rapidly evolving field. Early praise for Optical Metamaterials: "...this book is timely bringing to students and other new entrants to the field the most up to date concepts. The authors are amongst the leaders in the field and ideally positioned to write such a comprehensive volume: their enthusiasm shines through every chapter of the text. This book will I am sure play an important part in taking the subject of metamaterials to new heights of invention and application. We should all have a copy on our shelves." – Professor Sir John Pendry, Imperial College London "This book provides an understandable introduction to the field of optical metamaterials, including all the necessary background and a comprehensive review of this new paradigm in the science of light. Professor Shalaev, a world-leading expert in optics and metamaterials, and his former student, Dr. Cai, a rising star in his own right, have skillfully developed a volume that will prove important for both experts and students just entering the exciting field of photonic metamaterials and transformation optics. This book will certainly find a place within easy reach on my shelf." – Professor Victor G. Veselago, A.M.Prokhorov Institute of General Physics, Moscow "This is a nice treatment and a lucid description of the rapidly growing field of optical metamaterials. In this book, Wenshan Cai and Vladimir Shalaev have done a tremendous job in making this exciting scientific topic accessible to those interested in this field. They have discussed its fundamental concepts and potential applications in a clear and engaging way, providing the reader with a fascinating overview of this active area of research. I enjoyed reading this book, and I highly recommend it to all who wish to learn about the optical metamaterials. It tells a fascinating story about this field of optical science and engineering." – Nader Engheta, H. Nedwill Ramsey Professor of Electrical and Systems Engineering, University of Pennsylvani
Optical time reversal from time-dependent epsilon-near-zero media
No full textMaterials with a spatially uniform but temporally varying optical response have applications ranging from magnetic field-free optical isolators to fundamental studies of quantum field theories. However, these effects typically become relevant only for time variations oscillating at optical frequencies, thus presenting a significant hurdle that severely limits the realization of such conditions. Here we present a thin-film material with a permittivity that pulsates (uniformly in space) at optical frequencies and realizes a time-reversing medium of the form originally proposed by Pendry [Science 322, 71 (2008)]. We use an optically pumped, 500 nm thick film of epsilon-near-zero (ENZ) material based on Al-doped zinc oxide. An incident probe beam is both negatively refracted and time reversed through a reflected phase-conjugated beam. As a result of the high nonlinearity and the refractive index that is close to zero, the ENZ film leads to time reversed beams (simultaneous negative refraction and phase conjugation) with near-unit efficiency and greater-than-unit internal conversion efficiency. The ENZ platform therefore presents the time-reversal features required, e.g., for efficient subwavelength imaging, all-optical isolators and fundamental quantum field theory studies
High-Order Nonlinear Frequency Conversion in Transparent Conducting Oxide Thin Films
No full textThe study of conductive oxides has gained momentum within the photonics community due to their unique linear and nonlinear optical properties. Despite recent experiments reporting on high harmonic generation from thin films, the optical/electronic behavior of these compounds at the nanoscale is still not fully understood due to the lack of a suitable theoretical model. In the present work, aluminum zinc oxide is excited near its epsilon-near-zero crossing point using incident femtosecond pulses having peak power densities in the 1 TW cm-2 range. A relatively efficient frequency up-conversion including even and odd harmonics up to the seventh order is observed. A hydrodynamic-Maxwell theoretical approach is adopted, capable of simultaneously taking into account linear and nonlinear dispersions, nonlocal effects, surface, magnetic, and bulk nonlinearities in a spectral region that spans over two and a half octaves from the UV to the NIR region. The study enables a deeper understanding of the fundamental material parameters regulating optical nonlinearities, providing important insights to engineer this class of materials for applications in sensing, ultra-fast physics, and spectroscopy.Subwavelength aluminum zinc oxide films are optically pumped near their epsilon-near-zero point, observing relatively efficient frequency up-conversion reaching the seventh order. A modified hydrodynamic-Maxwell model is used, accounting for linear and nonlinear dispersions, nonlocal effects, and nonlinearities across a broad spectral region, thus advancing the understanding of these materials for sensing, ultra-fast physics, and spectroscopy. imag
- …
