Topological Photonics
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Topological Photonics
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Author : Xiaoyong Hu
language : en
Publisher: Frontiers Media SA
Release Date : 2022-07-07
Topological Photonics written by Xiaoyong Hu and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-07-07 with Science categories.
Topological Photonics
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Author : Andrea Blanco-Redondo
language : en
Publisher: Elsevier
Release Date : 2024-09-01
Topological Photonics written by Andrea Blanco-Redondo and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-09-01 with Technology & Engineering categories.
Topological Photonics: Fundamentals and Applications provides an introduction to the key principles and advances in the understanding of topology and the design of new photonic materials systems and their applications. Section 1 elaborates on the necessary fundamental concepts to understand the field, starting from background discoveries in condensed matter physics and delving into describing the underlying concepts and the experimental progress in 1D, 2D, 3D topological photonics systems as well as in synthetic dimensions and non-Hermitian platforms. Section 2 highlights the most promising applications of topological photonics, including the current progress and most important challenges for each of them. Topological Photonics is suitable for those working in academia and R&D in the subject areas of materials science, engineering-particularly researchers and practitioners working in the research fields of topological materials, optics, and photonics.
Topological Photonics In 3d Photonic Structures
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Author : Jiho Noh
language : en
Publisher:
Release Date : 2020
Topological Photonics In 3d Photonic Structures written by Jiho Noh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Topological insulators are materials that have an insulating bulk but robust conducting states on their edges. These states are topologically protected in the sense that they are inherently robust to defects and disorders that are unavoidable in all materials platforms. The growing interest on this topic has been highlighted by the 2016 Nobel Prize in Physics, which was awarded "for theoretical discoveries of topological phase transitions and topological phases of matter" to David J. Thouless, F. Duncan M. Haldane, and J. Michael Kosterlitz. Recently, it was experimentally demonstrated that photonic edge states could be "topologically protected" in diverse artificial dielectric structures called photonic topological insulators. This implies both new opportunities to study more exotic topological models due to the diversity and flexibility of the photonic platforms, and potential technological applications for robust photonic devices even in the presence of fabrication imperfections. From these realization of photonic topological insulators started a research field of topological photonics, which is a rapidly emerging field in which ideas from topological physics are incorporated to design and control the behavior of light. In this dissertation, we present a collection of studies on topological photonics using lattices of directly-written evanescently-coupled single-mode waveguides and three-dimensional photonic crystals. In the first part, we present our studies on higher-order topological insulators. Higher-order topological insulator is a new phase of matter, in which states being topologically protected are two or more dimensions lower than the system dimension, in contrast to the conventional topological insulators which possess states being protected that are only a single dimension lower than the system dimension. For the first time in any experimental platform, we experimentally demonstrated the higher-order topological insulator by observing the presence of a topologically protected zero-dimensional state localized at the corners of a femtosecond-laser-written waveguide array, and we have shown that this system can be used to topologically protect the mode frequency at mid-gap and to minimize mode volume. In addition, we studied a higher-order topological pumping using femtosecond-laser-written waveguide array, where we observe corner-to-corner transport through nontrivial adiabatic pumping cycles in 2D crystals with vanishing dipole moments. This observation of higher-order topological pumping is equivalent to studying chiral hinge states in a 3D topological system, since mapping the dynamical phenomenon demonstrated here from two spatial and one temporal to three spatial dimensions, this transport is equivalent to the observation of the chiral nature of the gapless hinge states in a 3D second-order topological insulator. In the second part, we present two different experimental demonstrations of photonic Weyl points. A Weyl point is a point degeneracy between two bands in a three-dimensional bandstructure, with linear dispersion in all three dimensions in its vicinity, which is the simplest topological degeneracy that can exist in the three-dimensional space. First, we realized a type-II Weyl point at optical wavelengths using femtosecond-laser-written waveguide array, where we observed two different signatures of a type-II Weyl point: conical diffraction at the Weyl-point wavelength and Fermi-arc surface states above the Weyl-point wavelength. This work is the first demonstration of a Weyl-point in the optical wavelength regime, which opened up the possibilities of studying complex phenomena as a result of an interplay between the Weyl dispersion and non-Hermitian, nonlinear, and quantum optics, etc. Also, we realized a charge 2 Weyl point in a low-contrast PhC fabricated by direct laser writing using Nanoscribe, where we experimentally observed the Weyl point from a reflection spectrum obtained by Fourier-transform infrared spectroscopy. This work also shows that the wavelength of Weyl points in such a 3D structure can be tuned between near-IR and mid-IR wavelength range by simply changing the lattice constant and that it is possible to observe the topological phenomenon in 3D PhCs even without high-contrast materials. In the third part, we present our experimental realization of a time-reversal invariant photonic topological insulator by incorporating the idea of the 'valley-Hall effect' from solid-state physics into analogous photonic structures using the femtosecond-laser-written waveguide array. Here, we observed the existence of valley-Hall topological edge states at the boundaries between two different inversion-symmetry-broken honeycomb photonic lattices. This study shows the possibility to open very large band gaps, which allows us to study in a regime that was not possible in solid-state 2D materials, and has the technological application as a straightforward route to realizing time-reversal invariant topological edge states, which can directly be applied to nanoscale on-chip photonics. In the fourth part, we present our work on a non-Abelian braiding of photonic topological zero modes. In this work, we directly realized the braiding of photonic topological zero modes localized at the vortices of an order parameter using the femtosecond-laser-written waveguide arrays, and we measured the non-Abelian Berry phase that varies according to the direction of the braiding process using an interferometer constructed using waveguides. This study of non-Abelian braiding in a classical system of optical waveguide arrays will be a good platform to be further developed for quantum systems, where the non-Abelian braiding can be used as a basis for robust quantum information processing.
Topological Photonics Light Sources
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Author : Babak Bahari
language : en
Publisher:
Release Date : 2019
Topological Photonics Light Sources written by Babak Bahari and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
In integrated photonics, cavity resonators play an important role. They are the basis of light sources, which are one of the fundamental building blocks of any integrated circuit. So far, cavities are designed base on their size, shape, and photon lifetime, and requiring any extra features increase their complexity. However, cavities can present some topological behaviors with peculiar characteristics that can enhance their functionalities. Two of these topological behaviors, which are the main focus of this thesis, are Topological insulators (TIs), and Bound states in the continuum (BIC). In the following thesis, we explored theoretically and experimentally the topological singularities in cavities made of periodic structures, and their applications in designing integrated light sources (i.e., lasers). Structures are constructed on a gain material of InGaAsP multiple quantum wells, which emits in the telecommunication wavelength range ([lambda]~1.55 [mu]m), and operates at room temperature. In the first part of the thesis, we study TIs and design topological cavities for integrated light sources using hybrid photonic crystals (PhCs) with non-zero phase transition between them. Thus the optical wave is fully confined at the boundary of PhCs, and propagates in one direction. The topological cavities can have any arbitrary geometry while preserving high functionality. Furthermore, we demonstrate that topological cavities are able to be used to generate structured lights with very large topological charges, while they maintain small foot-print and no-complexity. The second part is dedicated to the bound states, which are the type of topological singularities with positive energies in the continuum region. These topological singularities offer many unique characteristics such as tunability of their position in the reciprocal space and carrying non-zero topological charges. Furthermore, the number of singularities can be controlled by crystal symmetry. In this thesis, we present the first experimental demonstration of simultaneously generation and steering multiple vortex beams form an extended PhC cavity. Our results indicate the application of the topological behavior of cavities as an extra degree of freedom in designing integrated photonic chips with enhanced functionalities.
Topology In Optics
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Author : David S. Simon
language : en
Publisher:
Release Date : 2021
Topology In Optics written by David S. Simon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Geometrical optics categories.
Topology in Optics: Tying light in knots (Second Edition) provides the background needed to understand a broad range of unexpected phenomenon and developments arising from topological effects in optics. Assuming only a background in physics at the advanced undergraduate level, it requires no prior familiarity with topology. Revised and expanded with two new chapters, Topological Photonics and Optical Knots and Links, this will be an invaluable reference for undergraduate and graduate students as well as researchers and engineers in optics and related areas.
Topological Photonics In Non Hermitian And Scattering Systems
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Author : Charles C. Wojcik
language : en
Publisher:
Release Date : 2022
Topological Photonics In Non Hermitian And Scattering Systems written by Charles C. Wojcik and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
In photonics, topological effects can be used to design systems with robust and novel behavior. These topological effects are traditionally studied in closed systems without gain, described by Hermitian Hamiltonians. However, many systems in photonics do have gain or loss and can be described by non-Hermitian Hamiltonians. Systems with inputs and outputs are also widespread in photonics and are usually described by a scattering matrix. In this Thesis, we study topological features in non-Hermitian and scattering systems in photonics. First, we give a characterization of the space of all gapped non-Hermitian Hamiltonians using the mathematical framework of homotopy theory. We do this pedagogically in two-band systems, starting with the familiar Hermitian case before generalizing to the non-Hermitian setting, and then giving several physical interpretations of the results. Next, we study the topology of many-band non-Hermitian systems, and we see the importance of braid-group eigenvalue topology emerge. We provide a complete description of eigenvalue topology in gapped and gapless systems, again using the mathematics of homotopy theory. Finally, we move to scattering systems, where we study a topological feature in the spectrum of the scattering matrix known as a scattering threshold. Here, the scattering matrix has a square-root branch point, and we show that this singularity leads to a universal behavior in a wide variety of physical systems.
Topological Photonic Crystals In One Two And Three Dimensions
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Author : Sachin Vaidya
language : en
Publisher:
Release Date : 2023
Topological Photonic Crystals In One Two And Three Dimensions written by Sachin Vaidya and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023 with categories.
The recent discovery of topological phases of matter has revolutionized our understanding of condensed matter systems. The information that describes these phases is stored across the entire system, and as a result, some of their properties are protected from local perturbations. These systems exhibit unique phenomena such as transport channels that exist on their boundaries and features that are robust to disorder. Topological phases were first discovered in condensed matter physics but the underlying principles were soon extended to many wave systems such as photonic and acoustic systems. The field of topological photonics aims to both realize novel topological phases in photonic systems and develop applications based on their robust properties. This dissertation aims to further our understanding of topological photonics and lies at the intersection between photonic crystals and topological band theory. In the first two parts of this dissertation, we present two studies that experimentally realize charge-2 Weyl points and observe their splitting in three-dimensional chiral woodpile photonic crystals. This is done at technologically-useful infrared wavelengths by using a state-of-the-art 3D micro-printing technique that employs low loss materials. In the next two parts, we focus on developing a complete topological classification of bands in one- and two-dimensional photonic crystals under crystalline symmetries. Based on this classification, we propose a strategy to diagnose and design a wide variety of topological photonic crystals. We then use this framework to show that Chern insulators can have a meaningful notion of relative polarization whose effects can be seen at the boundary between two Chern insulators with the same Chern number. In the last two parts, we explore miscellaneous topics in photonic crystals. In the first of the two parts, we theoretically predict bound states in the continuum that are localized to point defects in two-dimensional photonic crystals. This allows for the confinement of light in the absence of photonic bandgaps. In the last part, we present the observation of a localization transition in one-dimensional photonic quasicrystals. In addition, we observe a surprising phenomenon that occurs in this system, a second transition of some states to a delocalized regime upon further increasing the quasiperiodic disorder.
Glide Symmetric Z2 Magnetic Topological Crystalline Insulators
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Author : Heejae Kim
language : en
Publisher: Springer Nature
Release Date : 2022-01-25
Glide Symmetric Z2 Magnetic Topological Crystalline Insulators written by Heejae Kim and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-01-25 with Computers categories.
This book presents a comprehensive theory on glide-symmetric topological crystalline insulators. Beginning with developing a theory of topological phase transitions between a topological and trivial phase, it derives a formula for topological invariance in a glide-symmetric topological phase when inversion symmetry is added into a system. It also shows that the addition of inversion symmetry drastically simplifies the formula, providing insights into this topological phase, and proposes potential implementations. Lastly, based on the above results, the author establishes a way to design topological photonic crystals. Allowing readers to gain a comprehensive understanding of the glide-symmetric topological crystalline insulators, the book offers a way to produce such a topological phase in various physical systems, such as electronic and photonic systems, in the future.
Non Hermitian Topological Photonics In Coupled Optical Fibre Loops
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Author : Sebastian Weidemann
language : en
Publisher:
Release Date : 2022
Non Hermitian Topological Photonics In Coupled Optical Fibre Loops written by Sebastian Weidemann and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
In this thesis, the interplay between topology, disorder, and dissipation is investigated both theoretically and experimentally. Embedded into the field of non-Hermitian physics, one-dimensional lattice models are studied, which are governed by a Schrödinger equation with a non-Hermitian Hamiltonian. These models are experimentally implemented by means of classical light propagation in coupled optical fibre loops.eng
Topology And Aperiodicity In Engineered Photonic Media
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Author : Jonathan Guglielmon
language : en
Publisher:
Release Date : 2020
Topology And Aperiodicity In Engineered Photonic Media written by Jonathan Guglielmon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The discovery of topological phases of matter represented a significant development in our understanding of condensed matter systems and initiated a new research direction driven by the realization that there exist materials whose properties are deeply connected to concepts from topology. These systems possess a number of unique features, including surface states that are topologically protected and properties that exhibit a surprising robustness to disorder. While these ideas were originally developed in the context of condensed matter systems, research in photonics has shown that some of these ideas have counterparts in photonic systems. This has led to the growth of a field now known as topological photonics, a field driven both by the fundamental goal of realizing topological phenomena in photonic systems and by the applied goal of using the unique features of these systems to develop photonic devices that are robust to fabrication imperfections that can be detrimental to device functionality. In the first two parts of this dissertation, we present two studies which, taken together, connect with both of these goals. We begin by studying the Floquet topological phase diagram of a photonic system consisting of an array of evanescently coupled helical waveguides. The helical waveguide motion effectively makes this a time-periodic, driven system and the parameter space associated with the frequency and amplitude of the driving function leads to a rich Floquet topological phase diagram. We probe this phase diagram by experimentally demonstrating that the drive amplitude can be used to control the chirality of a chiral edge state. This result probes the interplay between topology and driven systems using a highly tunable photonic platform. We then turn to the question of how chiral edge states can be used to improve a specific class of photonic devices: slow-light systems. Slow-light systems are capable of enhancing interactions between light and matter, a feature with a large number of potential applications. Unfortunately, this enhancement comes at the cost of significant backscattering, detrimental Anderson localization, and reduced operating bandwidth. In this dissertation, we theoretically show how chiral edge states can be used to address these problems. In particular, we show how engineering the edge termination of a topological system can produce a chiral edge state that winds many times around the Brillouin zone as it crosses the bulk bandgap, yielding a slow mode that is broadband and robust. In the latter two parts of this dissertation, we study aperiodic photonic structures in the context of two topics: Landau levels and eigenstate localization. These topics are distinct from, but have connections to, topological systems. Landau levels are highly degenerate energy levels that emerge when a charged quantum particle is confined to two dimensions and subject to a strong uniform magnetic field, as in the original realization of the quantum Hall effect. If analogous Landau levels could be realized for light, the high density of states could be used to enhance light-matter interactions. However, photons are charge-neutral particles and therefore do not directly respond to magnetic fields. In this dissertation, we theoretically demonstrate how introducing a periodicity-breaking strain to certain two-dimensional photonic crystals results in the emergence of pseudomagnetic fields that act on light propagating through the strained structures. By suitably engineering the strain, we show that these pseudomagnetic fields give rise to photonic Landau levels. We then consider a different class of aperiodic photonic structures in the context of eigenstate localization. Whereas the first two sections of this dissertation focus on chiral edge states--states which circumvent Anderson localization--in this section, we search for photonic structures with the opposite feature: structures that generate maximally localized eigenstates. We motivate this problem by applications where one wishes to suppress crosstalk in systems of closely packed waveguides. We use numerical optimization techniques to search for optimal structures. We then design a set of analytically constructible, self-similar structures that perform comparably to the numerically optimized structures. We characterize these structures, noting the existence of a localization-delocalization phase transition and studying a family of related periodic structures with increasingly larger unit cells that are able to suppress diffraction at increasingly larger propagation distances.