Topological photonics is a rapidly emerging field of research in which geometrical and topological ideas are exploited to design and control the behavior of light. Drawing inspiration from the discovery of the quantum Hall effects and topological insulators in condensed matter, recent advances have shown how to engineer analogous effects also for photons, leading to remarkable phenomena such as the robust unidirectional propagation of light, which hold great promise for applications. Thanks to the flexibility and diversity of photonics systems, this field is also opening up new opportunities to realize exotic topological models and to probe and exploit topological effects in new ways. This article reviews experimental and theoretical developments in topological photonics across a wide range of experimental platforms, including photonic crystals, waveguides, metamaterials, cavities, optomechanics, silicon photonics, and circuit QED. A discussion of how changing the dimensionality and symmetries of photonics systems has allowed for the realization of different topological phases is offered, and progress in understanding the interplay of topology with non-Hermitian effects, such as dissipation, is reviewed. As an exciting perspective, topological photonics can be combined with optical nonlinearities, leading toward new collective phenomena and novel strongly correlated states of light, such as an analog of the fractional quantum Hall effect.

Topological Photonics

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

The importance of the Fano resonance concept is recognized across multiple fields of physics. In this Review, Fano resonance is explored in the context of optics, with particular emphasis on dielectric nanostructures and metasurfaces. Rapid progress in photonics and nanotechnology brings many examples of resonant optical phenomena associated with the physics of Fano resonances, with applications in optical switching and sensing. For successful design of photonic devices, it is important to gain deep insight into different resonant phenomena and understand their connection. Here, we review a broad range of resonant electromagnetic effects by using two effective coupled oscillators, including the Fano resonance, electromagnetically induced transparency, Kerker and Borrmann effects, and parity–time symmetry breaking. We discuss how to introduce the Fano parameter for describing a transition between two seemingly different spectroscopic signatures associated with asymmetric Fano and symmetric Lorentzian shapes. We also review the recent results on Fano resonances in dielectric nanostructures and metasurfaces.

Fano resonances in photonics

Transformation optics describes the capability to design the path of light waves almost at will through the use of metamaterials that control effective materials properties on a subwavelength scale. In this review, the physics and applications of transformation optics are discussed.

Transformation optics and metamaterials

We demonstrate theoretically that Fano resonance can induce a negative optical scattering force acting on plasmonic nanoparticles in the visible light spectrum when an appropriate manipulating laser beam is adopted. Under the illumination of a zeroth-order Bessel beam, the plasmonic nanoparticle at its Fano resonance exhibits a much stronger forward scattering than backward scattering and consequently leads to a net longitudinal backward optical scattering force, termed Fano resonance-induced negative optical scattering force. The extinction spectra obtained based on the Mie theory show that the Fano resonance arises from the interference of simultaneously excited multipoles, which can be either a broad electric dipole mode and a narrow electric quadrupole mode, or a quadrupole and an octupole mode mediated by the broad electric dipole. Such Fano resonance-induced negative optical scattering force is demonstrated to occur for core–shell, homogeneous, and hollow metallic particles and can therefore be expe...

Fano Resonance-Induced Negative Optical Scattering Force on Plasmonic Nanoparticles

We demonstrate a sharply asymmetric reflection in a geometrically symmetric magnetic metamaterial (MM) system, which originates from the coupling of electromagnetic (EM) wave to magnetic surface plasmon resonance states and the broken time reversal symmetry in MM. Based on this effect, we have designed unidirectional EM waveguide, wave bender, and beam splitter. Our simulations indicate that the designs possess the merits of robustness against strong defect and disorder, controllability with an external magnetic field, in addition to the finite working bandwidth and the high transmission efficiency.

Magnetically controllable unidirectional electromagnetic waveguiding devices designed with metamaterials

Dynamical and phase-diagram study on stable optical pulling force in Bessel beams

We demonstrated a construction of negative-index material (NIM) with epsilon(eff)=mu(eff)=-1 employing ferrites only, with no metallic components. Our design of the NIM is motivated by recent coherent potential approximation results and corroborated by exact numerical calculation demonstrating the negative refraction of an electromagnetic beam, with equal incident and refraction angles, as well as by the slab imaging phenomena, with the source-image separation twice as the slab thickness. The ferrite only based scheme furnishes the fabricated NIM with magnetically tunable working frequency, less loss and the air-matched wave impedance.

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Manipulating Negative-Refractive Behavior with a Magnetic Field

Bartol Research Institute, University of Delaware, Newark, Delaware 19716, USA(Dated: May 8, 2008)We identify diﬀerent types of the photonic band gaps (PBGs) of two dimensional magnetic pho-tonic crystals (MPCs) consisting of arrays of magnetic cylinders and study the diﬀerent tunability(by an external static magnetic ﬁeld) of these PBGs One type of the band gaps comes from in-ﬁnitely degenerate ﬂat bands and is closely related to those in the study of plasmonics In addition,such PBGs are magnetically tunable and robust against position disorder We calcualte the trans-mission of the PBG’s and found excellent agreement with the results of the photonic band structurecalculation Positional disorder of the lattice structure aﬀects the diﬀerent types of PBGs diﬀerently

Shiyang Liu

Papers

Fano Resonance-Induced Negative Optical Scattering Force on Plasmonic Nanoparticles

Magnetically controllable unidirectional electromagnetic waveguiding devices designed with metamaterials

Dynamical and phase-diagram study on stable optical pulling force in Bessel beams

Manipulating Negative-Refractive Behavior with a Magnetic Field

Formation of robust and completely tunable resonant photonic band gaps