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

Graphene plasmons were predicted to possess ultra-strong field confinement and very low damping at the same time, enabling new classes of devices for deep subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. While all of these great prospects require low damping, thus far strong plasmon damping was observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this letter we exploit near-field microscopy to image propagating plasmons in high quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine dispersion and particularly plasmon damping in real space. We find unprecedented low plasmon damping combined with strong field confinement, and identify the main damping channels as intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key for the development of graphene nano-photonic and nano-optoelectronic devices.

Highly confined low-loss plasmons in graphene-boron nitride heterostructures

We describe the history, guiding mechanism, recent advances, applications, and future prospects for hollow-core negative curvature fibers. We first review one-dimensional slab waveguides, two-dimensional annular core fibers, and negative curvature tube lattice fibers to illustrate the inhibited coupling guiding mechanism. Antiresonance in the glass at the core boundary and a wavenumber mismatch between the core and cladding modes inhibit coupling between the modes and have led to remarkably low loss in negative curvature fibers. We also summarize recent advances in negative curvature fibers that improve the performance of the fibers, including negative curvature that increases confinement, gaps between tubes that increase confinement and bandwidth, additional tubes that decrease mode coupling, tube structures that suppress higher-order modes, nested tubes that increase guidance, and tube parameters that decrease bend loss. Recent applications of negative curvature fibers are also presented, including mid-infrared fiber lasers, micromachining, and surgical procedures. At the end, we discuss the future prospects for negative curvature fibers.

Negative curvature fibers

종격동 종양 및 낭종 27례에 대한 임상적 고찰

The application of topology in optics has led to a new paradigm in developing photonic devices with robust properties against disorder Although considerable progress on topological phenomena has been achieved in the classical domain, the realization of strong light-matter coupling in the quantum domain remains unexplored We demonstrate a strong interface between single quantum emitters and topological photonic states Our approach creates robust counterpropagating edge states at the boundary of two distinct topological photonic crystals We demonstrate the chiral emission of a quantum emitter into these modes and establish their robustness against sharp bends This approach may enable the development of quantum optics devices with built-in protection, with potential applications in quantum simulation and sensing

A topological quantum optics interface

An ultralow bending-loss trench-assisted single-mode optical fiber is designed and fabricated in this letter. The experimental results show that the fiber can support an ultralow bending loss of 0.05 dB/turn at a sharp bend radius of 5 mm at 1550 nm. This letter is considered to be of significance for the design and fabrication of bend insensitive fibers (BIFs), specifically for verifying the value of trench-assisted BIF designs. Furthermore, the fast growth of fiber-to-the-home applications will benefit from this letter.

Ultralow Bending-Loss Trench-Assisted Single-Mode Optical Fibers

A compact multifunctional fiber sensor for simultaneous underwater measurement of salinity, temperature and strain

Magnetic resonators based on metamaterials are valuable for numerous applications including perfect absorber, sensing and medical imaging. However, due to the existence of the difficulty in magnetic excitation in planar metasurface, the study of magnetic metamaterial resonators is less reported, particularly in contrast to the electrical resonators. In this paper, the three-dimensional split ring resonator (SRR) metamaterials featuring dual-band magnetic plasmonic resonance modes are proposed and numerically analyzed. We calculate the electromagnetic field distributions of the three-dimensional metamaterials at the resonant frequencies to elucidate the resonant characteristics of the dual modes (fundamental LC mode and high-order magnetic plasmonic resonance mode). The influences of geometric parameters of the constituent meta-atoms on the resonance frequencies of the two resonance modes are analyzed by numerical calculations. The results show that the resonance frequency of the high-order magnetic resonance mode is nearly independent of the standing columns of the metamaterials owing to the special resonant characteristic of the high-order mode. Benefiting from the independence, the frequency interval between the dual modes can be customized by adjusting the dimensions of the column. In addition, by tuning the dimension of the columns, the quality factors of the resonances can reach the highest value of 176 for LC mode and 270 for the high-order mode, respectively. In light of practical application, we evaluate refractive index sensing performance of the proposed metamaterials, the maximum sensitivity can reach 474 GHz/RIU for LC mode and 446 GHz/RIU for high-order resonance, respectively. We also explore the universality of the special resonant characteristic of the high-order mode in other similar three-dimension SRR metamaterials, which shows all of these three-dimension magnetic plasmonic metamaterials provide potential platforms for multiband magnetic metamaterial applications.

/pdf/numerical-analysis-of-magnetic-plasmonic-resonance-modes-in-1c15qqyv3n.pdf

Numerical Analysis of Magnetic Plasmonic Resonance Modes in Three-Dimension Split Ring Resonator Metamaterials

Novel few-mode optical fibers create an exciting opportunity for achieving very high transmission capacity and channel density. By introducing air-holes and employing elliptical ring core shape, the degeneracy of a mode group can be splitted, leading to large separation between two adjacent modes. Based on this idea, we report two kinds of air-holes assisted elliptical ring core fibers, each of which can support 10 (or even more) distinct polarization-maintaining modes over a broad wavelength range of 1.51–1.63 µm. The proposed fibers might be promising candidates for mode-division multiplexing system.

Polarization-Maintaining Few-Mode Optical Fibers with Air-Hole Structures

We present a single-mode multilayer-core fiber with a large mode
area (LMA) and a low bending loss in this Letter. A low equivalent
core-cladding refractive index difference is achieved by exploiting the
multilayer structure. The multilayer structure has a better bending
performance than a traditional step-index core and this structure also
contributes to realizing different curved refractive index profiles that
have a better bending performance. An index trench is also introduced to
dramatically reduce the bending loss. The experimental results show that,
at a wavelength of 1550 nm, the mode area of the fabricated fiber is about
215.5 μm2 and the bending loss is 0.58 dB/turn at a 10 mm
bending radius. The LMA and excellent bending performance can be obtained
simultaneously with the proposed fiber.

Haisu Li

Papers

Ultralow Bending-Loss Trench-Assisted Single-Mode Optical Fibers

A compact multifunctional fiber sensor for simultaneous underwater measurement of salinity, temperature and strain

Numerical Analysis of Magnetic Plasmonic Resonance Modes in Three-Dimension Split Ring Resonator Metamaterials

Polarization-Maintaining Few-Mode Optical Fibers with Air-Hole Structures

Multilayer-core fiber with a large mode area and a low bending loss