Photonic Band Gap Materials: Light Control at Will




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Light Transportation in 1D Periodical and Disordered Structures Made of Single-Negative Metamaterials



Hong Chen

1 Pohl Institute of Solid State Physics, Tongji University,

Shanghai 200092, P. R. China


Abstract


Much interesting has been attracted recently on metamaterials for their unusual properties of manipulating photons. There are mainly two kinds of metamaterials: double-negative materials (DNMs) with simultaneously negative pernittivity ε<0 and negative permeability (μ<0); and single-negative metamaterials (SNMs) with ε<0 and μ>0 (ε-negative metamaterials (ENMs)), or ε>0 and μ<0 (μ-negative metamaterials (MNMs)). Contrasted to propagating modes in usual materials and DNM, SNMs are opaque and support only evanescent modes, leading to novel effects on light transportation. Our recent studies show that the light tunneling, instead of the light scattering, plays important role in 1D photonic crystals made of ENM and MNM. Our main results are: (1) There exits a “spatially-average-single-negative” (SASN) gap whose edges correspond to zero (volume) averaged permittivity ( ) and zero (volume) averaged permeability ( ), and the SASN gap is invariant to the geometrical scaling and insensitive to the incident angle and disorder. (2) The SASN gap and light tunneling in a heterostructure made of ENM and MNM are observed experimentally in microwave regime. (3) Completely transparency induced by resonant tunneling in 1D disordered structures made of SNMs are studied theoretically and experimentally, and a scheme to engineer necklace states in 1D disordered systems is proposed.


This research was supported by CNKBRSF (grant 2006CB921701), by CNSF (grant 10634050 and 10704055), by the Program for Key Basic Research of the Shanghai Science and Technology Committee (grant 08dj1400301).


Magneto-Optical Photonic Crystals: Tunability and Time-Reversal Symmetry Breaking



Zhi-Yuan Li, Rong-Juan Liu, and Jin-Xin Fu

Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences,Beijing 100190, China

Tel:010-82648106, E¬-mail:lizy@aphy.iphy.ac.cn


Abstract

Photonic crystals can manipulate powerfully the transport of photons through photonic band gaps, defect states, and unique dispersion properties. Magnetic materials exhibit interesting magneto-optical effects. Magneto-optical photonic crystals can bring the two classes of unique effects together, open new windows for controlling light propagation behaviors, and offer a platform to explore some fundamental physical problems. Several optical devices have been proposed and investigated, such as one-way waveguides, optical isolators, optical circulators, tunable negative refraction and superprism devices, and so on. In this talk we will report our recent progress of experimental and theoretical studies on magneto-optical photonic crystals made from dielectric alumina materials, metallic materials, and magneto-optic materials of YIG (yttrium-iron-garnet) in the microwave regimes.

In particular we will discuss three topics: (1) Tunability of original band gaps under dc magnetic field, which arises due to change of the permeability tensor of YIG; (2) Breaking down of the structure-symmetry induced intrinsic degeneracy of photonic bands and opening of a new band gap by external magnetic field; (c) Breaking down of the time-reversal symmetry by magnetic field, which leads to one-way propagation of electromagnetic waves. Such one-way wave-guiding behaviors can be controlled by designing different types of defects into the magneto-optical photonic crystals.


New phenomena around Dirac point in two-dimensional photonic crystal



Xiangdong Zhang

Department of Physics, Beijing Normal University, Beijing 100875, China

zhangxd@bnu.edu.cn


Abstract


A new transport regime of electromagnetic wave in two-dimensional photonic crystal near the Dirac point has been demonstrated by exact numerical simulation. In this regime, the conductance of photon is inversely proportional to the thickness of sample, which can be described by Dirac equation very well. Based on it, we have investigated dynamic behavior of photon transport around the Dirac point. Some unusual beating effects, which can be regarded as optical analogue to Zitterbewegung of relativistic electron, have been observed by exact numerical simulation. Zitterbewegung represents an oscillatory motion of free electrons described by the Dirac equation in the absence of external fields, which is caused by the interference between the positive and negative energy states. It was believed that the experimental observation of the effect is impossible since one would confine the electron to a scale of the Compton wavelength. Here we have found that such a phenomenon for photons can be observed by measuring the time dependence of the transmission coefficient through photonic crystal slabs. Thus, it is particularly suited for experimentally observing this effect. Such a phenomenon has been observed experimentally for acoustic wave in 2D sonic crystal. The other related phenomena of wave transport around the Dirac point in two-dimensional photonic crystal will be also discussed.


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