Papers by Keyword: Photonic Crystal (PC)

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Authors: Chien Jang Wu, Ya Ju Lee, Tzu Chyang King, Wen Kai Kuo
Abstract: A design of multichannel transmission filter at microwave is proposed. It is based on the use of the finite plasma photonic crystal operating at frequency below the plasma frequency. We consider a design structures of (AB)qA, where A is the dielectric material, B is the plasma layer, and q is the number of periods. It is found that the number of channels is equal to q-1. We show that the locations such multiple channels are in the pass band of the infinite plasma-dielectric photonic crystal. The idea of such design is thus to engineer the photonic pass band, which is fundamentally different from the usual design by engineering the photonic stop band like the multilayer Fabry-Perot transmission filter. The physical mechanism of multiple channels is also discussed.
Authors: Ying Hu, Gui Qiang Liu, Xiang Nan Zhang, Zheng Jie Ca
Abstract: In this paper, a channel drop filter (CDF) is composed of two cubic lattice circular ring resonator cavities and point micro-cavities in a two-dimensional photonic crystal. The photonic band gap is calculated using the plane wave expansion (PWE) method and the optical characteristics of proposed structure are studying by the finite difference time domain (FDTD) method with perfectly matched layers (PMLs) acting as the boundary conditions . Two different wavelengths centered at 1773 nm and 1742 nm have been successful separation in this CDF. These demonstrate that our proposed structure is suitable for photonic integrated circuits (PICs) and coarse wavelength division multiplexing (WDM) optical communication systems.
Authors: Xiang Nan Zhang, Gui Qiang Liu, Ying Hu, Zheng Jie Cai, Yuan Hao Che
Abstract: We design a new two-sided coupling channel drop filter (CDF) based on a two-dimensional (2D) photonic crystal (PC). Three channels formed by line defects for light propagation, two L4 resonators positioned at both sides of the input waveguide for light coupling, and one point defect micro-cavity in the bus waveguide for wavelength-selective reflection are introduced into the PC structure. The optical characteristics of this proposed structure are calculated by finite-difference time-domain (FDTD) method combined with the perfectly matched layers (PMLs) as the boundary conditions. Three wavelengths centered at 1550, 1575 and 1610 nm within the limit of communication windows are successfully separated in three channels by adjusting the size of coupling rods and the positions of L4 resonators and micro-cavity. High transmission efficiency and more than 20 nm channel spacing are achieved. These demonstrate that our proposed structure is suitable for photonic integrated circuits (PICs) and coarse wavelength division multiplexing (WDM) optical communication systems.
Authors: Guo Yan Dong, Xiu Lun Yang, Xiang Feng Meng
Abstract: Zero phase delay of electromagnetic wave (EMW) transmission can be realized based on the wavefront modulation of photonic crystals (PhCs). When the phase velocity is controlled perpendicular to the group velocity with wavefronts (or phasefronts) parallel to the direction of energy flow, the phase will keep constant in transmission process despite of the increase of propagating length. The phase different between the incident and transmitted waves is measured to demonstrate that the phase can remain invariable in PhCs instead of zero-index materials or zero-averaged-index PhC superlattices. This effect can be extended to other artificially engineered materials, and will open a new route to obtain perfect zero-phase delay propagation for EMW.
Authors: Pei Liu, Xiao Song Zhang, Chuan Zhen Xin, Meng Zhen Li, Lan Li
Abstract: In this research, a triangular two-dimensional (2D) photonic crystal (PC) was hypothetically introduced into the active layer of a PbS quantum dots (QDs) electroluminescent (EL) device. The attributes of the photonic band gap effect and diffraction effect were considered and evaluated for device performance improvement. We designed and optimized the 2D-PC structure parameters to enhance the emission intensity at wavelength 1124 nm. The optimal structure parameter of PC is determined by normalized radius of r/a=0.49 and lattice constant of a=540 nm when the thickness of PC slab h is 74 nm. The 3D stimulation view of light propagation validates and supports the proposed strategy. The results provide a theoretical prediction for ideal PbS QDs-based EL device.
Authors: Guo Hua Wen, Zheng Biao Ouyang
Abstract: A new type of two-dimensional square-lattice photonic crystal structure made of rotated square cylinders and cross thin plates is presented and numerically investigated using the plane-wave expansion method. The largest absolute photonic bandgap (APBG) reaches 14.3%. The proposed structure can have promising application for its large APBG and convenience in designing optical circuits.
Authors: Jin Xia Gao, Ji Jiang Wu
Abstract: One-dimensional dielectric photonic crystals (PCs) with complex substitutional defect layers, consisting of superconducting (SC) and dielectric sublayers are theoretically studied. The influence of the incidence angle on the photonic gap spectra is theoretically analyzed. The pronounced difference in the transmittivity spectra of the PCs with right-handed (RH) and left-handed (LH) positions of the superconducting defect sublayer with respect to the dielectric defect sublayer is demonstrated. It is observed that, for the case of RH SC defect sublayer, the position of the defect mode and the transmittivity at the defect mode frequency strongly depend on the thickness of the superconducting sublayer as well as on the temperature. But the defect modes of the PCs with LH SC defect sublayer are nearly invariant upon the change of the thickness of the superconducting sublayer and the temperature.
Authors: T. Chantakit, S. Kamoldilok, K. Srinuanjan, P.P. Yupapin
Abstract: The effective numerical aperture calculation in two-dimensional Photonic crystal waveguide has been proposed. In this paper we present the analysis of ray optics refracted inside nanorods and at the boundaries between rods, which separates rod gap is much smaller than the incident wavelength assumed to reflect on the region. In operation, the resolving numerical aperture was compared with the finite difference time domain method via OptiFDTD software. Although numerical aperture mentioned above was found to be extremely close to fiber optics, a transmission passes though compartments of the rods are observed due to significant estimation of transmission and reflection of electric field. The compared simulation results will be discussed. By the aforementioned is that in the near future we will modify wave equation in periodic media of waveguide structures reached to the transverse electric equation of beam propagation in the two-dimensional Photonic crystal waveguide analysed.
Authors: Guo Yan Dong, Ji Zhou
Abstract: Anomalous optical transmission phenomena have ever been discovered in various metamaterials, which can be modulated more easily in Photonic crystals (PhCs). Compared with the regular PhCs composed of round rods closely packed in air, the equal frequency contours (EFC) of honeycomb lattice PhCs constituted by trigonal rods are more rounded and more suitable to realize the all-angle left-handed negative refraction (AALNR) in the low band region. Due to the hex EFC distribution, the regular PhC can be applied in the optical collimator design. In the higher band regions, the more complicated refraction behaviors can be excited based on the intricate undulation of one band or the overlap of different bands in PhCs. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.
Authors: Guo Yan Dong, Ji Zhou
Abstract: Due to the existence of photonic bandgap derived from the periodical dielectric structure in wavelength scale, many novel optical phenomena can be demonstrated in photonic crystals (PhCs). Anomalous propagation of electromagnetic waves in X-band is demonstrated experimentally in a two-dimensional triangular lattice PhC. The experimental measurements of electric field are carried out in a near-field scanning system. The phenomena of anomalous refractions are observed and analyzed in respect of anisotropy of equal frequency surfaces in the PhC. The analysis results of numerical simulation are compared with the experimental measurements and good agreements are obtained.
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