Coupling Characteristics Of Step Index Holey Fiber

Coupling characteristics of dual-core step index holey fiber couplers are analyzed by a vectorial beam propagation method in conjunction with the finite element method. Here we considered the two cores to be separated by a distance d. The proposed structure exhibits a very simple geometry, and each fiber that composes the coupler is obtained through the inclusion of a very small air radius hole at the core of one conventional step index fiber. The introduction of the small air hole produces an ultra-flattened chromatic dispersion in the fiber. © 2007 IEEE.245249J. P. da Silva, V. F. Rodríguez-Esquerre and H. E. Hernández-Figueroa, Step Index holey fiber for ultra-flattened chromatic dispersion,OSA/Integrated Photonics Research Symposium, IPR 2006, V. 1, pp. 1-4, Connecticut/USA, 2006Correia, D., Rodríguez-Esquerre, V.F., Hernández-Figueroa, H.E., Genetic-algorithm and finite-element approach to the synthesis of dispersion-flattened fiber (2001) Microwave and Opt. Technol. Lett, 31, pp. 245-248Saitoh, K., Florous, N., Koshiba, M., Ultra-flattened chromatic dispersion controllability using a defected-core photonic crystal fiber with low confinement losses (2005) Opt. Express, 13, pp. 8365-8371H. E. Hernández- Figueroa, F. A Fernández, Y. Lu and J. B. Davies, Vectorial finite element modelling of 2D leaky waveguides, IEEE Trans. Magn. 31, 1710-1712, (1995)Correia, D., da Silva, J.P., Hernández-Figueroa, H.E., Genetic Algorithm and Finite-Element Design of Short Single-Section Passive Polarization Converter (2003) IEEE Photonics Technol. Lett, 15, pp. 915-917da Silva, J.P., Hernández-Figueroa, H.E., Frasson, A.M.F., Vectorial finite-element BPM analysis for transverse anisotropic media (2003) J. Lightwave Technol, 21, pp. 567-576Fleming, J.W., Material dispersion in lightguide glasses (1978) Electron. Lett, 14, pp. 326-328Nguyen, H.C., Kuhlmey, B., Steel, M.J., Smith, C., Magi, E., McPhedran, R.C., Eggleton, B., Leakage of the fundamental mode in photonic crystal fiber tapers (2005) Opt. Lett, 30, pp. 1123-112

2D Analysis of Multimode Photonic Crystal Resonant Cavities with the Finite Volume Time Domain Method

In this paper an accurate analysis of two-dimensional (2D) Photonic Crystal (PhC) based multimode resonant cavities is carried out. The analysis is performed with a robust and accurate Finite Volume Time Domain (FVTD) technique. The analysis proves the ability of the FVTD method to extract different resonant modes from a multimode PhC resonant cavity with the use of appropriate source profiles. A detailed explanation on how the source is engineered and used to excite different modes is given. Furthermore, parameters such as resonant frequency and quality factor for each resonant mode are accurately calculated

Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion?

Necrotrophic pathogens cause major pre- and post-harvest diseases in numerous agronomic and horticultural crops inflicting significant economic losses. In contrast to biotrophs, obligate plant parasites that infect and feed on living cells, necrotrophs promote the destruction of host cells to feed on their contents. This difference underpins the divergent pathogenesis strategies and plant immune responses to biotrophic and necrotrophic infections. This chapter focuses on Arabidopsis immunity to necrotrophic pathogens. The strategies of infection, virulence and suppression of host defenses recruited by necrotrophs and the variation in host resistance mechanisms are highlighted. The multiplicity of intraspecific virulence factors and species diversity in necrotrophic organisms corresponds to variations in host resistance strategies. Resistance to host-specific necrotophs is monogenic whereas defense against broad host necrotrophs is complex, requiring the involvement of many genes and pathways for full resistance. Mechanisms and components of immunity such as the role of plant hormones, secondary metabolites, and pathogenesis proteins are presented. We will discuss the current state of knowledge of Arabidopsis immune responses to necrotrophic pathogens, the interactions of these responses with other defense pathways, and contemplate on the directions of future research