1,721,132 research outputs found
Empirical formulas for calculating loss in hollow core tube lattice fibers
Get PDFIn this paper scaling laws governing loss in hollow core tube lattice fibers are numerically investigated and discussed. Moreover, by starting from the analysis of the obtained numerical results, empirical formulas for the estimation of the minimum values of confinement loss, absorption loss, and surface scattering loss inside the transmission band are obtained. The proposed formulas show a good accuracy for fibers designed for applications ranging from THz to ultra violet band
Confinement losses in honeycomb fibers
No full textThe confinement losses in honeycomb photonic bandgap fibers are numerically investigated by means of the finite element method. Honeycomb fibers with both an extra hole and a low refractive index region as defects are considered. It is shown that by means of a proper design, confinement losses lower than 0.1 dB/km at λ=1.55 μm can be obtained with four hole rings
Numerical analysis of plastic hollow core microstructured fiber for Terahertz applications
No full textPropagation loss and dispersion characteristics of a hollow core microstructured fiber in the THz regime are numerically investigated. The fiber cladding consists of a triangular lattice formed by a periodic arrangement of dielectric tubes of Teflon. Numerical results show that guidance mechanism is the sameof kagome and square lattice fibers. Low loss and low dispersion frequency ranges can be tuned just by changing the thickness of the tubes irrespectively of their diameter. Propagation loss four decades lower than the bulk absorption and dispersion lower 0.03 ps/(nm km) can be obtained over a band of about 1.7 THz centered at 2.1 THz
Single-mode propagation in triangular tube lattice hollow-core terahertz fibers
No full textThe mode properties of hollow-core fibers with a cladding formed by a periodic arrangement of dielectric tubes in a triangular lattice for THz applications are numerically investigated. The fiber supports a high number of modes. Effectively single-mode operation can be obtain by reducing the core size, but at the expense of high fundamental mode propagation loss. Single-mode propagation can be obtained by exciting the fiber with a linear polarized gaussian beam with proper spot size
Hollow core photonic band gap fiber for THz applications
No full textIn this article, a hollow core photonic band gap fiber is numerically investigated to obtain low-loss waveguiding in the terahertz region (0.1-10 THz) of the electromagnetic spectrum. Waveguide design in this spectral region is an arduous challenge due to the high-conductivity losses of metals and high-absorption of the dielectrics. Numerical results show the possibility to reach propagation loss two decades lower than the bulk absorption losses of the material used to fabricate the fiber, and low dispersion over a wide range of wavelength
Confinement Loss in Kagome and Tube Lattice Fibers: Comparison and Analysis
No full textIn this paper, a thorough numerical analysis of the confinement loss in kagome and tube lattice fibers is presented. The results show that the confinement loss strongly depends on the shape of the struts composing the core boundary and the cladding. This explains why confinement loss in kagome fibers is much higher than in tube lattice ones. In fact, the closer to a perfectly circular arc the struts, the lower the confinement loss. For this reason, struts shape must be carefully controlled during the fabrication process
Comparison of the Jones Matrix Analytical Models Applied to Optical System Affected by High-Order PMD
No full textAbstract—The analytical models for the Jones matrix of anoptical fiber affected by high-order polarization-mode dispersion(PMD) are studied in an original comparative analysis with thepurpose of finding a useful, precise, and stable tool for the systemperformance evaluation. First, a preliminary deterministic studyis done to explain how the conceptual difference among the modelsreflects onto their representation of the fiber PMD effects interms of Jones matrix coefficients and dispersion vector. Then, theanalytical models with PMD up to third order are exploited forthe calculation of the outage probability on the sensitivity penaltyat the receiver, and the results obtained are compared with thoseof the discrete random wave-plate numerical model, assumed as afaithful description of the real fiber. Two different approaches areused for the outage probability evaluation: an analytical method,which is precise and faster but can only be used with PMDparameters up to second order, and a semi-analytical methodthat allows a comparison of the numerical and analytical resultswith homogeneity, when the statistics of high-order PMD arenot known. The analytical model, which describes the dispersionvector as rotating on a circumference in the Stokes space, is foundto be the most accurate in the system performance computation
Elliptical hollow core tube lattice fibers for terahertz applications
No full textHollow core microstructured fibers whose cladding is composed by an elliptical arrangement of circular dielectric tubes are numerically investigated. Birefringence, differential group delay, and polarization dependent loss are evaluated for different values of ellipticity in order to quantify its effect on the two polarizations of the fundamental core mode. All these parameters have a minimum at the center of each transmission window and they assume maximum values at the edges. In particular, the birefringence goes always to zero irrespective of ellipticity. This proves that tube lattice fibers are strongly immune against unwanted core shape deformation, in particular when the working frequency is close to the center of the transmission windows. On the other hand they are not suitable to obtain polarization maintaining fibers
Numerical Analysis of Propagating and Radiating Properties of Hollow Core Photonic Band Gap Fibres for THz Applications
No full textHollow core photonic bandgap fibres (HC-PBGFs) are numerically investigated in order to obtain low loss wave-guiding and good aperture field distribution in the terahertz region (0.1-10 THz) of the electromagnetic spectrum. The purity of the aperture field distribution at the HC-PBGF section combined with low loss propagation and high coupling efficiency with free-space propagating Gaussian beams suggest a possible employment of such a structure as aperture antennas, for possible feed systems in THz applications and in THz wireless sensing
Analytical estimation of confinement loss in tube lattice fibers
No full textIn this work, we propose an analytical formula for estimating confinement loss in Tube Lattice Fibers. The formula is based on a single-tube model and the comparison with numerical simulations of three TLFs designed to work in the UV, NIR, and THz spectral ranges shows good agreement
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