An analytical study of modal dispersion characteristics of helically clad crystal-cored optical fiber

The uniaxial crystal cored optical fiber, with optical axis parallel to the fiber axis, having helical cladding is proposed and a characteristic equation is derived. Employing helical boundary conditions, the characteristic equation is found and dispersion curves are drawn for different K-co (the ratio of longitudinal and transverse refractive index) values and for different modal order nu. The field components in the core region of the proposed fiber are found and a curve between effective-index vs. normalized frequency is drawn. Our studies show that the anisotropic parameter (K-co) influences the dispersion characteristics and modal cut-offs and the modal grouping occurs at different V number for different K-co values. It is also observed that the helix pitch angle psi has no any pronounced effect on propagation characteristics of the proposed fiber. (C) 2012 Elsevier GmbH. All rights reserved.