ON THE FIELD PATTERNS OF HELICAL CLAD DIELECTRIC OPTICAL FIBERS

Abstract

An analytical investigation of the lightwave propagation through dielectric optical fibers with helical clads is presented with the emphasis on their hybrid field patterns. The helical clad section is effectively realized by introducing conducting windings on the core-clad boundary. Using Maxwell’s equations, a rigorous analytical approach is implemented to determine the higher order field patterns in such fibers. For simplicity, two particular values of the helix pitch angle are considered, viz. 0◦ and 90◦. The nature of fields is presented in both the situations corresponding to different allowed values of the propagation constants and the fiber diameters. The radial distributions of fields corresponding to hybrid modes are presented under different situations, which exhibit the patterns like spikes. The observed smooth match of the fields at the core-clad interface validates of our analytical approach. The presence of a little higher amount of field in the fiber clad section is essentially attributed to the helical windings introduced over the fiber core. Further, the existence of considerable amount of evanescent waves in such fibers opens up the possibility of their applications in optical sensing.