Transmission characteristics of circular and elliptical helically cladded optical fibers – A comparative analysis

• Waves in twisted clad complex structured circular and elliptical fibers are analyzed.
• Exact forms of field functions are considered for elliptical fibers.
• Angle of helix pitch plays determining role for wave sustainment in fiber structures.
• Variations of confinement patterns are studied for the aforesaid two fiber types.
• Helix pitch affects more to the elliptical fiber than the circular one.

Lightwave propagation through complex structured optical fibers, viz. twisted clad fibers with circular as well as elliptical cross-sections, are taken into account. Twists in the fiber are considered in the form of conducting sheath helix structures introduced at the core–clad interface. Wave propagation in such fibers can be controlled by suitably adjusting the helix pitch angle – the prime motivation of this work, which is tuned to emphasize on the power confinement patterns (or the fractional modal power) of these on a comparative platform. Taking into account a few low-order hybrid modes, variations of confinement are studied for the aforesaid two fiber types in respect of changes in the helix pitch angle. The obtained results indicate profound impact of introducing the helical structure – the feature that would find potential technological applications. Furthermore, helical clad elliptical fibers are found to be more responsive than the circular ones in terms of the variations in pitch angle.