In a twin-core optical fiber a propagating light pulse periodically transfers power between its two cores. Experiments by Tjugiarto et al. [Opt. Lett. 17, 1058 (1992)] have demonstrated that this coupling length is considerably reduced when the fiber is also spun. A coupled-mode analysis reveals a pitch resonance that couples a cladding mode with the circularly polarized core mode whose handedness matches that of the helical twist of the cores. This resonance mechanism explains the observation of enhanced coupling and claddingmode cross coupling.
© 1996 Optical Society of America
J. Nathan Kutz and David J. Muraki, "Enhanced power transfer and mode coupling in spun twin-core optical fibers," Opt. Lett. 21, 863-865 (1996)