Polarization behavior of spun fiber versus conventional fiber under strong slight twisting

In this article, the authors attempt to treat both strong twisting and slight twisting of fiber via a consistent asymptotic approach to the coupled‐mode theory. In strong twisting, an admirably simple and useful asymptotic equation is derived in the form R 2 τ = const., which relates the minimum required twist rate τ with the minimum allowable radius of curvature R. In slight twisting, an oscillatory pattern of the polarization behavior clearly reveals the advantageous feature of a twist‐spun fiber, which is made by a prior spinning of the fiber before a twisting. © 1995 John Wiley & Sons, Inc.