Polarization Phenomena in Optical Fibers

Abstract

In ordinary axially-symmetrical single-mode fibers, two mutually-independent orthogonal HE11, modes can be propagated. In the framework of Cartesian coordinates, these are the HE11x mode which has the principal electric field component in the x-direction, and the HE11y, mode which has principally the y- component of the electncfield. We hereafter omit the suffix 11 for simplicity and call these HEx and HEy modes. On the other hand, any linearly-polarized HE11, mode can be expressed as a combination of two circularly-polarized, clockwise and counter-clockwise rotating HE11 modes. Hence, we may equivalently say that in an axially symmetrical fiber, two mutually-independent, circularly-polarized, clockwise and counter-clockwise rotating modes can be propagated. We hereafter call these clockwise and counter-clockwise HE11 modes the HE+ mode and HE− mode.