Birefringence and polarization characteristics of single-mode optical fibers under elastic deformations

Abstract

Birefringence and polarization dispersion caused by: 1) elliptical core, 2) twist, 3) pure bending, 4) transverse pressure, and 5) axial tension are studied by treating these deformations as perturbations to step-index single-mode fiber with a round core. These effects ate formulated in terms of fiber structure and perturbation parameters and are compared comprehensively. Birefringence depends strongly on factors 1)-4), while polarization dispersion depends on factors 1), 3), and 4). Polarization performance of twisted elliptical core fibers was also studied. Twist in an elliptical core fiber gives rise to a polarization whose major axis points in an intrinsic direction with an azimuthal angle <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\phi_{t}z</tex> , where φ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</inf> is the torsion per unit length and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</tex> is the fiber length.