Fast and direct measurement of the linear birefringence profile in standard single-mode optical fibers.

Luis Costa,Hugo Martins,Luca Palmieri,Sonia Martin-Lopez,Miguel Gonzalez-Herraez,María R Fernández-Ruiz,Regina Magalhães

doi:10.1364/ol.382559

Abstract

Phase birefringence in optical fibers typically fluctuates over their length due to geometrical imperfections induced from the drawing process or during installation. Currently commercially available fibers exhibit remarkably low birefringence, prompting a high standard for characterization methods. In this work, we detail a method that uses chirped-pulse phase-sensitive optical time-domain reflectometry to directly measure position-resolved linear birefringence of single-mode optical fibers. The technique is suitable for fiber characterization over lengths of tens of kilometers, relying on a fast measurement ($ {\sim} 1\,\, {\rm s} $∼1s) with single-ended access to the fiber. The proposed method is experimentally validated with three different commercial single-mode optical fibers.

Highlights

Single-mode optical fibers consist of circularly symmetric waveguides with isotropic material properties and no preferential orientation for the electric field
Imperfections in the geometry arising during the drawing process, and elasto-optic effects induced during cabling/installation, induce local anisotropies and asymmetries that manifest as birefringence. This translates into polarization mode dispersion (PMD), which is a limiting factor for long-haul, high-bit-rate connections in modern communication links
Distributed characterization of birefringence is achieved by either techniques relying on indirect estimation or those based on direct measurements

Summary

Introduction

Single-mode optical fibers consist of circularly symmetric waveguides with isotropic material properties and no preferential orientation for the electric field. Techniques based on φOTDR measure changes in the optical path across a section of fiber spanning half the probe pulse width, by measuring the interference resulting from light that is elastically backscattered by intrinsic inhomogeneities within the fiber (hereby referred to as scatterers). The presented method directly recovers the birefringence spatial profile of state-of-theart single-mode optical fibers with high sensitivity, over long lengths, and in a short measurement time (∼1 s).

Results

Conclusion