Abstract
In this paper a technique to measure the distributed birefringence profile along optical fibers is proposed and experimentally validated. The method is based on the spectral correlation between two sets of orthogonally-polarized measurements acquired using a phase-sensitive optical time-domain reflectometer (ϕOTDR). The correlation between the two measured spectra gives a resonance (correlation) peak at a frequency detuning that is proportional to the local refractive index difference between the two orthogonal polarization axes of the fiber. In this way the method enables local phase birefringence measurements at any position along optical fibers, so that any longitudinal fluctuation can be precisely evaluated with metric spatial resolution. The method has been experimentally validated by measuring fibers with low and high birefringence, such as standard single-mode fibers as well as conventional polarization-maintaining fibers. The technique has potential applications in the characterization of optical fibers for telecommunications as well as in distributed optical fiber sensing.
Highlights
Birefringence is a property that can be accidentally or intentionally induced in optical fibers and is characterized by the presence of distinct refractive indices for two given orthogonallypolarized lightwaves propagating in the fiber [1,2,3]
Optical pulses are amplified by an Erbium-doped fiber amplifier (EDFA), followed by a tunable optical filter (TOF) used to suppress the amplified spontaneous emission generated by the optical amplifier
The optimized polarization alignment to the slow and fast axes of the polarization-maintaining fibers (PMF) has been realized as described in the previous section
Summary
Birefringence is a property that can be accidentally or intentionally induced in optical fibers and is characterized by the presence of distinct refractive indices for two given orthogonallypolarized lightwaves propagating in the fiber [1,2,3]. The longitudinal birefringence fluctuations resulting from fabrication are typically small, these can be significantly affected by external factors such as temperature and strain, as well as by bends and twists introduced during cabling and installation processes [1,2]. Currently manufactured single-mode fibers (SMF) show low levels of birefringence (e.g. Δn ~10−7), small random fluctuations in the core circularity along the fiber (and in the fiber birefringence) can lead to undesired changes in the state of polarization of the propagating light [2,3]. Some short fiber sections can abnormally show large birefringence, being a crucial factor on scaling polarization-mode dispersion (PMD) [1,4], which can significantly distort optical signals and limit the performance of high-speed optical communications systems, especially over long distances
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
