Birefringence for Elliptical-Core Fibers with Low Ellipticities

Miami A Mohammed

doi:10.30526/35.1.2798

Abstract

Model birefringence was measured for elliptical-core fibers with low ellipticities, note the birefringence depends strongly on the frequency, especially when fiber is being operated near the higher mode cutoff where ν for circular fiber of the single-mode type that correspond to the birefringence maximum. When ν this also correspond to the birefringence maximum that can be introduced in an elliptical core fiber while still operating in the single-mode regime near the higher mode cutoff. Also the birefringence is proportional to the fiber core ellipticity when core ellipticity is much less than unity, but this birefringence deviates from the linear for the large core ellipticities.

Highlights

The possibility of using polarization-sensitive components in optical systems based on single–mode fiber waveguides accounts for the great interest that elliptic fibers are attracting .Ellipticity of the core cross section is on of the main imperfections in real optical fibers, which frequency lifts the degeneracy between the two main orthogonally polarized modes of an ideal circular fiber end give rise to birefringence .In the case when specific polarization characteristics of optical waveguides are achieved by geometric effects it would be of interest to study other axially asymmetric fibers, and to investigate more fully the phenomenon of mode birefringence of elliptic fibers[1]
Figure 4show the phase difference as a function of normalized frequency for various valuesof ellipticity core(0.185,0.227,0.37,0.45,0.77) and index different between core and cladding (∆=2.3× 10−3), this birefringence depends strongly on the frequency or ν value. These graphs demonstrate that when the parameters of elliptic fiber vary only within the limits of the single –mode fiber regime, the maximum δβ near 2< ν < 2.4 at which the single -mode fiber is being operated near the high mode cutoff are considered (ν≈2.4 for step –index fiber)
For value ν slight greater than 2.4 this is typical of elliptic fibers with small ellipticity of the core, while still near the limit of the single-mode regime, the difference between the group velocity is zero and the dispersion of a signal transmitted by a single –mode fiber with the parameters for this range is minimal .in this range modal birefringence is close to its maximum value

Summary

Introduction

The possibility of using polarization-sensitive components in optical systems based on single–mode fiber waveguides accounts for the great interest that elliptic fibers are attracting .Ellipticity of the core cross section is on of the main imperfections in real optical fibers, which frequency lifts the degeneracy between the two main orthogonally polarized modes of an ideal circular fiber end give rise to birefringence .In the case when specific polarization characteristics of optical waveguides are achieved by geometric effects it would be of interest to study other axially asymmetric fibers, and to investigate more fully the phenomenon of mode birefringence of elliptic fibers[1]. In addition to the manufacture of asymmetric structures to increase the birefringence in the fiber through thermal stress that occurs during the manufacturing process, this results in a high birefringence in the fiber for all guided spatial modes, which can be used in the multiplexinput transmission system. in the same year, two types of fibers with semi-circular holes were designed in the Sagnac ring, where the design is designed to coincide with torsion, malleability and temperature. This new combination of fibers results in a high sensitivity to torsion-induced binary breakage at a certain temperature. Typical single- mode fibersare found to have a period of a few centimeters

EllipticalCore Fibers

Experimental Part

Results and Discussion

Conclusion