Polarization-maintaining fibers and their applications are reviewed. The classification of high-birefringent fibers and low-birefringent fibers and their fabrication methods and characteristics are discussed in Section II. Analytical methods and numerical methods for fiber design on the birefringence are presented in Section III. Degradation factors of polarization maintenance expressed as crosstalk or mode-coupling parameters caused by internal origins such as structural imperfections, wavelength, and nonlinear effects, and by external origins such as temperature fluctuations, mechanical perturbations, and electromagnetic effects, are discussed in Section IV. Characterization methods on beat length, mode coupling, stress distribution, and mechanical strength are presented in Section V. Applications to the fiber devices and nonlinear effects, and splicing methods for the polarization-maintaining fibers are described in Sections VI and VII.

Polarization-maintaining fibers and their applications

Polarization mode dispersion (PMD) in short and long single-mode fibers was measured by a polarization-maintaining Michelson interferometer. A nonnegligible PMD was found in some standard fibers. The sensitivity enables PMD to measure the bend-induced PMD of a fiber rolled on a 28-cm diameter drum. A theoretical model for PMD with random mode coupling is developed, and an explicit equation for the time-of-flight distribution is presented. Comparison between measurements on short and long fibers with residual birefringence leads to an estimation of the coupling length on the order of 20-30 m. >

Polarization mode dispersion of short and long single-mode fibers

The polarization properties of single-mode optical fibers are easily modified by environmental factors. While this can be exploited in a number of fiber sensor devices, it can be troublesome in applications where a stable output polarization-state is required. Fibers with both low and high birefringence have been developed to enhance or diminish their environmental sensitivity, and recent progress in each area is reviewed. Low-birefringence fibers are described which are made by spinning the preform during the draw. In addition, developments in high-birefringence fibers which maintain a polarization state over long lengths are summarized. The effect on performance of external factors such as bends, transverse pressure, and twists is analyzed. Consideration is also given to polarization mode-dispersion as a potential limiting factor in ultrahigh bandwidth systems.

Development of low- and high-birefringence optical fibers

Development of Low- and High-Birefringence Optical Fibers

In this Letter a new method is proposed for measuring the beat length of linearly birefringent optical fibers. In this method the beat length is determined from the wavelength dependence of the phase difference between two orthogonally polarized HE(11) modes at the output end of a sample fiber. The important feature of this method is the wide range of the measurable beat length (0.4 mm-1 m:) The principle, the experimental setup, and the result of the experiment are described.

Wavelength-sweeping technique for measuring the beat length of linearly birefringent optical fibers

A simple method is described for the determination of the modal birefringence in single-mode fibres. Measurement of the state of polarisation for various twist rates on a straight short-length fibre give the birefringence ?s and the elasto-optic coefficient g. Linearly or circularly polarised input light can be used. The measurement range spreads from 10 to 1040/m. Comparisons are made with previously reported methods.

Birefringence measurement in twisted single-mode fibres

A frequency domain determination of polarisation mode dispersion in single mode fibres is described, which allows one to obtain directly the group delay difference for long fibres. The results of such measurements are shown on a birefringent fibre with elliptical cross-section which maintains an extinction ratio between linearly polarised eigenstates greater than 10 dB over 1 km.

Polarisation mode dispersion measurements in long single mode fibres

Monomode fibres have been spliced with a CO2 laser. The average splice loss for 50 splices was 0.18 dB. The average breaking stress of the splices was 1 GPa. Splice loss lower than 0.4 dB was possible with bad fibre ends (breaking angle about 4°) or with core eccentricity as large as 4 μm.

P. Lamouler

Papers

Birefringence measurement in twisted single-mode fibres

Polarisation mode dispersion measurements in long single mode fibres

Monomode fibre fusion splicing with CO2 laser