Measurement of birefringence and ellipticity of polarization eigenmodes in spun highly birefringent fibers using spectral interferometry and lateral point-force method.

We show that the spectral interferometry method and the lateral point-force method used up to now to measure spectral dependence of the group and the phase modal birefringence in highly birefringent fibers with linearly polarized eigenmodes, can be after some modifications extended for the class of spun highly birefringent fibers with elliptically polarized modes. By combining the two methods, it is possible to determine spectral dependence of the group and phase elliptical birefringence in spun highly birefringent fibers. Moreover, if the fiber spin pitch is independently measured, the spectral dependence of ellipticity angle of polarization eigenmodes as well as the built-in linear phase and group birefringence, can be also obtained using the analytical relations between the parameters of spun and non-spun fibers. We demonstrate the effectiveness of the proposed approach in spectral measurements (700-1600 nm) of the spun side-hole and microstructured highly birefringent fibers with different birefringence dispersion and spin pitches ranging from 4.1 to 200 mm.