LP(01)-LP(02) interference using a spectrally extended light source: measurement of the non-step-refractive-index profile of optical fibers

Simultaneous dispersion measurements of multiple fiber modes using virtual reference interferometry

We present the simultaneous measurement of first and second order dispersion in short length (< 1 m) few mode fibers (polarization and transverse) using virtual reference interferometry. This technique generates results equivalent to balanced spectral interferometry, without the complexity associated with physical balancing. This is achieved by simulating a virtual reference with a group delay equal to that of the physical interferometer. The amplitude modulation that results from mixing the interferograms, generated in both the unbalanced interferometer and the virtual reference, is equivalent to the first order interference that would be produced by physical balancing. The advantages of the technique include speed, simplicity, convenience and the capability for simultaneous measurement of multiple modes. The theoretical framework is first developed and then verified experimentally.

Direct deflection method for determining refractive-index profiles of polymer optical fiber preforms

We present a method for determining the refractive-index profile of polymer optical fiber preforms through a direct-deflection measurement. The method is simple to use, compact, and has good resolution. The profile is obtained from the deflection data by numerically integrating the differential-ray equation for a radial refractive-index gradient. Corrections for topographical deviations are also discussed. Results for both graded-index and step-index fibers are presented.

Four-wave mixing in non-step-index optical fibers: a sensitive technique for measurement of refractive-index profiles

Investigation of four-wave mixing 6.4-mum core-diameter fiber with 520-610-nm pump light is used to develop a new technique for characterizing the refractive-index profiles of non-step-index fibers. Deviation from the step-index profile is measured. Small variations in the refractive index between different segments of the same commercial fiber is measured with a sensitivity of 0.0001.