Investigation of pulse broadening in Gradan optical fibers

Measurements were made of the optical pulse dispersion in Gradan optical fibers having different refractive index profiles. The dependence of the pulse broadening on the waveguide length was also studied. It was established that, for one group of graded-index waveguides, the pulse broadening increased linearly with length (for waveguide lengths of less than 1 km) in agreement with the regular waveguide model. For another group of graded-index waveguides, it was found that as the waveguide parameters varied with length, the pulse broadening with increasing length was slower than that predicted by the regular waveguide model. Response functions and frequency characteristics were obtained for some waveguides. The average pulse dispersion in step-index waveguides was 10 nsec/km, that in graded-index waveguides was 3-4 nsec/km, and in certain samples the average dispersion was less than 1 nsec/km.