An interferometric technique for measuring the refractive index profile of a graded index optical fiber

Precise measurement of refractive index profile of an optical fiber is crucial for the measurement of different characteristics, such as the signal bandwidth of the fiber. We present a simple and inexpensive method for mapping the refractive index profile of an optical fiber. This method uses an interferometric technique to map the refractive index profile of a fiber. Comparing the index profile simulated theoretically with the experimental one, the difference between the refractive index of clad and that at the center of core for a graded index fiber was found to be 0.018. This technique also enables one to determine whether the fiber is a step index fiber or a graded index fiber