A simple refractive index measurement method for step-index fiber based on radial displacement optical power scan

Abstract

In this paper, a novel method for measuring the refractive index of single-mode step-index fiber based on radial displacement optical power scan is proposed. The radial displacement optical power curves of different fibers have different bending degrees and a r parameter is used to characterize the bending degree of the radial displacement optical power curve. The r–n polynomial formulas of different core diameters are obtained via beam propagation method, which are used for the calculation of the fiber refractive index. As proof of principle, two commercial single-mode step-index fibers were measured experimentally. Simulation results reveal that the refractive index measurement error is within ±0.0003. The measurement formulas of optical fiber refractive index are given by simulation and the measuring range is 6.0 to 10μm with an interval of 0.5μm. This method has the advantages of low cost, convenient operation, and can be used under laboratory conditions.