Analysis on the effects of fiber end face scratches on return loss performance of optical fiber connectors

This paper introduces a novel model for analyzing the optical interface performance degradation due to scratches on optical fiber end face. The model indicates that the contribution to the return loss (RL) of a scratch is determined by its size, location, and its relative reflectivity, which is defined as the ratio of the average reflectivity of the scratch to the base reflectivity of the defectless end face. Based on this new model, the effects on RL are analyzed for scratches of various numbers, different sizes, with different relative reflectivities, and at different locations. This quantified analysis provides a solid base to establish the specifications of inspection criteria of optical fiber connectors. With the new model, the relative reflectivity of a scratch was tested, and estimations of the RL of scratched connectors were performed, which were in good agreement with measurement results.