Measurements of Excitation Condition and Quantitative Mode Analysis in Optical Fibers

The purpose of this paper is to describe an accurate method for determining the modal-power distribution along optical fibers and also to present a technique for measuring the launching conditions produced by an input laser beam. Experimental results demonstrate both the accuracy and the effectiveness of those methods for investigating the transmission characteristics of optical waveguides. Various factors having an important influence upon the accuracy are discussed, and appropriate methods for minimizing the systematic errors also are presented.