Brillouin optical time domain reflectometry for estimating loss and crosstalk at the splice point in few-mode fibers

Abstract

We propose a technique using Brillouin optical time domain reflectometry for estimating the loss and crosstalk at a splice point in few-mode fibers. The technique measures the splice loss of a fundamental mode using a feature where the Brillouin gain spectrum differs depending on the mode. Then, the splice loss of the higher-order mode and the modal crosstalk at the splice point are estimated from the measured loss of the fundamental mode. We reveal the feasibility of our technique in a comparison of the experimental results with the numerically calculated ones. The fiber under test we used was two mode fibers with a graded-index profile. We found that the splice loss of the LP01 mode can be yielded by measuring the splice loss under the condition that the scattered light of the LP01 mode becomes larger than that of other modes. Moreover, we determined that the loss and crosstalk of the LP11 mode could be yielded using the measured loss of the LP01 mode and the approximate expression of the mode coupling coefficient at the splice point.