Mode coupling at arc-fusion splices in graded-index fibers

Mode coupling at an arc-fusion splice has been investigated theoretically and experimentally. It has been certified experimentally that fiber parameters change at an arc-fusion splice. A mode transfer matrix has been derived which describes mode coupling at splices with fiber parameter changes along the fiber axis. The mode-coupling effects on the frequency response of spliced graded-index fibers have been investigated. Length dependence of 3 dB bandwidth has been measured for 10 km long graded-index fiber both with and without a splice. It has been clarified that the mode-coupling effect at the splice broadens the 3 dB bandwidth by 10 percent in the long fiber link in comparison with that for the fiber without a splice.