Abstract
An indirect measurement technique for Raman gain efficiency distribution along the transmission line based on the OTDR is proposed. Our proposed technique is a novel and simple technique for estimating Raman gain efficiency distribution by utilizing the relationship between Raman gain coefficient and relative-index difference for the GeO_2-doped core fibers. Measurement experiments of Raman gain efficiency are made on the optical transmission line composed of four 3-km long single-mode fibers and our present technique is compared with the technique using a pump light. Furthermore, our technique is applied to the optical fiber cables installed in the field, and their Raman gain efficiency distributions are successfully estimated.
