In recent years, photoelectric composite submarine line has become popular in the field of power transmission and data communication. The new type of line, which combines with optical cables and power lines, transmits electricity and data, saving costs and reducing construction times. It is favored in applications such as offshore transmission and communications across the sea. With the increasingly important role of the photoelectric composite sea cable, the safety protection of the composite submarine cable is highlighted.

As a concealed project, the submarine line is limited by the installation and the landing mode. The ambient temperature is not uniform. With the increasing of marine development activities, mechanical damage to submarine line caused by aquaculture, fishing nets and anchors in the sea area has occurred often. Seawater corrading, erosion and other factors are likely to cause the water-blocking performance of the submarine lines to deteriorate and insulation aging, causing leakage currents, which causes the temperature at the fault point to rise, resulting in breakdown failures and huge economic losses. Seriously affect the safe operation of submarine lines. Online monitoring of the temperature of the lines, especially the submarine line connector and the sea-land line joints, will be an important measure to ensure the healthy operation of the lines.

Distributed optical fiber temperature & strain sensing system provides a simple and effective solution for the protection of photoelectric composite submarine lines. Using optical fiber as sensing unit, combining with advanced distributed optical fiber sensing technology, so that the protection of submarine cables can be completed without re-construction, which is of great significance to ensure the safety of submarine lines in engineering.