Fault Location on Optical Amplifier Submarine Transmission Systems.

This paper addresses some solutions to overcome the problems that arise which optical time domain reflectometry (OTDR) is applied to optical amplifier submarine transmission systems. It designs a backscatter path that feeds the backscattering into the opposite line without causing any degradation in the main signal transmission. This paper proposes a new modulation format, FSKASK, and confirms that the proposed approach can both eliminate optical surge generation and improve OTDR performance. An FSK-ASK OTDR is applied to an 890- km commercial amplifier submarine transmission system with a 90-km span. Field trials successfully demonstrate that the OTDR can locate a fault in all spans with a spatial resolution of 1 km after averaging the sum of 2²⁰ measurements. The FSK-ASK OTDR proves to be very useful in maintaining a reliable submarine transmission system because it can locate subtle fiber anomalies along the entire length from a terminal end. [ABSTRACT FROM AUTHOR]