1610nm DFB Laser Pigtail. A Coherent Optical Time Domain Reflectometer (COTDR) provides dB vs. km attenuation traces of amplified (repeatered) line systems over the entire length of the submarine cable. A submarine optical Fiber Pair (FP) is tested by launching a test signal in transmit (Tx) direction fiber.
A fiber pair is tested by launching a test signal into the out going fiber and receiving the scattered light on the in-coming fiber. Light scattered in the transmission fiber is coupled to the incoming fiber in the loop-back couplers in each amplifier pair in a repeater.
