Upon detection of a fiber break, the optical amplifier at the fiber break point is shut down to prevent the intensive optical power from injuring the maintenance personnel.
Figure 1 shows how to achieve the IPA function. When there is a fiber break on the line, the amplifier 3 and 1 are shut down. Then all the downstream optical amplifiers have no optical power output due to the amplifier
feature.
When the optical signals are restored to normal, the optical amplifier will work again. And the amplifier 3 and 1 will be restarted.
