The FBG reflector is a standard SC type connector structure, which package a special FBG in the ceramic ferrule. The fiber bragg grating reflector is a low-cost specific band reflector mounted on the optical network unit (ONU) side. It can reflect light pulses (1650 +/- 5 nm) from the OTDR on the fiber line terminal (OLT) side nearly 100%, while the working bands of the passive optical network (PON) are transmitted normally. The OTDR can determine whether the fiber line is normal by detecting the signal reflected by the fiber grating reflector. When the reflected signal is lower than the normal value, the line loss is too large; when the reflection value is 0, the optical fiber line is broken. Therefore, we can maintain the fiber line in time by the real-time monitoring of the fiber line. Talk to us