Receivers are low stressed devices and highly reliable. But the electronics behind them can fail. If there is receiver power but no communications, a loopback test to see if the receiver is working is the best test of its status. Summary Fiber optic networks are tested in a similar manner to any other network, but require specialized FO test equipment. Care must be taken to keep all components clean, since dirt on any opticalsurface will cause loss.
Improper connections are one of the major problems.
Testing and tracing with a visual tracer or fault locator will help connect all fibers properly. Networks specify end to end loss specifications to include the connectors on the end, so a double-ended loss test is required. When troubleshooting, receiver power is the first thing to test. Then work back toward the transmitter, segment by segment. Many transcievers can be tested with optical loopbacks to verify proper operation.