1. Test whether the optical power is within the required range of the index. If there is no light or the optical power is small，there are three basic approaches：
A. Check the wavelength and measurement unit (dBm) selected by the optical power.
B. Clean the end face of the optical fiber connector and the optical port of the optical module
C. Check whether the end face of the optical fiber connector is black and scratched, whether the optical fiber connector is broken, and replace the optical fiber connector for interchangeability test.
D. Check the optical fiber connector for small bends.
E. Re-plug test of Hot-pluggable optical module.
F. Replace the optical module on the same port or the same optical module.
2. The optical power is normal but the link fails, in this case, you need to check the link light.
When using optical modules, we should know how to use correctly to avoid damage.