wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths of laser light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity.
In the application of optical fiber communication system, we often encounter a problem, the quality of optical fiber insertion loss is large, which causes the optical module to fail to work or to cause packet loss. So we will use the optical amplifier to amplify the optical signal at this time.
