First Mile Access Networks and Enabling Technologies

Coarse Wavelength-Division Multiplexing

CWDM per se is multiplexing multiple optical signals in the same fiber by using the property of wavelength domain diversity. We have multiple signals each at some distance (in terms of wavelength) from each other, and these signals are multiplexed together in the same fiber. Unlike in DWDM where multiple signals are packed with each signal at a relatively short spacing from its adjacent neighbors, in CWDM the signals have a larger spacing (relative to DWDM), hence relaxing the optical requirements.

In a commercial DWDM system, the channel spacing as defined by the International Telecommunications Union (ITU) is 0.8 nm, or 1.6 nm typical, with some implementations of 0.4 nm also seen. Because so many channels ...