There are CWDM coarse wavelength division multiplexing technology and DWDM dense wavelength division multiplexing technology in WDM technology. The two technologies have been specifically mentioned in the previous article. From a literal point of view, these two technologies are different in the density of a band. , But the actual technology and application are still very different.

① Different wavelength intervals
The CWDM carrier channel spacing is wider, and each band is separated by 20nm. Therefore, only 8 to 16 wavelengths can be multiplexed on the same optical fiber, while the DWDM carrier channel spacing is relatively narrow, with 0.2nm, 0.4nm, and 0.8nm intervals in each band. , 1.6nm, can reuse 80 to 160 wavelengths, the difference between "sparse" and "dense" names comes from this;

②Different wavelength ranges
The working wavelength range of CWDM is between 1270nm-1610nm, and the working wavelength of DWDM is selected in CWDM, there are 1525nm-1565nm (C band) 1570nm-1610nm (L band) these two bands;

③Different device costs
CWDM modulated laser uses uncooled laser, while DWDM uses cooled laser. The cooled laser uses temperature tuning, and the uncooled laser uses electronic tuning. Due to the uneven temperature distribution in a wavelength range, temperature tuning is very difficult to achieve, and the cost is also high. Therefore, the cost of DWDM is much higher than CWDM technology;

④ Application difference
DWDM optical modules can complete long-distance, large-capacity long-distance trunk network transmission tasks. Some large-capacity metropolitan area network core nodes, telecommunications, metropolitan area networks, backbone networks, and some data centers will also be applied to DWDM optical modules and equipment. Compared with DWDM, the cost of CWDM will be much lower, mainly used in the access layer of the metropolitan area network, enterprise network, campus network, etc. CWDM optical modules are widely used, which greatly saves users’ network upgrade costs;

⑤Wave division multiplexer/demultiplexer is different
CWDM optical modules need to be used with CWDM wavelength division multiplexers and CWDM demultiplexers to achieve transmission, while DWDM optical modules need to be used with DWDM wavelength division multiplexers and DWDM demultiplexers.