Among the WDM technologies, there are CWDM coarse wavelength division multiplexing technology and DWDM dense wavelength division multiplexing technology. These two technologies not only have different densities in one band, but also have great differences in actual technology and application.
CWDM carrier channel spacing is wide, each band interval 20nm, therefore, the same optical fiber can only reuse about 8 to 16 wavelengths, while DWDM carrier channel spacing is relatively narrow, each band interval has 0.2nm, 0.4nm, 0.8nm, 1.6nm, can reuse 80 to 160wavelengths, which leads to the difference between "sparse" and "dense" terms.
The working wavelength range of CWDM is between 1270nm-1610nm, while the working wavelength of DWDM is selected in CWDM. There are two bands: 1525nm-1565nm (C band), 1570nm-1610nm (L band).
DWDM optical module can complete long-distance, large-capacity long-distance trunk network transmission tasks, some large-capacity metropolitan area network core nodes, telecom 5G, metropolitan area network, backbone network, some data centers will also be applied to DWDM optical modules and equipment. Compared with DWDM,CWDM, the cost will be much lower, mainly used in man access layer, enterprise network, campus network and so on. CWDM data center optical transceiver is widely used, which greatly saves users' cost of upgrading the network. 5 wavelength division multiplexer / demultiplexer is different.
CWDM optical module needs to be used with CWDM wavelength division multiplexer and CWDM demultiplexer to achieve transmission, while DWDM optical module needs to be used with DWDM wavelength division multiplexer and DWDM demultiplexer.
The CWDM modulated laser uses an uncooled laser, while the DWDM uses a cooled laser.
Temperature tuning is used for cooling laser and electronic tuning is used for non-cooling laser.
Because the temperature distribution is very uneven in a wavelength range, the temperature tuning is very difficult and the cost is very high.
Therefore, the cost of DWDM is much higher than that of CWDM technology.