In WDM technology, there are CWDM coarse wavelength division multiplexing technology and DWDM dense wavelength division multiplexing technology. Literally, these two technologies have different degrees of density in a band, but there are still many practical technologies and applications. difference.

①The wavelength interval is different

The CWDM carrier channel spacing is wider and each band is 20nm apart, so only about 8 to 16 wavelengths can be multiplexed on the same fiber, while the DWDM carrier channel spacing is relatively narrow, with 0.2nm, 0.4nm, 0.8nm between each band , 1.6nm, 80 to 160 wavelengths can be multiplexed, the difference between "sparse" and "dense" titles comes from this;

②The wavelength range is different

The working wavelength range of CWDM is between 1270nm-1610nm, while the working wavelength of DWDM is a part of CWDM, and there are two bands of 1525nm-1565nm (C band) and 1570nm-1610nm (L band);

③The cost of the device is different

CWDM modulated lasers use uncooled lasers, while DWDMs use cooled lasers. Cooled lasers are temperature tuned and uncooled lasers are electronically tuned. Due to the uneven temperature distribution in a wavelength range, temperature tuning is very difficult and expensive to implement. Therefore, the cost of DWDM is much higher than that of CWDM technology;

④Application difference

DWDM optical modules can complete the transmission tasks of long-distance and large-capacity long-distance trunk networks. Some large-capacity metropolitan area network core nodes, telecom 5G, 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, and it is 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 the user's cost of upgrading the network;

⑤Different wavelength division multiplexers/demultiplexers

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.

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