CWDM coarse wavelength division multiplexing technology and DWDM dense wavelength division multiplexing technology are both applications of WDM. The two are similar in principle, but there are great differences in some specific characteristics and application scenarios to meet the needs of different application scenarios.

WDM, is wavelength division multiplexing, is a communication technology that combines a series of optical signals carrying information but with different wavelengths into one beam and transmits it along a single optical fiber; at the receiving end, the optical signals of different wavelengths are separated by some method. This technology can transmit multiple signals on one optical fiber at the same time, and each signal is transmitted by a certain wavelength of light, which is a wavelength channel. The application of WDM technology has completely changed the data transmission mode. WDM has greatly enhanced the data carrying capacity, greatly improved the utilization rate of optical fiber, minimized the requirement for a large amount of wiring, effectively reduced costs, and made it a key technology for seeking high-capacity, cost-effective data transmission infrastructure.

As mentioned above, both CWDM and DWDM are derived from wavelength division multiplexing technology, but they differ in wavelength mode and usage scenarios. CWDM is a low-cost WDM transmission technology for the access layer of metropolitan area networks. The most important advantage of CWDM is its low equipment cost. DWDM can achieve large-capacity data transmission on existing optical fiber technology facilities, avoiding the cost and complexity of laying new optical fibers, and is widely used in the field of optical communications, such as optical fiber backbone networks, optical fiber access networks, and data centers.