In the construction of metropolitan area networks, especially for long-distance OTN optical transmission networks, wavelength division multiplexing (WDM) equipment is particularly important.
Dense wavelength division multiplexing (DWDM) equipment has the ability to transmit over long distances with its high bandwidth, while coarse wavelength division multiplexing (CWDM) equipment has lower costs than DWDM.
So， what are the specific differences between DWDM and CWDM? And how do we choose the appropriate WDM equipment to build a cost-effective optical transmission system? This article will answer these questions for you.
1. What is CWDM and DWDM
CWDM is a cost-effective solution for optimizing existing fiber networks by reducing the channel spacing between wavelengths. This passive technology enables the transportation of any protocol over the link, as long as it is at a specific wavelength.
For example, T1 over fiber at 1570nm can transport alongside 10Gbps Ethernet at 1590nm. By using CWDM optical devices, it is possible to increase the bandwidth of existing fiber infrastructure and alleviate fiber exhaustion. CWDM optical devices come in various configurations, such as 4-channel, 8-channel or 16-channel mux/demux modules, as well as add/drop modules.
DWDM aims at increasing the bandwidth of existing fiber networks. It allows combination of data signals from multiple sources over a single pair of optical fibers, while keeping the data streams completely separate.
DWDM uses a tighter wavelength spacing that accommodates more channels on a single fiber. The technology is particularly effective for systems with more than eight active wavelengths per fiber, as it maximizes the utilization of available optical bandwidth.
2. Differs between CWDM and DWDM
CWDM and DWDM optical multiplexing technologies differ in several ways:
CWDM devices have a wider channel spacing of 20nm and can transmit 18 wavelengths in the 1271nm to 1611nm spectrum grid. In contrast, DWDM devices have smaller channel spacing and can transmit 40, 80, or 160 wavelengths.
DWDM devices can transmit over longer distances than CWDM devices due to the highly integrated wavelengths in the fiber. The maximum transmission distance of CWDM devices is typically 160km, while DWDM devices can exceed this range.
CWDM devices have lower technical requirements for their laser systems and can use non-cooled lasers. In contrast, DWDM devices require cooled lasers, which increase energy consumption and system cost but also provide better performance, higher security and longer lifespan.
DWDM devices are typically more expensive than CWDM devices due to their more complex technology and higher energy consumption. However, with the popularity of DWDM technology, DWDM modules’ prices have decreased by 20%-25% compared to CWDM modules.
3. How to Choose： CWDM vs DWDM
When deciding between CWDM and DWDM optical multiplexing equipment, it’s important to consider your network’s specific requirements and scenarios. As the demand for bandwidth continues to increase, DWDM equipment has made significant strides in cost reduction and is gaining popularity in the market. However, for low-speed network construction and short-distance transmissions, CWDM equipment still offers a price advantage and is a more feasible option.
In some cases, a hybrid approach using both CWDM and DWDM equipment also works well. CWDM equipment offers advantages such as lower-cost distributed feedback laser systems and low-priced passive filters, which widely use in DWDM systems. Although using CWDM technology in a DWDM system can save on the cost of optical modules, the larger channel spacing of CWDM can limit the number of available wavelengths, which in turn reduces the system’s transmission capacity compared to a dedicated DWDM system.
Fibconet’s team of professionals can assist you in evaluating the costs and pricing of CWDM and DWDM equipment. Base on your network’s specific needs and requirements, we can provide you with a personalized quote and comprehensive after-sales service to ensure your satisfaction. Contact us today to learn more about our services and how we can help you optimize your optical network.