The difference between CWDM and DWDM

2017-09-02
With the development of the optical communication industry,new technology and cost-saving solutions are derived.Such as the widely used of CWDM and DWD.Today we learned about CWDM and DWDM.

CWDM is a low-cost WDM transmission technology face to the access layer of metropolitan area network.Saving fiber resources and networking cost.It solves two problems:1.The shortage of optical fiber; 2.Multiservice transparent transmission.Can build the network and conduct business in a short time.
 
Advantages of CWDM:
※The most important is that the cost of the equipment is low.
※ Can reduce the operating costs of Network.
※Can significantly improve the transmission capacity of optical fiber, improve the utilization of fiber resources.
※ Small size and low power consumption.
※ Good flexibility and extendibility.
 
DWDM can combine and transmit different wavelengths at the same time in the same optical fiber.To ensure the efficiency, one optical fiber is converted into a plurality of virtual optical fibers. The application forms of DWDM:open DWDM and integrated DWDM.

Advantages of DWDM:
※Its protocol and transmission speed is irrelevant.
※The OMU and ODU of integrated DWDM are respectively used at the transmitter and the receiver
※ The structure of integrated DWDM is simple and smaller,only about one-fifth of the open DWDM, save room resources
※ Integrated DWDM only use passive components at the transmitter and the receiver(eg:OMU or ODU).Telecom operation unit can order directly from manufacturers to reduce the supply chain,lower costs, save equipment costs.

Both CWDM and DWDM are wavelength division multiplexing, so what are their differences? CWDM(Coarse Wavelength Division Multiplexer)and DWDM(Dense Wavelength Division Multiplexer),their difference is “Dense” and “Coarse”.CWDM is a close relative of DWDM.

Their differences:
1) The spacing of CWDM carrier channel is wider.Only 5 to 6 wavelengths of light wave can be multiplexed on the same optical fiber.
2) CWDM modulated laser uses a non - cooling laser, while DWDM uses a cooling laser.The cooling laser uses temperature tuning, and the non - cooling laser uses electronic tuning.The temperature distribution is very uneven in a very wide wavelength region,so it is very difficult to realize the temperature tuning,and very costly.CWDM avoid this difficulty,and significantly reduces the cost,only 30% of DWDM.So CWDM is very popular in the general business applications providers.Simply said: DWDM is a subdivision of CWDM.

3) The using environment of device is different.CWDM is mainly used in the convergence layer and access layer;DWDM is used in railway communication work environment.

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