CWDM VS DWDM
WDM systems are divided into different wavelength patterns:
CWDM (Multiplexing Division Wavelength Division) and DWDM (Multiplexing Division Division).
There are many differences between CWDM and DWDM: distances, DFB lasers and transmission distances.
The channel distance between individual wavelengths transmitted over the same fiber serves as the basis for defining CWDM and DWDM.
Typically, the distance in CWDM systems is 20 nm, while most DWDM systems today offer a wavelength difference of 0.8 nm (100 GHz) according to the ITU standard.
Due to the wider CWDM focal length, the number of channels (lambdas) in a link is significantly reduced, but the optical interface components do not have to be as accurate as the DWDM components.
Therefore, CWDM equipment is significantly cheaper than DWDM equipment.
Both CWDM and DWDM architectures use DFB (Distributed Feedback Lasers).
However, CWDM systems use DFB lasers that do not cool down.
These systems typically operate from 0 to 70% and the laser wavelength in this range is about 6 nm. With a laser wavelength of up to ± 3 nm, the wavelength drift causes a longitudinal wavelength change of about ± 12 nm.
DWDM systems, on the other hand, require cooler DFB lasers because the semiconductor laser wavelength drops from about 0.08 nm / ℃ at room temperature.
DFB lasers are cooled as temperature in DWDM systems to neutralize wavelengths from outside the scattering band of multiple devices and demultiplexer filters.
Due to the unique features of CWDM and DWDM, they are deployed for different transmission distances. Typically, CWDM can travel up to 160 km anywhere.
If we need to transmit data over a long distance, a DWDM system is the best choice.
DWDM supports wavelengths of 1550 nm, which can be extended to hundreds of kilometers for transmission distances.
Result
WDM works by combining and splitting signals across systems ranging from telecommunications systems to imaging systems.
There are many WDM products, including CWDM MUX / DEMUX, DWDM MUX / DEMUX, CWDM and DWDM optical plug-ins, WDM filters and so on.
From the introduction of WDM above, you can better understand "What is WDM", "Why we need WDM as well as the benefits of WDM, mode and applications."
