A DWDM wavelength division multiplexer, or any WDM wavelength division multiplexer, enables you to take advantage of other resources such as wavelength spectrum. DWDM wavelength division multiplexing is used for long-distance high-capacity transmission. The commonly used DWDM equipment is DWDM multiplexer, there are also DWDM SFP and DWDM SFP+ optical modules.
If the requirements are met, there can be one high-speed interface, multiple low-speed interfaces running in parallel in a WDM system, or two high-speed interfaces running in parallel on most compact WDMs. We benefit a lot from DWDM technology, but do you know the drawbacks?
DWDM wavelength division multiplexing is very complex and expensive
However, if you have limited fiber and you need the bandwidth that DWDM provides, it may be more economical than the alternative of overbuilding fiber optic cables. Before planning and designing a DWDM system, a good characterization study of existing fibers and paths is highly recommended.
Sometimes this information can be obtained from installation tests, but over time the information may change with new constructions, repositioning, splicing, etc. PMD (Polarization Mode Dispersion) is a dynamic factor in fiber optic equipment that also needs to be addressed in DWDM path calculations.
DWDM wavelength division multiplexing requires high-quality optics and well-cooled and stable lasers
DWDM wavelength division multiplexing requires keeping all signals in a specific frequency band. Since different wavelengths of light have different properties in fiber optic cables, the two most useful bands are used in fiber optic cables. Also, it depends on the amplifier, as it is not easy to make an amplifier that can amplify a large range of the spectrum without introducing other problems or noise.
DWDM wavelength division multiplexing is inherently more complex than separate quartz glass and parallel links because multiple signals share a single fiber, mix them together and split them again. As a result, the cost is higher, the power is higher, and the optics in filters and other components are loose, making it harder to diagnose the problem.
DWDM wavelength division multiplexing network is not a flexible network
For the flexibility of a DWDM network, an expensive ROADM (Reconfigurable OADM) is required. High loss, with attenuation around 10 dB in some cases.
Compared to DWDM wavelength division multiplexing, CWDM wavelength division multiplexing is easier to use and less expensive, but has less wave number and bandwidth. It takes some good financial and traffic planning to figure out what's best for your needs. A CWDM multiplexer gives you a cheaper multiplexing scheme but has more restrictions on distance etc.
In less demanding situations, CWDM wavelength division multiplexing can be used. A larger spectral area is occupied, and a larger spectral range is used for each channel. Meaning it can be produced with cheaper components. But the trade-off is distance and maximum utilization of spectrum.
In short, the choice of DWDM or CWDM wavelength division multiplexing technology depends on the specific application scenario.
