Wavelength Division Multiplexing, WDM is a technique that multiplexing several signals over a single fiber optic cables by optical carriers of different wavelength, using light from a laser or a LED. According to the number of wavelengths it supports, there are Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM).
CWDM was introduced as a low-cost approach to increasing bandwidth utilization of the fiber infrastructure. By using several wavelengths/colors of the light, 18 channels are viable and defined in the ITU-T standard G.694.2. CWDM systems typically provide 8 wavelengths, separated by 20nm, from 1470nm to 1610nm.
Benefits of CWDM
Passive equipment that uses no electrical power
Extended Temperature Range (0-70C)
Much lower cost per channel than DWDM
Scalability to grow fiber capacity with little or no increased cost
Protocol Transparent
Simple to install and use
Drawbacks of CWDM
16 channels may not be enough
Passive equipment offers no management capacities
DWDM packing WDM channels denser than in CWDM systems, 100 GHz spacing (approx. 0.8nm), more channels and higher capacity can be achieved using DWDM. IUT-T recommendation G.694.1 defines the DWDM channels spectrum. DWDM comes in two different versions: an active solution and a passive solution. An active solution is going to require wavelength management and it a good fit for applications involving more than 32 lines over the same fiber. In most cases, passive DWDM is looked at as a more realistic alternative to active DWDM.
Benefits of DWDM
Up to 32 channels can be done passively
Up to 160 channels with an active solution
Active solutions typically involve optical amplifiers to achieve longer distances
Drawbacks of DWDM
DWDM is very expensive
Active solutions require a lot of set-up and maintenance expense
"Passive" DWDM solution still requires power
Optical Add/Drop Multiplexing (OADM)
By optical add/drop multiplexing techniques, wavelength channels may be added and dropped at intermediate nodes using passive optical components only. Optical Add/Drop Multiplexers are used in WDM Systems for multiplexing and routing fiber optic signals. They can multiplex several low-bandwidth streams of data into a single light beam, and simultaneously, it can drop or remove other low-bandwidth signals from the stream of data and direct them to other network routers. There are CWDM OADM and DWDM OADM.
FiberStore offer a wide range of WDM optical networking products that allow transport of any mix of service from 2Mbps up to 200Gbps. Our highly reliable WDM/CWDM/DWDM products include CWDM
multiplexers and demultiplexer, DWDM Multiplexers and demultiplexers, CWDM & DWDM Optical Add-drop Multiplexer, Filter WDM modules, CATV amplifier, OEO converters as well as many other most demanding CWDM DWDM networking infrastructure equipment.