What is WDM

WDM is short for Wavelength Division Multiplexing. WDM is a fundamental passive optical component for optical system. Through one WDM can multiplex different wavelengths of light over a single, installed multimode network to add bandwidth.
Based on its special physical feature, for example, a fused dual-channel WDM will be able to double the data transmission bandwidth at very low cost. Also, WDM offers an attractive solution to increasing LAN bandwidth without disturbing the existing embedded fiber, which populates most buildings and campuses, and continue to be the cable of choice for the near future. The technology makes flexible and efficient planning of optical networks possible for satellite, broadcast, instrumentation and signal distribution. In general, This technology offers particular benefits when installing new channel capacity into a pre-existing fiber network with a fixed number of fiber cores in the backbone. it allows to expanding the capacity of your network without laying more fibre and having to recondition all network.
WDM systems are divided into different wavelength patterns – Coarse WDM (CWDM) and Dense WDM (DWDM).
It is possible to combine 2, 4 or 8 separate signals onto a single fiber wether using the WDM or CWDM.


Products are available from 1310nm/1550nm WDM duplexers up to ITU-T G.694.2 compliant 8-channel CWDM multiplexers and demultiplexers.  
CWDM (Coarse Wavelength-division Multiplexing) allows eight or fewer channels to be stacked in the 1550 nm region of optical fiber, the C-Band.
DWDM (Dense Wavelength-division Multiplexing) is able to transmit many of closely spaced wavelengths in the 1550 nm region over a single optical fiber. Wavelength spacings are usually 100 GHz or 200 GHz.
DWDM makes use of cooled laser technology and extends the transmission distances. Since DWDM provides greater maximum capacity and tends to be used at a higher level in the communications hierarchy than CWDM. CWDM is a robust technology and is typically used for Metropolitan Area Networks or WANs for distances up to 120kms. The creation of GBIC and small form factor pluggable (SFP) transceivers utilizing standardized CWDM wavelengths allows something very close to a seamless upgrade in even legacy systems that support GBIC/SFP interfaces. Due to a flexible and future-proof CWDM system, Costs have been optimized, network performance and capacity have been improved, usually mean a return of investment in a few months – operating costs on fibre leasing are reduced by 80%.