Introduction to WDM
Wavelength Division Multiplexing (WDM) technology multiplies fiber capacity by multiplexing optical light signals of different wavelengths onto a single optical fiber. The technology is well standardized in the ITU G.695 and G.694 recommendations and widely used in datacom and telecom networks.
Due to the physical nature of light, the signals on WDM wavelengths are completely independent from each other and data streams with different line-rates and protocols can be transported on a single fiber or fiber pair. Traditional telecom signals (PDH, SDH/SONET), IP data (Ethernet, Gigabit Ethernet or 10G Ethernet) and storage data (8G/4G/2G/1G Fibre Channel) can therefore be transported over a single infrastructure without complex protocol conversion technologies. To build a passive WDM system, two types of components are required:
• Optical Multiplexer Units (OMU’s) which combine and split light signals of WDM wavelengths
• WDM transceivers, which generate light signals of specific WDM wavelengths
CWDM and DWDM
WDM comes in two flavours; CWDM and DWDM. Coarse WDM is a robust technology able to create 18 independent channels and was first to adapt a transceiver footprint. The CWDM channel spacing is 20 nm and a specific color coding is used which enables simple industry standard set- up procedures. CWDM is typically used for un-amplified transmission up to 200 km.
Dense WDM uses cooled lasers and can also be amplified. The channel spacing is typically 100 GHz (ca. 0.8 nm) and DWDM channels are usually used in the 1530 - 1560 nm band. Optical amplifiers and dispersion compensation modules allow DWDM transmission to be extended beyond the transceiver characteristics.
SmartOptics WDM filter products are designed and tested to the highest international telecom standards providing unparalled functionality and reliability.