WDM Networking

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.