Precision OT logo


Multiplexing: Everything you Need to Know

Oct 24th, 2014

In this blog post, we’ll take a look at Wavelength Division Multiplexing and its two types: coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM). Multiplexing First, let’s talk about the basis of WDM: multiplexing. While historically large bandwidth of optical fiber was unlikely to be used by a single client or application, bandwidth sharing throughout multiple sources began; thus, multiplexing was born. Three divisions on multiplexing approaches emerged: time division multiplexing (TDM), space division multiplexing (SDM), and wavelength division multiplexing (WDM). For the purpose of this blog, we’ll focus on WDM. WDM In layman’s terms, Wavelength Division Multiplexing is the process in which optical signals with differing wavelengths are combined for transmitting through a MUX, and then separated through a DEMUX. This technology allows multiple wavelengths/channels to be transmitted across a single fiber. WDM technology has two sub-categories that are commonly used today; these are known as CWDM and DWDM.  CWDM and DWDM CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing) are similar in the way that they both function by means of multiplexing, but are different in the way that they are comprised and defined. Some differences are:  Both CWDM and DWDM have specific Grid Channel data as shown below: CWDM:*%7C543%7C*%7Cetc%7C*%7CCWDM-Channels.pdf DWDM:*%7C543%7C*%7Cetc%7C*%7CDWDM-Channels.pdf The use of multiplexing has evolved the world of fiber optic networks in a significant way. From WDM to CWDM and DWDM, these variations of multiplexing are commonly used today throughout networks and systems around the world. For more information on CWDM and DWDM compatible transceivers, visit

Back to list page