The basics of Wavelength Division Multiplexing (WDM)
By Tom Jeffers, Product Manager, AFL
Wavelength Division Multiplexing (WDM) is a technology that increases the data-carrying capacity of optical fiber by allowing multiple streams of data to be transported using different wavelengths of light. The primary benefit of WDM technology is that it requires just a single optical fiber which, in most cases, has already been deployed. Therefore, it is a much less expensive option for expanding network capacity compared to installing additional fiber cables.
With 18 total wavelengths available, Course Wavelength Division Multiplexing (CWDM) is popular and a good start for most customers due to its relatively low cost and high increase in capacity versus a single data stream. However, as bandwidth demands increase, it becomes necessary for those same customers to add additional capacity. Dense Wavelength Division Multiplexing (DWDM) allows you to add this additional capacity without replacing your existing CWDM infrastructure and with minimal, if any, service interruption.
Contrary to popular belief, it is possible to use both CWDM and DWDM in the same network. However there are some considerations to make before expanding from CWDM to DWDM. For customers anticipating the need to use both CWDM and DWDM, there are two primary options:
1: Plan Ahead – Leave CWDM wavelengths open for future DWDM expansion
2: Override – Use CWDM ports to pass DWDM channels
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In addition to technological constraints, rack space is often a concern in highly-congested headends where expansion occurs. AFL offers small form factor DWDM Card Guide Modules (CGM™) in various configurations that are available to increase the number of channels per rack unit. These plug-and-play modules install quickly and easily into the CGM Plus high-density rack-mount panel. The CGM Plus can hold LGX and CGM devices interchangeably, which provides a seamless migration path from legacy modules.
Read the white paper for more information on DWDM expansion.