Coarse Wavelength Division Multiplexing (CWDM)

Typically, in fiber-optic communications, Wavelength Division Multiplexing (WDM) technology enables bidirectional communications over one strand of fiber as well as multiplication of capacity. Generally, these technique enables carriers to deliver more services over their existing optical fiber infrastructure by combining multiple wavelengths on a single fiber. Each service is carried over a separate wavelength, thus increasing the capacity of the fiber by the number of wavelengths transmitted. Coarse Wavelength Division Multiplexing (CWDM)  and Dense Wavelength Division Multiplexing (DWDM) are both mature WDM technologies, using standardized ITU-T wavelengths.

CWDM components have been  more popular in-terms of low cost entry point for many customers for the GbE rates, due to the difference in economic scale. CWDM is defined as a technique for combining multiple “wavelengths” onto a single fiber. CWDM also refers to the filter device, which is used for multiplexing separate wavelengths, onto the single fiber.

Expansion is achieved as traffic demands continue to rise, CWDM have proofing itself  to be the perfect alternative for carriers who are looking to upgrade the capacity of their installed optical network without replacing existing equipment with higher bit rate transmission equipment, and without installing new fibers. CWDM solutions provide 8 wavelengths capability, enabling to transport 8 client interfaces over the same fiber.

It is well known fact that CWDM systems have been available since the 1990s, but carriers have been reluctant to deploy solutions that were not standardized as a result of regulations and standards driven nature of the telecommunication sector.With full ITU-T standardization completed in 2003 provided a capacity boost in the access networks deployments which resulted in the dramatically increase in the demand of CWDM.

That is, With the demand for very high-speed broadband and for reduced deployment costs for systems in metro and access networks, higher bit rates are required. One solution is to increase bit rates using CWDM application. By using CWDM, carriers will not need to retire equipment before its time, or dig up the ground to install new fiber. Due to its low cost and simple deployment, Coarse Wavelength Division Multiplexing (CWDM) is now well-positioned to help carriers maximize their network capacity in the access, metro and regional network segments. CWDM supports fewer wavelengths than DWDM, but is available at a fraction of the cost of DWDM.

 CWDM attractive solution with its technologically simplicity and easy implementation. Moreover,  it doesn’t  require special power and temperature controls. The transmitters are compact and are easily incorporated into existing circuitry, like media converters and switches. This makes CWDM attractive for areas with moderate traffic growth projections.than DWDM, and it addresses traffic growth demands without overbuilding the infrastructure.

CWDM wavelengths are spaced at 20nm increments, from 1471nm to 1611nm. Also the distance between two CWDM termination points can span up to 100km, depending on the interface speed and the quality of optical fibers. This makes regenerative CWDM systems suited for applications in the metro-regional space, as well.

Keywords
(CWDM) Coarse Wavelength Division Multiplexing,  (WDM) Wavelength Division Multiplexing, ( ITU-T) International Telecommunication Union- Telecommunication. (nm) Nanometers