Understand Ports On CWDM and DWDM MUX/DEMUX

Posted on by FS.COM

It is quite common to use CWDM or DWDM to increase the existing fiber optic network without adding any fibers. Using WDM MUX/DEMUX is necessary to build a CWDM or DWDM network. Now there are different ports installed on the CWDM and DWDM MUX/DEMUXs to add more beneficial to the fiber optic network. This post will offer details about the ports on CWDM and DWDM MUX/DEMUX.


The Must-Have Ports on CWDM and DWDM MUX/DEMUX

The basic function of the CWDM and DWDM MUX/DEMUX is combining data rate of different wavelengths over the same fiber cable to increase the network capacity. Thus, channel ports supporting different wavelengths and Line port used to connect the WDM MUX/DEMUX are the must-have ports for these devices.

Channel Port

CWDM uses 18 wavelengths ranging from 1270nm to 1610nm with a channel space of 20nm. Channel port count on CWDM MUX/DEMUX is usually ranging from 2 to 18. The following picture shows a full-channel CWDM MUX/DEMUX with all the 18 CWDM wavelengths: 1270nm, 1290nm, 1310nm, 1330nm, 1350nm, 1370nm, 1390nm, 1410nm, 1430nm, 1450nm, 1470nm, 1490nm, 1510nm, 1530nm, 1550nm, 1570nm, 1590nm, 1610nm.


DWDM uses the wavelength ranging from 1470nm to 1625nm usually with channel space of 0.8nm (100GHz) or 0.4nm (50GHz). DWDM MUX/DEMUX can support much more wavelengths that of CWDM MUX/DEMUX. The channel port of a DWDM MUX/DEMUX is usually ranging from 4 to 96.

Line Port

There are two types of line port available for CWDM and DWDM MUX/DEMUX. One is dual fiber line port, and the other is single fiber line port. The selection of the line port depends on applications. The WDM MUX/DEMUX with a single fiber line port is very different from the WDM MUX/DEMUX with a dual fiber line port on the using of wavelengths.

Dual-fiber MUX/DEMUX uses the same wavelength for dual-way transmission, which means the TX port and RX port of every duplex channel port supporting the same wavelength. The WDM MUX/DEMUXs with dual fiber line ports installed on the two ends of the network could be the same.

signle-fiber DWDM MUX/DEMUX

For single-fiber WDM MUX/DEMUX, all the wavelengths just flow in one direction. And the TX port and RX port of every duplex channel port supporting two different wavelengths. The above picture shows the front panel of an 8-channel DWDM MUX/DEMUX with single-fiber line port. As it is clearly marked the TX port and RX port use different wavelengths. If you choose a single-fiber WDM MUX/DEMUX on one side of the network, there should be a single-fiber WDM MUX/DEMUX which supports the same wavelengths but has the reverse order on the TX port and RX port of every duplex channel port. Please note, the line port of some  single-fiber CWDM MUX/DEMUXs is made into a duplex port, but one one port is function. Here takes the example of FS.COM FMU CWDM MUX/DEMUX as an example, as shown in the following picture, the single-fiber CWDM MUX/DEMUX has a duplex port, but one of the port marked as “N/A” is not in use.

single-fiber CWDM line-port

The Functioning Ports on CWDM and DWDM MUX/DEMUX

Except the above mentioned must-have channel ports and line port, WDM MUX/DEMUX can also be added with other ports which bring more profits to the existing WDM network. The following will introduce these special ports that are often added on CWDM and DWDM MUX/DEMUX.

Expansion Port

Expansion port added on WDM MUX/DEMUX is really useful. If you installed a CWDM network which just using several of the CWDM wavelengths, you can use this expansion port to increase the network capacity by connecting the expansion port with the line port of another CWDM MUX/DEMUX supporting different wavelengths. Then the network of this CWDM network can be increased easily. Both CWDM MUX/DEMUX and DWDM MUX/DEMUX support this expansion port. Kindly click the following picture for details of how to use expansion port.

WDM Expansion Solution
1310nm Port and 1550nm Port

The 1310nm and 1550nm are actually WDM wavelengths. How could these two wavelengths become special? It can be recognized that many fiber optic signals for are transmitted over 1310nm and 1550nm. Many fiber optic transceivers support long distances use these two wavelengths. However, the standard channel port on WDM MUX/DEMUX can only be connected to color coded fiber optic transceiver like CWDM SFP/SFP+ and DWDM SFP/SFP+. With these special designed 1310nm port and 1550nm port, the signal running through ordinary fiber optic transceivers can be combined together with other CWDM wavelengths.

Please note that DWDM MUX/DEMUX can only add special 1310nm port. For CWDM MUX/DEMUX, not all the wavelengths can be added, if you add special 1310nm or 1550nm port on the device. There is a simple rule for how to add the special ports and other standard channel ports on CWDM MUX/DEMUX. If you want to add 1310nm or 1550nm ports on your CWDM MUX/DEMUX, wavelengths which are 0-40nm higher or lower than 1310nm or 1550nm cannot be added to the MUX. The following table shows the specific details.

IF Add Special Port Other Channel Port Can be Added
1310nm port 1370nm, 1390nm, 1410nm, 1430nm, 1450nm, 1470nm,
1490nm, 1510nm, 1530nm, 1550nm, 1570nm, 1590nm, 1610nm
1550nm port 1270nm, 1290nm, 1310nm, 1330nn, 1350nm, 1370nm,
1390nm, 1410nm, 1450nm, 1470nm, 1490nm
1310nm port and 1550 port 1270nm, 1290nm, 1310nm, 1350nm, 1510nm, 1530nm,
1550nm, 1570nm, 1590nm


Monitor Port

Many technicians will add a monitor port on CWDM or DWDM MUX/DEMUX for better network monitoring and management. If you choose a single-fiber WDM MUX/DEMUX, the monitor port should be a simplex fiber optic port. For dual-fiber WDM MUX/DEMUX, you can add a duplex monitor port for the whole network monitoring, or just add a simplex port for MUX or DEMUX monitoring.

MUX/DEMUX monitor port


The above mentioned ports are the most commonly used in WDM MUX/DEMUX. All these ports can be customized in FS.COM where affordable complete solutions for CWDM, DWDM and DWDM over CWDM network are available. Kindly contact sales@fs.com for more details if you are interested.

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