Installation Guide to CWDM MUX/DEMUX System

CWDM MUX/DEMUX System Overview

Coarse Wavelength Division Multiplexing (CWDM) is a wavelength multiplexing technology for access networks. It is designed to increase fiber optic network capacity without adding additional fibers. The wavelengths of CWDM channels range from 1270nm to 1610nm with 20nm spacing, which allows the use of cost-effective lasers. CWDM MUX/DEMUX system is a passive, optical solution to increase the flexibility and capacity of existing fiber lines in high-speed networks. By adding more channels into available fibers, the CWDM MUX/DEMUX system enables greater versatility for data communications in ring, point-to-point, and multipoint topologies for both enterprise and metro applications.

CWDM MUX/DEMUX System Components

All CWDM system components are passive and require no power supplies. They consist of the rack mount chassis, a set of CWDM MUX/DEMUX and CWDM OADM (Optical Add/Drop Multiplexing) modules with color-coded ports. The CWDM MUX/DEMUX takes 4 or 8 different wavelength channels and multiplexes them onto one common fiber cable for transmission to the network. Then it demultiplexes the channels it receives from the network and sends each channel to a different device. Multiple modules may be chained through the expansion port on the four-channel modules. Thus it increases flexibility and enables growth for evolving networks.

The CWDM OADM module can add or drop CWDM channels into an existing backbone ring. It provides the ability to drop one CWDM channel from the network fiber, while allowing all other channels to continue pass to other nodes. Similarly, the drop/insert module removes an individual channel from the network fiber, however, it also provides the ability to add that same channel back onto the network fiber. The drop/insert module supports two paths (east and west) for dropping and adding, so that network viability is maintained in a ring topology, even if a break occurs in the ring.

CWDM MUX/DEMUX System Installation Guide

Step1: Mount the system chassis on the rack. The CWDM rack-mount chassis can be mounted in a standard 19-inch cabinet or rack. Make sure that you install the rack-mount chassis in the same rack or an adjacent rack to your system so that you can connect all the cables between your CWDM MUX/DEMUX modules and the CWDM SFP transceivers.


Step2: Install the CWDM MUX/DEMUX modules. First loose the captive screws on the blank of module panel and remove the panel. Then align the module with the slot of the chassis shelf and gently push the module into the slot. Finally, ensure that you line up the captive screws on the module with the screw holes on the shelf and tighten them up.


Step3: Install CWDM SFP transceivers. Since each channel has a specific wavelength, transceivers must comply with the right wavelengths. Each wavelength must not appear more than once in the system. Device pairs must carry transceivers with the same wavelength.

Step4: Install the CWDM MUX/DEMUX to the switch. After inserting the CWDM SFP transceiver into the switch, single-mode patch cables are used to connect the transceiver to the CWDM MUX/DEMUX module.


Step5: Connect the CWDM MUX/DEMUX pairs. In a CWDM MUX/DEMUX system, multiplexer and demultiplexer must work in pairs. Two strands of single-mode patch cables are needed in the duplex MUX/DEMUX module and one strand for the simplex one. Simply insert single-mode cables from your system equipment to the appropriate port on the CWDM MUX/DEMUX or OADM module.


CWDM MUX/DEMUX system is an attractive solution for carriers who need to upgrade their networks to accommodate current or future traffic needs while minimizing the use of valuable fiber strands. With CWDM technology, you can accommodate Ethernet and SONET on a single fiber that enables converged circuit/packet networks at high demand access sites. Besides, CWDM MUX/DEMUX can work seamlessly with transceivers to optimize link length, signal integrity and network cost, thus becoming a single rack-mount solution for enhanced design, power and space efficiency.

Basic Things To Know About PM Patch Cables

Standard fiber patch cables are widely discovered in our life, but fiber patch cables also have other special types, such as the mode conditioning cables, fiber loopbacks, etc. These special fiber patch cables are usually used for some particular applications. In this article, we will mainly introduce the basic knowledge of PM (polarization maintaining) patch cables.


Function of PM Patch Cables

In fiber optic industry, polarization maintaining fiber is a single-mode fiber that can maintain a linear polarization light propagation during the whole transmission inside fiber. As long as the light is linearly launched into the fiber, its polarization in the fiber path will not change. PM patch cable is a fiber optic cable consisting of PM fiber and high-quality ceramic fiber optic connectors. With the special polarization maintaining function, PM patch cables have the characteristics of low insertion loss, high extinction ratio, high return loss, excellent changeability over a wide wavelength range and excellent environmental stability and reliability.

How to Choose PM Patch Cables?

PM patch cables have various types according to different classification bases. To choose the right type of PM fiber patch cable, you may consider the following aspects.


Similar to standard fiber optic cables, the common connectors for PM fiber patch cables are LC, SC, FC and ST types. Connectors on both ends of the cable can be identical or different, such as LC-LC or LC-SC connectors. The special part is that connector ends are capped for better protection since the PM connectors are made to be more sophisticated.


PM fiber patch cables all use the PM fibers. However, PM fibers can be different according to different shapes of the inside rod. This special rod can ensure the linear polarization of input and output light in the fiber. The following picture shows the examples of “Panda” and “Bow-Tie” styles of PM fiber.


Cable Jacket

With or without cable jacket are both common for PM fiber patch cables. Generally speaking, there are three types of PM cables – 250μm bare fiber PM cable, 900μm loose tube jacket PM cable and 3mm loose tube jacket PM cable.


The standard cable length of PM fiber patch cables is 1 meter. If other lengths are required, the cable is able to be customized to the required lengths as well.

Where to Use PM Patch Cables?

Since PM fibers are typically used to guide linearly polarized light from point to point, PM fibers can be used for many special applications in optical sensors or telecommunications and sensor research. PM fiber patch cables are especially useful for polarization sensitive fiber optical systems where optical light needs to be maintained at a linear state. PM fiber patch cables can be used with other devices like interferometric sensors, integrated optics, fiber amplifiers in high-speed and coherent telecommunications.


As one type of special fiber patch cables, PM patch cables are particularly designed for keeping the polarization of linear optical lights. PM patch cable is definitely a good solution to ensure the high performance of data transmission. FS.COM offers various types of PM patch cables with length customization service. If you are interested in more details, please kindly visit FS.COM or contact us via