CWDM has been a reliable and cost-effective solution for increasing capacity of fiber optic networks for over a decade. With CWDM, multiple wavelengths are transmitted over the fiber optic link, creating independent and simultaneous data streams that carry any protocol regardless of what is transmitted on the other wavelengths. CWDM supports up to 18 wavelengths, and each wavelength can transport up to 10G of data. Data from virtually any type of communications equipment (including servers, switches and routers) can be carried over a CWDM network. 

Challenges with CWDM deployments include adding network connectivity at different locations along the CWDM Common Line that transports all the CWDM wavelengths, and adding CWDM wavelengths to ring networks.

CWDM Products

iConverter® CWDM Optical Add Drop Multiplexers

iConverter Optical Add Drop Multiplexers (OADM) are part of the iConverter Multi-Service Platform and used to add new network connectivity to locations on CWDM networks. iConverter CWDM MUX/DEMUX modules and Optical Add and Drop modules can be installed in a variety of compact and high-density chassis.

iConverter Transponders

iConverter Transponders are protocol-transparent fiber-to-fiber media converters, and are available as compact, unmanaged standalone units or  managed chassis plug-in modules. iConverter Transponders provide reliable and cost-effective conversion between different wavelengths using  CWDM SFP Transceivers and CWDM SFP+ and XFP Transceivers.

CWDM Add Drop Multiplexer Overview

iConverter CWDM/AD OADM Multiplexers add (multiplex) and drop (de-multiplex) selected channels, or wavelengths, on one or both directions of a CWDM Common Line fiber link. Using CWDM/AD modules, network designers can add new access points anywhere on a CWDM network, without impacting the remaining channels traversing the network.

In this application example, a 1-Channel OADM is installed along a CWDM Common line that is transporting four wavelengths through the Common Line port (COM).  The wavelengths are multiplexed onto the Common Line using two iConverter 4-Channel CWDM/X Multiplexers.  The 1-Channel OADM drops off the 1510nm wavelength at a network location along the Common Line.  The 1-Channel OADM can drop off wavelengths in two directions, and in this case, enables two different 1510nm network links. Access points can be added to linear, bus, and ring networks, where the dual-direction ring design provides redundant protected architecture.

The schematic drawing at right shows a 2-Channel CWDM/AD OADM with Common Left and Common Right ports that connect to the CWDM Common Line transporting all the CWDM wavelengths, and Channel Ports that add and drop specific wavelengths.  The Left and Right Channel ports enable links in each direction on the Common Line, and are deployed in ring networks and point to point networks with independent links on either side of the OADM.  A 1-Channel OADM works the same way, but with only one Left and one Right Channel Port.

Single-Fiber iConverter OADMs are also available.

The following application examples illustrate how iConverter Optical Add Drop Multiplexers (OADM) enable a daisy-chain network and a resilient ring network.

Daisy Chain CWDM Add Drop Network

This is an example diagram, a CWDM/X Multiplexer and multiple CWDM/AD OADM Multiplexers are deployed in a daisy chain (or linear drop) network.  This network originates with four Ethernet switches with fiber ports that are connected to a 4-Channel CWDM/X Multiplexer.  The switches can be 100Mbps, Gigabit or 10G.  CWDM SFPs are installed in the switches to support the 1510, 1530, 1550 and 1570 wavelengths and are connected to the corresponding channel ports on the CWDM/X Multiplexer with fiber patch cables (shown in the colors of the wavelengths).

The 1510 wavelength is multiplexed onto the Common Line along with the other three wavelengths and dropped off at the first 1-Channel CWDM/AD OADM. 

The 1530 wavelength is multiplexed onto the Common Line, passes through the first 1-Channel CWDM/AD OADM, and is dropped off at the second 1-Channel CWDM/AD OADM. 

The 1550 and 1570 wavelengths are multiplexed onto the Common Line, pass through the two 1-Channel CWDM/AD OADMs and dropped off at a 2-Channel CWDM/AD OADM. 

This is how to use CWDM/X Multiplexer modules with CWDM/AD OADM modules to create a network with multiple locations along a Common Line fiber daisy chain. Note that the higher wavelengths are utilized for the longest distances due to them having the lowest attenuation.

Resilient Ring CWDM Network

This application diagrams shows a dual fiber ring with CWDM wavelengths that enable two independent and reslient ring networks with Ethernet fiber switches that support the spanning tree network protocol.  Network A (shown in green) is transported on the 1510nm and Network B (shown in blue) is transported on the 1530nm wavelength. 

Network A has an active data path (via the CWDM wavelength) on the left and a fail-over data path on the right that are controled by the switches in case of a network fault.  The 1510nm wavelength is being added and dropped by the 1-Channel CWDM/AD OADM Multiplexer at the top left of the ring, and at the 2-Channel CWDM/AD at the bottom.  The Network A 1510nm wavelength passes through the 1-Channel OADM on the top right.

Network B also has active and fail-over data paths.  The 1530nm wavelength is being added and dropped by the 1-Channel CWDM/AD OADM Multiplexer at the top right of the ring, and the 2-Channel CWDM/AD at the bottom.  The Network B 1530nm wavelength is passing through the 1-Channel OADM on the top left.

This is how CWDM OADM Modules are used to connect and bypass switch nodes on the ring. Note that many more CWDM wavelengths and and nodes can be added to the ring.