CWDM Mux/Demux Modules and Devices

WDM devices (CWDM, DWDM, etc.) are proven and viable solutions for meeting the growing capacity needs in future FTTX applications, including mobile backhaul.

CWDM Mux/Demux: Fiber Optical Multiplexer

FTTH networks are typically considered fiber-rich and the passive optical components involved are 1×16, 1×32 or even 1×64 splitters that split the signal to multiple users. However, when it comes to businesses, campus environments or MDUs, multi-service operators are typically limited to one or two fibers. It is in these applications that wavelength division multiplexing technologies, such as Coarse WDM (CWDM) and Dense WDM (DWDM) can be used to increase the bandwidth capabilities and deliver multiple services to multiple end users.

CWDM Mux (fiber optical multiplexer) can combine four, eight, or up to 18 wavelengths onto a fiber. The channel spacing is set to 20 nm in a wavelength range that spans the window from about 1250 to 1650 nm — a window that could include 20 channels. The coarse spacing allows for very reduced temperature and wavelength stability requirements on the components, and requires filters with large, almost 20-nm bandwidths.

CWDM Mux: Optical Wavelength Multiplexer

A wavelength multiplexer (CWDM MUX) (or optical multiplexer (OM)) is a branching device with two or more input ports and one output port, where the light in each input port is restricted to a preselected wavelength range and the output is the combination of the light from the input ports.

A wavelength demultiplexer (CWDM DMUX) (or optical demultiplexer (OD)) is a device which performs the inverse operation of a wavelength multiplexer, where the input is an optical signal comprising two or more wavelength ranges and the output of each port is a different preselected wavelength range.

Both wavelength multiplexers (CWDM MUX) and wavelength demultiplexers (CWDM DEMUX) are generally called “WDM Devices” since often the same device can be used to multiplex and demultiplex channels.

CWDM OADM

An optical add/drop multiplexer (CWDM OADM) subsystem is a wavelength selective branching device (used in WDM transmission systems) having a wavelength “drop” function in which one or more optical signals can be transferred from an input port to either an output port or drop port(s) depending on the wavelength of the signal. An CWDM OADM also has a wavelength “add” function in which optical signals presented to the add port(s) are also transferred to the output port.