The muxponder (from multiplexed transponder) has different names depending on vendor.

In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity.

A WDM system uses a multiplexer at the transmitter to join the several signals together and a demultiplexer at the receiver to split them apart. With the right type of fiber, it is possible to have a device that does both simultaneously and can function as an optical add-drop multiplexer. The optical filtering devices used have conventionally been etalons (stable solid-state single-frequency Fabry–Pérot interferometers in the form of thin-film-coated optical glass). As there are three different WDM types, whereof one is called “WDM”, the notation “xWDM” is normally used when discussing the technology as such.

DWDM systems

The terminal multiplexer contains a wavelength-converting transponder for each data signal

Intermediate optical terminal

a remote amplification site that amplifies the multi-wavelength signal that may have traversed up to 140 km or more

Intermediate line repeater

placed approximately every 80–100 km to compensate for the loss of optical power as the signal travels along the fiber.

DWDM terminal demultiplexer.

De-multiplexed signals are usually sent to O/E/O output transponders prior to being relayed to their client-layer system