Diffraction gratings are often used in monochromators, spectrometers, lasers, wavelength division multiplexing devices, optical pulse compressing devices, and many other optical instruments.

A wavelength division multiplexing means for performing an electro/optical conversion of the serial data of the downstream frame and performing a wavelength division multiplexing thereof.

For example, Advantest manufactures optical spectrum analyzers, which measure wavelengths and levels of optical signals transmitted through wavelength division multiplex (WDM) transmission systems.

These are often used to separate channels in telecommunications networks that use wavelength division multiplexing on long-haul optic fibers.

If there are not many fiber-optic cables to the node, wavelength division multiplexing can be used to combine multiple optical signals onto the same fiber.

Telecommunications networks employing wavelength division multiplexing have add-drop multiplexers with banks of miniature tuned fused silica or diamond etalons.

This is typically done using coarse wavelength division multiplexing CWDM because the wider 20 nm spacing of the wave bands makes these systems much less susceptible to interference.

Using dense wavelength division multiplex (DWDM), 24 Gbit/s speed was achieved with a total of 16 different wavelength signals.

The applicability of supercontinua for use in wavelength division multiplexed (WDM) systems for optical communications was investigated heavily during the 1990s.

Originally, the term "coarse wavelength division multiplexing" was fairly generic, and meant a number of different things.