Optical interleaver

An optical interleaver is a 3-port passive fiber-optic device that is used to combine (Mux) two sets of dense wavelength-division multiplexing (DWDM) channels (odd and even channels) into a composite signal stream in an interleaving way.

For example, optical interleaver takes two multiplexed signals with 100 GHz spacing and interleaves them, creating a denser DWDM signal with channels spaced 50 GHz apart.

For example, in most DWDM equipment, the standard channel spacing is 100 GHz.

But spacing the signal-carrying frequencies every 50 or even 25 GHz can double or even quadruple the number of channels per fiber.

Currently, there are two approaches to building optical interleaver: 1) Step-phase Michelson interferometer, and 2) Birefringent crystal networks.