tunable laser

Tunable lasers are used in wavelength division multiplexing(WDM) and in dense wavelength division multiplexing( DWDM) as replacement lasers. InDWDM technology, one hundred or more wavelengths are used, and thus just as many lasers.

Since the corresponding wavelength is no longer available for information transmission if a laser fails, and since one does not want to set up each laser redundantly, tunable lasers are used for this purpose. These lasers can be tuned over a wavelength range of 40 nm, so that they can cover a total of 50 wavelengths in a 100 GHz raster (0.8 nm).

Technologically, these are tunable semiconductor laser diodes or also VCSEL las ers with a tunable cavity.