A DFB Laser (distributed feedback laser) is a type of laser diode, quantum cascade laser or optical fiber laser. The active region of the DFB Laser contains a periodically structured element or diffraction grating.

DFB Laser 1310nm 1490nm 1550nm

The structure builds a one-dimensional interference grating (Bragg scattering) and the grating provides optical feedback for the laser.

DFB lasers tend to be much more stable than Fabry-Perot or DBR lasers and are used frequently when clean single mode operation is needed, especially in high speed fiber optic telecommunications. Semiconductor DFB lasers in the lowest loss window of optical fibers at about 1.55um wavelength, amplified by Erbium-doped fiber amplifiers , dominate the long distance communication market, while DFB lasers in the lowest dispersion window at 1.3um are used at shorter distances.