The DFB laser uses a grating optical filter device based on the FP laser so that the device has only one longitudinal mode output. The characteristics of this type of device are: large output optical power, small divergence angle, extremely narrow spectrum, and high modulation rate, which are suitable for high-speed medium and long-distance communication.

DFB (Distributed Feedback Laser) generally uses two wavelengths of 1310nm and 1550nm, which are divided into cooling and non-cooling, and the transmission distance is generally more than 40 kilometers.

DFB laser performance parameters:

  1) Working wavelength: the central wavelength of the spectrum emitted by the laser.

2) Side mode suppression ratio: the power ratio of the main mode of the laser to the maximum side mode.

  3) -20dB spectral width: the spectral width is reduced by 20dB from the highest point of the laser output spectrum.

4) Threshold current: When the operating current of the device exceeds the threshold current, the laser emits a laser with good coherence.

5) Output optical power: the optical power emitted by the laser output port.