Many people ask what is the difference between FB and DFB lasers. Today, Xiaobian will give you a brief introduction, hoping it will help you to some extent.

The difference between FP and DFB lasers is actually the difference between "whether there is a selection" and "whether the light can be controlled". When we say FP, we usually refer to Fabry-Perot laser (FP/FP-LD), while DFB is a distributed feedback laser.

The most essential difference between FP and DFB

FP laser: Multi-longitudinal mode, unfixed wavelength, large drift and low cost.

DFB laser: single longitudinal mode, accurate wavelength locking, small drift and high cost.

Explain the structural differences clearly.

FP laser: It works by cavity reflection.

Structural features: coating on the cavity surface at both ends; The laser is reflected back and forth in the cavity to form optical oscillation; There is no mechanism to "select a specific wavelength"; So there will be multiple longitudinal modes emitting light at the same time.

DFB laser: Bragg grating (periodic structure) is directly engraved in the chip waveguide; This grating will produce the strongest feedback to a certain wavelength; "Select" this wavelength and kill all other wavelengths; Therefore, it is strictly a single longitudinal mode.

The above is a brief introduction to the difference between FP laser and DFB laser. I hope it will help you after reading it.