Improved λ/4 phase-shifted DFB semiconductor laser with spatial hole burning compensation using grating chirp

A λ/4 phase-shifted distributed feedback (DFB) semiconductor laser with a preformed chirped grating used to compensate the spatial hole burning (SHB) induced index change is proposed and analyzed. It shows that compared with the three phase shifted DFB laser which is known for its good performance to eliminate SHB, the proposed SHB compensated laser has better single longitudinal mode property, narrower spectral linewidth and better dynamic characteristics.

► Chirped grating is used for compensating the spatial hole burning in the DFB laser.
► The method to generate the chirped grating in DFB semiconductor lasers is presented.
► Single longitudinal mode performance, linewidth and dynamic characteristic are all improved.
► The fabrication error analysis and fabrication suggestion are given.