Spatial hole burning compensation using chirp for DFB semiconductor laser

The symmetrical chirp of the waveguide grating is used for compensating the index change of the laser cavity caused by the spatial hole burning. This structure has some advantage in that it has the large above gain margin comparing with the three phase shift DFB laser. This means it has the better SMSR property under the high injection current than the three phase shift DFB semiconductor laser. We also calculate the linewidth of the proposed DFB laser. Due to the small mirror loss, we find this structure has the narrower linewidth than the three phase shift DFB semiconductor laser.