Phase‐shifted distributed feedback laser with linearly chirped grating for narrow linewidth and high‐power operation

Phase‐shifted distributed feedback laser with linearly chirped grating (PS‐CG‐DFB) was analyzed. The field distribution, threshold gain difference between the lasing mode and the next lowest threshold gain mode, linewidth of the lasing mode, and output power of PS‐CG‐DFB were self‐consistently calculated under different injection levels. It is found that the lasing mode pattern and the carrier concentration distribution are ‘‘locked’’ at high injection level due to the strong interaction between carriers and photons. The chirped grating compensates the spatial hole burning effect to the mode stability and makes the mode stable in the whole injection region.