Spectral linewidth characteristics of /spl lambda//4-Shifted MQW-DFB Lasers as a Function of Coupling Coefficient

The lasers used in coherent transmission systems need to produce output that has a narrow spectral linewidth, and this means that their rebroadening and linewidth floor have to be reduced. Spatial. hole burning has been suggested to cause rebroadening and to elevate the linewidth floor [1,2], and we have previously reported that a 56-kHz linewidth can be achieved by using a corrugation-pitch modulated structure to suppress spatial hole burning [3].