Differential gain, refractive index, and linewidth enhancement factor in high-speed GaAs-based MQW lasers - influence of strain and p-doping

The addition of strain and p-doping in high-speed GaAs-based MQW lasers are assessed experimentally in terms of their potential for both increasing the differential gain, theta g/theta N, and reducing the modulus of the differential refractive index, |theta n/theta N|, in order to decrease the linewidth enhancement factor, alpha. The increased differential gain with strain alone is found to be offset by a corresponding increase of |theta n/theta N|. The further addition of p-doping, on the other hand, simultaneously increases theta g/theta N and decreases theta n/theta N, yielding a substantial reduction in alpha.