The relation of doping level to K factor and the effect on ultimate modulation performance of semiconductor lasers

For the first time, K, which is the ratio of the damping factor gamma to the square of the resonance frequency f/sub 0//sup 2/, is shown to depend on the doping level for bulk semiconductor lasers. Since the differential gain is known to depend on the doping level in the active layer, K also depends on the differential gain. The results presented strongly suggest that an effective means to decrease the damping is by increasing the doping level of the active region of the semiconductor laser. Since damping must be reduced in order to increase the maximum damping-limited bandwidth, this result may have important implications for improving the modulation bandwidths of bulk lasers and may be equally significant with respect to damping and the ultimate achievable bandwidth in quantum-well lasers.<>