On the relationship between small and large signal modulation capabilities in highly nonlinear quantum dot lasers

The small signal modulation response of semiconductor lasers is commonly used to predict large signal modulation capabilities. Recent experiments suggest that this prediction may fail in some quantum dot (QD) lasers. We present a model supported by experiments, which shows that when the small signal modulation response is limited by gain compression and the gain is large, the laser can be modulated at very high bit rates. This effect is inherent to dynamics governing all semiconductor lasers but the conditions needed for high bit rate modulation in the presence of narrow small signal bandwidths are only obtainable in QD lasers.