Delay induced instabilities in a quantum dot semiconductor laser

Delay-induced instabilities are well-known in semiconductor laser physics. The most famous example is the occurrence of low frequency fluctuations, which are observed near the lasing threshold when a semiconductor laser is subjected to weak optical feedback [1]. Our experiments with semiconductor lasers based on quantum dot (QD) materials have shown that these lasers do not exhibit similar instabilities. However, under strong optical feedback the system displays an instability range at high temperature. These instabilities are very different from those commonly observed in quantum well lasers. The experimental conditions include high pumping current, strong optical feedback, and a relatively long external cavity. The observations include periodic oscillations at the delay period, which evolve to chaos. In addition, there is bistability between these oscillations and stable steady state regime of operation.