Effects of Carrier Relaxation and Homogeneous Broadening on Dynamic and Modulation Behavior of Self-Assembled Quantum-Dot Laser

The important tradeoff between frequency bandwidth and single-mode behavior of multimode self-assembled InAs-GaAs quantum-dot (QD) laser by increasing temperature or homogeneous broadening is addressed. The effects of carrier dynamics on the frequency response of columnar-shaped self-assembled QD laser are analyzed. The phonon bottleneck problem is simulated. It is shown that to prevent the effect of phonon bottleneck on the frequency behavior, carrier relaxation lifetime must be less than a critical value about a few pico seconds, which is in agreement with the experimental results. Results show that carrier recombination in wetting layer has no important effect on the modulation response; however, carrier recombination inside dots degrades frequency response drastically.