Carrier dynamics in quantum dot lasers

We analyze the impact of slow intraband relaxation and strong carrier localization on the characteristics of quantum dot (QD) lasers. Relatively long intraband relaxation times and population filling of the QD ground state lead to carrier pile-up on excited states, reducing the laser efficiency and max. output power. Strong carrier localization in the QDs and consequently large thermal hopping time within the QD ensemble results in the absence of quasi-thermal equil. under lasing conditions, as evidenced by stimulated and spontaneous emission spectra. The impact of these specific phys. characteristics of QD active regions on the laser high-frequency modulation properties is analyzed, particularly with regards to the differential gain, the gain compression and the linewidth enhancement factors