Differential gain and gain compression in quantum-dot lasers

The dynamics of optical gain in semiconductor quantum dots (QDs) is investigated. Simple analytical expressions are derived, which directly connect the laser dynamical response to capture and intradot relaxation rates. The effect of hole spreading in the valence band and spectral hole burning in the QD ensemble is also quantitatively assessed. The analysis shows that intradot relaxation constitutes the main limitation in the dynamics and points to possible routes towards the improvement of QD lasers.