Quantum Dot Lasing: Local Field Effects

O.Khasanov, G.Rusetsky, N.Rubtsova, V.Samartsev

Scientific and Practical Materials Research Centre of NAS of Belarus, Belarus

One of the fundamental properties of quantum dots (QD) is quantum confinement of electrons motion in the tree directions, which leads to discrete spectrum and a large exciton binding energy. Under these conditions local field effects such as excitation induced shift (EIS) and excitation induced dephasing (EID) may influence in substantial degree on QD optical properties as well as on QD lasing. In this work we take into account both local field effects and compare their impact on the QD lasing regimes in general, and on lasing thresholds, in particular. Importantly, these local field effects depend on the QD size. If the EIS dominates in small QDs with strong confinement of interacting electron-hole pairs, then the EID effect plays a dominant role in large QDs under intensive exciton-exciton interaction. In the intermediate cases both factors may have the comparable effect. The only EIS slightly shifting the first laser threshold decreases in significant extend the second lasing threshold. The EID also slightly shifts the first lasing threshold to higher values of the pumping, but unlike the EIS it leads to a significant increase of the second lasing threshold.