Recovery time scales in quantum dot devices

The physics of quantum dot (QD) based optical devices has been studied intensively due to their interesting blend of atomic and solid state properties. Recently, attention has focused on their amplification and absorption properties and has led to QD materials finding favour in such applications as monolithic mode-locked lasers, semiconductor optical amplifiers (SOAs), electroabsorption modulators and saturable absorber mirrors. We present experimental results together with an analytical analysis of the nonlinear recovery of QD based SOAs in forward and reversed bias modes. The study reveals the role of capture and escape processes in the formation of two stages of recovery.