The nonlinear absorption and phase recovery of quantum dot based reverse-biased waveguide electro-absorbers

The physics of quantum dot based optical devices has been studied intensively due to their interesting blend of atomic and solid state properties. Recently, attention has been focused on their absorption properties and has led to QD materials finding favour in such applications as monolithic mode-locked lasers, electro-absorption modulators and saturable absorber mirrors. In this study we perform a detailed experimental investigation of the ultrafast absorption and phase dynamics of a QD InAs/GaAs structure under reverse bias conditions using single colour pump-probe measurements. Experimental results reveal the fundamental timescales and underlying dynamical processes occurring in such absorbers. We will also consider the impact of the observed absorption and phase dynamics on some current applications of QD absorbers.