Saturation Spectra of1550nmQuantumDashOptical Amplifiers: ModelandExperiments

Saturation spectra ofQuantum dashoptical amplifiers operating at1550nmweremodeled in detail properly taking into account inhomogeneous gainandfast response time. Experimental results which confirm themodearealso presented. Nonlinear gainproperties ofquantumdot(QD)andquantumdash(QDash) optical amplifier aremainly determined bytheir inhomogeneously broadened nature (1)andthefastresponse (21. Thispaperpresents a theoretical modelandexperimental confirmations forcross saturation in1550nmQDashamplifiers Thegainmediumismodeled asasystem whichcouples acarrier reservoir (the wetting layer) andacomplex, inhomogeneous gainregion. Thewetting layer hasaquantum well-like density ofstate (DOS)function andis commontomanydiscrete groups ofdifferent quantum dashsizepopulations, eachhaving wirelikeproperties characterized byaground state transition energy. Themodelcalculates propagation ofthecomplex electric field (rather than thepower) andhence includes coherent nonlinear interactions. Thedynamics governing thecarrier density inthewetting layer, NMvandineachoftheintra-dash energy levels NjA,k aredescribed bythefollowing rate equations