Comparison of gain and phase recovery dynamics among optical pumping schemes in quantum-dot semiconductor optical amplifiers

Abstract

We numerically compare the gain and phase recovery acceleration of quantum-dot (QD) semiconductor optical amplifiers (SOAs) caused by four optical pumping schemes: the single-color optical pumping tune to the quantum-well (QW) carrier reservoir; the QD excited state (ES) ensembles; and the QD ground state (GS) ensembles together with multicolor optical pumping tuned to the GS and ES ensembles of QDs. The temporal responses of the gain and phase recoveries caused by the four optical pumping schemes are calculated and compared by solving 1088 coupled rate equations at the same pumping conditions. Among the four optical pumping schemes, the single-color optical pumping to the ES ensemble shows the fastest response of the gain and phase recovery. This results from the large carrier occupation ratio at the GS and ES ensembles and the high modal gain at the pumping wavelength, which facilitates the reduction of the carrier recovery time within the GS and ES ensembles due to the increased stimulated recombination rate caused by the optical pumping beam.