Carrier dynamics in inhomogeneously broadened InAs/InP quantum-dot optical amplifiers

We report on multi-wavelength pump-probe characterization of the fundamental gain dynamics in recently developed InAs/InP quantum-dot semiconductor optical amplifiers. Recovery of the gain at various wavelengths following a powerful optical pump pulse, was recorded at different bias levels and different excitation powers. Wavelength dependencies of gain saturation depth, of the level to which the gain recovers and of the recovery rates were obtained. Unlike in quantum-dash amplifiers, these quantum-dots exhibit no instantaneous gain response, confirming their zero-dimensional nature.