Optical nonlinearity in GaAs quantum dots

We have measured the optical saturation intensity of GaAs quantum dots and have found it to be 50 W/cm2; more than an order of magnitude smaller than that reported for GaAs quantum wells. Compared to such quantum wells, our quantum dots also show a larger amount of saturation, again by more than an order of magnitude. We find that the saturation intensity of our quantum dots depends exponentially on the photoexcitation energy, with greater intensities required for photon energies closer to the bottom of the quantum dot confinement potential.