Role of two-photon absorption in ultrafast semiconductor optical switching devices

Abstract
We report measurements of the two-photon absorption coefficient of GaAs optical waveguide structures at 1.06 μm. We show that for pulse lengths longer than ∼1 ps, light-induced index changes sufficient to induce all-optical switching will be predominantly due to carriers generated by two-photon absorption. These results allow us to predict limitations for ultrafast all-optical GaAs devices.