1.7-ps consecutive switching in an integrated multiple-quantum-well Y-junction optical switch

Ultrafast all-optical switching has been demonstrated in a Y-junction waveguide device fabricated on a GaAs-AlGaAs multiple quantum well structure. The mechanism responsible for switching is attributed to the optical Stark effect which enabled consecutive switching events spaced 1.7 ps apart. Carrier generation due to linear absorption of the band-tail states and the observed two-photon absorption results in a gradual slope in the background. Our experiments indicate that nonlinear refraction due to the AC Stark effect is most pronounced when the excitation field is polarized with the E-field parallel to the interfaces.