InGaAs/GaAs photorefractive multiple quantum well device in quantum confined Stark geometry

We have demonstrated photorefractive InGaAs/ GaAs multiple-quantum-well dev ices in the quantum confined Stark geometry. A four-wave-mixing diffraction efficiency up to 0.3% is obtained at a wavelength of 949 nm. Proton implan tation strongly reduces the maximum diffraction efficiency although it satu rates the diffraction efficiency at smaller grating period comparing to as- grown device. We have also observed higher order diffractions. It is found that the space-charge field changes its pattern temporally from a sinusoida l pattern to a rectangular one with decreasing its modulation depth.