High-efficiency Stark-geometry photorefractive quantum wells with intrinsic cladding layers

Output diffraction efficiencies approaching 40% and input diffraction efficiencies approaching 3% have been achieved in photorefractive p-i-n quantum well diodes operating in the longitudinal Stark geometry. The device structure consists of a low-temperature-grown multiple quantum well isolated from the doped contacts by an intrinsic standoff layer of Al0.5Ga0.5As. All charge trapping and screening occurs within the quantum wells without the need for trapping in specialized buffer layers used in previous designs. This new design operates at lower voltages (18 V) and lower fields (6 V/mu m) than previously demonstrated. (C) 1996 American Institute of Physics.