Contraction of aluminum oxide thin layers in optical heterostructures

Abstract

We precisely determine the contraction of AlAs in multilayer optical waveguides, associated with selective oxidation of AlAs/GaAs epitaxial heterostructures. The average thickness of each layer was determined via x-ray reflectometry before and after oxidation, yielding an induced shrinkage of 11.4%+/-0.7% normal to the stack. The waveguide refractive indices were evaluated via modal-index measurements in the near-infrared. The achieved accuracy is compatible with form-birefringent phase matching in AlGaAs guided-wave frequency converters. (C) 2003 American Institute of Physics