Low-pressure selective MOVPE has been performed to fabricate a GaInAs/InP MQW-based arrayed waveguide wavelength demultiplexer having, a linearly varying refractive-index distribution. By means of an asymmetric SiO2 mask with a wide mask section on one side of the array, waveguides of different thickness are fabricated on (100)-oriented n-InP substrates. In this report, desired characteristics of the waveguide array are obtained by a simple method for estimating strain in the GaInAs wells layer in an MQW waveguide from only the result of simple measurements: conventional X-ray diffraction (XRD), photoluminescence (PL) peak wavelength, and well layer thickness. (c) 2006 Elsevier B.V. All rights reserved.