GaInAs/TnP MQW-based arrayed-waveguide wavelength demultiplexer with linearly varying refractive-index distribution has been achieved by low-pressure selective MOVPE. Using an asymmetric SiO2 mask with wide mask on one side of the array, waveguides with different array thickness are fabricated parallel to the [0 1 1] direction on (1 0 0)oriented n-InP substrates under growth conditions of 640 degreesC and 100 Torr. To connect the arrayed waveguides to the input and output star couplers based on Rowland circle geometry for focus of light, arrayed waveguides tilted with respect to the [0 1 1] direction were required for interfacing with a star coupler. In this paper, the cross-sectional profiles of the tilted waveguides are investigated, revealing the transformation of the waveguide profiles from trapezoidal profiles with sidewall (l l 1)B planes to inverted trapezoidal profiles without exposed (I I 1)B planes with increasing tilt angle with respect to the [0 1 1] direction. (C) 2004 Elsevier B.V. All rights reserved.