Narrow-stripe selective MOVPE is an attractive technique for fabricating integrated photonic devices. However, in the case of densely integrated devices, in which several optical waveguides are close together, interference occurs between the masks, and the characteristics of the grown waveguide layers are affected by several mask stripes. To realize densely integrated photonic devices with a high performance, we have to simulate waveguide structures, including not only PL-wavelength but also layer thickness and induced strain, while taking the mask interference effect into account. In the proposed simulation we introduced separate mask interference constants for indium and gallium species to obtain both the thickness and the composition of the InGaAsP layers. We experimentally obtained different relationships between layer thickness and PL-wavelength for the InGaAsP bulk arrayed waveguide, which was attributed to a different interference effect between each group III species. The measured characteristics of the arrayed MQW waveguides agreed well with the simulation. The simulation method is useful for designing densely integrated waveguides fabricated by narrow-stripe selective MOVPE. (C) 2003 Elsevier B.V. All rights reserved.