We present our work done towards the development of a quantum well polarization-conversion modulator. This modulator will consist of multiple repetitions of quantum well structures exhibiting large electrorefractive effects. In them, a channel waveguide supporting only the fundamental TE-like and TM-like modes will be subjected to an applied electric field. Changes in this applied field cause the effective refractive index of one of the modes to increase and that of the other to decrease. Using these structures shows that short (similar to 2-3 mm) modulators, with 90 degrees polarization rotation, low chirp (similar to +/- 0.1), and low drive electric fields (similar to 10 kV/cm) can be achieved. In this article, numerical. simulations based on the effective-mass envelope-function approximation are used to study the influence of layer thickness and compositional variations on the electrorefractive properties of these quantum well structures. (c) 2006 American Vacuum Society.