A numerical model of non-linear polarization rotation in a tensile-strained bulk semiconductor optical amplifier is presented. The model uses a wideband model of the SOA to determine the carrier density and the TE and TM mode gains. The carrier density distribution is used to determine the phase difference between the TE and TM components of the amplified probe. The SOA Mueller matrix can be modeled as a diattenuator and phase shifter. The Mueller matrix is used to determine the Stokes vector of the amplified probe if its input Stokes vector is known. Stokes vectors can be easily measured using a polarization analyzer. The model is used to predict the polarization rotation of a probe signal induced by a co-propagating pump. © 2008 IEEE.