The existence of localized states at InSb-like interfaces of A1Sb/InAs superlattices is predicted using empirical pseudopotential calculations. These predictions are shown to be in agreement with those of ab initio pseudopotential calculations performed using the local density approximation of density functional theory, demonstrating the ability of the empirical approach to describe the microscopic features of the interface. The frequency dependence of the absorption coefficient is calculated for a series of A1Sb/InAs superlattices with differing interface configurations, and the role of the interface localization in determining the optical response is identified.