We have investigated the far‐infrared reflectivity spectra of two series of InAs/GaSb superlattices grown with GaAs‐ or InSb‐like interfaces. Significant differences in the spectra induced by the interface bond type can be observed. The theoretical simulation of the experimental data allowed us to accurately determine the energy of the interface TO phonons and the actual thickness of the region in which they are localized. The inactivity of the InAs TO phonon vibration at the interface can be explained by modeling a nonhomogeneous strain accommodation across the heterointerfaces. ©1995 American Institute of Physics.