The infrared transmission spectra of (GaAs)n(AlAs)nsuperlattices (1≤n≤5) grown on (001) GaAs have been studied in the region of the AlAs‐like phonons using polarized light and oblique incidence. The longitudinal optical (LO) phonon frequency decreases with increasing confinement. Forn<3 the width of the LO phonon band increases due to disordering at the interfaces. The width of the transverse optical (TO) phonon band is substantially larger than that of the LO one. The LO phonon linewidth is mainly attributed to intrinsic damping, whereas that of the TO one is ascribed to radiative damping of polaritons. ©1995 American Institute of Physics.