We calculate the absorption of infra-red radiation by a magnetic superlattice composed of alternating ferromagnetic films. Although the films are ferromagnetic, the interfacial interaction is antiferromagnetic (i.e. Fe/Gd or Co/Gd). As has been shown previously, such a system can exist in several distinct phases, and we calculate the power absorption for these different phases. The spin wave modes of the system were found and used to construct a Green's function via an eigenvector expansion. The incoming radiation was modeled as an oscillating magnetic field which was assumed to decay into the material. Given this driving field, the Green's function yields the response of the system. Our results indicate that a simple absorption measurement can be used to probe for surface and bulk magnetic phase transitions. Additionally, we can find the response of the system to a spatially uniform driving field and thus calculate the local susceptibility. We discuss the possibility of using such a susceptibility to find dipole-exchange modes in magnetic superlattices.