  We present a detailed study of the oscillations and optical properties for
vacuum, in a model for the dark sector that contains axion-like particles and
hidden photons. In this model, both can couple to photons. We provide bounds
for the couplings versus the mass, using current results from ALPS-I and PVLAS.
We also discuss the challenges for the detection of models with more than one
hidden particle in light shining trough wall-like experiments.
