  We investigate the possibility that a (light) hidden sector extra photon
receives its mass via spontaneous symmetry breaking of a hidden sector Higgs
boson, the so-called hidden-Higgs. The hidden-photon can mix with the ordinary
photon via a gauge kinetic mixing term. The hidden-Higgs can couple to the
Standard Model Higgs via a renormalizable quartic term - sometimes called the
Higgs Portal. We discuss the implications of this light hidden-Higgs in the
context of laser polarization and light-shining-through-the-wall experiments as
well as cosmological, astrophysical, and non-Newtonian force measurements. For
hidden-photons receiving their mass from a hidden-Higgs we find in the small
mass regime significantly stronger bounds than the bounds on massive hidden
sector photons alone.
