  We show that using the properties of the photon Green's function one can
successfully describe the propagation of arbitrary nonclassical optical
radiation through structured materials. In contrast to the similar input-output
approach, our method is not restricted neither to the spatial homogeneous
matter nor to the specific direction of light beam incidence or outcoupling.
Several quantum states of light are addressed in detail, such as Fock, Glauber,
and different squeezed light states, and their Green functions are given.
Furthermore, it is demonstrated how scattering of light at a slab can be
described with Poynting's energy flow vector, and how experimental setups can
be modeled.
