  In the light of the interest in the transport of single photons in arrays of
waveguides, fiber couplers, photonic crystals, etc., we consider the quantum
mechanical process of the tunneling of photons through evanescently or
otherwise coupled structures. We specifically examine the issue of tunneling
between two structures when one structure already contains few photons. We
demonstrate the possibility of both photon aided and inhibited tunneling of
photons. The Bosonic nature of photons enhances the tunneling probability. We
also show how the multiphoton tunneling probability can be either enhanced or
inhibited due to the presence of photons. We find similar results for the
higher order tunneling. Finally, we show that the presence of a squeezed field
changes the nature of tunneling considerably.
