  The relation between the macroscopic quantum coherent nature of superfluids
and the coherent properties of optical interference patterns will be utilized
to examine the optical properties of superfluid hydrodynamics. A Bragg pattern
imposed on the superfluid (either holographically or using a phase mask) is
expected to induce periodic variations in the local index of refraction of the
normal and super fluid components. The altered optical properties can then be
probed by a second coherent light source. In this manner, the behavior of the
probe beam can be switched using the specific characteristics of the imposed
pattern. Acoustic modes should also manifest measurable affects on incident
coherent radiations.
