  We show that a Rubidium vapor can be produced within the core of a photonic
band-gap fiber yielding an optical depth in excess of 2000. Our technique for
producing the vapor is based on coating the inner walls of the fiber core with
an organosilane and using light-induced atomic desorption to release Rb atoms
into the core. We develop a model to describe the dynamics of the atomic
density, and as an initial demonstration of the potential of this system for
supporting ultra-low-level nonlinear optical interactions, we perform
electromagnetically-induced transparency with control-field powers in the
nanowatt regime, which represents more than a 1000-fold reduction from the
power required for bulk, focused geometries.
