Low-Light-Level Optical Interactions with Rubidium Vapor in a Photonic   Bandgap Fiber
  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. 
Saikat Ghosh, Amar R. Bhagwat, C. Kyle Renshaw, Shireen Goh, Brian J.   Kirby and Alexander L. Gaeta