Rubidium diffusion in microscale spectroscopy and slow light platforms

This paper presents an approach to quantifying the diffusion rate of rubidium in glass microchannels. These types of microchannels are often used in integrated systems (chip and fiber based) which utilize light and rubidium vapor interactions to produce quantum interference phenomena such as slow light. The test platforms reported here were made using glass capillaries connected to larger glass chambers through glassblowing. Rubidium diffusion was monitored in two different ways. First, fluorescence measurements were taken over time at different points down the length of the capillary. Second, optical absorption measurements were taken through the large glass chambers on either side of the capillaries. Results indicate that reaching measurable atomic densities in microscale geometries can take many days or even weeks.