How to Store Light and Understand the Laser Principle

Wonderful site! Includes a comprehensive open-access encyclopedia of photonics and links to suppliers.

As to the actual question of storing light, article admits the impracticality of any sort of "box o' mirrors" approach. Although truthfully it would make a fun experiment. I think nature provides a much more elegant solution in the form of crystals that can absorb and re-emit photons when excited, of which modern tech has made ample use thereof.