  This book chapter is the first part of a review of nanoporous materials for
optical applications. Whereas the second part [J.Sauer, F. Marlow and
F.Schueth, pp. 153-172 of the same volume] discusses material properties, this
part gives a self-contained discussion of fluorescence and lasing in dielectric
microresonators, with special emphasis on the hexagonal morphology found in
molecular-sieve-dye compounds.
