Absorption properties of an optically active medium can be changed drastically by a Fabry-Perot microcavity. Optically active medium of the cavity includes a host material which is not optically active and at least one rare earth ion which provides optical activity to the medium. The Fabry-Perot cavity...http://www.google.fr/patents/US5363398?utm_source=gb-gplus-shareBrevet US5363398 - Absorption resonant rare earth-doped micro-cavities
