Spontaneous emission modifications in planar microcavities: Application to auto-fluorescence control for thin films under UV irradiation.

Spontaneous emission control for rare earth ions implanted inside planar multidielectric microcavities is presented. Rigorous classical electrodynamics analysis are presented and compared in order to compute the electromagnetic power provided by sources located inside planar dielectric multilayer structures. Radiation patterns are measured in Ta2O5/SiO2 microcavities implanted with praseodymium ions. Although we demonstrate a significant enhancement of the spontaneous emission in a direction normal to the layer (up to 30%), we show that a large amount of the emitted power is carried by the guided modes of the structures. As a direct application for thin films auto-fluorescence modifications, we concentrate on visible dielectric thin film luminescence under UV irradiation for the high index/low index couple HfO2/SiO2. We exploit those results in an attempt to understand the proper luminescence of three different mirror stacks, both in terms of luminescence efficiency and angular emission. This study introduces the "luminescence engineering" concept which may appear as a relevant thin films design criterion for biological applications.