RF-sputtering technique for fabrication of dielectric multilayer structures with low-threshold coherent emission at 1.5 um

Glasses based systems activated by rare earth ions are the starting point of numerous photonic devices and the control and the enhance of the emission properties of emitters is a crucial challenge for these kinds of active systems. The tailoring of the dielectric surrounding of the source is a viable possibility and several geometry, materials and fabrications protocols have been proposed at this aim. Among the different possible approaches, one-dimensional (1D) photonic crystals, that are the simplest photonic band-gap device exploitable to manipulate the emission and absorption properties of rare earth ions, are well known to provide good results in the nanometric confinement of the light. However, on these kinds of structures, the dependence of the final product on the fabrication protocol remains a crucial task of the research in material science. Various techniques that could be employed to fabricate oxide dielectric materials and rf-sputtering is a promising route to fabricate rare earth-activated 1D photonic crystals. Here we discuss some recent results regarding the design, fabrication and characterization of Er doped SiO/TiO 1D photonic microcavity (fig. 1). Different geometrical configurations are compared in order to put in evidence the effect of the geometry of the photonic crystals on the emission features [1]. Coherent emission is assessed with threshold at about 4pW observed on the optimized sample (fig. 2) and a first step towards the integration on the tip of the fiber is presented. We show as the rf-sputtering technique is suitable for the fabrication of high-quality structures matrix for coherent emission based on active glass. We present the steps used in the fabrication protocols and the optical, spectroscopic, structural and morphologic results of the samples.