Fluorescence of Ta2O5 thin films doped by kilo-electron-volt Er implantation: Application to microcavities

Luminescent layers are prepared by the implantation of kilo-electron-volt Er ions into tantalum pentoxide (Ta2O5) thin films made by ion plating. The implantation fluences range from 3.3 x 10(14) to 2 x 10(15) ions/cm(2), and the energies range from 190 to 380 keV. Refractive index, extinction coefficient, and losses on guided propagation are investigated. We show that these Er-implanted layers present an absorption as low as that of the nonimplanted films. When optically pumped with an Ar+ laser (lambda = 0.488 mu m) beam, implanted films show peaked fluorescence spectra centered near 1.53 and 0.532 mu m. We show that the fluorescence intensity is correlated with the intensity of the pump beam in the region where Er ions are implanted. Radiation patterns of Er ions located inside a single layer or inside a Ta2O5/SiO2 dielectric stack made by ion plating are also investigated. We show that, in any case, spontaneous emission of Er ions can be spatially controlled. (C) 1996 Optical Society of America