Glass Microspherical Lasers

We report experimental results obtained in our laboratories in the development of Er3+-doped glass microspherical cavities for the fabrication of compact and low threshold laser sources at 1.55 ?m. We investigate three different approaches in order to fabricate the microspheres including direct melting of Er3+-doped glass powders, coating of silica microspheres with an Er3+-doped sol-gel layer, and synthesis of Er3+-doped monolithic microspheres using the sol-gel route in acid catalysis. Details of the different fabrication processes are presented together with the photoluminescence characterization in free space configuration of the microspheres and of the glass precursor. We analyse the photoluminescence spectra of the whispering gallery modes of the microspheres exited using evanescent coupling and we demonstrate laser action in a wide range of wavelengths around 1.55 ?m.