Photoluminescence and lasing in whispering gallery mode glass microspherical resonators

Abstract

We report experimental results regarding the development of Er 3+ -doped glass microspherical cavities for the fabrication of compact sources at 1.55 μm. We investigate several different approaches in order to fabricate the microspheres including direct melting of Er 3+ -doped glass powders, synthesis of Er 3+ -doped monolithic microspheres by drawing Er 3+ -doped glass, and coating of silica microspheres with an Er 3+ -doped sol–gel layer. 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 have analyzed the photoluminescence spectra of the whispering gallery modes of the microspheres excited using evanescent coupling and we demonstrate tunable laser action in a wide range of wavelengths around 1.55 μm. As much as 90 μW of laser output power was measured in Er 3+ -doped glass microspheres. • Different approaches in microsphere fabrication and various types of post-processing. • Trimming of photorefractive glass microsphere lasers with UV light. • Peak power record of 90 μW by pumping at 1480 nm.