Upconversion channels in Er3+:ZBLALiP: multicolour microspherical light   source
  We present results on the realization of an all-taper coupled, multicolour microspherical glass light source fabricated from the erbium doped fluoride glass ZBLALiP. Whispering gallery mode lasing and upconversion processes give rise to laser and fluorescent emissions at multiple wavelengths from the ultraviolet to the infrared. A single-mode tapered fibre coupling scheme, which serves to both launch pump light at 980 nm into the microresonator cavity and collect the resulting infrared lasing, is employed. We demonstrate the use of a second separate fibre taper to outcouple the upconversion spectrum over several hundred nanometers. Thirteen discrete emissions ranging from 320 to 850 nm have been observed in the upconversion spectrum. The absorption and fluorescence properties are studied and the processes responsible for the generation of the observed wavelengths are outlined. 
Danny G. O'Shea, Jonathan M. Ward, Brian J. Shortt, Michel Mortier,   Patrice F\'eron and S\'ile Nic Chormaic