Coupling of nanoemitters with whispering gallery modes in silica microspheres and microtoroids

We report on several enhancements in silica microcavities fabrication, characterization and functionalization. A special emphasis is put on mode identification, which gives access to the fundamental mode in both microspheres and microtoroids and to functionalization by nanoemitters, which open the way to original low threshold lasers. A record value of a threshold of 40 nW has been demonstrated for a microsphere doped with rare-earth oxide nanoparticles.