Erbium-implanted silica microsphere laser

Spherical silica optical microresonators were doped with erbium ions by ion implantation at energies of 925 keV and 2.05 MeV using a rotating stage. After thermal annealing at 800 °C, light was coupled into the microsphere using a tapered optical fiber. An optical quality factor as high as 1.9x10⁷ was observed at ? = 1450 nm, corresponding to a modal loss of only 0.01 dB/cm. When pumped at 1450 nm, multi-mode lasing around 1570 nm is observed at a threshold between 150 and 250 µW depending on the overlap between mode and Er distribution. This work demonstrates the compatibility of ion implantation and microresonator technology.