An erbium-doped microlaser is demonstrated utilizing SiO microdisk resonators on a silicon chip. Passive microdisk resonators exhibit whispering-gallery-type modes (WGM's) with intrinsic optical quality factors of up to 6x107 and were doped with trivalent erbium ions (peak concentration ~3.8x1020 cm-3) using MeV ion implantation. Coupling to the fundamental WGM of the microdisk resonator was achieved by using a tapered optical fiber. Upon pumping of the 4/15/2-->4/13/2 erbium transition at 1450 nm, a gradual transition from spontaneous to stimulated emission was observed in the 1550-nm band. Analysis of the pump-output power relation yielded a pump threshold of 43 µW and allowed measuring the spontaneous emission coupling factor: β ≈1x10-3.
Phys. Rev. A
Photonic Materials

Kippenberg, T.J, Kalkman, J, Polman, A, & Vahala, K.J. (2006). Demonstration of an erbium-doped microdisk laser on a silicon chip. Phys. Rev. A, 74(Article number: 51802), 1–4. doi:10.1103/physreva.74.051802