Physical Review Letters
Measuring and Modifying the Spontaneous Emission Rate of Erbium near an Interface
E. Snoeks, Ad Lagendijk, Albert Polman
Abstract
Erbium implanted sodalime silicate glass was covered with a range of transparent liquids. The spontaneous emission rate of ${\mathrm{Er}}^{3+}$ around 1.54 $\ensuremath{\mu}$m shows clear changes depending on the liquid refractive index and Er depth. A rigorous quantum mechanical calculation shows that the effect of the interface on the spontaneous emission rate is fully described by the classical density of optical modes as a function of distance from the interface. The data provide the first direct determination of the radiative transition rate $(45{s}^{\ensuremath{-}1})$ at 1.54 $\ensuremath{\mu}$m of ${\mathrm{Er}}^{3+}$ which is widely used in optical amplifiers.