Applied Physics Letters
Absence of the enhanced intra-4f transition cross section at 1.5μm of Er3+ in Si-rich SiO2
Hans W. Mertens, Albert Polman, I. M. P. Aarts, W. M. M. Kessels, M. C. M. van de Sanden
Abstract
We present measurements of the optical absorption cross section of the I15∕24→I13∕24 transition at 1.5μm of Er3+ ions embedded in SiO2 and Si-rich oxide, using cavity ringdown spectroscopy on thin films. The peak absorption cross section for Er3+ embedded in Si-rich oxide (10at.% excess Si) was found to be (8±2)×10−21cm2 at 1536nm, similar to typical values for Er embedded in SiO2. The data imply that the silicon nanoclusters incorporated in Si-rich oxide do not enhance the peak cross section of the Er3+ I15∕24−I13∕24 transition by 1-2 orders of magnitude, contrary to what has been reported in earlier work.