1.7 μm Excited State Absorption Measurement in Erbium-doped Silicate Glasses

Abstract

Planar erbium doped waveguide amplifiers are important components in the development of integrated optical communication circuits at 1.5 μm. Such devices must achieve high gains in short lengths and thus require high erbium concentrations (>1019 cm−3). At these doping levels, however, the amplifier gain and efficiency are degraded by ion-ion interactions in the form of uniform and clustered upconversion [1], Upconversion is a problem in erbium-doped glasses because the 4I13/2→4/15/2 emission and 4I13/2→4I9/2 ESA transitions overlap. Therefore, it is of fundamental interest to measure the ESA spectrum. Wyatt [2] measured the tail of this spectrum to demonstrate that absorption of 1.55 μm photons from the 4I13/2 level could not occur. We have measured, for the first time, the full 1.7 μm ESA spectrum in erbium-doped glasses and used it to estimate the uniform upconversion rate. The silicate glasses studied are suitable for the development of ion-exchanged waveguide amplifiers at 1.5 μm.