Erbium-ytterbium co-doped aluminium oxide waveguide amplifiers fabricated by reactive co-sputtering and wet chemical etching.

We report on the fabrication and optical characterization of erbium-ytterbium co-doped aluminum oxide (Al₂O₃:Er³⁺:Yb³⁺) waveguides using low-cost, low-temperature deposition and etching steps. We deposited Al₂O₃:Er³⁺:Yb³⁺ films using reactive co-sputtering, with Er³⁺ and Yb³⁺ ion concentrations ranging from 1.4-1.6 × 10²⁰ and 0.9-2.1 × 10²⁰ ions/cm³, respectively. We etched ridge waveguides in 85% pure phosphoric acid at 60°C, allowing for …