High-gain On-chip Er:Ta2O5 Amplifier with Multi-stage Pumping

Erbium-doped tantalum pentoxide (Er:Ta 2 O 5 ) is an excellent material platform for achieving efficient optical amplification in photonic integrated circuits (PICs). In this paper, we present a multi-stage distributed pumping approach for efficiently pumping erbium ions to develop a fully integrated high-gain on-chip Er:Ta 2 O 5 waveguide amplifier. The spiral Er:Ta 2 O 5 waveguides are designed to support single-mode operation at 1550 nm and are optimized for low losses. The undoped Ta 2 O 5 waveguides for pump delivery are designed to maximize pump light coupling into the gain waveguides, ensuring efficient erbium ion excitation and achieving high optical gain. When compared with a single-stage optically pumped Er:Ta 2 O 5 waveguide amplifier, gain improvements of over 3.5 dB are observed for similar doping concentrations of Er 3+ ions and waveguide length.