480 Gbps WDM Transmission Through an Al₂O₃:Er³⁺ Waveguide Amplifier

The increasing need for more efficient communication networks has been the main driving force for the development of complex photonic integration circuits combining active and passive building blocks towards advanced functionality. However, this perpetual effort comes with the cost of additive power losses and the research community has resorted to the investigation of different materials to establish efficient on-chip amplification. Among the different proposals, erbium-doped waveguide amplifiers appear to be a promising solution for high performance transmission in the C-band band with low fabrication cost, due to their CMOS compatibility and integration potential with the silicon\silicon nitride photonic platforms. In this paper we provide a holistic study for high-speed WDM transmission capabilities of a monolithically integrated Al ₂ O ₃ :Er ³⁺ spiral waveguide amplifier co-integrated with Si ₃ N ₄ components, providing a static characterization and a dynamic evaluation for (a) 4 × 40 Gbps, (b) 8 × 40 Gbps and (c) 8×60 Gbps WDM transmissions achieving clearly open eye diagram in all cases. The active region of the erbium doped waveguide amplifier consists of a 5.9 cm Al ₂ O ₃ :Er ³⁺ spiral adiabatically coupled to passive Si ₃ N ₄ waveguides combined with on chip 980 nm/1550 nm WDM Multiplexers/Demultiplexers. Experimental results reveal bit-error rate values below the KR4-FEC limit of 2×10 ^-5 for all channels, without any DSP applied on the transmitter or receiver side for a 4×40 Gbps and 8×40 Gbps data stream transmission.