16×56-Gbps WDM transmission in an atomic-layer-deposited Er-doped waveguide amplifier

Driven by the increasing demand for efficient optical communication, on-chip amplifiers have become essential components in photonic integrated circuits for realizing cost-efficient and compact wavelength-division multiplexing (WDM) receivers. In this work, we investigate the WDM signal transmission performance of an on-chip erbium-doped aluminum-oxide waveguide amplifier, fabricated using atomic layer deposition. The waveguide amplifier demonstrates a net gain of >5.0 dB across the entire C-band, with a peak value of 11.1 ± 1.5 dB at 1531.6 nm, corresponding to an off-chip net gain of 7.1 ± 1.5 dB. A maximum on-chip output power of 4.1 ± 1.4 dBm at 1531.6 nm is achieved. Broadband performance is further confirmed by a 16-channel gain measurement. Finally, a 16-channel 56-Gbps WDM transmission is demonstrated, with the Q² values comparable to those of the back-to-back transmission, highlighting the potential of the amplifier for high-speed coherent data transmission.