64Gb/s PAM4 and 160Gb/s 16QAM modulation reception using a low-voltage Si-Ge waveguide-integrated APD

We demonstrate waveguide-integrated silicon-germanium avalanche photodiodes with a maximum responsivity of 15.2 A/W at 16x avalanche gain, and 33 GHz bandwidth. Intensity-modulation-direct-detection (LMDD) and coherent channel reception test demonstrated the APD's performance with higher-order formats, allowing 32 Gbaud PAM-4 and 40 Gbaud 16QAM channel reception without any digital signal processing conventionally used for receiver impairments mitigation. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement