A high-performance monolithic integrated wavelength division multiplexing silicon (Si) photonics receiver chip is fabricated on a silicon-on-insulator platform. The receiver chip has a 25-channel Si nanowire-arrayed waveguide grating, and each channel is integrated with a high-speed waveguide Ge-on-Si photodetector. The central wavelength, optical insertion loss, and cross talk of the array waveguide grating are 1550.6?nm, 5–8?dB, and ?12–?15??dB, respectively. The photodetectors show low dark current density of 16.9??mA/cm2 at ?1??V and a high responsivity of 0.82?A/W at 1550?nm. High bandwidths of 23 and 29?GHz are achieved at 0 and ?1??V, respectively. Each channel can operate at 50?Gbps with low input optical power even under zero bias, which realizes an aggregate data rate of 1.25?Tbps.