  Coherent optics has profoundly impacted diverse applications ranging from
communications, LiDAR to quantum computations. However, building coherent
systems in integrated photonics previously came at great expense in hardware
integration and energy efficiency: the lack of a power-efficient way to
generate highly coherent light necessitates bulky lasers and amplifiers, while
frequency and phase recovery schemes require huge digital signal processing
resources. In this work, we demonstrate a high-coherence parallelization
strategy that facilitates advanced integrated coherent systems at a minimum
price. Using a self-injection locked microcomb to injection lock a distributed
feedback laser array, we boost the microcomb power by a record high gain of up
to 60 dB on chip with no degradation in coherence. This strategy enables tens
of highly coherent channels with an intrinsic linewidth down to the 10 Hz level
and power of more than 20 dBm. The overall electrical to optical wall-plug
efficiency reaches 19%, comparable with that of the state-of-the-art
semiconductor lasers. Driven by this parallel source, we demonstrate a silicon
photonic communication link with an unprecedented data rate beyond 60 Tbit/s.
Importantly, the high coherence we achieve reduces the coherent-related DSP
consumption by 99.999% compared with the traditional III-V laser pump scheme.
This work paves a way to realizing scalable, high-performance coherent
integrated photonic systems, potentially benefiting numerous applications.
