  Recent advances in photonic integration have propelled microwave photonic
technologies to new heights. The ability to interface hybrid material platforms
to enhance light-matter interactions has led to the developments of ultra-small
and high-bandwidth electro-optic modulators, frequency synthesizers with the
lowest noise, and chip signal processors with orders-of-magnitude enhanced
spectral resolution. On the other hand, the maturity of high-volume
semiconductor processing has finally enabled the complete integration of light
sources, modulators, and detectors in a single microwave photonic processor
chip and has ushered the creation of a complex signal processor with
multi-functionality and reconfigurability similar to their electronic
counterparts. Here we review these recent advances and discuss the impact of
these new frontiers for short and long term applications in communications and
information processing. We also take a look at the future perspectives in the
intersection of integrated microwave photonics with other fields including
quantum and neuromorphic photonics.
