  Strong coupling enables a diverse set of applications that include optical
memories, non-magnetic isolators, photonic state manipulation, and signal
processing. To date, strong coupling in integrated platforms has been realized
using narrow-linewidth high-Q optical resonators. In contrast, here we
demonstrate wideband strong coupling between two photonic bands. The indirect
interband photonic transition is controlled by electrically driving phonons in
a linear silicon waveguide. Under large acoustic drive, the system features a
Rabi-like energy exchange between two waveguide modes, demonstrating strong
coupling. When tuned to unity energy conversion, our system unlocks a set of
powerful applications, including optical modulators, routers and filters. In
particular, we demonstrate a low loss (-2.08 dB) acousto-optic modulator (AOM)
with pump suppression ratio > 55 dB. We also reconfigure our system to
demonstrate a non-magnetic, low-loss (< 1 dB) and broadband (59 GHz 10 dB
isolation bandwidth) optical isolator.
