  The coherent transduction of information between microwave and optical
domains is a fundamental building block for future quantum networks. A
promising way to bridge these widely different frequencies is using
high-frequency nanomechanical resonators interacting with low-loss optical
modes. State-of-the-art optomechanical devices rely on purely dispersive
interactions that are enhanced by a large photon population in the cavity.
Additionally, one could use dissipative optomechanics, where photons can be
scattered directly from a waveguide into a resonator hence increasing the
degree of control of the acousto-optic interplay. Hitherto, such dissipative
optomechanical interaction was only demonstrated at low mechanical frequencies,
precluding prominent applications such as the quantum state transfer between
photonic and phononic domains. Here, we show the first dissipative
optomechanical system operating in the sideband-resolved regime, where the
mechanical frequency is larger than the optical linewidth. Exploring this
unprecedented regime, we demonstrate the impact of dissipative optomechanical
coupling in reshaping both mechanical and optical spectra. Our figures
represent a two-order-of-magnitude leap in the mechanical frequency and a
tenfold increase in the dissipative optomechanical coupling rate compared to
previous works. Further advances could enable the individual addressing of
mechanical modes and help mitigate optical nonlinearities and absorption in
optomechanical devices.
