  We theoretically study Hawking radiation processes from an analog acoustic
black hole in a flowing superfluid of exciton-polaritons in a one-dimensional
semiconductor microcavity. Polaritons are coherently injected into the
microcavity by a laser pump with a suitably tailored spot profile. An event
horizon with a large analog surface gravity is created by inserting a defect in
the polariton flow along the cavity plane. Experimentally observable signatures
of the analog Hawking radiation are identified in the scattering of phonon
wavepackets off the horizon, as well as in the spatial correlation pattern of
quantum fluctuations of the polariton density. The potential of these table-top
optical systems as analog models of gravitational physics is quantitatively
confirmed by numerical calculations using realistic parameters for
state-of-the-art devices.
