  An ${\rm SU(1,1)}$ interferometer uses a sequence of two optical parametric
amplifiers for achieving sub-shot-noise sensitivity to a phase shift introduced
in between. We present the first realization of a wide-field ${\rm SU(1,1)}$
interferometer, where the use of a focusing element enables spatially multimode
operation within a broad angle. Over this angle, the interference phase is
found to be flat. This property is important for the high sensitivity to the
phase front disturbance. Further, $-4.3\pm0.7$ dB quadrature squeezing, an
essential requirement to the high sensitivity, is experimentally demonstrated
for plane-wave modes inside the interferometer. Such an interferometer is
useful not only for quantum metrology, but also in remote sensing, enhanced
sub-shot-noise imaging, and quantum information processing.
