  Optical phased arrays (OPAs) which beam-steer in 2D have so far been unable
to pack emitting elements at $\lambda/2$ spacing, leading to grating lobes
which limit the field-of-view, introduce signal ambiguity, and reduce optical
efficiency. Vernier schemes, which use paired transmitter and receiver phased
arrays with different periodicity, deliberately misalign the transmission and
receive patterns so that only a single pairing of transmit/receive lobes permit
a signal to be detected. A pair of OPAs designed to exploit this effect thereby
effectively suppress the effects of grating lobes and recover the system's
field-of-view, avoid potential ambiguities, and reduce excess noise. Here we
analytically evaluate Vernier schemes with arbitrary phase control to find
optimal configurations, as well as elucidate the manner in which a Vernier
scheme can recover the full field-of-view. We present the first experimental
implementation of a Vernier scheme and demonstrate grating lobe suppression
using a pair of 2D wavelength-steered OPAs. These results present a route
forward for addressing the pervasive issue of grating lobes, significantly
alleviating the need for dense emitter pitches.
