  Integrated photonic active beamforming can significantly reduce the size and
cost of coherent imagers for LiDAR and medical imaging applications. In current
architectures, the complexity of photonic and electronic circuitry linearly
increases with the desired imaging resolution. We propose a novel photonic
transceiver architecture based on co-prime sampling techniques that breaks this
trade-off and achieves the full (radiating-element-limited) field-of-view (FOV)
for a 2D aperture with a single-frequency laser. Using only order-of-N
radiating elements, this architecture achieves beamwidth and side-lobe level
(SLL) performance equivalent to a transceiver with order-of-N-squared elements
with half-wavelength spacing. Furthermore, we incorporate a pulse amplitude
modulation (PAM) row-column drive methodology to reduce the number of required
electrical drivers for this architecture from order of N to order of square
root of N. A silicon photonics implementation of this architecture using two
64-element apertures, one for transmitting and one for receiving, requires only
34 PAM electrical drivers and achieves a transceiver SLL of -11.3dB with 1026
total resolvable spots, and 0.6 degree beamwidth within a 23x16.3 degree FOV.
