An optical sensing device includes a planar substrate and an array of optical transceivers disposed on the planar substrate. Each optical transceiver includes a photodetector, at least one turning mirror having a reflective surface disposed diagonally relative to the substrate, and multiple waveguides disposed parallel to the substrate. The waveguides include a transmit waveguide, which is coupled to convey outgoing light from a coherent light source to the at least one turning mirror for output from the optical transceiver, and a receive waveguide, which is coupled to receive incoming light reflected by the at least one turning mirror and to convey the incoming light to the photodetector.