Opt. Express 27, 3817–3823 (2019)

Ghost imaging is being explored for many applications such as remote sensing at low light levels, time-resolved 3D imaging and flow cytometry. However, existing ghost imaging systems can be bulky because of the spatial light modulator that is usually employed to generate the required illumination pattern. Now, Yusuke Kohno and co-workers from Japan have reported the use of a large-scale silicon photonic optical phased array (OPA) chip as an alternative solution. Their OPA chip (4 mm × 4 mm footprint) features 128 phase shifters and makes it possible to perform ghost imaging with over 90 resolvable points in one dimension, without the need for any calibration. The extension to 2D imaging was also reported by using an off-chip diffraction grating and a tunable laser to cover another axis. With the possibility of integrating grating couplers and a light source on the same chip, the team say that a single-chip, ultra-high-speed, 2D ghost imaging module could be realized in the future.