Researchers in France have developed a 256-channel beam steering device for Lidar sensors in driverless cars (writes Nick Flaherty).

The development at CEA-Leti in Grenoble involved 3D Integration of through-silicon vias (TSVs) and flip-chip technologies to package the optical devices.

The 10 µm-diameter TSVs significantly improve interconnect density by distributing them on the whole backside surface of the devices. Combining

40 µm fine-pitch flip chips on a silicon interposer, the integration increases the performance and compactness of Lidars, while lowering their cost for use in autonomous vehicles.

The researchers developed steering concepts using wafer-level silicon technology, including optical phase arrays. A 1550 nm wavelength beam was then brought into the circuit through grating couplers, then guided through silicon oxide waveguides to the steering area. This provides precise, latency-free information on the position and speed of obstacles surrounding road transport vehicles, independently of light conditions and with sharp angular resolutions.