Photonic Integrated Circuits for Long-Range Solid-State LiDAR Applications

LiDAR provides high resolution detection of objects over large distances using light. However, fulfilling the performance metrics of mass-reproducible solid-state LiDAR is an ongoing challenge. Particularly, automotive forward-looking LiDAR requires projecting and receiving light at distances over 200m. Large frame rates, high angular resolution and wide field-of-view are essential to construct an accurate 3D point cloud of the surrounding environment. To have a sufficient photon count on the LiDAR detector, a collimated beam of high power needs to be emitted from the transmitter. To utilize LiDAR for the automotive industry, the device needs to be low cost, with small form-factor and low power consumption. Therefore, implementing LiDAR on photonic chips is a promising approach due to the low-cost volume production of CMOS foundry processes, the low power consumption of photonic components and the small chip-based form-factor compared to other LiDAR implementations. The two main functionalities that photonics contribute to the LiDAR engine are ranging (determining the distance to an object) and beam steering (pointing the beam in a certain direction). In our work, we focus on the latter functionality, based on the concept of optical phased arrays (OPAs). An OPA is an array of optical antennas where the amplitudes and phases of the emitted optical signals are controlled to manipulate the total far-field radiation pattern. This pattern corresponds to the light signal that is projected onto the object to be detected. Designing OPA architectures with high fill-factor and antennas with long length and high efficiency should make it possible to attain the field-of-view and resolution requirements of automotive LiDAR. Low power circuits of small form-factor require optimizing the photonic components to have low loss, small footprint, along with improving dense circuit routing techniques. Such improvements pave the way to build large scale photonic circuits for a fully integrated LiDAR system.