Photonic integrated circuits for coherent LiDAR

LiDAR is considered an essential enabling technology for the future of mobility, both for autonomous driving, as well as efficient use of low air space by drones and UAVs. Today’s LiDAR systems are quite primitive, and make use incoherent detection methods, which makes them vulnerable for crosstalk and interference. Especially in future scenarios where the surroundings are populated with many other LiDAR emitters, The LiDAR ranging and beam scanning engine should be robust against direct ‘attacks’.

Coherent LiDAR is one of the techniques that can help here. Instead of just detecting the reflected photon pulses, the incoming signal is coherently mixed with a local oscillator, which creates a well-defined beat tone that can be used for detecting object distance and velocity. This mixing acts as a strong filter that rejects a lot of the unwanted crosstalk from unrelated sources.

There are different methods for implementing coherent LiDAR (and more particular the coherent ranging that does the distance detection), but in this PhD you will look at solutions based on photonic integrated circuits. These are chips which contain multiple optical elements (e.g. lasers, modulators, detectors, …) connected together by optical waveguides. Such a photonic circuit can take care of the light generation in multiple laser sources, multiplexing them together, and couple them to free space using on-chip antennas. In this PhD, the various elements of such a system will be studied, but the focus will be on the ranging and the antennas themselves. In particular, the work will involve

• Building a model of a ranging engine, and how it interacts with free space (including the effects of unwanted sources of noise and ‘attacks’)
• Simulating new concepts for on-chip antennas, and prototyping them on chip to verify their performance experimentally. This will be done either in the IMEC facilities, or in the university clean room at Ghent University.
• Designing circuits for coherent ranging, combining . These circuits will then be fabricated in a standard foundry process, after which they should be combined with simple electronic drivers and experimentally tested in a LiDAR test setup in IMEC.

The PhD candidate is expected to have a good knowledge of photonics. Basic electronics know-how is a valuable asset, and programming skills  (Python) are also required.