Highly coherent – that is narrow linewidth - laser sources are at the heart of numerous applications: ranging from terabit per second coherent communication, LiDAR for autonomous driving or driver assistance, to fibre sensing or optical atomic clocks. Yet, neither the principles of narrow linewidth lasers nor how they are manufactured, have changed in the past 30 years; fiber lasers, the workhorse for narrow linewidth, rely on bulk fibre based optical components assembled manually. In recent years, triggered by new applications in particular in FMCW LiDAR, the demand for integrated lasers that combine the coherence of a narrow linewidth fibre laser with high frequency agility and fast tuning, and can be manufactured wafer-scale in large volume at low cost has become a technological bottleneck. 
Here we overcome these challenges and will demonstrate for the first time a mass manufacturable, compact, wafer-scale narrow linewidth laser with unprecedentedly agile tuning and precise laser tuning. To achieve this novel technology, we will employ recent findings on a hybrid electro-opto—mechanical integrated laser obtained in the FET Proactive project “Hybrid Optomechanical Technologies.” To combine the conflicting properties of ultrahigh coherence and fast and precise tuning, we will combine sub-micron piezo-electrical actuators that rely on AlN – a proven MEMS technology - that combine an electrical and mechanical engineered degrees of freedom with silicon nitride ultra-low loss integrated photonic circuits. The combined hybrid opto-electro-mechanical device exhibits unique performance characteristics in terms of linewidth and frequency agility not attained anywhere to date, making them ideal sources for LiDAR.
FMCW LiDAR is a next generation perception technology enabled by narrow linewidth highly tunable lasers that has major advantages compared to the currently used time of flight LiDAR: it is eye-safe and crucially can give both velocity and distance information in the same pixel – massively simplifying the object classification. FMCW can even operate in glaring sunlight, is immune to crosstalk from other sensors, and is ideally suited for long-range detection as required for autonomous driver assistance. It is, however, compounded by the very stringent requirements: it requires exceptionally narrow linewidth, highly linear tuning of the laser, and above all, this technology, being applied to mass markets, is required to be manufactured in large volumes at low cost. 
Ultra-stable, fast and linearly tunable lasers are also key enabling technology for reconfigurable, ultra-broadband wireless transmitters for future wireless communications. Using the unoccupied mmWave band above 100 GHz requires low-cost yet very high-performance tunable laser systems and high bandwidth photoreceivers to cope with the requirements of dense mesh area coverage imposed by the significant atmospheric absorption at these frequencies.
In this project, we will manufacture such hybrid integrated lasers using volume-manufacturing compatible techniques only – using both monolithic and transfer printing techniques - improve their tuning and linewidth further and test them in a relevant application scenario for FMCW LiDAR and validate the combination of NOEMS technologies and integrated photonics devices for use in optical communication by demonstration of tight phase locking using the novel actuator technology.

Project partners

• THALES RESEARCH & TECHNOLOGY - France (coordinator)
• Universiteit Gent - Belgium
• Ecole Polytechnique Fédérale de Lausanne - Switzerland