Mobile and low-cost LiDAR systems are key components for next-generation car navigation and industrial robots. For use in these applications, they need to be as energy efficient and as small as possible. Furthermore, operation over a wide temperature range and manufacturing with high output quantity at low cost are necessary. Potentially all of these general requirements should be fulfilled by a basic technology. And this is exactly the approach taken by the joint research project PLUS „Pulse-Laser and Scanner for LiDAR applications: Automotive, Consumer, Robotic“.
For such LiDAR applications, FBH develops and realizes a particularly small semiconductor-based pulse source with high beam quality, leading to a high image resolution. The focus here is on combining edge-emitting laser diodes with driver circuits into pulsed laser light sources with high peak power and excellent beam quality. They shall be applied in various LiDAR systems of the industrial project partners. A high peak power is important to achieve a large operating distance and a high signal-to-noise ratio, whereas beam quality and pulse width determine the spatial resolution of the LiDAR system.
Bragg reflectors for wavelength stabilization are implemented into the laser chip. They lead to a sufficiently small wavelength shift within the targeted temperature range. Furthermore, a suitable vertical layer structure and an appropriate active region will be developed, both especially optimized for the required pulsed operation. However, challenges are to reduce current leakage within the operation mode far above the threshold current and to ensure the required optical gain over a temperature range of 125 K within the small wavelength range. Due to typical operation conditions implying that laser diodes are exited with current pulses below 20 ns width and with more than 100 W peak power, compact and ultrafast high-current drivers with great efficiency are requested. These laser drivers will be realized using novel high-performance GaN transistors, which currently offer the greatest potential with respect to switching speed, power, and efficiency.
The system is supplemented by a small-sized scanning unit for high-precision light deflection, which will be developed by project partners. A micromechanical solution for the scanner will be investigated, designed to enable a high scanning speed along with a wide optical aperture. All components of the complete system need to be adapted to suit the different application scenarios. Hence, developments aim at a fully customizable “LiDAR technology kit” where the complete system is assembled from those laser sources, driver circuits, optics, and further components most suited for the respective application. The industry-led research consortium brings together all the expertise required to achieve this goal.