UTA (Texas) project aims to improve laser steering on self-driving cars

18 Nov 2022

US NSF funding Weidong Zhou's group investigating beam steering device based on VCSELs.

A professor at the University of Texas at Arlington Electrical Engineering department is leading a project to explore an optical laser beam steering device for 3D sensing in autonomous driving cars.

To make the device, Weidong Zhou, UTA professor in the Department of Electrical Engineering, will use a four-year, $400,000 U.S. National Science Foundation grant titled Fast 2D Beam Steering Device Integrated Directly on High Power VCSEL Arrays.

Zhou commented, “We’re investigating an optical beam steering device based on the electrical tuning of photonic crystal cavities, a type of nanophotonic structure, that can be designed to manipulate light beams. Right now most existing methods use mechanical movements to steer the light beam direction. That’s slow and bulky. What we’re doing is much faster, very compact and more reliable.”

High-speed beam steering is important in many emerging applications, including autonomous driving, augmented reality, free space communications, 3D sensing and imaging systems. Zhou said the type of vertical-cavity, surface-emitting laser (VCSEL) used in the project is also deployed in computer mice, fiber optic communications, face identification, smart phones, laser printers and smart glasses.

“VCSEL arrays can provide a disruptive technology for high-performance laser detection and ranging systems,” he said. “In addition, the project offers a platform for student education and training and helps workforce preparation in photonics and optics, semiconductors, sensing and imaging, nanotechnology and manufacturing.”

Diana Huffaker, chair of the Department of Electrical Engineering, said the application for Zhou’s project could reach the entire semiconductor sector. “A new-age optical beam steering device would speed up so many aspects of the semiconductor world,” she said. “It could revolutionize that world in making current operations so immediate and so effortless.”

MEMS micro-mirrors improve lidar sensing for vehicles

CEA-Leti has announced that a research program is leading to improved MEMS micro-mirrors for vehicles. This innovative technology aims to detect car tires (150mm high) from a distance of 100 meters. These research results emerged from the European Vizta project and are protected by three new patents.

MEMS micro-mirrors for automobile lidar are tiny (2mm wide) but essential components that reflect a laser beam and direct it, thanks to their up-down-left-right movements. This helps lidar sweep an area and detect vehicles, pedestrians and obstacles.

The innovations developed by Leti are protected by three patents. These improvements will increase lidar range and security as well as reduce energy consumption and manufacturing costs.

To improve the mechanism used to move the mirrors, the researchers replaced the traditional electrostatic or electromagnetic solutions with a PZT piezo-electric solution that only requires 20V (versus 150V for an electrostatic mirror). This innovative solution also eliminates the need for bulky magnets, which are required for an electromagnetic mirror.

CMOS-friendly manufacture

These innovative micro-mirrors were designed to work at 1550nm in order to limit ocular risk and support the high-power laser beam required for long-range lidar applications. To achieve this improvement, researchers replaced the habitual gold reflector with layers of Bragg deposited on silicon.

This solution offers two advantages: first, the reflectors are four times less absorbent and thus less prone to overheating by the laser, which makes it possible to increase incident power. And second, these layers can be deposited with CMOS compatible processes thus reducing the cost of manufacturing.

To reinforce ocular safety for pedestrians, the researchers added a self-diagnostics function that could enable the laser to switch off when the mirror is not moving. The research carried out as part of the Vizta framework also includes an optical characterization bench, packaging and a dedicated electronics pilot interface. The mirrors were integrated into an industrial partner's existing 3D lidar system and their compatibility with the desired goal was confirmed. Mirror control will continue to be improved in order to scan specific parts of a scene with greater precision.