A self-driving car has a hard time recognizing the difference between a toddler and a brown bag that suddenly appears into view because of limitations in how it senses objects using lidar. The autonomous vehicle industry is exploring “frequency modulated continuous wave” (FMCW) lidar to solve this problem. Researchers have built a way that this type of lidar could achieve higher-resolution detection of nearby fast-moving objects through mechanical control and modulation of light on a silicon chip.
FMCW lidar detects objects by scanning laser light from the top of an autonomous vehicle. A single laser beam splits into a comb of other wavelengths, called a microcomb, to scan an area. Light bounces off of an object and goes to the detector through an optical isolator or circulator, which ensures all reflected light ends up at the detector array.
What the researchers developed uses acoustic waves to enable faster tuning of these components, which could bring higher-resolution FMCW lidar detection of nearby objects. The technology integrates microelectromechanical systems (MEMS) transducers made of aluminum nitride to modulate the microcomb (modulation of light) at high frequencies ranging from megahertz to gigahertz.