Modulation Of Light Enhances LiDAR

Due to limitations in how it can sense objects using lidar, a self-driving vehicle struggles to distinguish between a toddler and a brown bag that abruptly appears in view. The autonomous vehicle business is looking into “frequency modulated continuous wave” (FMCW) lidar to address this issue. Researchers have developed a method for lidar that uses mechanical control and light modulation on a silicon chip to achieve higher-resolution detection of nearby fast-moving objects.

By scanning laser light from the top of an autonomous vehicle, FMCW lidar identifies objects. A single laser beam divides into a microcomb of different wavelengths to scan an area. It is ensured that all reflected light reaches the detector array by passing through an optical isolator or circulator after reflecting off an item.

Faster tuning of these components is made possible by the technology the researchers created using acoustic waves. It could lead to higher-resolution FMCW lidar detection of nearby objects. Microelectromechanical systems (MEMS) transducers made of aluminum nitride are integrated into the technology to modify the microcomb (modulation of light) at high frequencies between megahertz and gigahertz.

Launching a corkscrew-like stress pulse into a silicon chip, an array of phased MEMS transducers used in smartphones to identify cellular bands stirs light at gigahertz frequencies. Light can only travel in one way due to the stirring motion.

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