Ambient light immunity of a frequency-modulated continuous-wave (FMCW) LiDAR chip

Area of Science:

• Photonics
• Autonomous Systems
• Optical Sensing

Background:

• Interference in light detection and ranging (LiDAR) systems poses a challenge for autonomous vehicles.
• Frequency-modulated continuous-wave (FMCW) LiDAR offers potential advantages in ambient light immunity over traditional time-of-flight (ToF) LiDAR.

Purpose of the Study:

• To theoretically analyze and experimentally investigate interference in FMCW LiDAR systems.
• To evaluate the impact of system parameters on interference probability and sunlight contamination.
• To assess the feasibility of FMCW LiDAR for safety-critical applications like autonomous driving.

Main Methods:

• Theoretical modeling of interference considering spatial, frequency, and intensity overlaps.
• Experimental validation using a silicon photonics FMCW LiDAR chip with slow-light grating beam scanners.
• Systematic variation of wavelength range, sweep bandwidth, and sweep period to observe interference effects.

Main Results:

• Interference probability between FMCW LiDARs can be reduced below safety standards by increasing resolution points.
• Incoherent sunlight does not cause interference with FMCW LiDAR due to coherent detection.
• Interference suppression is achievable by increasing resolution points and moderately adjusting common parameters.
• Sunlight contamination can cause unwanted beam shift due to heating, but is manageable with wavelength filtering.

Conclusions:

• FMCW LiDAR exhibits robust performance against interference from other LiDARs and sunlight, especially when optimized for resolution.
• The coherent detection mechanism provides superior ambient light immunity compared to ToF LiDAR.
• System parameter tuning and wavelength filtering are effective strategies for mitigating residual interference and sunlight contamination in FMCW LiDAR applications.