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upstart writes in with an IRC submission:

Light shaken and stirred to help autonomous vehicles better scan for nearby fast-moving objects:

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.

[...] 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.

[...] The technology integrates microelectromechanical systems (MEMS) transducers made of aluminum nitride to modulate the microcomb at high frequencies ranging from megahertz to gigahertz. The optical isolator that the team developed as part of this process is further described in a paper published in Nature Communications.

[...] “The stirring motion modulates light such that it can only travel in one direction,” said Sunil Bhave, a Purdue professor of electrical and computer engineering.

[...] Other transducers in the same technology excite an acoustic wave that shakes the chip at megahertz frequencies, demonstrating sub-microsecond control and tuning of the laser pulse microcomb or soliton.

Journal Reference:
Junqiu Liu, Hao Tian, Erwan Lucas, et al. Monolithic piezoelectric control of soliton microcombs, Nature (DOI: 10.1038/s41586-020-2465-8)
Hao Tian, Junqiu Liu, Bin Dong, et al. Hybrid integrated photonics using bulk acoustic resonators [open], Nature Communications (DOI: 10.1038/s41467-020-16812-6)

Original Submission