Serpentine Optical Phased Arrays for Scalable Integrated Photonic Lidar Beam Steering

The University of Colorado, Boulder’s news, Leap in lidar could improve safety, security of new technology, by  discusses a new work, a new study published in The Optical Society, by Nathan Dostart, Bohan Zhang, Anatol Khilo, Michael Brand, Kenaish Al Qubaisi, Deniz Onural, Daniel Feldkhun, Kelvin H. Wagner, and Miloš A. Popović. Simpkins explains,

“In a new paper, published in Optica, they describe a new silicon chip—with no moving parts or electronics—that improves the resolution and scanning speed needed for a lidar system.

“We’re looking to ideally replace big, bulky, heavy lidar systems with just this flat, little chip,” said Nathan Dostart, lead author on the study, who recently completed his doctorate in the Department of Electrical and Computer Engineering.


Current commercial lidar systems use large, rotating mirrors to steer the laser beam and thereby create a 3-D image. For the past three years, Dostart and his colleagues have been working on a new way of steering laser beams called wavelength steering—where each wavelength, or “color,” of the laser is pointed to a unique angle.


They’ve not only developed a way to do a version of this along two dimensions simultaneously, instead of only one, they’ve done it with color, using a “rainbow” pattern to take 3-D images. Since the beams are easily controlled by simply changing colors, multiple phased arrays can be controlled simultaneously to create a bigger aperture and a higher resolution image.


“We’ve figured out how to put this two-dimensional rainbow into a little teeny chip,” said Kelvin Wagner, co-author of the new study and professor of electrical and computer engineering. “

Serpentine optical phased arrays for scalable integrated photonic lidar beam steering, The Optical Society, OSA publishing

The Optical Society, OSA publishing

Fig. 4. Demonstration of 2D wavelength steering with a SOPA. (a) Far-field camera image of a 200 nm scan (see Visualization 1), with only 1500 spots sampled out of 16,500. The grating lobe-limited FOV is 35.8×5.535.8∘×5.5∘. The under-sampling of the scan (every 10th point) and saturated over-exposure applied in post-processing for visibility cause the appearance of diagonal curves that are not the actual scan loci; their curvature arises from the group velocity dispersion. The spot pattern at 1550 nm is shown at the bottom to demonstrate the grating lobe-limited FOV. (b) A 5×5.55∘×5.5∘ subsection of the full scan, with only 70 spots sampled. The true scan loci are depicted by the dotted lines as a guide to the eye, and the colors are re-coded for the narrower bandwidth. (c) Wavelength scanning along the fast axis with three non-adjacent spots spaced by 3 GHz. (d) Wavelength scanning along the slow axis with three non-adjacent spots spaced by 82 GHz. (e) Single-wavelength spot at 1550 nm.

Courtesy of The Optical Society, OSA publishing

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