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Time-stretch LiDAR as a spectrally scanned time-of-flight ranging camera


The need for imaging and ranging in robotics has brought LiDAR (light detection and ranging) to the forefront of consumer technology1. Among various approaches, time-of-flight ranging sets the benchmark for robust operation due to illumination with high-energy pulses and direct detection. Conversely, spectrally scanning using tunable lasers is an inertia-free solution that offers fast scanning. The realization of a time-of-flight LiDAR with fast spectral scanning has not been possible because of difficulty in creating pulsed tunable sources. We demonstrate a wavelength-scanned time-of-flight LiDAR that realizes single-shot imaging and inertia-free scanning in one dimension with a rate of 1 MHz using a single laser and a single detector. We report two implementations of this concept, the first with a gain-switched supercontinuum source at 1,550 nm, and the second with a frequency-domain mode-locked laser at 1,060 nm. We show foveated imaging with both approaches as a potential solution to the big data predicament in three-dimensional imaging.

Fig. 1: Time-stretch LiDAR enables spectrally scanned time-of-flight imaging in 1D at an approximately MHz linescan rate.
Fig. 2: Two implementations of the proposed LiDAR.
Fig. 3: LiDAR based on the true time delay method permits inertia-free imaging in 1D with an adaptive foveated vision for optical data compression.
Fig. 4: LiDAR based on the FDML implementation achieves inertia-free imaging in 1D with a high number of pixels and flexible imaging parameters.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.


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This work was performed at the Photonics Laboratory at UCLA. It was supported in part by the Office of Naval Research MURI programme on Optical Computing, and by the National Institutes of Health grant no. R21EB019645. S.K. acknowledges a postdoctoral research fellowship from the German Research Foundation (DFG, project KA 4354/1-1), a junior professorship with financial support by the state of Schleswig-Holstein (Excellence Chair Programmme by the universities of Kiel and Luebeck) and funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy (EXC 2167-390884018).

Author information




B.J. conceived the time-stretch LiDAR concept and its two implementations. Y.J. designed and built the true time delay source and conducted the LiDAR measurements. S.K. designed and built the FDML-based discrete spectro-temporal source and assisted in the experiments. Y.J. performed data analysis and visualizations. All authors wrote the manuscript. B.J. supervised the research.

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Correspondence to Yunshan Jiang or Sebastian Karpf.

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Scanning approach and range analysis.

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Jiang, Y., Karpf, S. & Jalali, B. Time-stretch LiDAR as a spectrally scanned time-of-flight ranging camera. Nat. Photonics 14, 14–18 (2020).

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