Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

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.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

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.

Similar content being viewed by others

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.


  1. LiDAR drives forward. Nat. Photon. 12, 441 (2018).

  2. Poulton, C. V. et al. Coherent solid-state LiDAR with silicon photonic optical phased arrays. Opt. Lett. 42, 4091–4094 (2017).

    Article  ADS  Google Scholar 

  3. Hulme, J. C. et al. Fully integrated hybrid silicon two dimensional beam scanner. Opt. Express 23, 5861–5874 (2015).

    Article  ADS  Google Scholar 

  4. Howland, G. A., Lum, D. J., Ware, M. R. & Howell, J. C. Photon counting compressive depth mapping. Opt. Express 21, 23822–23837 (2013).

    Article  ADS  Google Scholar 

  5. Sun, M. J. et al. Single-pixel three-dimensional imaging with time-based depth resolution. Nat. Commun. 7, 12010 (2016).

    Article  ADS  Google Scholar 

  6. Tearney, G. J., Shishkov, M. & Bouma, B. E. Spectrally encoded miniature endoscopy. Opt. Lett. 27, 412–414 (2002).

    Article  ADS  Google Scholar 

  7. Mahjoubfar, A. et al. Time stretch and its applications. Nat. Photon. 11, 341–351 (2017).

    Article  ADS  Google Scholar 

  8. Goda, K. & Jalali, B. Dispersive Fourier transformation for fast continuous single-shot measurements. Nat. Photon. 7, 102–112 (2013).

    Article  ADS  Google Scholar 

  9. Solli, D. R., Ropers, C., Koonath, P. & Jalali, B. Optical rogue waves. Nature 450, 1054–1057 (2007).

    Article  ADS  Google Scholar 

  10. Solli, D. R., Herink, G., Jalali, B. & Ropers, C. Fluctuations and correlations in modulation instability. Nat. Photon. 6, 463–468 (2012).

    Article  ADS  Google Scholar 

  11. Herink, G., Jalali, B., Ropers, C. & Solli, D. R. Resolving the build-up of femtosecond mode-locking with single-shot spectroscopy at 90 MHz frame rate. Nat. Photon. 10, 321–326 (2016).

    Article  ADS  Google Scholar 

  12. Herink, G., Kurtz, F., Jalali, B., Solli, D. R. & Ropers, C. Real-time spectral interferometry probes the internal dynamics of femtosecond soliton molecules. Science 356, 50–54 (2017).

    Article  ADS  Google Scholar 

  13. Roussel, E. et al. Observing microscopic structures of a relativistic object using a time-stretch strategy. Sci. Rep. 5, 10330 (2015).

    Article  ADS  Google Scholar 

  14. Evain, C. et al. Direct observation of spatiotemporal dynamics of short electron bunches in storage rings. Phys. Rev. Lett. 118, 054801 (2017).

    Article  ADS  Google Scholar 

  15. Goda, K., Tsia, K. K. & Jalali, B. Serial time-encoded amplified imaging for real-time observation of fast dynamic phenomena. Nature 458, 1145–1149 (2009).

    Article  ADS  Google Scholar 

  16. Chen, C. L. et al. Deep learning in label-free cell classification. Sci. Rep. 6, 21471 (2016).

    Article  ADS  Google Scholar 

  17. Nakagawa, K. et al. Sequentially timed all-optical mapping photography (STAMP). Nat. Photon. 8, 695–700 (2014).

    Article  ADS  Google Scholar 

  18. Mahjoubfar, A. et al. High-speed nanometer-resolved imaging vibrometer and velocimeter. Appl. Phys. Lett. 98, 101107 (2011).

    Article  ADS  Google Scholar 

  19. Wu, J. L. et al. Ultrafast laser-scanning time-stretch imaging at visible wavelengths. Light Sci. Appl. 6, e16196 (2017).

    Article  Google Scholar 

  20. Suzuki, T. et al. Single-shot 25-frame burst imaging of ultrafast phase transition of Ge2Sb2Te5 with a sub-picosecond resolution. Appl. Phys. Express 10, 092502 (2017).

    Article  ADS  Google Scholar 

  21. Buus, J., Amann, M. C. & Blumenthal, D. J. Tunable Laser Diodes and Related Optical Sources (Wiley-Interscience, 2005).

  22. Diebold, E. D. et al. Giant tunable optical dispersion using chromo-modal excitation of a multimode waveguide. Opt. Express 19, 23809–23817 (2011).

    Article  ADS  Google Scholar 

  23. Yegnanarayanan, S., Trinh, P. D. & Jalali, B. Recirculating photonic filter: a wavelength-selective time delay for phased-array antennas and wavelength code-division multiple access. Opt. Lett. 21, 740–742 (1996).

    Article  ADS  Google Scholar 

  24. Jalali, B. & Fathpour, S. Silicon photonics. J. Lightwave Technol. 24, 4600–4615 (2006).

    Article  ADS  Google Scholar 

  25. Boyraz, O. & Jalali, B. Demonstration of a silicon Raman laser. Opt. Express 12, 5269–5273 (2004).

    Article  ADS  Google Scholar 

  26. Suzuki, K., et al. Low insertion loss and power efficient 32 × 32 silicon photonics switch with extremely-high-Δ PLC connector. In Optical Fiber Communication Conference Th4B-5 (Optical Society of America, 2018).

  27. Jalali, B. & Mahjoubfar, A. Tailoring wideband signals with a photonic hardware accelerator. Proc. IEEE 103, 1071–1086 (2015).

    Article  Google Scholar 

  28. Solli, D. R. & Jalali, B. Analog optical computing. Nat. Photon. 9, 704–706 (2015).

    Article  ADS  Google Scholar 

  29. Chen, C. L., Mahjoubfar, A. & Jalali, B. Optical data compression in time stretch imaging. PLoS ONE 10, e0125106 (2015).

    Article  Google Scholar 

  30. Huber, R., Wojtkowski, M. & Fujimoto, J. G. Fourier domain mode locking (FDML): a new laser operating regime and applications for optical coherence tomography. Opt. Express 14, 3225–3237 (2006).

    Article  ADS  Google Scholar 

  31. Karpf, S. & Jalali, B. Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture. Opt. Lett. 44, 1952–1955 (2019).

    Article  ADS  Google Scholar 

  32. Jiang, Y., Zhao, S. & Jalali, B. Optical dynamic range compression. APL Photon. 3, 110806 (2018).

    Article  ADS  Google Scholar 

  33. Biedermann, B. R., Wieser, W., Eigenwillig, C. M. & Huber, R. Recent developments in Fourier domain mode locked lasers for optical coherence tomography: imaging at 1,310 nm vs. 1,550 nm wavelength. J. Biophoton. 2, 357–363 (2009).

    Article  Google Scholar 

  34. Karpf, S. et al. Spectro-temporal encoded multiphoton microscopy. Preprint at (2017).

Download references


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

Authors and Affiliations



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.

Corresponding authors

Correspondence to Yunshan Jiang or Sebastian Karpf.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Scanning approach and range analysis.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

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

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing