Massively parallel coherent laser ranging using a soliton microcomb

By J. Riemensberger, A. Lukashchuk, Maxim Karpov, W. Weng, E. Lucas, Junqiu Liu, Tobias J. Kippenberg. Nature, 2019

601 citations recorded by the source corpus.

Coherent ranging, also known as frequency-modulated continuous-wave (FMCW) laser-based light detection and ranging (lidar)1 is used for long-range three-dimensional distance and velocimetry in autonomous driving2,3. FMCW lidar maps distance to frequency4,5 using frequency-chirped waveforms and simultaneously measures the Doppler shift of the reflected laser light, similar to sonar or radar6,7 and coherent detection prevents interference from sunlight and other lidar systems. However, coherent ranging has a lower acquisition speed and requires precisely chirped8 and highly coherent5 laser sources, hindering widespread use of the lidar system and impeding parallelization, compared to modern time-of-flight ranging systems that use arrays of individual lasers. Here we demonstrate a massively parallel coherent lidar scheme using an ultra-low-loss photonic chip-based soliton microcomb9. By fast chirping of the pump laser in the soliton existence range10 of a microcomb with amplitudes of up to several gigahertz and a sweep rate of up to ten megahertz, a rapid frequency change occurs in the underlying carrier waveform of the soliton pulse stream, but the pulse-to-pulse repetition rate of the soliton pulse stream is retained. As a result, the chirp from a single narrow-linewidth pump laser is transferred to all spectral comb teeth of the soliton at once, thus enabling parallelism in the FMCW lidar. Using this approach we generate 30 distinct channels, demonstrating both parallel distance and velocity measurements at an equivalent rate of three megapixels per second, with the potential to improve sampling rates beyond 150 megapixels per second and to increase the image refresh rate of the FMCW lidar by up to two orders of magnitude without deterioration of eye safety. This approach, when combined with photonic phase arrays11 based on nanophotonic gratings12, provides a technological basis for compact, massively parallel and ultrahigh-frame-rate coherent lidar systems. A massively parallel coherent light detection and ranging (lidar) scheme using a soliton microcomb—a light source that emits a wide spectrum of sharp lines with equally spaced frequencies—is described.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Ophthalmology

View Paper: https://www.semanticscholar.org/paper/79d0feecf94c323663a5dff490e6b791c502af01

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In Atomic and Molecular Physics, and Optics

  1. Lukas Chrostowski
  2. Michael Hochberg
  3. Wim Bogaerts

In Electrical and Electronic Engineering

  1. Lukas Chrostowski
  2. Michael Hochberg
  3. Sudip Shekhar
  4. Bhavin J. Shastri
  5. Wim Bogaerts
  6. Shankar Kumar Selvaraja
  7. R. Baets

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