  Light detection and ranging (LiDAR) has been widely used in autonomous
driving and large-scale manufacturing. Although state-of-the-art scanning LiDAR
can perform long-range three-dimensional imaging, the frame rate is limited by
both round-trip delay and the beam steering speed, hindering the development of
high-speed autonomous vehicles. For hundred-meter level ranging applications, a
several-time speedup is highly desirable. Here, we uniquely combine fiber-based
encoders with wavelength-division multiplexing devices to implement all-optical
time-encoding on the illumination light. Using this method, parallel detection
and fast inertia-free spectral scanning can be achieved simultaneously with
single-pixel detection. As a result, the frame rate of a scanning LiDAR can be
multiplied with scalability. We demonstrate a 4.4-fold speedup for a maximum
75-m detection range, compared with a time-of-flight-limited laser ranging
system. This approach has the potential to improve the velocity of LiDAR-based
autonomous vehicles to the regime of hundred kilometers per hour and open up a
new paradigm for ultrafast-frame-rate LiDAR imaging.
