Electro-optic frequency comb-enabled precise distance measurement with megahertz acquisition rate

TL;DR

This paper introduces a novel electro-optic frequency comb method enabling high-speed, high-precision distance measurement suitable for autonomous vehicles and robotics, achieving megahertz acquisition rates and millimeter-level accuracy.

Contribution

The authors developed and demonstrated a new RRMFC technique with integrated lithium niobate modulators, achieving unprecedented acquisition rates and precision in LiDAR applications.

Findings

Achieved 25 MHz acquisition rate for distance measurement.

Demonstrated millimeter-level precision with a single laser.

Enabled high-speed 3D imaging for autonomous systems.

Abstract

Artificial intelligence empowered autonomous vehicles and robotics have to sense the fast-changing three-dimensional environment with high precision and speed. However, it is challenging for the state-of-the-art ambiguity-free light detection and ranging (LiDAR) techniques to achieve absolute distance measurement with simultaneous high precision and high acquisition rate. Here we demonstrate an electro-optic frequency comb-enabled precise absolute distance measurement method, repetition rate modulated frequency comb (RRMFC), with megahertz-level acquisition rate. To achieve RRMFC, we designed and fabricated an integrated lithium niobate phase modulator with a modulation length of 5 cm and a half-wave voltage of 1.52 V, leading to over 50 sidebands and a continuously tunable repetition rate. Leveraging these unique features, RRMFC can directly resolve distance in time domain, leading to an acquisition rate as high as 25 MHz and an Allan deviation down to 13.77 {\mu}m at an averaging time of 724 {\mu}s. Based on RRMFC, we achieved high-speed 3D imaging at millimeter-level precision with a single laser. RRMFC-based LiDAR allows the autonomous vehicles and robotics to sense the fine details of fast-changing environment with high precision.